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BIOSPHERE<br />
RESEARCH - NEWS - PHOTOGRAPHY - EXPEDITIONS<br />
Skewed biological views - Research in the rain - Following wild dogs - Prairie Violence<br />
BIOSPHERE - 1
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Image of the issue<br />
News in Brief<br />
Opinion:<br />
Skewing our view<br />
Saving the sea turtle<br />
with a little green light<br />
A partnership between<br />
fungi and a woodpecker<br />
4 - 5<br />
6 - 17<br />
18 - 23<br />
24 - 31<br />
32 - 39<br />
40- 45<br />
46-55<br />
56-63<br />
64- 65<br />
In the Field: Squirrels &<br />
martens of rainy Wales<br />
How do they hunt?<br />
Tracking wild dogs.<br />
Violent encounters.<br />
Prairie dogs & ground<br />
squirrels<br />
Recommended reads<br />
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2 - BIOSPHERE BIOSPHERE - 3
IMAGE OF THE ISSUE<br />
Kyle Moore<br />
Here’s one of our favourite shots from this year’s Mammal Photographer<br />
of the Year Competition from the Mammal Society. Kyle Moore was<br />
the winner in the 16-18 age category. Check out the whole bunch on<br />
their Flickr account.<br />
4 - BIOSPHERE BIOSPHERE - 5
NEW DISCOVERIES FROM<br />
ECOLOGY<br />
VEGGIE SPIDERS<br />
For the Bagheera kiplingi jumping spider, there is<br />
no web-spinning and lying in wait, nor are there<br />
acrobatic leaps to pounce on prey. This spider, rather<br />
uniquely, is vegetarian.<br />
A comprehensive review has discovered that, while B.<br />
kiplingi appears to be alone for now as a completely<br />
veggie spider, there may be more plant-nibbling<br />
arachnids on the planet than you might think. In fact,<br />
it appears that it might actually be quite common.<br />
So far, 60 species across 10 taxonomic groups have<br />
been identified as omnivorous, as happy to tuck into<br />
vegetation as they are to eat an insect.<br />
Spiders, of course, cannot eat solid food. Much like<br />
their relatives perched in a web and sucking out<br />
the juices of their victims, the veggie spiders have<br />
to somehow get around the problem of ingesting<br />
solids. This can be via digestive enzymes breaking<br />
up a leaf into manageable mush prior to eating,<br />
or simply sticking to the relatively easy option of<br />
slurping up sap or sweet nectar.<br />
Partially-vegetarian spiders have now been identified<br />
on every continent barring Antarctica, and it clearly<br />
opens up their ability to feed on other sources if<br />
traditional insect prey is scarce. While you are still<br />
more likely to see the classic spider and fly scenario,<br />
don’t be too surprised if you ever see a tiny jumping<br />
spider hopping from flower to flower, feasting on<br />
nectar, and acting as an unexpected pollinator!<br />
Martin Nyffeler, Olson, E, Symondson, W. (2016) Plant-eating by<br />
spiders. Journal of Arachnology doi: http://dx.doi.org/10.1636/<br />
P15-45.1<br />
© Maximilian Paradiz, Des Colhoun<br />
A SMELLY PROTECTION<br />
Aposematism is a well-known, widespread<br />
defence strategy. Warning signals let<br />
predators know that a toxic individual would<br />
not be a wise dinner choice. Often, the warning<br />
signal features garish, clashing colours, vivid<br />
reds or yellows. But what about warning<br />
nocturnal predators that rely more on<br />
their nose than vision to track down<br />
a meal?<br />
The parasite Heterorhabditis<br />
bacteriophora, a nematode that<br />
infects insect larvae, is known<br />
to turn its hosts red. That’s the<br />
visual warning covered, enough<br />
to deter watching birds. New<br />
research has highlighted how the<br />
nematode also avoids nocturnal<br />
hunters that rely on scent rather<br />
than visual clues, by making its host<br />
unappetisingly smelly.<br />
It is an example of not only parasite-induced<br />
aposematism, but an olfactory warning that<br />
helps to the keep the host alive long enough for<br />
its uninvited nematode guests to reproduce.<br />
Jones, R, Fenton, A, & Speed, M. (2016) Parasite-induced<br />
aposematism protects entomopathogenic nematode<br />
parasites against invertebrate enemies. Behavioural<br />
Ecology, doi: 10.1093/beheco/arv202<br />
COLONY COLLAPSE<br />
Ant colonies are often exploited by other<br />
invertebrate species. Beetles and larvae galore<br />
infiltrate or feed without repercussions, though the<br />
overall interactions are usually on a small enough<br />
scale not to damage the host nest.<br />
In the case of the parasitic moth Eublemma albifascia,<br />
the exploitation can lead the entire ant colony that<br />
hosts them to an early demise. The female moth will<br />
often lay eggs directly onto the ant nest, which are<br />
taken into the colony by worker African weaver ants<br />
(Oecophylla longinoda). Once inside, the larvae use<br />
‘cuckoo strategy’ behaviour to solicit food and receive<br />
far more attention from the captivated workers than<br />
even the queen.<br />
DRESSING DOWN<br />
Males of the avian world are famed for their<br />
flamboyant, flashy feathers and colourful<br />
displays. In contrast, females are generally more drab<br />
in appearance. A new theory has arisen on why this<br />
may be.<br />
The toned-down appearance of female<br />
birds could help their camouflage<br />
- many feature dull browns that<br />
help them disappear into the<br />
background. Or using resources<br />
on elaborate ornamentation and<br />
brighter colours may lower fertility<br />
overall. Scientists at the University<br />
of Exeter, however, have another<br />
theory: the females just want to be<br />
left alone.<br />
It certainly appears that the drab<br />
colouring could be part of the female<br />
repertoire for avoiding attention - if she were<br />
to advertise her sexual quality more openly with<br />
colours and displays, the increase in attention may<br />
lead to a decrease in her fecundity, according to the<br />
researchers. So, alongside other anti-harassment<br />
tactics, toning it down could be a valuable<br />
contribution to simply finding some much-needed<br />
peace and quiet.<br />
D.J. Hosken, S.H. Alonzo, N. Wedell. Why aren’t signals of<br />
female quality more common? Animal Behaviour, 2016; 114: 199<br />
DOI:10.1016/j.anbehav.2016.02.015<br />
Colonies have been found harbouring large numbers<br />
of these deceptive caterpillars, up to 350 in some<br />
cases. As the ants scurry and work to supply the<br />
caterpillars with the resources they need, the queen<br />
is fatally neglected. She starves, stops laying eggs, and<br />
eventually dies. With her goes the future of the colony.<br />
After this point, without her pheromone influence,<br />
only males will be produced by the remaining ants,<br />
and, as a result of the moth’s interference, what was<br />
once a thriving and industrious colony will eventually<br />
fade and fall to empty ruins.<br />
Dejean, A, Orivel, J, Azemar, F. et al. (2016) A cuckoo-like parasitic<br />
moth leads African weaver ant colonies to their ruin.<br />
Named after the<br />
legendary city of<br />
El Dorado, the frog<br />
Pristimantis dorado<br />
was found in the cloud<br />
forests of the Andes.<br />
“The Spaniards assumed<br />
Colombia’s wealth was<br />
its gold, but today we<br />
understand that the real<br />
riches of the country<br />
lie in its biodiversity,”<br />
said researcher Andrew<br />
Crawford.<br />
Alaska’s first new<br />
butterfly species<br />
in three decades.<br />
The Tanana Arctic<br />
butterfly (Oeneis<br />
tanana) of their aspen<br />
and spruce forests<br />
is well-camouflaged<br />
to its environment,<br />
and appears to be an<br />
ancient hybrid of two<br />
related species - Oeneis<br />
chryxus and Oeneis<br />
bore.<br />
NEW<br />
SPECIES<br />
LINE UP<br />
Micrixalus herrei is<br />
a dancing frog from<br />
India’s Western Ghats<br />
region. While the<br />
frog itself has been<br />
previously described, its<br />
tadpoles had never been<br />
documented. Tadpoles<br />
found burrowing<br />
through streambeds<br />
turned out to be the<br />
enigmatic young of the<br />
frog, famed for its legwaving<br />
displays.<br />
The land of the<br />
lemurs has 3 new<br />
primates to add to its<br />
repertoire. The new<br />
species are all mouse<br />
lemurs - small and<br />
nocturnal - and they<br />
can only be found in<br />
the south and east<br />
of Madagascar. Their<br />
discovery brings<br />
the total number of<br />
known mouse lemur<br />
species to twenty<br />
four.<br />
6 - BIOSPHERE BIOSPHERE - 7
NEW DISCOVERIES FROM<br />
CONSERVATION<br />
VIRTUAL REALITY FOR JAGUAR CONSERVATION<br />
Formulating plans to help conserve the wild jaguars<br />
of South America is notoriously difficult. The<br />
cats are threatened, vulnerable to habitat loss, and<br />
incredibly secretive. Not only that, but the Amazon is<br />
a tricky place to work with.<br />
A team led by the University of Queensland, however,<br />
has an idea. “Since we can’t take all the experts to<br />
the Amazon jungle, we thought instead about ways<br />
that we could take the jungle to the experts,” said<br />
the team’s Kerrie Mengerson.<br />
To help conserve jaguars and give them the greatest<br />
chance of surviving and reproducing, wildlife<br />
corridors need to be created and protected. This<br />
way, isolated populations can reach each other and<br />
mingle, preserving the jaguar’s gene flow.<br />
So how does the team plan to achieve this, and<br />
how are they going to get the Amazon back to<br />
the world’s leading experts? The answer is by using<br />
virtual reality. An expedition into the rainforests can<br />
map and create a virtual environment, including key<br />
details and a wealth of information about where<br />
jaguars are likely to move, live, and hunt. Other<br />
experts can then tap in to the VR-environment and<br />
statistical modelling will enable the team to build<br />
up a knowledge base for where and how to create<br />
the much-needed corridors.<br />
It is a novel and enterprising scheme, and could be<br />
great news for not only the jaguars of the Amazon,<br />
but also future conservation efforts around the world.<br />
GALAPAGOS MPA<br />
The Galapagos Islands are about<br />
to benefit from a new marine<br />
protected area (MPA) created by<br />
Ecuador.<br />
Around the Wolf and Darwin<br />
islands, at the northern end of<br />
the archipelago, an area of 15,000<br />
square miles will become protected,<br />
approximately the size of Belgium.<br />
This area is home to brilliant<br />
biodiversity, including 34 species of<br />
sharks that should benefit greatly<br />
from the new no-take zone, as shark<br />
fin-harvesters may be kept at bay.<br />
A number of smaller MPAs dotted<br />
around the Galapagos have also<br />
been announced, bringing the<br />
total protected waters of the iconic<br />
islands to around 30%.<br />
“These pristine waters around the<br />
Galapagos archipelago are precious<br />
not just for Ecuadorians but for the<br />
whole balance of our ocean systems,”<br />
explained Ecuador’s Environment<br />
Minister Daniel Ortega Pacheco.<br />
“Shark populations in steep decline<br />
around the world come here to<br />
rest and breed and we want to<br />
guarantee complete sanctuary for<br />
them.”<br />
ASH EXTINCTION<br />
It is the third most common tree in Britain, and its range extends<br />
across Europe, from as far north as the Arctic Circle, to Turkey in<br />
the south, but the ash tree (Fraxinus excelsior) is facing extinction<br />
The arrival of the emerald ash borer - a colourful invasive beetle<br />
- from eastern Europe is likely to decimate the widespread trees<br />
already hit by the impact of the fungal disease ash-dieback.<br />
Scientists investigating the plight of the ash believe the trees<br />
face an uphill battle when the two problems combine, and will<br />
likely be entirely wiped out. While the borer beetle itself does<br />
not harm ash trees, its burrowing larvae cause internal damage<br />
that eventually kills its host. The emerald ash borer is expected to<br />
arrive in western Europe and Britain within years.<br />
The trees are an iconic part of the landscape, common in bringing<br />
the sight of green to our towns and cities as well as swathes of<br />
woodland, and without them, the British countryside in particular<br />
will never look the same again.<br />
Thomas, P (2016. Biological Flora of the British Isles: Fraxinus excelsior, Journal<br />
of Ecology. doi: 10.1111.1365-2745.12566<br />
BIODIVERSITY BENEFITS<br />
Eradicating invasive mammals from islands brings<br />
a welcome boost to the local biodiversity. With the<br />
non-native rodents, feral cats, and goats that bring so<br />
much extra predation, competition and habitat loss<br />
gone, life can bloom and ecosystems can rebalance.<br />
And it’s worth it. The investment into removing<br />
the invasive species is a cost-effective conservation<br />
strategy, suggests the team who have undertaken<br />
the first global study to quantify the costs of this<br />
method. “Twenty one billion dollars (US) are spent<br />
globally each year on nature conservation,” said lead<br />
author Holly Jones, of the Northern Illinois University.<br />
conservation intervention is benefitting hundreds<br />
of native animals and endangered species. This is<br />
fantastic news in the race to prevent extinctions.”<br />
As a result of their findings, not to mention the invasive<br />
eradications that have already taken place on various<br />
islands, four species have been recommended to<br />
be downlisted on the IUCN’s red list. They are the<br />
island fox of California state, the Seychelles’ magpie<br />
robin, Cook’s petrel of New Zealand, and Mexico’s<br />
black-vented shearwater. Just four species among<br />
many that could benefit from what appears to be a<br />
powerful tool for cost-effective conservation.<br />
© Robert Pitman, U.S. Department of Agriculture, USFWS<br />
SEAWORLD CEASE BREEDING ORCAS<br />
SeaWorld have announced that they will cease all orca breeding<br />
programmes at their centres.<br />
The marine theme park chain has also stated that they will no longer<br />
keep any killer whales in captivity after the current generation dies.<br />
A total of 23 orcas remain at SeaWorld parks, including the infamous<br />
Tilikum, the adult male that featured in the seminal documentary,<br />
Blackfish.<br />
It is a huge breakthrough for groups who have been campaigning<br />
against SeaWorld due to the treatment and living conditions of the<br />
intelligent and highly social marine mammal. The marine parks<br />
