Better the devil you know?

MSc project investigates whether Tasmanian devils scents convey individually-specific signals, and whether these can be used to increase the success of reintroduction attempts.

Elizabeth Reid-Wainscoat (MSc student, University of California, Los Angeles)

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Captive devil being release at Narawntapu State Park September, 2015. Photo: E. Reid-Wainscoat.

The Tasmanian devil is a carnivorous marsupial that has suffered dramatic population decline in the past 20 years due to a contagious fatal cancer called Devil Facial Tumor Disease or DFTD. Due to this devastating disease, the Tasmanian devil is now endangered. To protect against possible extinction researchers decided to collect some of the remaining healthy individuals from the wild and start a captive breeding program. The goal was to help counteract the effects of this disease by supplementing the wild population with healthy, vaccinated individuals from the captive population. However, this strategy of reintroducing captive animals to the wild has proven very difficult with a variety of other species. Specifically, it is very hard to simulate the wild environment in captivity and thus captive animals often do not have the skills needed to survive. In addition, the stress of being released into a novel environment can cause the animals to disperse immediately from the area into environments that are potentially more dangerous and less suitable for their ecological needs.

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Wild devil investigating a latrine site. Photo: E. Reid-Wainscoat.

To address these issues a collaborative project was developed by the San Diego Institute for Conservation Research and the Save the Tasmanian Devil Program to study the behavioral ecology of the Tasmanian devil. Although Tasmanian devils are considered solitary, it is widely known that they use latrine sites, or communal areas of scat and urine deposition, within any given population. This means that although they might not interact physically, they may be using scent cues to communicate which individuals are in an area. This is interesting because although they do not defend territories, there is the potential that they are more familiar with the individuals within their population because of the scent cues they leave at known latrine sites. This could mean that introducing new individuals into a population could disrupt the social system in place and could cause heightened levels of aggression between resident devils and the new individuals entering the population. This is especially problematic because DFTD is contagious so if infected devils are biting healthy devils the disease is going to spread through the population more quickly.

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Captive devil investigating (L) and counter-marking (R) a conspecific scat.
Photo: Debra Shier

 

Previous studies have shown that familiarization of individuals can increase survival and decrease dispersal post-release. Thus, this study is testing the effects of familiarization via scent cues between release candidates and resident devils prior to release. We hope to encourage social integration between the two groups of Tasmanian devils and decrease dispersal from the release site to ensure the reintroduction efforts successfully increase wild Tasmanian devil populations. Specifically, we are identifying the level of specificity that we can expect the Tasmanian devils to be communicating with their scent cues. This involves testing their scent gland secretions as well as their scat for specific chemical components that could be gender and/or individually specific. If we can show that there are detectable differences between individuals then this will support preliminary behavioral findings that suggest they are able to discriminate between individuals. We can then test the impact of familiarization on aggression levels to determine if familiarization could potentially reduce disease transmission rates. Finally, we want to test what effect familiarization has on survival post-release to determine the most effective strategies to re-establishing the Tasmanian devil wild population.

Collaborators:

STDPSan Diego ZooUSyd