Brown treecreeper re-introduction into eucalypt woodland in the Australian Capital Territory, Australia

Summary

The brown treecreeper (Climacteris picumnus), Vulnerable and locally extinct from the Mulligans Flat and Goorooyarroo Nature Reserves in the Australian Capital Territory through habitat degradation, particularly the loss of tree hollows and coarse woody debris, was reintroduced in November 2009 as part of a large experimental restoration project testing combinations of habitat treatments across the 1,623-hectare reserve complex. Seven cooperatively breeding social groups, 43 birds total, were sourced from a well-studied, stable population 200 km away and hard-released intact to preserve social bonds, with leg-bands on all birds and radio transmitters on 18 adults, deliberately distributed across different habitat treatment combinations to test effects on survival and settlement. Short-term survival was strong, 93% at 24 hours and 91% at three days, with high social cohesion maintained immediately after release, and supplemented coarse woody debris measurably increased ground- and log-foraging behavior; however, numbers declined steadily over the following three months, all four confirmed deaths among radio-tracked birds were attributed to native predators, and every tracked bird eventually left its release site, dispersing farther than typical natal dispersal and ultimately settling preferentially in drier, low-vegetation-cover areas rather than the predicted optimal treatment sites. Difficulties included medium-term survival well below natural wild populations, higher-than-expected predation possibly linked to fewer refuge areas at the release site, and the logistical challenge of tracking widely dispersing birds. The project rates itself partially successful, crediting the release process itself, evidenced by very high initial survival and group cohesion, even though it did not meet its medium-term survival and establishment criteria.