Trialing captive-releases of the critically endangered regent honeyeater in NE Victoria, Australia

Summary

The regent honeyeater (Anthochaera phrygia), Critically Endangered with a population as low as 400 birds after severe habitat clearance across southeastern Australia, has been the subject of a national recovery program since 1994, including a captive breeding population managed by Taronga Zoo, maintained at around 50 individuals even as the wild population continued to decline. Following a largely unsuccessful 2000 trial release of nine birds in New South Wales, the recovery team refined husbandry and field techniques and conducted three larger trial releases, in 2008, 2010 and 2013, within more intact habitat in Chiltern-Mt. Pilot National Park, Victoria, releasing 109 captive-bred birds in total after hardening them in holding aviaries with cut eucalypt flowers. Each release fitted a subset of birds with radio transmitters for daily tracking, alongside color leg bands and extensive citizen-science-assisted monitoring; short-term survival exceeded 70% at ten weeks across releases with no clear effect of age or sex, and over 25% of the 2010 cohort and over 10% of the 2013 cohort were re-sighted at least a year later, both well above typical rates for banded wild birds. Difficulties included a harness design that injured birds before redevelopment, avian predation claiming up to 10% of each cohort, a greater than 90% post-release nest failure rate, volunteer fatigue, and competition from aggressive native noisy miners. The project rates itself successful, crediting the species' strong captive fecundity, well-researched release-site and timing choices matched to peak eucalypt flowering, intensive citizen-science-supported monitoring, and the species' surprising behavioral robustness despite its critical status.