Caribbean Compass Yachting Magazine - November 2020

OUR ISLAND BIRDS BY BELA BROWN
I’M
rather fond of Tropical Mockingbirds. Not only are
they impeccably clad in elegant shades of grey and
white, but they’re bold, perceptive creatures, with
intelligent, expressive eyes that look as though
they’re saying “I’m watching you!’’
Yes, make no mistake — they are watching and may even remember
you. According to a study carried out in 2009 by biologists at the
University of Florida, Mockingbirds can recognize and remember the faces
of people perceived as dangerous to their nests. The research describes
how student volunteers approached and touched 24 nests for four days
in a row, wearing different clothing and approaching from different
directions each day. The birds acted more hostile each succeeding day, as
they became increasingly familiar with the volunteers, flushing out earlier
and attacking, even grazing the intruders’ heads at times. However, when
different people approached the nest, the birds remained unruffled. A
Professor of Biology at University of Florida, Doug Levey, says, “Sixty
seconds of exposure was all it took for mockingbirds to learn to identify
different individuals and pick them out of all other students on campus.’’
This stands in sharp contrast with laboratory studies in which pigeons
recognized human faces only after substantial training.
Tropical Mockingbirds (Mimus gilvus) are song virtuosos found from
southern Mexico to northern South America and from the eastern coast
of Brazil to the southern Lesser Antilles as far north as Antigua. They
were introduced to Trinidad and Panama where populations are now
well established.
The species favours open habitats, including beaches, grassy wetlands,
farmlands, towns, gardens and boatyards. You can spot them perched on
exposed shrubs and treetops, telephone lines, fences and laid-up boats.
They can be seen hawking swarming termites after the first heavy rains,
or on the ground disturbing insects by flashing their wings repeatedly —
lifting and spreading them in striking “archangel fashion’’ while uttering
an occasional, almost absent-minded “tcherk.’’
The Tropical Mockingbird,
A Delightful Songster
Tropical Mockingbirds are
closely related to the famous
Northern Mockingbird (Mimus
polyglottos). Although most experts
treat them as two separate species,
they are sometimes classified as
one. They’re almost identical, the
main difference being that the
Tropical Mockingbird has less
white on its wings and primary
feathers. Otherwise, their
behaviour, songs and calls are
often undistinguishable and
individuals are known to
interbreed and produce young in
areas where the two species meet.
However, unlike their northern
counterparts, who are famous for
mimicking other species of birds,
Tropical Mockingbirds very rarely
mimic, though some individuals
are known to have accomplished
some spectacular mimics,
including learning the Brazilian
national anthem.
Like their northern relatives,
Tropical Mockers have larger-thanlife
personalities that make them
one of the most conspicuous birds
in their habitat. They are absolutely fearless, with a fierce spirit that when
provoked can inflict dread in the hearts of their bravest foes. Certainly,
while other birds give alarm calls in the presence of a predator, this hottempered
little bundle of feathers will not think twice about confronting a
cat, dog or hawk that gets too close to its nest, meeting them head on with
a full artillery of beak, feathers and swooping feet.
Yet, for all their displays of temper, Tropical Mockingbirds rarely
physically fight among themselves. Instead, they establish territorial
boundaries and entice their mates with skill and imagination. Males are
territorial all year round and engage in musical battles that can go on for
many days and occasionally through the night. Singing at night tells
neighbors that there is a sharp, tireless and sleepless dominant male
present on the land. The quality of the songs diminishes greatly during
territorial disputes, as birds hold back on creativity and instead focus all
their energy on unrelenting repetitiveness and volume — qualities much
admired by other males. Repetitiveness is a way of asserting male
dominance between top-ranking males. Male dominance is determined by
how repetitive and consistent their songs are and the older the male, the
more consistent the song.
A few months back, I had the opportunity to witness the theatricals of
a male mockingbird firsthand, as a top-ranking male selected a perch a
few feet from our house from which to assert his dominance. The bird
sang non-stop for hours at a time and only stopped singing for short
feeding breaks, piping fragmented phrases between mouthfuls, as if
survival depended on continuous singing — and to him, it did! Had he
shown weakness, the other males would soon start to encroach on his
land and losing part of his territory would drastically diminish the
chances of finding a mate and rearing a family. So, the impudent fellow
kept his song on high volume and his diaphragm working hard, until he
was sure he’d won the battle.
Males and females both sing and are very similar in appearance, making
it quite difficult to tell them apart. However, males are the more creative
singers, with a much greater range of vocalizations and song consistency.
The song consists of over one hundred syllables and includes long, clear
whistles, trills and phrases with a staccato quality.
Tropical Mockingbirds are socially monogamous, with cooperative
breeding recorded in some populations. The breeding season occurs
throughout the year, but tends to peak at the onset of the rainy season
when there is an increase in the insect population. Females place
cleverness above brute strength and are attracted to the males with the
largest, most consistent repertoire. Thus, males will sing their most
complex songs when courting a potential mate, who, hopefully, will listen
in rapturous devotion.
Once paired, a couple will chase each other around uttering soft and
harsh sounds, touring the territory while looking for the best spots to
build a nest, usually somewhere a couple of metres from the ground.
Males sing before and during copulation. Then, the homemaking females
help their mates line the inner cup of the nest, while males build the outer
foundation with small sticks, leaves and other material.
Tropical Mockingbirds are multi-brooders, raising as many as four
broods per season. The females lay two or three eggs, which they alone
incubate for 11 to 15 days, while the males defend the nest and territory
from potential predators, such as domestic cats, iguanas and mongoose.
They’re bold, perceptive creatures, with intelligent, expressive eyes that look as though
they’re saying ‘I’m watching you!‘
Both the male and female will defend the nest when faced with a serious
threat and if necessary, unrelated mockingbirds will rush in to help a
besieged couple. Once the chicks hatch, both parents care for the
hatchlings, until eventually the males take over feeding and teaching the
fledglings to fly, while the females begin the construction of a new nest
and the incubation of a new clutch. The immature birds from earlier
clutches may stay and help raise their younger siblings.
Juveniles are not born knowing how to sing. Instead they start out with
baby talk and learn to sing by mimicking the adults. Later, they begin to
sing “plastic songs’’ — using adult sounds with well-defined phrases, but
with a fair amount of babbling and displaced phrases in the mix. As they
get older, their songs become highly consistent and therefore more
dominant, leading to successful mating and reproduction.
As you see, contrary to popular belief, mockingbirds don’t sing for our
pleasure, but rather out of necessity. Nevertheless, by singing their
beautiful songs, these popular, delightful songsters unwittingly fill the
world with beauty and cheer.
NOVEMBER 2020 CARIBBEAN COMPASS PAGE 21