appear to be well on the way to trying to counter the damage that has<br />
been done to their reputation and image (not to mention the captive<br />
orcas themselves), pledging to donate $50million to marine mammal<br />
rescue and rehabilitation causes over the next five years.<br />
“We’ve helped make orcas among the most beloved marine mammals<br />
on the planet,” stated the President of SeaWorld Entertainment. “As<br />
society’s understanding of orcas continues to change, SeaWorld’s is<br />
changing with it.”<br />
Jones, H, Holmes, N, Butchart, S. et al. (2016) Invasive mammal<br />
“A small fraction of this goes to eradication of invasive<br />
The next step will be to encourage other marine and sea-life parks<br />
eradication on islands results in substantial conservation gains.<br />
species, yet this relatively simple, cost-effective<br />
across the world to also adopt the same approach.<br />
PNAS, doi: 10.1073/pnas.1521179113<br />
8 - BIOSPHERE BIOSPHERE - 9
NEW DISCOVERIES FROM<br />
CLIMATE CHANGE<br />
MASS BLEACHING<br />
An enormous aerial survey of the Great Barrier<br />
Reef (GBR) is under way, and the reports so far<br />
are pretty bleak. Almost 93% of reefs on Australia’s<br />
iconic site have been hit by bleaching, and it is<br />
thought to be the worst mass bleaching event the<br />
world has witnessed.<br />
Coral bleaching occurs as waters warm beyond<br />
their usual high summer temperatures. The algal<br />
symbionts that give coral its colour are lost, and it<br />
quickly turns bone-white. Coral can recover from<br />
bleaching events, but if left exposed, without its<br />
algae for long periods, and under the continued<br />
stress from high water temperatures, the reef will<br />
eventually die.<br />
SNOWSHOES FORCED OUT<br />
The snowshoe hare of North America could be<br />
forced out of its native range by climate change.<br />
It is a species that is perfectly adapted for life in the<br />
snow: the snowshoe hare is so called because of its<br />
delightfully over-sized feet, which allow it to move<br />
over deep snow with relative ease, while predators<br />
sink and flounder in their pursuit. Its coat, too, is<br />
key - it changes from brown to white in winter,<br />
matching its background blanket of snow.<br />
A warming climate changes things, however.<br />
Researchers from the University of Wisconsin-<br />
Madison have discovered that the southern<br />
boundaries of the snowshoe hare are shifting north.<br />
No snow means no hares. The animals aren’t likely<br />
to stick around if their historic range warms to the<br />
point where snowfall is minimal or non-existent,<br />
and those that do remain will be especially<br />
vulnerable and quickly picked off, for predators<br />
they will be an irresistible shining white beacon in<br />
the drab landscape.<br />
As is always the case if one species disappears from<br />
an area, the ecological consequences of the range<br />
shift will also likely be significant. Snowshoe hares<br />
are an important food source for many mammals<br />
and raptors of the northern wilds, and their range<br />
shift will undoubtedly have knock-on effects.<br />
Sultaire, S, Pauli, J, Martin, K. et al. (2016) Climate change<br />
surpasses land-use change in the contracting range boundary<br />
of a winter-adapted animal. Proceedings of the Royal Society<br />
B. DOI: 10.1098/rspb.2015.3104<br />
© Denali National Park and Preserve, FarbenfroheWunderwelt<br />
Of over 900 individual reefs that form the GBR so<br />
far surveyed, only 68 have been reported to have<br />
escaped any instances of coral bleaching. These<br />
southern reefs benefitted from cooler, cloudy<br />
weather during the late Australian summer, and so<br />
appear to have dodged the worst.<br />
While the researchers quickly survey from the air,<br />
diving teams are moving in to examine each reef<br />
up close and confirm the spotters’ reports. Perhaps<br />
the divers will be able to share news that is a little<br />
more hopeful!<br />
BLOWING BUBBLES<br />
There may yet be a way to protect struggling reefs,<br />
however. By forever blowing bubbles, a new<br />
technique is thought to help reefs resist the effects<br />
of ocean acidification.<br />
Scientists from Stanford have suggested that<br />
bubbling air through seawater for just a few hours<br />
can enhance the transfer rate of CO2 between air and<br />
ocean. The process is estimated to be 30 times faster<br />
than the natural transfer rate, and results in a large<br />
reduction of CO2 present in a marine environment.<br />
The ‘bubble stripping’ looks to be a potentially<br />
affordable and useful method for lowering acidity<br />
in coastal ecosystems and coral reefs. In particular,<br />
in tropical areas, the bubbling could be run by solar<br />
power, further boosting the cost-effectiveness.<br />
“If you operate your bubbler in an area that is<br />
upstream of a large section of coral, you could<br />
reduce CO2 levels for an entire reef,” concluded<br />
Robert Dunbar, of Stanford University.<br />
A long term solution? Time will tell, but the research<br />
and implementation of bubblers is definitely<br />
something to keep an eye on, and is a cause for<br />
optimism.<br />
David A. Koweek, David A. Mucciarone, Robert B. Dunbar. Bubble<br />
Stripping as a Tool To Reduce High Dissolved CO2in Coastal<br />
Marine Ecosystems. Environmental Science & Technology, 2016;<br />
DOI:10.1021/acs.est.5b04733<br />
BIRDWATCH RESULTS ARE IN<br />
mild winter in the UK has seen boosts to the<br />
A numbers of small birds in British gardens.<br />
The RSPB’s Big Garden Birdwatch is a brilliant bit<br />
of citizen science, tapping in to a valuable resource,<br />
and inspiring families to engage with the life in their<br />
gardens and local green spaces. Every year it sees<br />
members of the public - citizen scientists - spending<br />
an hour recording bird species and numbers on<br />
their local patch, and, once the data is analysed, it<br />
allows an insight into the health of the UK’s bird<br />
populations.<br />
In its 37th year, the recent results have shown that<br />
milder temperatures throughout the winter appear<br />
to have benefitted small birds like the long-tailed tit<br />
(Aegithalos caudatus) and coal tit (Periparus ater),<br />
with their numbers up 44% and 25% respectively<br />
since last year’s survey. The increased numbers<br />
demonstrate how warmer winters will see more<br />
small birds survive through to the spring. In addition,<br />
a consistent rise in numbers of long tailed and coal<br />
tits seen in gardens during the Watch over recent<br />
years suggests they are two species that are adapting<br />
to garden life. Rather than remaining on the fringes<br />
or hidden away in the wild, they are starting to make<br />
the most of the food readily available on bird-tables<br />
and feeders.<br />
The boost has seen the long tailed tit return to the<br />
top 10 most commonly seen species for the first<br />
time in almost a decade. For more details on how<br />
other British birds fared, check out the Big Garden<br />
Birdwatch results.<br />
https://ww2.rspb.org.uk/discoverandenjoynature/<br />
discoverandlearn/birdwatch/<br />
10 - BIOSPHERE BIOSPHERE - 11
NEW DISCOVERIES FROM<br />
BEHAVIOUR<br />
BLUFFING CRABS<br />
Like poker players, some fiddler crabs bluff when<br />
they have a weak hand, or in this case, claw.<br />
The crabs are famed for their huge claws on one side<br />
and dramatic waving as they show them off. To other<br />
males, it is a display of strength, a suggestion of who<br />
should not be messed with. To females looking on,<br />
the claw-waving goes hand-in-hand with the male’s<br />
burrow location in helping them to determine the<br />
quality of a mate.<br />
Claws, however, can fall off. Or, more likely given the<br />
pugnacious nature of many crabs, can be violently<br />
ripped off. And this is the start of a problem for male<br />
crabs. Yes, they can brilliantly grow the missing limb<br />
back, but it is weaker than its previous incarnation.<br />
Claw-waving stand-offs that escalate to combat<br />
could expose the weakness of the re-grown claw and<br />
leave the male crab in trouble. It could lose territory<br />
and potential mates, along with another long period<br />
of recuperation as the lost limb slowly returns.<br />
So, as discovered by researchers in Japan, these<br />
A HEADBUTT ALARM<br />
Honey bees have been found to use a sophisticated<br />
alarm system to warn each other of danger: they<br />
headbutt each other.<br />
It is actually more complex than that, of course, but<br />
essentially that’s how the Asian honey bee (Apis<br />
cerana) conveys urgent messages to its peers. The<br />
headbutts are in the form of short vibration pulses,<br />
and the length and frequency of the vibrations<br />
appear to correspond to different threats. A large<br />
predator such as a giant hornet nearby means high<br />
frequency butting, while a longer bout of vibrations<br />
appears to instead suggest an imminent threat to<br />
individuals turn to deception. If they have been forced<br />
to regenerate a limb in their lifetime, they bluff. Firstly,<br />
re-grown claws were often larger than original claws,<br />
suggesting a dishonest physical signal. Secondly, the<br />
behavioural bluff: the dishonest crabs start contests<br />
with a large amount of aggression, hoping the<br />
opponent will retreat, but, if an actual brawl looks<br />
imminent, avoidance becomes the better option,<br />
and they quickly back down. A fantastic example of<br />
dishonesty and deception in the natural world.<br />
“The findings are in line with current theories that<br />
predict that animal signals are generally honest, but<br />
each signalling system allows for deception,” said<br />
author Tsunenori Koga.<br />
Daisuke Muramatsu, Tsunenori Koga. (2016) Fighting with an<br />
unreliable weapon: opponent choice and risk avoidance in<br />
fiddler crab contests. Behavioral Ecology and Sociobiology,; DOI:<br />
10.1007/s00265-016-2094-2<br />
the hive. It is an endearing image: if a bee needs to<br />
stop one of its peers heading into an area it has just<br />
left and knows is dangerous, it will quickly perform<br />
its alarm-boop as a warning.<br />
Social mammals are well known to have an array<br />
of alarms, but the researchers involved believe<br />
they have identified the first sophisticated alarmsignalling<br />
system in a social insect.<br />
Tan, K, Dong, S, Li, X. et al. (2016) Honey bee inhibitory signaling<br />
is tuned to threat severity and can act as colony alarm signal.<br />
PLOS Biology, http://dx.doi.org/10.1371/journal.pbio.1002423<br />
© http://www.nps.gov,<br />
PRICKLY PANIC<br />
Porcupines are not to be trifled with. A<br />
fearsome array of spines that have frustrated<br />
many predators’ efforts to claim a meal. Yet, it<br />
appears that the porcupine feels that its spines<br />
simply aren’t enough to make it feel safe.<br />
A new study from the University of Wisconsin<br />
has discovered that even when incredibly<br />
hungry, and with their brilliant defence in<br />
place, the North American porcupine’s<br />
(Erethizon dorsatum) behaviour is<br />
still heavily influenced by their<br />
predators.<br />
In the depths of winter,<br />
porcupines tend to rely more<br />
on their own stores of fat due<br />
to the scarcity of food. At this<br />
point, we’d perhaps expect<br />
porcupines to be taking more<br />
risks to find a meal, prioritising<br />
long-range foraging over<br />
predator avoidance. Instead,<br />
that inherent fear of predators<br />
seems to play a part in the winter<br />
movements of porcupines, and they<br />
opt against foraging further afield.<br />
Despite their deadly defences, and despite the<br />
hunger gnawing at them, porcupines still show<br />
great awareness of their vulnerability, and their<br />
movements and behaviour are driven more<br />
than anything by the risk of predation..<br />
Pokallus, J & Pauli, J. (2016) Predation shapes the<br />
movement of a well-defended species, the North<br />
American porcupine, even when nutritionally stressed.<br />
Behavioural Ecology, doi: 10.1093/beheco/arv176<br />
MAMA’S BOYS<br />
Male mammals can usually be placed in one of two<br />
categories: those that stay at home, remaining<br />
part of the group they were born in, or those that<br />
embark on their own adventures, looking to establish<br />
themselves and breed elsewhere. Traditionally, the<br />
stay-at-home mammals have been thought of as the<br />
lesser males, failing to form or join groups or father<br />
their own offspring. But insights into the males in<br />
hyena societies have begun to suggest otherwise.<br />
Hyenas form matriarchies - the<br />
females dominate and hold<br />
all the influence in the highly<br />
social groups. Male spotted<br />
hyenas (Crocuta crocuta) that<br />
remain close to their mum<br />
appear to benefit from this<br />
dominance, going against<br />
the trend that would suggest<br />
they will be second-class, and<br />
have little to no reproductive<br />
success. They have instead<br />
BUM-DRUMMING<br />
new form of caterpillar communication has been<br />
A uncovered, and it’s novel to say the least. Masked<br />
birch caterpillars (Drepana arcuata) reach out to new<br />
friends by drumming... with their bum.<br />
The species forms groups, working together to build<br />
large silken shelters where they can all safely develop.<br />
But to make new friends for this enterprise, the<br />
caterpillars must first find each other, and at<br />
just 1mm in length, it isn’t an easy task.<br />
This is where the so-called ‘analdrumming’<br />
communication comes<br />
to the fore. Some caterpillars<br />
will start to build, interspersing<br />
their activities with a bit of<br />
drumming, and any other<br />
nearby D. arcuata will soon be<br />
picking up good vibrations and<br />
arriving to help.<br />
Previously, researchers had<br />
identified that the caterpillars<br />
could rub hairs on their rear ends<br />
against leaves in order to generate<br />
vibrations. The vibrations were of<br />
course thought to be some form of<br />
signalling. Now, the latest research from<br />
Carleton University (as yet unpublished) appears to<br />
have confirmed the call-to-action use of this innovative<br />
addition to their repertoire.<br />
The study provides the first evidence that the tiny<br />
caterpillars use a combination of drumming and<br />
scraping with their bottoms to create the vibrations<br />
