The impact of headstarting on the survival and naivete of an endangered terrestrial mammal after return to the wild

Complete separation of endangered prey from introduced predators improves prey survival at the cost of reduced predator recognition and antipredator behaviours, termed 'prey naivete'. Headstarting is a conservation strategy that has been used to improve the survival of juveniles for numerous species, whereby prey is separated from predators only in their vulnerable early life stage before release to the wild. However, by isolating prey from predators headstarting could compromise prey individuals' antipredator behaviour. Here, we evaluate the effects that headstarting has on the survival, dispersal, body condition and flight initiation distance (FID) of a terrestrial mammal, the bridled nailtail wallaby Onychogalea fraenata. Young bridled nailtail wallabies were isolated from predators in a 9.2 ha predator-free fenced exclosure and were released into the wild once their body mass exceeded 3 kg. There was no difference in dispersal, body condition or survival of headstarted wallabies compared to wild-raised wallabies. FID of headstarted wallabies assessed using night-vision goggles was lower than wild-raised wallabies in the week following release, but converged with that of wild-raised wallabies within 4 weeks post-release. Our results show that headstarting can be an effective conservation strategy for terrestrial mammals whose early life stages are vulnerable to introduced predators.

Automated summary

The study shows that headstarting can effectively protect terrestrial mammals whose early life stages are vulnerable to introduced predators. Bridled nailtail wallabies isolated from predators in a 9.2 ha predator-free fenced exclosure and released into the wild did not show any differences in dispersal, body condition, or survival compared to wild-raised wallabies.