Using translocation of North Island robins to counter effects of forest fragmentation in the central North Island of New Zealand

Summary

Massey University researchers used North Island robins (Petroica longipes), a common but declining forest bird, as a research tool to test whether translocation can counteract habitat fragmentation, rather than to rescue an endangered species. Working in fragmented native forest patches near Benneydale in the central North Island, where about 40 percent of patches already held robins, the team translocated 34 birds to six unoccupied fragments in 2005 and 72 birds to seven more in 2006, sourcing birds from a nearby pine plantation scheduled for felling to avoid any conservation cost to the source population. Birds were lured with mealworms into spring-loaded clap traps, colour-banded, fitted with pelvis-harnessed radio transmitters, held briefly in modified carrying boxes, and released in small, sex-balanced groups of up to five pairs per patch to spread monitoring effort and improve learning between translocations. Only 29 percent of translocated birds remained in their target patches by the following breeding season, with dispersal strongly correlated with patch isolation, though natural colonists were subsequently drawn in by the translocated birds. Comparing 49 breeding robins across ten newly occupied fragments against 77 in naturally occupied fragments over two seasons found slightly higher reproductive rates but lower adult survival in the new fragments. The project rated itself Successful, reporting that although the underlying research is not yet concluded, robins have established and successfully bred in most of the previously unoccupied fragments.