necessary to not only communicate, but to form social<br />
bonds and build a team.<br />
https://soundcloud.com/cdellamore/caterpillar-anal-drumming<br />
been found to be as successful in breeding as the<br />
males that venture off to meet other groups.<br />
“Mothers provide social support to their stay-home<br />
sons and ensure they acquire a high social rank<br />
among breeding males,” explains Eve Davidian of the<br />
Leibniz Institute for Zoo and Wildlife Research. “This<br />
gives the mama’s boys privileged access to both food<br />
and females, allowing them to invest a lot of time<br />
consorting females.”<br />
The finding is the first time<br />
that, in group-living mammals,<br />
males that stay back rather<br />
than dispersing can be just as<br />
successful as those that leave<br />
home to make their own way.<br />
Davidian, E, Courtiol, A, Wachter, B. et<br />
al. (2016) Why do some males choose<br />
to breed at home when most other<br />
males disperse? Science Advances, 2 (3):<br />
e1501236 DOI:10.1126/sciadv.1501236<br />
12 - BIOSPHERE BIOSPHERE - 13
NEW DISCOVERIES FROM<br />
EVOLUTION<br />
THE CASE OF A COMB JELLY’S POO<br />
It might not be the question on everyone’s lips, but<br />
“How do comb jellies poo?” is certainly one that<br />
has intrigued some evolutionary scientists and left<br />
others rather excited when the answer was revealed.<br />
Why is it so important? Well, the first animals all<br />
lacked an anus. They fed and excreted through the<br />
same hole. Even their modern-day descendants still<br />
do - anemones, sponges, and jellyfish. The evolution<br />
of a second hole brought huge benefits, as animals<br />
could then continue to feed even as they were<br />
digesting meals and ridding themselves of waste.<br />
Comb jellies (ctenophores) are an animal whose<br />
lineage evolved before other animals developed<br />
guts and anuses. They too were thought to feed and<br />
excrete through the same opening. So it came as a<br />
great surprise when a video by William Browne of<br />
the University of Miami showed the jellies expelling<br />
waste from a sphincter-like hole at their rear.<br />
The implications are that comb jellies seem to have<br />
independently developed guts and pores that act in<br />
FISH WALKS LIKE FROG<br />
Deep in a collection of caves on the border of<br />
Thailand and Myanamar lives a rather special<br />
fish. It is small and eyeless, common features of<br />
cave-dwelling animals at home in the dark. It also<br />
has two pairs of fins that, from above, resemble<br />
beautiful wings. But most significantly, this fish<br />
climbs waterfalls and walks like an amphibian.<br />
Fish dragging themselves onto land isn’t that<br />
unusual. It is an iconic image of evolution. However,<br />
they normally shift their weight by hopping with<br />
their pectoral fins or wiggling their way forward.<br />
The discovery of how Cryptotora thamicola walks<br />
changes things - it takes ‘steps’ in the same way<br />
some land vertebrates do. The fish moves one front<br />
fin in time with the rear fin on the opposite side,<br />
then alternates. This creates the same waggling<br />
walk as seen in amphibians such as salamanders.<br />
How does it achieve this? By filming and modelling the fantastic fish, scientists were able to determine that<br />
its pelvis and vertebral column are fused, allowing power to be shifted from its limb-like fins to its core.<br />
The discovery is a wonderful example of convergent evolution, as a fish, deep in caves and long-since<br />
separated from any lines that led to walking, independently evolved a way to waddle.<br />
Brooke E. Flammang, Apinun Suvarnaraksha, Julie Markiewicz, Daphne Soares. Tetrapod-like pelvic girdle in a walking cavefish.<br />
Scientific Reports, 2016; 6: 23711 DOI: 10.1038/srep23711<br />
the same way as an anus. Or, perhaps a common,<br />
ancient ancestor once evolved the necessary parts<br />
that were somehow then lost by anemones and<br />
sponges, as it might make sense for them to use the<br />
same opening if your rear is rooted to a rock! Either<br />
way, with the knowledge of how comb jellies poo,<br />
the standard view of evolution has been shaken.<br />
© Marsh Youngbluth, aphne Soares, Junglecat,<br />
PREGNANT T-REX<br />
Remains found in Montana, USA, have turned<br />
out to be those of a pregnant Tyrannosaurus<br />
rex, a discovery that has allowed a glimpse into the<br />
evolution of egg-laying from dinosaurs to modern<br />
birds.<br />
Scientists were able to identify that the T. rex was<br />
pregnant at the time of its death due to the presence<br />
of medullary bone - special tissue that is only formed<br />
in female birds just before and during the process of<br />
egg-laying. With this, birds do not need to weaken<br />
themselves by using calcium from their own bones<br />
to create egg-shell.<br />
The researchers involved, from North Carolina State<br />
University, suggest that the finding highlights how<br />
birds inherited egg-laying from their dinosaur<br />
ancestors. However, due to its fleeting appearance<br />
A PLASTIC PICNIC<br />
Plastic is everywhere. The amount produced,<br />
used, and then discarded is staggering. And it is<br />
estimated that only 10% actually gets recycled - the<br />
rest makes its way into landfills or as environmental<br />
litter. Being plastic, it doesn’t go away.<br />
Researchers have stumbled upon something<br />
with the potential to change things: a<br />
strain of bacteria that has evolved to<br />
digest plastic. Its discovery could be a<br />
breakthrough.<br />
The bacterium, Ideonella<br />
sakaiensis, can consume<br />
the most common type of<br />
plastic, polyethylene. It uses<br />
two enzymes to break the<br />
material down, and convert<br />
it to a compound that allows<br />
the bacteria to grow. But the<br />
process is a very time-consuming<br />
six weeks, and the bacteria isn’t<br />
likely to be a wondrous solution to the<br />
plastic problem. So far, studies have been<br />
conducted in laboratory conditions, and while<br />
the bacteria does degrade plastic, implementing it<br />
into the environment could prove difficult.<br />
However, there is room for optimism in the<br />
knowledge that microbes appear to be adapting<br />
and evolving to what we’re leaving throughout the<br />
environment.<br />
Yoshida, S, Hiraga, K, Takehana, T. et al. (2016) A bacterium<br />
that degrades and assimilates poly(ethylene terephthalate).<br />
Science, DOI: 10.1126/science.aad6359<br />
before egg-laying, the chances of finding more<br />
medullary bone in other fossils are incredibly slim,<br />
so further research that investigates the blurred lines<br />
between birds and dinosaurs could be a while in<br />
coming.<br />
Mary Higby Schweitzer, Wenxia Zheng, Lindsay Zanno, et al.<br />
(2016). Chemistry supports the identification of gender-specific<br />
reproductive tissue in Tyrannosaurus rex. Scientific Reports,<br />
2016; 6: 23099 DOI: 10.1038/srep23099<br />
ALL ANTS ON DECK<br />
When facing a flood, ant colonies respond<br />
brilliantly. They form up to rapidly create a raft,<br />
using their own bodies to support each other and<br />
the colony’s undeveloped eggs and larvae. A new<br />
study has now discovered that ants remember and<br />
take up the same positions as occupied on previous<br />
rafts.<br />
It is a wonderful display of<br />
teamwork, and one that<br />
Formica selysi ants of Europe’s<br />
floodplains appear to have<br />
fine-tuned. Ant workers that<br />
survive one flood become<br />
veterans, and seem to<br />
specialise in a position on<br />
the raft. They remember<br />
where they were on<br />
previous assemblages, and<br />
take up that position again<br />
as the ants once more link up<br />
to raft themselves to safety.<br />
“They are just plain cool,” said author<br />
Jessica Purcell. “Although people have<br />
observed self-assemblages in the past, it’s<br />
exciting to make new strides in understanding how<br />
individuals coordinate to build these structures.”<br />
The finding is thought to be the first time such<br />
memory has been demonstrated in ants during their<br />
impressive rafting survival strategy.<br />
Avril, A, Purcell, J, Chapuisat, M. (2016) Ant workers exhibit<br />
specialisation and memory during raft formation. The Science<br />
of Nature, 10.1007/s00114-016-1360-5<br />
14 - BIOSPHERE BIOSPHERE - 15
NEW DISCOVERIES FROM<br />
PHYSIOLOGY<br />
BINTURONG’S POPCORN AROMA UNRAVELLED<br />
The smell of warm popcorn can get most stomachsa-rumbling,<br />
but the source of the aroma in this<br />
particular case might not be quite so appetising:<br />
the binturong (Arctictis binturong).<br />
For a while, we didn’t know why<br />
the binturong smelled so sweet,<br />
but now we do. You might be<br />
surprised to find out that<br />
this mouth-watering smell<br />
comes, rather offputtingly,<br />
from the binturong’s urine.<br />
The researchers interested<br />
in these curious creatures<br />
spent time collecting<br />
samples of their urine,<br />
and analysed what they<br />
were made up of. The one<br />
compound that existed<br />
in every sample was called<br />
‘2AP’, and it’s the same one<br />
that is created when you heat<br />
corn, contributing to the aromas<br />
that get you salivating at the cinema<br />
desk.<br />
Unable to find the compound in the binturong’s own<br />
food, the researchers think that 2AP could be created<br />
by bacteria in the gut. Bacteria are responsible for<br />
breaking down sweat in our armpits in a similar sort<br />
FUNNY FEEDING<br />
Hydra are tiny freshwater predators, famed for<br />
their regenerative abilities and lack of aging.<br />
They anchor themselves to a surface, and stun and<br />
kill prey with stinging tentacles, but when it comes<br />
to actually eating their victims, things get especially<br />
interesting.<br />
Lacking a mouth would prove to be quite an obstacle<br />
for most. Not for hydra. Scientists have, for the first<br />
time, been able to record the<br />
bizarre process by which hydra<br />
feed. Once prey has been<br />
caught and paralyzed, the hydra<br />
contract their tentacles. As they<br />
do so the movement essentially<br />
rips open its skin to create a<br />
gaping maw into which the<br />
victim is vacuumed. The cells<br />
involved do not actually move<br />
of smelly process.<br />
Binturong are solitary creatures, so in order<br />
to communicate they leave messages<br />
in their environment for others. By<br />
soaking their feet and tail in urine,<br />
the binturong then spreads<br />
wee messages between<br />
the trees and bushes as it<br />
moves around, ready to be<br />
sniffed by the next passing<br />
binturong.<br />
The researchers believe<br />
that 2AP and other<br />
identified compounds<br />
contribute towards signals<br />
that tell other binturongs<br />
that they are around, and<br />
perhaps that they are ready<br />
to mate.<br />
Mystery solved. hopefully this<br />
story of urine, bacteria and a little<br />
bit of sweat won’t linger too long when<br />
you’re next munching on a hot bucket of buttered<br />
popcorn.<br />
Megu Gunji, Hideki Endo (2016) Functional cervicothoracic<br />
boundary modified by anatomical shifts in the neck of giraffe.<br />
Royal Society Open Science: doi:10.1098/rsos.150604.<br />
apart to create an opening, instead they actually<br />
change shape, stretching in a similar manner to how<br />
our pupils dilate. In some cases, the newly-created<br />
mouth somehow becomes larger even than the<br />
body of the hydra itself.<br />
“Evolutionarily, why do these animals have this weird<br />
mechanism for feeding? We don’t really have an<br />
answer for that yet,” says author Eva-Maria Collins of<br />
the University of California.<br />
Bizarre and mysterious,<br />
research into the strange<br />
characteristics of hydra<br />
continues.<br />
Carter, J, Hyland, C, Steele, R,<br />
& Collins, E-A. (2016) Dynamics<br />
of mouth opening in Hydra.<br />
Biophysical Journal. DOI: http://<br />
dx.doi.org/10.1016/j.bpj.2016.01.008<br />
© jinterwas , Dominic Sherony, Przemysław Malkowski,<br />
FOR FLIRTING, NOT FLYING<br />
Alongside showy hopping dance moves and enticing songs,<br />
some birds have other ways of flirting, and new research has<br />
highlighted how, in some birds, wing muscles may develop for<br />
reasons other than flying.<br />
Scientists at Wake Forest University studied a number of South<br />
American birds, comparing wing muscles in species that clap their<br />
wings as part of their displays with birds that use more traditional<br />
wooing methods. “Of the species studied, only the golden-collared<br />
and red-capped manakins produce exceptionally rapid wing<br />
movements as part of their acrobatic courtship displays,” explained<br />
author Matthew Fuxjager. Red-capped and golden-collared<br />
manakins are renowned for this fast wing-clapping behaviour, and<br />
the sound it generates is part of their attention-seeking repertoire.<br />
While muscle contraction frequency needed for a manakin to fly<br />
is approximately 25Hz, the wing muscles of the red-capped and<br />
golden-collared manakins are capable of contracting at closer to<br />
100Hz, which is rapid, to say the least. The finding suggests that<br />
the speedy capabilities of the wing muscles involved - the major<br />
humeral retractor - have evolved not for flight, but to impress<br />
females.<br />
Fuxjager, M, Goller, F, Dirkse, A. et al. (2016) Select forelimb muscles have evolved<br />
superfast contractile speed to support acrobatic social displays. eLife, DOI:<br />
10.7554/eLife.13544<br />
TRAP-JAW SPIDER<br />
The jaws of the trap-jaw spiders may be tiny, but<br />
they are incredibly fast, and snap shut in a manner<br />
similar to bear-traps.<br />
Spiders of the Mecysmaucheniidae family of New<br />
Zealand really are very small, often only growing as<br />
large as 2mm in length, so studying the mechanics<br />
of their speedy bite is not a simple task. But by<br />
using a combination of high-speed cameras and<br />
DNA analysis, scientists from Smithsonian Institute<br />
have managed just that. They report that the force<br />
at which the jaws snap shut is likely too strong for<br />
muscle-power alone. Instead, it is suspected that<br />
some form of stored energy is involved, such as is<br />
seen in a recurve bow, for example. When released,<br />
it allows the lightning fast movements that clamp<br />
EXPLOSIVE ESCAPE<br />
Moths have a number of ways of<br />
escaping the clutches of hungry<br />
