IDENTIFYING PREDATORS AT NESTS OF SMALL BIRDS IN A NEW-ZEALAND FOREST

Time-lapse video equipment uas used to film continuously at nests of t wo small passerines, the New Zealand Robin Petroica australis and the Tomtit Petroica macrocephala, in an indigenous broadleaf/hardwood fore st in central North Island, New Zealand, The nests were illuminated wi th infrared light. to allow night-time observations of predator and pa rent bird behaviour, and signs left at nests were linked to predator i dentity, Introduced Ship Rats Rattus rattus and the small native owl o r Ruru Ninox novaeseelandiae were filmed preying on eggs or chicks on 12 occasions, and Ship Rats scavenged on eggs on two occasions, Parent birds sometimes altered the signs left at nests after predation, whic h confused identification of the predator, while Ship Rat scavenger an d predator signs were indistinguishable. This suggests that attempts t o identify predators from nest signs could be misleading and potential ly a widespread problem. Time-lapse video filming with infrared illumi nation is potentially the least biased method of identifying predators , but it is expensive and so is best used in conjunction with simpler methods, This study found no evidence that filming altered predation r ates or that the predators or parent birds reacted strongly to the cam era or lights, so we believe that filming is a valuable and safe techn ique to guide management, for the recovery of critically endangered sp ecies that are threatened by predators.