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Estimating population dynamics (the number, gender, age and relatedness of individuals in a population) and viability (reproductive ability, adaptability) is essential to understanding the degree of security or threat facing a species. However, many methods of analysing these factors intrinsically change the value of the data. For example, anesthetising free-ranging animals repeatedly to take blood and tissue samples to determine reproductive and health status can cause so much stress that reproduction is inhibited, health is affected and may change the population’s behaviour towards that individual.
Zoo-based populations give us a unique opportunity to assess individuals that are accustomed to human contact, increasing confidence in the baseline data collected. Perhaps more importantly, having detailed knowledge of the Zoo-based population allows us to develop techniques for assessing population parameters non-invasively. For example, we now know that faecal and urine samples from an individual mirror hormone levels in the blood, with some delay. The Wildlife Reproductive Centre (WRC)based at the Taronga Western Plains Zoo can now collect information about the reproductive cycles of females, seasonality, diagnose pregnancy and predict when birth will occur in many species without even coming close to the animal. We can also assess levels of adrenal hormones (which indicate stress), take genetic samples and tell a great deal about diet and general health from these same “remote” samples.
Reproductive and adrenal hormones are metabolised to smaller fractions and excreted in the urine and faeces. The type of hormone fractions (called metabolites) and the way they are excreted (in urine or faeces) may differ from species to species. Specific techniques have been developed and validated for each species of interest, so that hormone concentrations can be assessed non-invasively. These techniques can be used to evaluate hormones from captive and wild animals, and combined with behavioural observations they increase our understanding of the biology of each species.
The Wildlife Reproductive Centre at Taronga Western Plains Zoo was the first of its kind in Australia when it was built in 1994. The WRC works with other staff within the Taronga Conservation Society Australia, other wildlife organisations or academic collaborators to gain information needed for the management of captive or free-ranging populations and to answer fundamental questions about reproductive biology and population dynamics and viability.
The WRC also incorporates the Animal Gene Storage Resource Centre of Australia (AGSRCA) which was established as a joint venture between the Taronga Conservation Society Australia and the Monash Institute of Reproduction and Development in 1995, and includes “frozen zoos” of genetic material at both sites. This program aims to develop new techniques to collect, preserve and store genetic material from endangered and other important species including the Black Rhinoceros, Greater Bilby, Common Wombat, Tasmanian Devil and African Wild Dog.
Asian Elephant Reproduction
The Wildlife Reproduction Centre (WRC) monitors all the females of the Zoo’s herd to determine the optimal time for natural mating or artificial insemination, and to diagnose pregnancy and determine the likely timing of birth. Work continues to determine the sex of the baby using hormonal changes in the pregnant female.
Remote Monitoring of Adrenal Activity in Rhinoceros
Our Zoo-based population provides us with an opportunity to test faecal hormone monitoring as a method for measuring adrenal activity in rhinos. In combination with keeper notes and behavioural observations, we are able to determine the best hormone analysis techniques for this species. This validation could prove useful to the assessment of adrenal activity in free-ranging populations in future research programs.
In Vitro Fertilisation of Rhino Eggs
Over the last five years, an international team of reproductive experts including IZW from Berlin and Australian equine experts has gathered at Taronga Western Plains Zoo to develop techniques to collect, mature and fertilise eggs from two non-reproductive black rhino females. Each year has advanced our knowledge and we are now capable of retrieving eggs, maturing them and have produced the world’s first rhino IVF embryo. Next steps will improve embryo development and transfer to surrogate mothers.
Analysis of factors governing captive breeding success in the Tasmanian devil (Sarcophilus harrisii)
(PhD Student Tamara Keeley, Honours Student Kellie Masters)
The objective of this study is to increase our knowledge of reproduction under different environmental conditions. We use non-invasive analysis of reproductive and adrenal hormones combined with behavioural observations during estrous, natural mating and parturition to determine potential factors governing breeding success. The results will guide the management of our insurance population to maximise breeding success as well as expanding our understanding of the species biology.
Reproductive parameters of subtropical Dugongs (PhD Student Elizabeth Burgess)
The Wildlife Reproductive Centre, in collaboration with PhD student Elizabeth Burgess, Dr Janet Lanyon (Marine Vertebrate Ecology Research Group at the University of Queensland) and staff at SeaWorld and the Sydney Aquarium we are studying zoo-based Dugongs to better understand Dugong reproductive biology and develop population models that incorporate reliable life history parameters. Hormone metabolite concentrations in faecal samples have been used to map reproductive patterns in known Dugongs, and paired with morphometric parameters to determine gender and reproductive state in wild dugongs. This information has improved the monitoring of this species from absolute numbers to include an understanding of population dynamics and viability.