bats. Some use distracting tails,<br />
while some fight back with sonarjamming<br />
noises, disrupting a bat’s<br />
ability to target them. For most,<br />
though, once caught, it is over.<br />
But not for a remarkable, newlydiscovered<br />
species of tiger moth.<br />
The moth, of the Arctiinae family,<br />
has a unique, and somewhat<br />
explosive, defence. When attacked,<br />
grabbed, or otherwise threatened,<br />
it produces an eruption of a sticky,<br />
silk-like substance from all over its<br />
body. Understandably, predators<br />
are likely to be a bit put off by this<br />
unexpected turn of events, and<br />
quickly drop the moth.<br />
The substance is so far unstudied,<br />
and the moth not yet officially<br />
described, but scientists are on<br />
the case to learn more about this<br />
remarkable defence. Theories<br />
include it being used as more of<br />
a distraction - think of a smokebomb<br />
allowing escape - or as a<br />
noxious, toxic substance that a bat<br />
will immediately spit out. Either<br />
way, the silk-like explosion is a novel<br />
and intriguing survival strategy.<br />
down on prey. It is the first time these physical<br />
characteristics have been found in an arachnid.<br />
Due to their size, and the difficulties observing them<br />
hunting in the wild, no-one is entirely sure what the<br />
spiders are actually clamping those fearsome jaws<br />
shut on - the current theory is that the spiders’ prey<br />
of choice is the springtail, tiny invertebrates of the<br />
Colembolla family.<br />
“This research shows how little we know about spiders<br />
and how much there is still to discover,” concluded<br />
Hannah Wood, of the Smithsonian National Museum.<br />
Wood, H, Parkinson, D, Griswold, C. et al. (2016) Repeated<br />
evolution of power-amplified predatory strikes in trap-jaw<br />
spiders. Current Biology, dx.doi.org/10.1016/j.cub.2016.02.029<br />
16 - BIOSPHERE BIOSPHERE - 17
OPINION<br />
OPINION<br />
© Moni Sertel, Jean-Jacques Boujot<br />
SKEWING<br />
our perception<br />
What would you like to study<br />
next year? The Bengal tiger, or<br />
the African water rat? It is an<br />
important question, for rarely,<br />
it seems, is there an impetus<br />
to study species that are<br />
highly successful, numerous or<br />
considered “ordinary”. This continued momentum<br />
towards the weird, wonderful and endangered can<br />
frequently be driven by the fact that endangered and<br />
exotic species attract funding, high journal impact<br />
and equally importantly, publicity. “Ordinary”, “less<br />
cute” species do not.<br />
From the perspective of species conservation and<br />
biodiversity, there has been much discussion about<br />
the prevalence of prioritising large, highly-visible and<br />
aesthetically pleasing species over smaller, more<br />
everyday animals. Habitat conservation typically<br />
does benefit all species that live within a preserved<br />
area, and so flagship animals, which are often used to<br />
front campaigns and high-profile research projects,<br />
do help support other species by attracting public<br />
support – and money – to the cause. But scientists<br />
must be careful not to overlook our planet’s other,<br />
less “glamorous” creatures. They are vital to our<br />
understanding of biology.<br />
With finite time, money and resources, preference<br />
currently is given to those species in critical danger<br />
of persecution or immediate need of protection:<br />
pandas, tigers, rhinos. But the impact of this on our<br />
knowledge of animal biology – their physiology,<br />
energetics, ecology and behaviour – is not yet fully<br />
understood. A scientific study on the physiology<br />
of the African elephant (Loxodonta Africana), for<br />
example, is unlikely to inform greatly on that of the<br />
African water rat (Dasymys incomtus) despite the<br />
fact that they frequently share the same habitat.<br />
Steve Portgual<br />
argues that a bias<br />
towards the weird<br />
and wonderful could<br />
skew our perception<br />
of animal biology.<br />
18 - BIOSPHERE BIOSPHERE - 19
OPINION<br />
OPINION<br />
We know much about<br />
long distance athletes like<br />
godwits (left) but what<br />
about the more ‘boring<br />
‘species like the dunnock<br />
(right)?<br />
Indeed, there is a chance that our focus on these exotic<br />
and endangered species is biasing our knowledge of<br />
animal biology. A recent review revealed that 42% of<br />
studies published in the selected journals focused<br />
on species listed as threatened. Conversely, only 4%<br />
involved research into those categorised as nonthreatened.<br />
more common and “successful” species are seemingly<br />
able to adapt and change to these pressures, and the<br />
mechanisms, characteristics and traits that enable<br />
them to do so.<br />
Where should we be looking?<br />
Phenotypic plasticity, the ability of an organism to<br />
change its observable traits in response to changes<br />
in the environment, has received much deserved<br />
attention in recent years, particularly in birds.<br />
cope better with climate and habitat change. Early<br />
studies on phenotypic plasticity have, as perhaps a<br />
logical starting point, focused on nature’s extremists<br />
and athletes, in line with the fascination for studying<br />
exotic and endangered species.<br />
Examples include long distance migratory shore<br />
birds, such as godwits, groups of which can migrate<br />
up to 11,000km over the open ocean without<br />
stopping. That these species are able to undertake<br />
such extensive and impressive migrations suggests<br />
a natural predisposition for plasticity of the body’s<br />
organs throughout the annual cycle, enabling them<br />
to cope with such energetically challenging and<br />
demanding events. Indeed, these species show<br />
much propensity for change in their digestive organs,<br />
muscles and fat stores.<br />
Other species have shown very rapid changes in their<br />
migratory habits and routes. Classic examples, which<br />
have attracted considerable attention, are blackcaps<br />
(Sylvia atricapilla) and chiffchaffs (Phylloscopus<br />
collybita) – both passerine birds which have, over the<br />
last 50 years, gradually begun moving from central<br />
Europe to overwinter in the UK, halting their migration<br />
post-breeding to sub-Saharan Africa, some 7,000km<br />
away. Why these unusual species would show this<br />
trait while other similarly-sized, closely-related birds<br />
with similar diets don’t is not fully understood. More<br />
work is needed on less “extraordinary” birds.<br />
Currently, the extent of this flexibility and what<br />
initiates such changes is unclear. Of course plasticity<br />
can only go so far in response to change. For<br />
example, metabolic rate cannot increase or decrease<br />
indefinitely, and at some juncture, anatomical factors<br />
will impose a limit on what degree of change is<br />
possible. This plasticity, however, has not been tested<br />
extensively in what one might consider a more<br />
“typical” or “ordinary” species, and particularly not in<br />
This means that we tend to study those animals<br />
that are struggling to adapt and modify under the<br />
pressures of human activity worldwide. And as a<br />
consequence, we spend less time discovering how It has been suggested that these species may well<br />
20 - BIOSPHERE BIOSPHERE - 21<br />
© Mdk572, Jacob Spinks
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their natural environment.<br />
Looking ahead<br />
It is possible that these “normal” species are capable<br />
of demonstrating equally admirable plasticity in<br />
their characteristics, but the environmental scenario<br />
which requires its exhibition has not yet arisen.<br />
Share your research<br />
experiences with<br />
BIOSPHERE<br />
© daddyboskeazy,<br />
Evolutionary ecologist Massimo Pigliucci has<br />
suggested a potential reason why there are few<br />
studies on this: “This field often relies on studies<br />
that are low-tech and tedious to carry out, and yet<br />
demanding high personnel costs and long periods<br />
of time, a combination that is sometimes difficult<br />
to justify to funding agencies when compared<br />
with more ‘high-tech’ science.” Understanding the<br />
potential and capacity for change in particular<br />
species is vital for predicting the responses of<br />
different species to anticipated changes in the<br />
climate and general landscape.<br />
A firm basis for understanding the capacity of a<br />
species to change can only come from a sound<br />
platform of good general knowledge of animal<br />
biology, in particular from those species which are<br />
numerous, prosperous, and operate successfully<br />
within a changing environment. Of course,<br />
important and vital research must continue into<br />
endangered species, but a longer and larger-scale<br />
outlook is critical if we are to recognise fully the<br />
extent of change that may take place in response to<br />
shifts in the climate. “Ordinary” should no longer be a<br />
dirty word when it comes to what is recognised and<br />
endorsed by funders and researchers.<br />
Steve Portgual is a Lecturer in Animal Biology<br />
and Physiology at Royal Holloway University,<br />
London.<br />
From The Conversation. Read here: http://<br />
theconversation.com/how-a-bias-towards-theweird-and-wonderful-skews-our-perception-ofanimal-biology-53701<br />
INSPIRE THE NEXT<br />
GENERATION OF<br />
SCIENTISTS<br />
info@biospheremagazine.co.uk<br />
22 - BIOSPHERE BIOSPHERE - 23
BEHAVIOUR<br />
Lighting<br />
When the needs of<br />
people and turtles<br />
collide, how can we<br />
reduce the conflict?<br />
Tanja Suarez Yana has<br />
been testing a new<br />
technology, with great<br />
success.<br />
the<br />
way<br />
O<br />
n my very first fishing trip, I was laden with all of the equipment<br />
for our research. Thermometers, a secchi disc, GPS units, watches,<br />
notebooks, tape measures and of course, the green LED lights<br />
were packed into countless bags and boxes. There is no port for<br />
the boats to dock in Sechura Bay, north-western Peru, no jetty<br />
for us to easily hop aboard. Instead, rafts made of only four or<br />
five tree trunks would facilitate our arrival to the vessel. You have<br />
to wait for the tide before jumping on to the raft and reaching the fishing boat.<br />
As you can imagine, it is essential that you have great balance, especially with<br />
such cumbersome equipment. That first time, great balance was not something I<br />
exhibited when a wave covered me to the top of my head, soaking not just me, but<br />
all of the equipment! The fishermen laughed with me – I hope not at me – each of<br />
the three times that I fell. I had not brought a change of clothes and it was a cold,<br />
windy morning.<br />
I was soaking wet and cold aboard this boat in the hopes of finding a practical<br />
solution to sea turtle conservation. To do this, it is essential to determine the main<br />
threats to the population you want to help. In Peru, small-scale bycatch are a<br />
serious problem as the government exerts little control and the existing laws<br />
are not enforced to a high level. Gillnets, a wall of netting that hangs in the water<br />
24 - BIOSPHERE BIOSPHERE - 25<br />
© ProDelphinus
BEHAVIOUR<br />
Knowing that<br />
sea turtles were<br />
visually oriented<br />
in this way led<br />
us to explore<br />
the possibilities<br />
of a visual cue<br />
that could deter<br />
sea turtles from<br />
harm’s way.<br />
Bemba seeds<br />
(Gilbertiodendron<br />
dewevrei)<br />
BEHAVIOUR<br />
10metres apart. The LED lights illuminate the<br />
net at a different wavelength of light than the<br />
target catch of guitarfish, flounders and rays can<br />
see. This was extremely important so fishermen<br />
would not lose out when trying to protect turtles,<br />
and ensured they were eager to experiment with<br />
the lights. Fishermen set the nets overnight, wait<br />
for the fish to become caught, and haul them<br />
in the next morning, so we have a lot of time to<br />
chat. I remember telling them how important<br />
conservation of marine endangered species was<br />
for me, not only because it was my job but also<br />
because I wanted them to get to know me as a<br />
friend and as a collaborator. Mr Chicona and his<br />
son Pedro have worked on this boat forever. Mr<br />
Chicona is a grumpy man, but a wonderful cook,<br />
and often cooked the best rice I have ever tasted!<br />
Several hours later, it was time to haul the nets.<br />
On my first trip they caught a large number of<br />
guitarfishes and one green sea turtle, which was<br />
still alive. That first moment when I saw that turtle<br />
is unforgettable for me. I was very excited. All of<br />
the species, whether they were target catch or<br />
bycatch, were recorded for the study. Their length<br />
and whether they were sexually mature was<br />
significant. We also noted the hours and duration<br />
of each set and haul, so we could infer which<br />
gillnet set were easier to work – those with lights<br />
or those without.<br />
in order to catch fish that get their gills caught,<br />
are commonly used in fisheries around the globe;<br />
however, they don’t just catch fish. When a sea<br />
turtle becomes caught on it, it usually drowns. In<br />
Sechura Bay, it has been calculated an average of<br />
321 green sea turtles (Chelonia mydas) are caught<br />
in gillnets every year. In fact, in one hauling you<br />
can get from 10 to even 30 turtles on board! These<br />
losses are detrimental, but few solutions have been<br />
tested.<br />
How can we help this sea turtle population to<br />
recover? These reptiles are opportunistic with their<br />
diet; basically they eat whatever they see to be a fit<br />
meal. Knowing that sea turtles were visually oriented<br />
in this way led us to explore the possibilities of a<br />
visual cue that could deter sea turtles from harm’s<br />
way. We decided to experiment with a light-emitting diode (LED)<br />
light to illuminate the nets and reduce the bycatch number. This<br />
dispositive was developed by John Wang who experiment with LED<br />
lights in gillnets fisheries in Mexico, obtaining positive results.Cheap,<br />
simple, robust and resistant to sea water, these LED lights wouldn’t<br />
affect target catch, so it could be a win-win for fishers and turtles<br />
alike. But would it work?<br />
This is what we aimed to find out, as well as calculating the cost<br />
