The great escape

By Natasha Tay. Australian animals get a bad rep for being a bit obtuse when it comes to predators, with more than half (73 of 124) of Australia’s Extinct, Threatened and Near Threatened terrestrial mammal species considered to be extremely susceptible to introduced red foxes and feral cats (Radford et al. 2018). For this reason, today many of our native species are confined to the safety of predator-free islands or fenced sanctuaries like Arid Recovery. Reintroduction attempts outside of such protected areas often fail due to predation. As such many conservation efforts have focused on removing these predators for the safety of our wildlife. Yet the dream of a future beyond fences is not lost- Arid Recovery’s Prey Naivety project is putting predators back into the equation.

Within the Red Lake expansion, burrowing bettongs (and greater bilbies) have been coexisting with a low density of cats since 2014. The idea is the large bettong population will be able to persist alongside cats and survive low levels of hunting. This coexistence may lead them to developing appropriate antipredator behaviours, e.g. getting better at hiding (‘avoidance behaviour’) or evading attacks (‘escape behaviour’) from cats.

A burrowing bettong. © Nathan Beerkens
A burrowing bettong. © Nathan Beerkens

Initial results from this project have been promising. Cat-exposed bettongs were more docile when trapped (a representation of hiding behaviour) and approached feed trays more slowly and cautiously in the presence of cat odour (see Saxon-Mills et al. 2018; West et al. 2018). These are ‘avoidance behaviours’ designed to reduce the chance of a cat encounter, but what about when the cat has already started its attack? Are bettongs getting better at escaping from a cat ready to pounce?

To answer this question, I trapped and tested the escape performance of bettongs from Red Lake (‘cat-exposed’) and bettongs from a population without cats (‘cat-naive’). Bettongs were placed in a runway, presented with a threatening stimulus, and encouraged to flee. I filmed how each bettong moved through the runway: recording details like speed and how often they changed direction trying to outmanoeuvre the threat during the chase.

Filming bettongs to measure their escape performance. © Natasha Tay

Newly published last week, my research found cat-exposed bettongs were more reactive, quickly hopping down the runway rather than hanging around to inspect the strange stimulus like their cat-naive counterparts did. Body mass also affected escape behaviour differently between the two populations. For the cat-naive bettongs, there was some evidence that bigger animals were slower than smaller animals. While in the cat-exposed population, larger animals performed longer bounds and were faster than smaller animals (as predicted by biological principles- bigger animals have longer limbs and can thus achieve faster speeds).

This result suggests the cat-naive animals were less motivated to flee than cat-exposed bettongs. Perhaps cat-naive bettongs, used to being the big bosses in their predator-free enclosures, did not think much of our ‘threatening’ stimulus. Bettongs living with cats, on the other hand, were able to transfer their general fear of cat predators to this new stimulus and fled down the runway at an intensity where body size affected their performance.

This work shows that introducing low levels of predation pressure can successfully promote the development of antipredator behaviours through selection and/or individual learning. Controlled predator exposure may be able to address some types of prey naivety and lead to increased survival outside predator-free sanctuaries.

You can read the full paper here: https://doi.org/10.1016/j.anbehav.2021.02.013

Tay, N.E., Fleming, P.A., Warburton, N.M. and Moseby, K.E., 2021. Predator exposure enhances the escape behaviour of a small marsupial, the burrowing bettong. Animal Behaviour, 175: 45-56.

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