NAIVE BILBIES SNIFF OUT CANINE FOE

The evolutionary timeframe necessary for naïve prey species to recognise and respond to novel predators is difficult to ascertain. For instance, does it scale to how long a species has coevolved with a predator (known as the ‘ghost of predators past’ hypothesis), is it based upon ontogenetic experience (altered behaviour based on plasticity or learning), or is it a generalised response triggered by shared characteristics of predators (known as the ‘predator archetype’ hypothesis)? The ‘ghosts of predators past’ hypothesis posits that prey species possess hard-wired antipredator responses to predators they have coevolved with over long timeframes. A December 2017 paper by Lisa Steindler and colleagues suggests support for that hypothesis in research conducted on predator-naïve greater bilbies (Macrotis lagotis, above) within a 60 km2 predator-free enclosure at Arid Recovery Reserve, South Australia, where bilbies have been isolated from predators for 16 years. Since the dingo (Canis lupis dingo) arrived in Australia some 4000 years ago, greater bilbies have coevolved with dogs on the continent for many centuries longer than the two centuries in which they have encountered cats (Felis catus). Bilbys’ burrow-emergence behaviour was found to differ accordingly when presented with olfactory stimuli (faeces) from introduced domestic dogs versus domestic cats. When dog faeces, which are chemically indistinguishable from dingo scats, were present, the bilbies spent more time with only their head and shoulders out of the burrow than they did when cat, rabbit, or unscented control faeces were present (in which case they emerged entirely). The findings support the ‘ghost of predators past’ hypothesis, as bilbies have retained antipredator responses to dogs/dingo scent while remaining oblivious to the danger of cats. In 2012, Carthey and Banks suggested that naturalisation of a predator should be deemed to have occurred once a prey species is no longer naïve towards it. Steindler et al. propose that this clear discrimination, even when these bilbies had no lifetime exposure to mammalian predators, supports the notion that dingoes should be considered a naturalised species in Australia.

Steindler LA, et al. 2018. Animal Behaviour. DOI: 10.1016/j.anbehav.2018.01.013