of saving a sea turtle. In order to do it, we set two sets of gillnets,<br />
one with and one without lights. A gillnet has a floatline that floats<br />
along the surface of the water to create the upper edge of the<br />
barrier. Along this floatline, an average of 221 lights were placed<br />
©Eva Leuf<br />
I, as an observer, could not intervene on hauling<br />
procedures, only watch, and try not to disturb their<br />
work. When a sea turtle was hauled in, the size<br />
of its shell was recorded, as well as the location<br />
using GPS loggers. We also noted the state we<br />
found them (alive or dead) and which part of its<br />
body had become entangled. Many came to the<br />
surface already drowned. All of these turtles were<br />
given first aid, inclining the body with the turtle’s<br />
head pointing down in order to expulse any foam.<br />
The nets remain in the sea approximately 16 hours<br />
so it is understandable that some turtles just could<br />
not survive. No matter if it was morning, afternoon<br />
or night, Pedro helped me to measure the size of<br />
each turtle. He learned how to tag the turtles and<br />
understood the importance of protecting them<br />
from his fishing. That was one of my personal<br />
biggest satisfactions.<br />
Indeed, one of our enquiries was if fishermen were<br />
willing to use the LED lights after the research<br />
finishes. At the beginning of the study, they<br />
thought lights were reducing the target catch. In<br />
the end, the results demonstrate that they caught<br />
the same amount of fish and rays, but green sea<br />
turtle bycatch reduced by over 60%. Not only is<br />
this good for the turtles, but this means less time<br />
and effort spent by the fishermen recovering sea<br />
turtles who have become entangled. The effort<br />
to recover their target catch remained the same.<br />
Even though this tool was intended to prevent<br />
26 - BIOSPHERE BIOSPHERE - 27<br />
©Tanja Suarez Yana
BEHAVIOUR<br />
BEHAVIOUR<br />
green sea turtle bycatch, three hawksbills<br />
(Eretmochelys imbricata) and one olive<br />
ridley (Lepidochelys olivacea) were caught<br />
incidentally during the research.<br />
However, the monetary cost for these LED<br />
lights is expensive. The LEDs we used in this<br />
study cost $10 (US Dollars), but in the near<br />
future there should be similar lights available<br />
for about $2. We estimated that the total cost<br />
for a typical fishing boat in this area would be<br />
about $1155 to $3003, and the whole fishery<br />
from $9200 to $24000. This is the first year<br />
cost, with the LED lights having a useful life<br />
of about three years before they would need<br />
to be replaced. Consequently, the costs<br />
needed for the second and third year would<br />
be significantly lower.<br />
Each trip the fishermen make a profit of<br />
about $82, so it is beyond their reach to buy<br />
the lights themselves. It is necessary to spread<br />
this research to governmental institutions<br />
and international non-profit organizations so<br />
they can support the implementation of this<br />
sea turtle conservation strategy. If 321 turtles<br />
“I prefer working with sea turtles,” he said<br />
to me once. Hearing those words made me<br />
feel it is possible to make a real change.<br />
© Tania Suarez Yana<br />
Left: Tania<br />
releasing a sea<br />
turtle.<br />
Right: Pedro<br />
measuring the<br />
shell of a turtle.<br />
©Tanja Suarez Yana<br />
are currently caught in gillnets each year in<br />
this bay, 202 turtles would be prevented from<br />
capture with this technology. That would<br />
mean cost prevention per turtle would be<br />
between $34 to $119. Surely, these results are<br />
encouraging for everyone. If solar-powered<br />
LEDs were developed, an ideal solution<br />
would be found.<br />
I observed Mr Chicona and Pedro in one vessel.<br />
But in total 8 fleets in Constante participated<br />
in this study. When we brought these results<br />
to the Constante community, the majority of<br />
fishermen were keen to use the LED lights in<br />
their set of gillnets. I think they see the benefit<br />
in less effort spent untangling sea turtles and<br />
also less time repairing the nets. Mr. Chicona<br />
had many sets of bottom gillnets unused<br />
because they were damaged, perhaps partly<br />
due to sea turtles becoming entangled.<br />
This was the first time LEDs were tested in<br />
active gillnet fishery. Researchers from all<br />
over the world that we have spoken to so<br />
far were very enthusiastic to know about<br />
this great potential tool with wide-scale<br />
28 - BIOSPHERE BIOSPHERE - 29
BEHAVIOUR<br />
©ProDelphinus<br />
implementation. We are now testing them in<br />
other net fisheries in Peru and Ecuador to see<br />
if we can replicate our findings in Constante.<br />
From this, we can gain even wider feedback<br />
from these fishermen and encourage many<br />
more stakeholders to get involved with it.<br />
Pedro is now a collaborator of ProDelphinus.<br />
He calls us when he recaptures a sea turtle.<br />
Furthermore, he releases the turtles and notes<br />
their capture locations. “I prefer working with<br />
sea turtles,” he said to me once. Hearing those<br />
words made me feel it is possible to make a<br />
real change, even though it can take us many<br />
months or even years.<br />
This research is a single but good episode of<br />
my experiences as a wildlife veterinarian so far.<br />
It gave me the opportunity to talk with coastal<br />
communities, know their issues and pass along<br />
information about sea turtle conservation. Now,<br />
the fishermen know that when a sea turtle is<br />
caught it suffers a long-term entanglement and<br />
consequently, stress. This place, Sechura Bay, is<br />
a wonderful source of food for these creatures.<br />
On every trip while awaiting tomorrow’s<br />
hauling, we could see several turtles coming up<br />
to the surface to breathe. Nature is wonderful<br />
and calming in these moments.<br />
Mangel, J. C., Ortiz, N., Wang, J., Alfaro-Shigueto,<br />
J., Pingo, S., Jimenez, A., ... & Godley, B. J. (2016).<br />
Reducing green turtle bycatch in small-scale<br />
fisheries using illuminated gillnets: The Cost of<br />
Saving a Sea Turtle. Marine Ecology Progress Series.<br />
545:251-259 DOI: 10.3354/meps11610<br />
30 - BIOSPHERE BIOSPHERE - 31
ECOLOGY<br />
ECOLOGY<br />
Could a fungus and a<br />
woodpecker be working<br />
together to accomplish<br />
mammoth tasks in the<br />
pine forests? Michelle<br />
Jusino investigates.<br />
© Michelle Jusino<br />
T<br />
he longleaf pine ecosystem<br />
of the southeastern United<br />
States is an amazing place,<br />
but sadly there is very little of<br />
it left. It generally consists of<br />
multi-aged longleaf pines in<br />
a sea of diverse herbaceous<br />
groundcover. Picture an open grass<br />
savannah with majestic pines. Fire is critical<br />
to maintaining the open forest structure.<br />
This was the setting of my research, and it<br />
was beautiful.<br />
These unique forests are home to an<br />
incredible diversity of native plants,<br />
fungi, arthropods, reptiles, amphibians,<br />
mammals, and birds, each connected<br />
to the other by the land they share and<br />
the resources they need. The focus of this<br />
story is on one particular bird species,<br />
only found in the longleaf pine ecosystem,<br />
the red-cockaded woodpecker (Picoides<br />
borealis). Red-cockaded woodpeckers are<br />
cooperatively breeding birds who live in<br />
family groups and are federally endangered<br />
in the United States. Their populations<br />
suffered huge losses with the degradation<br />
and subsequent lack of management of<br />
their endemic habitat, the longleaf pine<br />
ecosystem.<br />
Aside from being imperiled by human<br />
activities, these fascinating birds have<br />
traits that have enamoured behavioral<br />
researchers for decades. One set of<br />
behaviours that is most interesting, is<br />
designed to secure the one thing they need<br />
above all else to be successful: a place to<br />
live and to raise their young.<br />
Similar to many other woodpeckers, redcockaded<br />
woodpeckers nest and roost<br />
in cavities within trees. However, redcockaded<br />
woodpeckers do something that<br />
no other woodpecker does. They exclusively<br />
excavate through the outer sapwood and<br />
into the heartwood of relatively healthy<br />
living pine trees. This means the cavities are<br />
rooms housed entirely in the heartwood of<br />
32 - BIOSPHERE BIOSPHERE - 33
ECOLOGY<br />
ECOLOGY<br />
Right: A red<br />
cockaded<br />
woodpecker.<br />
Below: The fruiting<br />
body of red heart rot.<br />
© Michelle Jusino<br />
would have with tree resin, or sap. Although some can<br />
complete their cavities within a year, it takes these little<br />
birds on average about 8 years, and sometimes up to 20<br />
years or more! But, once a cavity is complete, it can be<br />
used by red-cockaded woodpeckers for decades. After<br />
they are done with a cavity, either by choice, or by force<br />
(the cavities are a coveted resource), it can be used for<br />
many more years by other cavity-users. So red-cockaded<br />
woodpecker excavations are more than just a hole in<br />
a tree. They are homes not only to the woodpeckers,<br />
but also to a wonderful diversity of other cavity-using<br />
birds, mammals, amphibians, reptiles, arthropods, and<br />
perhaps even fungi.<br />
In turns out that some of these fungi could be unexpected<br />
bedfellows for the woodpeckers, who could be enlisting<br />
the help of the fungi in their excavation efforts. For many<br />
years, red-cockaded woodpeckers have been thought<br />
to be associated with one fungus in particular, which<br />
goes by the name of ‘red heart rot’, or more officially,<br />
Fungi<br />
could be<br />
unexpected<br />
bedfellows<br />
for the<br />
woodpeckers<br />
living trees, with a hallway that goes through the<br />
sapwood. The cavities are very cozy and are built for<br />
just one, so every bird in a group requires its own<br />
cavity and one of these is used as the nest each year<br />
within a group, as the birds within a group help each<br />
other to raise young.<br />
Roosting and nesting in living pine trees offers<br />
additional home-security benefits to red-cockaded<br />
woodpeckers. The birds maintain active resin wells<br />
all around their cavities, so sap leaks from their trees,<br />
making them look like giant melting candle-sticks in<br />
the woods. This might help them to avoid predators<br />
like the carnivorous rat snake. The resin may hinder<br />
this and other raiders of bird nests, preventing them<br />
from climbing the tree and devouring the delicious<br />
birds inside.<br />
While the benefits of excavating living pines are<br />
evident, in practice it is a herculean undertaking for<br />
these diminutive creatures. Try to imagine being a bird<br />
that weighs about 50 grams (1.8 ounces), and using<br />
your face to drill a cavity into a living pine tree. Imagine<br />
the time it would take, and imagine the problems you<br />
Porodaedalea pini. Early researchers hypothesised that<br />
this fungus could help the woodpeckers by softening the<br />
tree tissues through which they excavate. If this was the<br />
case, the woodpeckers could perhaps help the fungus<br />
find new trees to colonize. While this story of symbiosis<br />
is intuitive and appealing, the evidence remained<br />
tenuous for decades. Links between the woodpeckers<br />
and red heart rot were largely based on limited visual<br />
observations of the fungus on the trees in which redcockaded<br />
woodpecker’s cavities were found.<br />
This is where I joined the story. When I started my doctoral<br />
work at Virginia Tech, I wanted to understand whether<br />
red-cockaded woodpeckers had a true symbiosis with<br />
red heart rot. Though neither of us were mycologists, I<br />
convinced my advisor and avian behavioural ecology<br />
expert, Jeff Walters, that the project was well worth<br />
exploring.<br />
We had a rocky start. Following the lead of previous<br />
researchers, we initiated a large-scale fruiting body<br />
survey on red-cockaded woodpecker cavity trees. A<br />
fruiting body is what you see when the conditions are<br />
34 - BIOSPHERE BIOSPHERE - 35
ECOLOGY<br />
We found<br />
decay fungi in<br />
my samples.<br />
And there<br />
were A LOT.<br />
just right in order for a fungus to reproduce – the<br />
mushrooms and toadstools you see growing in the<br />
autumn are the fruiting bodies of the fungi that<br />
grow beneath the soil. Similarly, wood decay fungi<br />
are often found fruiting on wood. To my dismay, after<br />
surveying countless cavity trees, we found very, very<br />
few fungi fruiting on red-cockaded woodpecker<br />
cavity trees. Sadly, fruiting body surveys are limited to<br />
identifying what is actually fruiting at any given time,<br />
so examining and identifying the fungi found fruiting<br />
on cavity trees is not the best way to determine which<br />
fungi, if any, are associated with the constructor of<br />
the cavities, as most of the fungi cannot be seen in<br />
this way. I needed to sort out a better way to sample<br />
red-cockaded woodpecker excavations for fungi.<br />
Because red-cockaded woodpecker cavities are<br />
critical to the birds, the sampling process had to be<br />
gentle on the trees. With the help of our collaborators,<br />
we designed a sampling device that could collect<br />
wood shavings within cavities. But it still wasn’t<br />
straightforward from here. The excavations that<br />
red-cockaded woodpeckers make are so far from<br />
the ground that getting to them required Swedish<br />
climbing ladders, a climbing harness, and a tree<br />
strap. When I finally hand my sampling device in<br />
hand, I was able to start collecting samples, but still<br />
needed a way to identify the fungi that I found. It is<br />
possible to grow some of the fungi in my samples to<br />
a level that I would be able to identify them, but it<br />
is a difficult process, and many fungi can be missed<br />
this way, so I wanted to explore other options.<br />
I decided it would be a good idea to explore DNAbased<br />
techniques…when you are already outside of<br />
your comfort zone nothing seems unrealistic! This is<br />
where Daniel Lindner, Mark Banik and the United<br />
States Forest Service Center for Forest Mycology<br />
Research come in. Dan and Mark were using DNAbased<br />
techniques to determine the fungi present<br />
