Translocation and reintroduction are used to reduce extinction risk associated with a small population and range size in threatened mammal species. We evaluated the outcome of a reintroduction of the bridled nailtail wallaby Onychogalea fraenata to Avocet Nature Refuge, a private refuge in central Queensland, Australia. This macropod was also reintroduced to Idalia National Park in western Queensland in 1996 and occurs in one natural population in central Queensland. We estimated population growth, adult and juvenile survival, and distribution changes since the last release of O. fraenata to Avocet in 2005, and evaluated female reproductive success and health. Although animals were in good condition, population size was a tenth of that of the 1996 Idalia reintroduction reported after 3 years and, unlike at Idalia, juvenile survival at Avocet was low. The likely causes are consistent with predictors of translocation and reintroduction failures in mammals. These are predation, the small number of individuals in each release, the likely suboptimal health status of reintroduced individuals, drought, and possibly lack of dispersal from the small area of preferred habitat. The lessons of this reintroduction are that future attempts are likely to have the best chance of success if they occur in non-drought years, at sites with large, non-fragmented areas of brigalow forest, involve the release of large groups of animals together, and are accompanied by intensive, long-term baiting to control introduced predators.

Bridled nailtail wallabies Onychogalea fraenata are endangered, medium-sized, nocturnal macropodids that persist at only one location in central Queensland, Australia. Characteristics of juvenile development, shelter use, anti-predator behaviour and maternal care were investigated in the wild using trapping, radio-tracking and spotlighting observations. Timing of developmental stages was identical to the pattern previously found in captivity, except for age at weaning which was much earlier in the wild. After young had left the pouch permanently at 17 weeks of age and weighing c. 800 g, they always spent the day concealed in dense cover, generally >200 m from their mothers. Juveniles were also alone in >50% of observations at night, and stayed closer to cover than did adult females. Young became independent of their mothers 7–8 weeks after permanent exit from the pouch and weighing c. 1800 g. Females with dependent juveniles changed their behaviour in ways likely to reduce predation on young. They reduced their home ranges, stayed closer to cover and became more wary than other females. Juveniles differed from adult females in their habitat use, anti-predator behaviour and shelter site preferences. Juveniles were more likely than adults to respond to threats by standing still or lying flat on the ground, whether or not they were in concealing cover. Juveniles used a wider range of smaller shelters than adults, and were less likely to use solid shelters such as hollow logs during the day. Because bridled nailtail wallabies have a ‘hider’ strategy of maternal care and the young rely on crypsis, successful breeding in the wild requires dense vegetation cover.