Zoological Parks Authority - Parliament of Western Australia - The ...

Zoological Parks Authority ANNUAL REPORT 2012
Agency Performance – Report on Operations
Directorate Reports
Animal Health Services and Research Directorate continued
Reproductive Biology Unit
Perth Zoo’s Post-doctoral Researcher,
Dr Lindsay Hogan, completed work on an
in-depth study into Numbat reproduction.
Using faecal samples collected from the Zoo’s
Numbat colony over an 18 month period, Dr
Hogan was able to map the hormonal changes
involved in the annual breeding cycle of male
and female Numbats. The analysis has helped
determine when a female Numbat is at her
peak breeding cycle, how long the cycle lasts
and how many cycles she has each season. It
is hoped that the research findings will increase
the number of Numbats born at Perth Zoo each
year for release into the wild.
Dr Hogan also used faecal steroid profiles to
identify the sex of frogs reared and bred at the
Zoo. Being able to sex animals prior to their
release into the wild helps ensure that founding
populations have the desired sex ratio.
Native Species Breeding Program
Perth Zoo’s Native Species Breeding Program
breeds threatened native species for release
into protected areas in conjunction with DEC
as part of species recovery plans. The program
includes critically endangered Western Swamp
Tortoise, Numbat, Dibbler and three species
of frogs.
Case Study
The Western Swamp Tortoise is Australia’s smallest tortoise and its
most endangered reptile. It is found naturally in ephemeral swamps
(swamps that fill in winter and spring and dry out in summer).
Unlike many reptiles, Western Swamp Tortoises are active in winter
when they feed and grow. During summer and autumn they sleep.
This is known as aestivation. As the swamps dry out, food becomes
harder to find and the tortoises retreat from the wetlands to burrow in the ground or under deep
piles of leaf littler and sleep until the rains come again, the swamps fill and food is plentiful.
The Western Swamp Tortoise was thought to be extinct for over 100 years until rediscovered
in 1953. In the 1980s there were estimated to be less than 30 left in the wild. Habitat loss and
introduced predators (foxes, cats, dogs and pigs) are major threats to the tortoise.
Thanks to a species recovery program and the efforts of Perth Zoo, the Department of
Environment and Conservation and other organisations, the Western Swamp Tortoise is now
facing a brighter future.
Since 1994, more than 570 Western Swamp tortoises bred at Perth Zoo have been released into
protected habitat near Perth. In addition to its breed-for-release program, Perth Zoo also holds an
insurance population of around 150-200 Western Swamp Tortoises.
The tortoises bred at Perth Zoo are not released until they are large enough to avoid being carried
off and eaten by ravens (a natural predator). Weighing just 4-6 grams when they hatch, the young
tortoises spend the first three years of their life at the Zoo, developing and growing until they
reach the required release weight of 100 grams.
Like all species, the Western Swamp Tortoise is vulnerable to climate change. Late rains delay the
release of the tortoises and if there is a drought they cannot be released.
Since the recovery program began, the tortoises have been released at various sites including
Twin Swamps, Ellenbrook and Mogumber Nature Reserves and more recently at Moore River
Nature Reserve.
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