in wood – it was exactly what I needed. We very<br />
quickly discovered that red-cockaded woodpecker<br />
excavations were inhabited by not one, but many<br />
species of fungi, and we set off to identify the decay<br />
fungi. Decay fungi were what we were looking for,<br />
because that’s what might help to break down the<br />
cavities with the woodpeckers. Easy, right? Well,<br />
not really, but after a fair amount of tweaking and<br />
adjusting our methods, we found decay fungi in my<br />
samples. And there were A LOT.<br />
Instead of just looking for one fungus – red heart<br />
rot – I now knew I was looking at many more taxa<br />
© Michelle Jusino<br />
of fungi than I expected. For each family group of<br />
red cockaded woodpeckers, there is a cluster of<br />
trees containing cavities and started cavities known<br />
as ‘cavity starts’. We selected 15 of these clusters in<br />
our study site in coastal North Carolina. I sampled<br />
every complete red-cockaded woodpecker-made<br />
cavity that the birds within these 15 groups were<br />
using, as well as all of the cavity starts. We sterilely<br />
drilled human-made cavity starts in 4 living longleaf<br />
pine trees in each of the 15 clusters and I sampled<br />
those new excavations as well, to represent a<br />
control group in previously non-excavated trees.<br />
We put steel screens over all of the human-drilled<br />
cavity starts to make them inaccessible to the birds<br />
following drilling. The screens were large enough to<br />
allow invertebrates and fungal spores in, but small<br />
enough to keep birds out. The initial sample of 15<br />
clusters were part of an initial survey to see if the<br />
fungal communities found in cavities, starts, and<br />
non-excavated trees were similar to each other. It<br />
turns out that the different excavations housed<br />
different fungal communities, though there was<br />
overlap between the cavities and the starts, but the<br />
human-drilled, previously non-excavated trees were<br />
completely different.<br />
We then set out to determine if the birds could<br />
somehow directly or indirectly influence the<br />
differences we saw in the fungal communities, so<br />
we swabbed adult red-cockaded woodpeckers at<br />
our study site for fungi. Additionally, after the resin<br />
from the fresh wounds in our screened human-<br />
36 - BIOSPHERE BIOSPHERE - 37
ECOLOGY<br />
in the cavity starts that we drilled, fungal communities<br />
in both accessible and inaccessible starts become<br />
more diverse over time.<br />
Additionally, the fungal communities in the starts<br />
that birds could access closely resembled those<br />
found in the cavities made by the birds, while those in<br />
inaccessible starts did not. So, the birds facilitate fungi<br />
indirectly by simply making a cavity start in a tree,<br />
and directly by continuing to visit that start. Needless<br />
to say, it was exciting to realise that red-cockaded<br />
woodpeckers are associated with many fungi, not just<br />
red heart rot.<br />
Taken all together, these results strongly suggest<br />
that red-cockaded woodpeckers have a symbiotic<br />
association with the fungi found in their excavations.<br />
Interestingly, the part of the story that we have<br />
evidence for, the part about the birds helping the<br />
fungi, is the part that was the most doubted, and the<br />
part that has long been thought to be true, the part<br />
about the fungi helping the birds, that is still untested!<br />
Red-cockaded woodpeckers are endangered, and<br />
are restricted by habitat. Humans can and do help<br />
red-cockaded woodpeckers by either drilling artificial<br />
cavities or by putting cavity insert boxes into living<br />
trees. These very special cavities, so important for redcockaded<br />
woodpeckers and a diverse community of<br />
other organisms, take such a long time to make that<br />
the birds just cannot make cavities fast enough - do<br />
the fungi present or absent in a tree somehow limit<br />
the rate of cavity excavation?<br />
drilled starts was dry, we were able to un-screen half of the drilled<br />
starts to make them accessible and available to the birds. In each<br />
of the 15 clusters, we un-screened two starts and left two screened,<br />
so we had a total of 30 accessible experimental drilled starts and 30<br />
that were inaccessible. I then proceeded to climb and sample each<br />
of those 60 trees once every six months for nearly two and a half<br />
years. I would do it all again sixty times.<br />
A little over two years after the starts were drilled, I sampled the<br />
trees one last time. What I found was incredible. So incredible that I<br />
re-analysed everything; I double and triple checked, and even tried<br />
different analyses. But no matter what I did, the result was the same.<br />
The woodpeckers have an incredible diversity of fungi on them,<br />
including many wood-decay fungi, and the fungal communities on<br />
the birds closely resembles those found in their complete cavities<br />
and to a lesser extent, those found in their cavity starts. Furthermore,<br />
If the fungi actually do quicken the very lengthy<br />
excavation process, then the symbiotic association<br />
my colleagues and I described could be a mutualism,<br />
where both species are helping one another. That test<br />
is top on my list. Another aspect I hope to explore<br />
in the future is whether red-cockaded woodpeckers<br />
specifically select trees already infected with certain<br />
fungal communities. And of course, we are left with the<br />
age-old question of which came first, the woodpecker<br />
or the fungus?<br />
We described an interesting symbiosis between one<br />
woodpecker and multiple fungi in one ecosystem. This<br />
association could be an evolutionary accident, unique<br />
to this ecosystem, or perhaps it’s a more common and<br />
widespread occurrence. I can’t wait to find out.<br />
Jusino, M. A., Lindner, D. L., Banik, M. T., Rose, K. R., &<br />
Walters, J. R. (2016, March). Experimental evidence of<br />
a symbiosis between red-cockaded woodpeckers and<br />
fungi. In Proc. R. Soc. B (Vol. 283, No. 1827, p. 20160106).<br />
The Royal Society.<br />
38 - BIOSPHERE BIOSPHERE - 39
IN THE FIELD<br />
Mammals<br />
in<br />
MIST<br />
the<br />
Catherine McNicol spends her field seasons<br />
in the Welsh rain, trying to understand the<br />
relationship between two of the UK’s mammals,<br />
one of which does not belong here.<br />
It’s not even lunchtime, I’ve fallen over about six<br />
times already and the weather would suggest<br />
I’m inside a cloud. But the less-than-graceful<br />
show goes on and I won’t be stopping until I have<br />
checked all of my squirrel traps and collared<br />
their slightly irritated occupants. This is fieldwork<br />
in the Welsh woods in a nutshell. Sometimes I<br />
wonder how on earth I found myself here.<br />
“I’m never working in the UK,” a past version of myself<br />
would say, “no way am I doing another degree.”<br />
Now with two degrees under my belt I find myself<br />
commencing a 3 year PhD working with a native<br />
species in the UK. Didn’t see that coming.<br />
My work focuses on the impact of reintroducing the<br />
native European pine marten (Martes martes) on a<br />
species that doesn’t naturally belong here: the grey<br />
squirrel (Sciurus carolinensis). Introduced in the late<br />
1800’s by Victorians who thought they looked nice,<br />
this invasive species thrived in the absence of natural<br />
predators and within 30 years was found in almost<br />
every corner of the UK. By the 1920’s, people realised<br />
these pesky Greys shouldn’t be introduced anymore<br />
and eventually strategies to control and eradicate<br />
their populations were implemented. These still<br />
continue today. But the trapping and dispatching<br />
of squirrels is highly labour intensive and draws<br />
parallels to painting the Forth Road Bridge: Once<br />
© Peter G W Jones<br />
40 - BIOSPHERE BIOSPHERE - 41
IN THE FIELD<br />
IN THE FIELD<br />
© Nik Hubbard<br />
you’ve finished, you have to start all over again. The<br />
ability of this species to colonise and repopulate<br />
areas is phenomenal, and culling efforts can be<br />
thwarted when juveniles from nearby areas quickly<br />
replace the squirrels that have been removed.<br />
This is where the pine marten comes in. Now, the<br />
pine marten is not a bird, nor is it a tree. I’m talking<br />
about the large cat-meets-ferret-meets-stoat-meetsfur-stole.<br />
With me? Good.<br />
These beautiful and elusive creatures, once common<br />
across the UK, have suffered huge population declines<br />
as a result of persecution, hunting for the fur industry<br />
and loss of their woodland habitat. As a result, their<br />
distribution is sparse and pretty patchy with the<br />
exception of Scotland, and remaining individuals are<br />
struggling to re-establish self-sustaining populations.<br />
Enter the Vincent Wildlife Trust. By boosting the<br />
residual and highly elusive population in mid-Wales,<br />
the Trust aims to restore pine marten numbers to<br />
healthy levels.<br />
These two species come together due to the results<br />
from a study in Ireland that found there were less<br />
grey squirrels in areas that pine martens existed.<br />
In the fashion of true science, we needed to find<br />
out if this was a one off occurrence or a UK-wide<br />
trend – this meant replication, improvement and<br />
investigation. The project is now underway - with 17<br />
Scottish martens roaming the Welsh woods since<br />
their introduction in September 2015, and 20 more<br />
due to arrive this summer. Summer, that small<br />
window of the year where it doesn’t rain, for about<br />
one week.<br />
Welsh rain is the kind of rain that doesn’t look so bad,<br />
but soaks you through. It’s the “I wish I’d brought a<br />
coat,” rain, the “it’s too warm for a coat but too wet<br />
for anything else,” rain, the “not heavy enough to stop<br />
the midges” rain. In Wales you can’t wait for the rain<br />
to stop, so here I am, slipping down muddy banks<br />
trying to catch and put radio collars on unsuspecting<br />
grey squirrels.<br />
Having never worked with squirrels before, or<br />
pine martens, or any wild mammal for that<br />
matter, the whole experience has been<br />
a steep learning curve. With my last<br />
rodent-related incident involving<br />
being bitten by my pet rabbit at<br />
the age of 12, I knew I had multiple<br />
hurdles in my way. But after some<br />
expert training by Mark Ferryman<br />
from the Forestry Commission<br />
(my funding organisation), I knew<br />
how to trap, collar and tag even<br />
the most unwilling of squirrels.<br />
So with 53 telemetry collars, fitted<br />
with GPS loggers, I was launched<br />
into the back of beyond to live in<br />
some unpronounceable village in<br />
mid Wales. Goodbye social life, goodbye<br />
civilisation, goodbye sanity.<br />
I was immediately faced with issue number one:<br />
I was<br />
immediately<br />
faced<br />
with issue<br />
number one:<br />
Nature.<br />
Nature. Apparently squirrels will not go into your<br />
traps for food if there is food elsewhere. In<br />
hind-sight this is obvious, but at the time<br />
I was positive I’d failed before I’d even<br />
seen a single squirrel. Lesson: make<br />
sure the timings of your fieldwork<br />
are appropriate for the species you<br />
are working with. And buy lots of<br />
cobnuts. Squirrels love cobnuts.<br />
Issue number two raised its ugly face<br />
very soon after: Nature. Apparently<br />
there are other animals in the<br />
woods apart from squirrels. After a<br />
week of being positively terrified and<br />
confused about why my traps were<br />
being uncovered and disturbed every<br />
night (visions of a creepy man in an anorak<br />
filled my mind) I discovered a nosey fox was<br />
to blame. Lesson: think about the ecosystem in<br />
which you are working and the other animals that<br />
live there. Foxes are very smart; some may even say<br />
© Andrej Chudý<br />
42 - BIOSPHERE BIOSPHERE - 43
IN THE FIELD<br />
fantastic.<br />
After nut-gate and fox-gate my collaring picked up<br />
and I became the pied piper of Pont-rhyd-y-groes.<br />
I developed a reputation as the ‘squirrel lady’ after<br />
chance encounters with dog-walkers, farmers and<br />
foresters in random patches of woodland. I drove<br />
around the valleys with a box of peanuts, maize<br />
and sunflower seeds in my boot and squirrel traps<br />
in my back seat. Even the staff in Screw-Fix knew<br />
about my squirreling after I explained to them why I<br />
needed so many zip-ties.<br />
© Nik Hubbard<br />
But then…issue number three appeared like a slap in<br />
the face: Technology. Nature had done its worst and<br />
now it was time for man-made devices to stamp on<br />
my optimism. Two months after I began collaring, I<br />
started to re-trap the squirrels to get the data from<br />
the GPS units I had applied to them. The six weeks<br />
worth of data I expected from them turned out<br />
to be two at best due to battery and signal issues.<br />
Insert emotional breakdown at the prospect of<br />
another two months alone in the woods with some<br />
crazy rodents. However, after the time and effort I<br />
had already sacrificed, I refused to be beaten and<br />
replaced the GPS units to collect another 2 weeks of<br />
data. Lesson: check your technology, check it again,<br />
check it in the field, then half your expectations.<br />
By this point I was teetering on the edge of insanity.<br />
My weekly food shopping was the only activity<br />
that reminded me what day it was and that it was<br />
socially unacceptable to only wear waterproofs or<br />
pyjamas. When winter storms began to arrive and<br />
I was banned from the woods due to risk of deathby-falling-tree<br />
I would spend my days worrying<br />
about my sites and the time that was running out.<br />
Trapping in stormy weather is risky and unadvisable,<br />
the animals can die of exposure to the elements if<br />
they are left in traps for too long. Sudden changes in<br />
the forecast would send me into a panic and result<br />
in frantic driving along country-lanes to close traps<br />
at my sites.<br />
If this wasn’t the PhD for me I think I would have<br />
sacked it in after one month. It truly is a labour<br />
of love, mixed with fear of failure, or simply fear.<br />
Some days, on the very rare occasions when the<br />
rain has stopped and the sun is shining, I do have<br />
