Return of the Fauna: Brown Treecreeper Reintroductions in Eucalypt Woodland
From October 2009 to December 2011, the Foundation for National Parks & Wildlife funded the first experimental reintroductions of the threatened Brown Treecreeper, Climacteris picumnus. This species was released into Mulligans Flat and Goorooyarroo Nature Reserves in the Australian Capital Territory, where large-scale habitat restoration experiments are ongoing.
The project was undertaken by the Fenner School of Environment & Society at the Australian National University.
Reintroduced Brown Treecreeper birds were monitored and tracked with radio devices purchased with the funding. This experiment helped re-establish a declining woodland bird species.
It also examined factors influencing the success of reintroduction programs and evaluated tests of habitat selection theories that underpin reintroductions and habitat restoration. This project will therefore guide the future design of these programs in many Australian and international environments.
Brown Treecreepers were released in two stages into Mulligans Flat and Goorooyarroo Nature Reserves, with releases in November 2009 and July 2010.
The reintroductions of Brown Treecreepers began to create a self-sustaining population in an area where this species had recently became locally extinct. These nature reserves are undergoing large-scale restoration providing a foundation for the release of the birds.
Between November and December 2009, translocation of 43 Brown Treecreepers from the Murrumbidgee and south east Wagga Wagga took place. By fitting 18 of these birds with radio-transmitters, the team monitored their location, behaviour and substrate use twice a day until the end of February. The remaining birds were also located each day to document survival.
Releasing the birds as a family group with dependent fledglings promoted group unity with most birds establishing contact with other family members almost immediately after release. The estimated 22 surviving birds is lower than hoped but is within the predetermined criteria for success. However this total estimation comes from visual sightings and it is likely that a number of birds are now in areas away from their family group making them more difficult to locate. Monitoring will continue monthly, including more detailed assessments on attempted or successful reproduction.
Brown Treecreepers are cooperative breeders with groups made up of breeding pairs and young offspring helpers that delay dispersal. Male helpers disperse to empty territories to establish a breeding position. As expected, a number of radio-tracked male helpers left their family presumably in search of a territory and or potential partner. One male bird still remains away from his family group, after travelling over 6.5km to habitat outside the reserves.
As well as these expected results, initial monitoring gave some unexpected results. Females generally remain with the family group. It was therefore surprising to observe four females leaving the group for up to three days at a time to explore the surrounding environment. Perhaps they were searching for higher quality habitat.
Initial examinations of substrate use for radio-tracked Brown Treecreepers show a high use of trunks and branches in comparison to logs and other ground substrates. This is surprising as previous studies have documented the Brown Treecreeper to spend a lot of their time foraging on the ground around areas of short grass or bare ground. This may be a result of cautious behaviour in an unfamiliar environment, or an indication of the quality of the ground layer within the environment.
The project team is now looking at the behaviour and habitat use of the reintroduced birds which will provide information about habitat quality and the effectiveness of the restoration sites. In particular, they will examine how Brown Treecreepers select habitats in unfamiliar environments. The Foundation looks forward to the final results of this project which will help treecreeper reintroduction programs elsewhere.