those “I’m so fortunate” moments. I spend every<br />
day outside surrounded by the sights and sounds<br />
of true British nature, something we overlook every<br />
day. The ancient beech woodland, the unexpected<br />
waterfalls, the red kites soaring above the valleys,<br />
the noisy jays squabbling in the undergrowth<br />
and the curious blue tits following me from trap<br />
to trap. I will admit, I don’t feel this way when it’s<br />
dark and raining and one leg has just sunk into a<br />
bog up to my thigh. But as biologists we often forget<br />
how much we know and how lucky we are to work<br />
with wildlife. The random encounters with dogwalkers<br />
or ramblers in the woods, and the resulting<br />
conversations always surprise me. In my mind, for<br />
conservation projects to be successful, they need<br />
to be understood and supported by surrounding<br />
communities and affected individuals. These simple<br />
conversations about what a pine marten is or why<br />
grey squirrels are detrimental are really important for<br />
the lifespan of the project. When there is a common<br />
understanding and a vested interest in supporting<br />
a conservation project, its continuation and success<br />
is more likely. Word-of-mouth is a great tool, and if<br />
I can get someone excited about the pine marten<br />
project, the positive attitude is contagious.<br />
Yes, the science is important, that’s why I spend<br />
countless days ploughing through data at my desk<br />
while the sun shines outside. It’s not all wandering<br />
through woodland with an aerial, chasing the blips<br />
coming from a radio collar. But fundamentally, if the<br />
work on the ground is not supported and sustained<br />
then what we are doing is bound to fail. So my wellies<br />
and waterproofs are always in my car boot, awaiting<br />
their next call of duty in the valleys.<br />
Catherine McNichol is a PhD researcher at the University<br />
of Exeter. Her research is in collaboration with the<br />
Vincent Wildlife Trust and Forestry Commission. Check<br />
out her blog: http://walkingwithaliens.blogspot.co.uk<br />
44 - BIOSPHERE BIOSPHERE - 45
THE<br />
THRILL<br />
OF<br />
THE<br />
HUNT<br />
How do African wild dogs<br />
hunt? We thought we knew,<br />
but their dominant habitats<br />
are changing, and with it<br />
comes a change in strategy.<br />
Maja Lorenc discusses the<br />
latest research into this<br />
Endangered species.<br />
© Charlesjsharp<br />
46 - BIOSPHERE BIOSPHERE - 47
BEHAVIOUR<br />
BEHAVIOUR<br />
Coloured dots snake their way<br />
around the screen, over and over<br />
again. Sometimes they end up<br />
in completely different places.<br />
Sometimes they converge, and that’s<br />
when they’ve made their kill.<br />
Each dot represents the GPS position of a member<br />
of an African wild dog (Lycaon pictus) pack in<br />
northern Botswana. There are six in total – Kobe the<br />
dominant male, Timbuktu the dominant female, MJ<br />
and Scorpion, the subdominant males, and Accra<br />
and Kigali, the subdominant females. Thousands<br />
of miles away in Hertfordshire, Dr. Tatjana Hubel, a<br />
researcher in the Structure and Motion Laboratory<br />
at the Royal Veterinary College, reconstructs their<br />
hunts by animating the GPS points that showed the<br />
dogs’ position and speed.<br />
The GPS position and instantaneous velocity signals<br />
come from special collars worn by each dog. These are<br />
no ordinary GPS tracking collars: they are completely<br />
decked out with a three-axis accelerometer module<br />
to provide specific force data, a dual-axis gyroscope<br />
to measure roll and pitch rotation rate, and a singleaxis<br />
gyroscope to measure rate of change in the<br />
direction of forward motion. Two batteries, one<br />
partially charged by in-built solar cells, power the<br />
collar and a micro-SD flash memory card provides<br />
on-board data storage. A microcontroller running<br />
custom software controls all this equipment and<br />
manages power consumption in an extremely<br />
unique and effective manner— but more about that<br />
later.<br />
You may recognise some of these terms if you are<br />
familiar with flight dynamics. It might seem like<br />
overkill to equip a wild dog as you would an aircraft,<br />
but the high-resolution data collected from these<br />
48 - BIOSPHERE BIOSPHERE - 49<br />
© Ben Yexley
collars gives researchers detailed insight into hunting<br />
dynamics as well as an estimate of how much energy<br />
is used during the hunt. For the endangered African<br />
wild dog, which is thought to live on the ‘knife’s edge’<br />
in terms of energy balance, such information could<br />
be crucial for its conservation.<br />
© Tatjana Hubel<br />
Studies on this subject have been done previously.<br />
Anywhere you search for ‘African wild dogs’ online,<br />
you will find that they are long-distance endurance<br />
hunters, working collaboratively to bring down prey.<br />
The investment of multiple dogs in chasing and<br />
bringing down a single prey leaves them with a small<br />
energy margin for survival. Though they tend to hunt<br />
with a deadly efficiency that scores them a large<br />
animal to feast on, thieving hyenas could swoop in<br />
and steal the kill. If that happens, the dogs will have<br />
wasted a load of precious energy without any food to<br />
replenish their resources.<br />
In grassland habitats such as the open plains of East<br />
Africa, direct observation of hunts often shows these<br />
principles to be true. However, habitat fragmentation,<br />
disease outbreaks, and human persecution that are<br />
driving the decline of African wild dogs left most of the<br />
remaining population in mixed woodland savannah.<br />
Due to the dense vegetation and low visibility of this<br />
habitat, the means by which packs in this particular<br />
environment approach and attack their prey is not<br />
well documented aside from observations made<br />
out in the bush. The hunting strategy of woodland<br />
savannah packs appears to differ from that of packs<br />
in open grassland, but no one had quantified exactly<br />
how.<br />
To solve this problem, an amazing collaboration<br />
50 - BIOSPHERE BIOSPHERE - 51
BEHAVIOUR<br />
BEHAVIOUR<br />
between the Structure and Motion Laboratory (SML) and the Botswana<br />
Predator Conservation Trust (BPCT) was formed. Together, the BPCT<br />
and SML teams recorded and characterised the interaction between a<br />
pack of woodland savannah-dwelling African wild dogs during a hunt<br />
and determined how this affects the balance of energy invested in the<br />
hunt and energy gained from feeding on a kill.<br />
African wild dog wearing a<br />
collar with a unique design,<br />
allowing for the collection of<br />
high speed chase data. Solar<br />
panels in the top box and a<br />
rechargeable battery in the<br />
bottom box extend the life<br />
span of the collar.<br />
© Julia Myatt<br />
Dr. J. Weldon “Tico” McNutt, director of the BPCT and Dr. Neil Jordan,<br />
a BPCT researcher, provided local African wild dog expertise from the<br />
ecology, behaviour and conservation perspective and proposed criteria<br />
for the careful selection of the study group based on pack size and<br />
composition, established the field research and monitored the study<br />
pack. To complement these expertise, Professor Alan Wilson, Dr Tatjana<br />
Hubel, Dr Julia Myatt and Dr Oliver Dewhirst,<br />
researchers from the SML, approached the question<br />
from the side of biomechanics, locomotion<br />
dynamics and energetics. The SML also provided<br />
the in-house built collars and analysed the data<br />
downloaded from them at regular intervals.<br />
This brings us back to those fancy tracking collars.<br />
Thanks to some clever programming, the collars<br />
recorded brilliantly fine-scale hunting data<br />
without wasting precious battery power. They were<br />
programmed to switch dynamically between four<br />
different operating states, dependent on animal<br />
activity level and the time of the day. This meant<br />
the collars would record just once an hour when<br />
the wild dogs were pretty inactive, increasing to<br />
every five minutes when the dogs were moderately<br />
active. When the collars sensed a chase, GPS fixes<br />
were recorded 5 times per second, adding highresolution<br />
accelerometer and gyroscope data for<br />
fine movement detail.<br />
Over the course of five months, the researchers<br />
gathered round-the-clock information on the<br />
dogs’ activity, with high-resolution details of entire<br />
chases, from the first few running steps to the<br />
consumption of prey. The result is a conclusive<br />
dataset on position and speed from all members<br />
of a pack— the first of its kind.<br />
The original plan was to observe hunts as a visual<br />
backup to collar data. “Initially Julia travelled out<br />
to Botswana to do a ‘labeling’ study with Neil<br />
– physically observing the dogs in the wild and<br />
then matching behaviours to GPS signals so that<br />
we [the data analysis group] would have an idea<br />
of what we were looking at,” says Tatjana. “Though<br />
we got some information from this, it was nearly<br />
impossible to observe a hunt from start to finish<br />
because of the trees.”<br />
Interestingly, the collar data showed that in this<br />
mixed woodland savannah environment, African<br />
wild dogs actually do not display any signs of<br />
collaboration when bringing down their prey.<br />
What the researchers found instead was that<br />
although the dogs set out on a hunt together, they<br />
split up into multiple, short, simultaneous chases<br />
as they approached a herd of prey, such as impala.<br />
Usually an individual and sometimes a smaller<br />
group would chase after the nearest impala,<br />
bringing it down if successful and summoning the<br />
rest of the pack to feast. If a dog missed its target,<br />
it’s no big deal— the likelihood that at least one<br />
other member of the pack had made a kill was<br />
high. Being the social animals that they are, African<br />
wild dogs generously share their meal with the<br />
rest of their pack. This is extremely advantageous<br />
as the dogs do not waste energy combining their<br />
efforts to make a single kill, but they all benefit by<br />
getting to eat. A 40-kg impala would feed the pack<br />
without the individual that killed it losing out, and,<br />
since the dogs eat only as much as they need and<br />
leave the carcass behind, group feeding greatly<br />
reduces wasted meat.<br />
Using information including the dogs’ hunt<br />
distance and kill rate data from the collars, pack<br />
composition, and estimated prey intake, the<br />
researchers populated an energy balance model<br />
to compare the energy gained from a kill with the<br />
cost of the hunt. What they discovered was that<br />
by engaging in multiple frequent, short hunts as<br />
well as group feeding, the dogs actually ended up<br />
with a surplus of energy. The margin was entirely<br />
sufficient to survive and support dependents, like a<br />
denning mother, young pups, guards, and injured<br />
pack members. Being energetically robust allows<br />
the pack to bounce back after a misfortune such<br />
as the theft of their kill— it looks like that ‘knife<br />
edge’ isn’t so sharp.<br />
52 - BIOSPHERE BIOSPHERE - 53
BEHAVIOUR<br />
BEHAVIOUR<br />
© Neil Jordan, Tatjana Hubel<br />
pack during the hunt. Sadly, Kobe became gravely<br />
injured or ill and died, and the collar signal told the<br />
researchers exactly on which day. “It was really sad,”<br />
recalls Tatjana. “His little dot didn’t move far from the<br />
den those last few days, and then it just stopped.”<br />
With access to the continuous storyline of the dogs’<br />
movements and daily rituals, it is almost easy to<br />
forget that Tatjana, the lead author of the study,<br />
did not see African wild dogs roaming free in their<br />
natural habitat until well after beginning the project.<br />
She felt like she knew them, but it did not prepare<br />
her for the moment she first spotted the beautiful,<br />
lethal predators in the bush. “We were on our way to<br />
find a place for the night, it was late and we still had<br />
to set up the tents, but coming around a bend in the<br />
road we were stopped by a pack of African Wild dogs<br />
sprawled out on the road. Admittedly they did not<br />
do anything particularly exciting, but the memory<br />
and rather bad pictures (due to the low light) will<br />
accompany me for a long time. I was never able to<br />
see them hunting in real life, but was privileged to<br />
observe them playing, resting, and having staring<br />
contests with hippos in the wild. And after all, I<br />
always have my little dots on my screen to stare at if I<br />
want to know about their hunting strategies.”<br />
Tatjana Y. Hubel, Julia P. Myatt, Neil R. Jordan,<br />
Oliver P. Dewhirst, J. Weldon McNutt & Alan M.<br />
Wilson (2016). Additive opportunistic capture<br />
explains group hunting benefits in African wild<br />
dogs. Nature Communications. DOI:10.1038/<br />
ncomms11033<br />
“My first opportunity to observe African wild dogs in<br />
How did the dogs manage to achieve relative success them. There was a fence between us and them, but<br />
the Okavango delta came after I had already stared<br />
in this environment? “We think it’s because they it was still a very …peculiar feeling being chased by<br />
for months at small GPS points representing their<br />
generally hunt medium sized prey,” says Tatjana. these predators. I can only imagine how their prey<br />
position. Tiny little dots that I had animated to show<br />
A larger animal would be difficult to take down must feel.”<br />
the position and movement of every single member of<br />
alone. This is a reassuring fact, since although they<br />
a pack chasing (for me invisible) prey. I had extracted Tatjana Y. Hubel, Julia P. Myatt, Neil R. Jordan,<br />
sometimes play like domestic puppies and have Data collected from the collars also gave the<br />
numbers and statistics in order to characterize their Oliver P. Dewhirst, J. Weldon McNutt & Alan M.<br />
colourful splotches and cute giant ears, African wild researchers some insight into the daily lives of the<br />
chases, read books about their behavior, discussed Wilson (2016). Energy cost and return for hunting<br />
dogs are deadly. Tatjana recalls: “[A PhD student] pack: Timbuktu was heavily pregnant and remained<br />
findings and ideas with co-authors and collected in African wild dogs and cheetahs. Nature<br />
and I once ran in front of a pack of captive wild dogs in the den much of the time, Kigali had a healed<br />
data on captive animals, but never encountered one Communications. DOI:10.1038/ncomms11034<br />
in order to motivate them to run so we could film leg injury and hung back towards the rear of the<br />
in the wild before,” she says.<br />
54 - BIOSPHERE BIOSPHERE - 55
BEHAVIOUR<br />
When<br />
COMPETITORS<br />
collide<br />
Herbivores.<br />
Harmless, right? Not so for the<br />
white tailed prairie dog. John Hoogland<br />
witnessed an event that astonished him,<br />
even after over four decades of studying<br />
these animals. Why did it happen?<br />
For 4 months every year for the past 43 years,<br />
I have observed prairie dogs every day, from<br />
dawn until dusk. Prairie dogs are rabbit-sized,<br />
herbivorous rodents that live in large colonies in<br />
the grasslands of western United States. When<br />
they start to wake up from hibernation in early<br />
March, I start my field season by capturing every<br />
prairie dog at my study-site, inserting numbered eartags<br />
for permanent identification, and then painting a unique<br />
marking on each side for identification from a distance.<br />
Several research assistants and I sit in observation towers<br />
and record all their social interactions until early July,<br />
after we have captured and eartagged the last baby. One<br />
day in May 2007 I witnessed a shocking event that I had<br />
never seen before in over 30 years of study.<br />
Prairie dogs are not peaceful grazers. Amicable<br />
interactions sometimes occur, but fights, chases, and<br />
territorial disputes are far more common. Adults of two<br />
prairie dog species that I had previously studied commonly<br />
kill and cannibalise each other’s juvenile offspring. I was<br />
watching closely for such infanticide when I saw Head-<br />
6, a female white-tailed prairie dog (Cynomys leucurus,<br />
hereafter “prairie dog”), violently and repeatedly attack a<br />
juvenile until it stopped moving. And then Head-6 just<br />
walked away. I assumed she had just killed a baby prairie<br />
dog, so I hurried from my tower to<br />
document my first case of infanticide<br />
for this prairie dog species.<br />
I was flabbergasted to find that the<br />
White tailed<br />
prairie dog.<br />
© Sandy Nervig<br />
56 - BIOSPHERE BIOSPHERE - 57
BEHAVIOUR<br />
BEHAVIOUR<br />
© Nick Vitale<br />
Top: A colony of<br />
white tailed prairie<br />
dogs around their<br />
burrow.<br />
© Sandy Nervig,<br />
Bottom: A white<br />
tailed prairie dog<br />
with a Wyoming<br />
ground squirrel in its<br />
jaws. Killings involve<br />
violent shaking and<br />
repeated biting.<br />
©John Hoogland<br />
victim was a baby Wyoming ground squirrel<br />
(Urocitellus elegans, hereafter “ground<br />
squirrel”) rather than a baby prairie dog. I<br />
scrutinised that baby again and again because<br />
I kept telling myself, “It must be a juvenile<br />
prairie dog.” But it wasn’t. The victim’s long tail<br />
proved that it was definitely a baby ground<br />
squirrel. As I slowly returned to my tower, I<br />
thought to myself, “This must be a fluke. We’ll<br />
never see another between-species killing<br />
again.” But Head-6 killed another ground<br />
squirrel the next day, and later in that same<br />
day one of my assistants saw a second prairie<br />
dog kill a ground squirrel.<br />
Within their large colonies, prairie dogs live<br />
in territorial family groups called clans. The<br />
typical clan contains a single adult male,<br />
between two and five adult females, one or<br />
two sexually immature males, and in late spring<br />
and summer, between five and ten juveniles.<br />
Females generally remain in the territory<br />
where they were born for their entire lives, but<br />
males usually disperse when they reach sexual<br />
maturity, which allows them to avoid incest by<br />
finding unrelated females with whom to mate.<br />
Like prairie dogs, ground squirrels are diurnal,<br />
herbivorous rodents that live in territorial<br />
family groups. They look remarkably similar<br />
and display many of the same behaviours as<br />
prairie dogs, but are only about half the size.<br />
Ground squirrels commonly live in the same<br />
meadows with prairie dogs, and the diets of<br />
the two species are almost identical.<br />
Once my assistants and I knew what to look<br />
for, we started seeing killings everywhere. In<br />
a typical killing, the marauder would catch<br />
a fleeing ground squirrel, viciously shake<br />
and repeatedly bite the ground squirrel in<br />
the head, neck, or thorax for several minutes<br />
until death, and then would calmly abandon<br />
the victim and resume foraging on nearby<br />
vegetation. Over the next 6 years following the<br />
first killing by Head-6, we observed a total of<br />
101 unambiguous killings.<br />
In over a third of these killings, an avian<br />
scavenger - either an American crow or a<br />
California gull - landed near the fresh carcass,<br />
seized it with its beak, and then flew away with<br />
it. We observed 58 additional cases of an avian<br />
scavenger picking up and flying away with a<br />
fresh carcass, and 4 more cases of a recently<br />
killed (un-scavenged) carcass aboveground<br />
with wounds similar to those after an observed<br />
killing. These 62 cases probably involved<br />
killings for which we did not observe the actual<br />
execution. If these inferences are correct, the<br />
total number of killings at our study-colony<br />
in a six-year period was a whopping 163!<br />
The interesting anecdote that began with<br />
Head-6 in May 2007 evolved, one kill at a<br />
time, into a robust database of violence<br />
between species.<br />
Killings were not the work of a few<br />
idiosyncratic individuals. Rather, we<br />
identified 47 different killers. Some of<br />
these killers were males, but three times<br />
as many were females. Most prairie dog<br />
killers struck only once, but 19 ‘serial killers’<br />
dispatched two or more ground squirrels.<br />
One female, whom we dubbed the gold<br />
medallist, killed 9 ground squirrels over 4<br />
years. The silver medallist struck 7 times in<br />
a single day, eliminating an entire litter of<br />
ground squirrels. And the bronze medallist<br />
killed 6 ground squirrels over 5 years. In 3<br />
of the 6 years of our research, the number<br />
of ground squirrels killed by prairie dogs<br />
was higher than the number killed by the<br />
combined efforts of 15 mammalian and<br />
avian predators like American badgers,<br />
coyotes, long-tailed weasels, prairie falcons,<br />
short-eared owls, and Swainson’s hawks.<br />
Our tracking of marked prairie dogs<br />
allowed us to document that 30% of<br />
females killed at least one ground squirrel<br />
during their lifetimes. Lactating females<br />
were responsible for 79% of killings, males<br />
for another 17%, and non-lactating females<br />
for the remaining 4%. Probably because<br />
ground squirrel juveniles cannot run fast<br />
and are easy to overpower, 96% of victims<br />
were juveniles. Our results raise several<br />
provocative questions. Why do prairie dogs<br />
chase and kill ground squirrels? Does this<br />
hostility contribute to their reproductive<br />
success? And why do ground squirrels<br />
continue to live in prairie dog colonies<br />
despite the high rate of killing?<br />
Prairie dogs benefit from their colonies in<br />
many ways. With so many animals living<br />
together, the probability of detecting a<br />
predator such as an American badger,<br />
coyote, or prairie falcon is high, and the first<br />
prairie dog to see the enemy commonly<br />
warns neighbours by giving an alarm call.<br />
Prairie dogs work together to excavate<br />
burrows, which can be as deep as 5 meters<br />
and extend horizontally as far as 30 meters,<br />
and they use these burrows to rear families<br />
and escape from predators and harsh<br />
weather. Further, prairie dogs cultivate<br />
the vegetation in their home territories by<br />
trimming tall and undesirable plants, and<br />
58 - BIOSPHERE BIOSPHERE - 59
BEHAVIOUR<br />
Top: Woodstork nest<br />
Bottom: Tricoloured<br />
heron nest<br />
© Nick Vitale<br />
BEHAVIOUR<br />
Left: White tailed<br />
prairie dog.<br />
© Richard Reading<br />
Right: Wyoming<br />
ground squirrel.<br />
© JTchagbele<br />
they fertilise the home turf with<br />
their urine and faeces.<br />
Ground squirrels frequently<br />
live in the same meadows<br />
with prairie dogs. They use<br />
the burrows that prairie dogs<br />
have dug for short periods as<br />
temporary refuge from predators, or for longer<br />
periods as a place to spend the night,<br />
or rear offspring. Further, the ground<br />
squirrels eat much of the same<br />
vegetation that the prairie dogs have<br />
carefully cultivated. Finally, ground<br />
squirrels respond to prairie dog<br />
alarm calls by increasing vigilance<br />
or submerging into a burrow.<br />
Ground squirrels thus parasitise the<br />
benefits of prairie dog coloniality,<br />
while offering nothing in return.<br />
How does killing of ground squirrels<br />
benefit prairie dogs? The most likely<br />
explanation is that killing reduces<br />
competition from the ground squirrels<br />
for food near the killer’s home-burrow.<br />
Killing leads to more vegetation not only for the<br />
mother herself, but also for her weaned offspring.<br />
Tellingly, 96% of killings occurred within 20 meters<br />
of the killer’s home-burrow, where the mother and<br />
her offspring do much of their foraging.<br />
I was astonished<br />
to learn that<br />
killing of ground<br />
squirrels by<br />
prairie dogs<br />
occurs, and is so<br />
common.<br />
killing might increase reproductive success. In my<br />
early analysis, I found that killers produce more<br />
offspring per year than non-killers. But this analysis<br />
did not consider seven other factors that might affect<br />
killing—age, body mass, clan size, and aggressiveness,<br />
for example. To examine the confounding effects of<br />
these other factors, I recruited Charles Brown, a good<br />
friend and my former graduate student who is now a<br />
Professor at the University of Tulsa. Brown has<br />
worked with large, complicated datasets<br />
for decades, and was just what my<br />
investigation of interspecific killing<br />
needed.<br />
Brown examined both ‘annual<br />
fitness,’ which was a combination<br />
of a mother’s survivorship and<br />
the number of offspring she<br />
produced within one year, and<br />
‘lifetime fitness,’ which was the<br />
number of offspring that survive<br />
for at least one year over a female’s<br />
lifetime. We discovered that killings<br />
per se dramatically increased both<br />
estimates of fitness. Indeed, the number<br />
of killings by a female prairie dog was the<br />
only significant predictor that we could identify<br />
of both her annual and lifetime fitness. Killing was<br />
even a stronger predictor of lifetime fitness than<br />
how long the female lived, which is the major factor<br />
that affects lifetime fitness for hundreds of other<br />
species. Annual fitness was two times higher for<br />
serial killers than for nonkillers, and lifetime fitness<br />
was three times higher for serial killers than for<br />
nonkillers. Killing of competitors of another species<br />
I was astonished to learn that killing of ground<br />
squirrels by prairie dogs occurs, and is so common.<br />
I was astounded once again when I learned that<br />
60 - BIOSPHERE BIOSPHERE - 61
White tailed<br />
prairie dog.<br />
© Sandy Nervig<br />
BEHAVIOUR<br />
has been documented<br />
before, but rarely among<br />
herbivores, and never in a way<br />
that has demonstrated that<br />
killing confers a reproductive<br />
advantage under natural<br />
conditions. The coupling of killing with increased<br />
fitness makes a persuasive story for prairie dogs.<br />
Killings of ground squirrels were subtle, quick,<br />
unpredictable, and unanticipated. Probably for<br />
this reason, my students and I did not detect<br />
a single killing in our first 4 years of research<br />
before the killing by Head-6. Charles Brown and<br />
I are optimistic that our story will encourage<br />
other behavioural ecologists to consider the<br />
possibility that their study-animals sometimes<br />
might covertly kill, or get killed by, competing<br />
individuals of other species. We hope our<br />
colleagues will now report such interspecific<br />
killings that previously seemed too bizarre to<br />
mention.<br />
Our optimism is already being rewarded. In the<br />
six weeks since the publication of our article,<br />
Professor Dirk Van Vuren of the University of<br />
California at Davis has informed me that he is<br />
suspicious that members of one species of large<br />
ground squirrels in his study-area in Colorado<br />
might be killing members of another species<br />
of smaller ground squirrels. And Lynda Watson,<br />
who has been live trapping and rearing blacktailed<br />
prairie dogs for over 30 years, has just<br />
informed me that she has observed, but has<br />
not previously reported, that black-tailed prairie<br />
dogs in southern Texas frequently kill Mexican<br />
ground squirrels.<br />
Our research might suggest that prairie dogs are<br />
savage, senseless killers of ground squirrels. But<br />
from another perspective, perhaps we should<br />
view the killers as excellent parents. Prepared to<br />
protect their offspring and the resources their<br />
families need to survive, prairie dogs are not<br />
so different from the way many people would<br />
react when faced with a trespassing nonhuman<br />
animal. Our investigation underscores two of the<br />
most compelling lessons I have learned from my<br />
four decades of research. First, long term research<br />
and careful analyses are crucial and decisive for<br />
understanding the ecology and social behaviour<br />
of animals as complex as prairie dogs. Second,<br />
when you spend a lifetime studying a captivating<br />
animal like I have, you have the opportunity to<br />
make fascinating discoveries that lead to novel,<br />
far-reaching conclusions.<br />
Hoogland, J. L., & Brown, C. R. (2016, March).<br />
Prairie dogs increase fitness by killing<br />
interspecific competitors. In Proc. R. Soc. B<br />
(Vol. 283, No. 1827, p. 20160144). The Royal<br />
Society.<br />
62 - BIOSPHERE BIOSPHERE - 63
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