Breeding Biology of the Bridled Tern (Sterna anaethetus) in New Caledonia

Bridled Terns (Sterna anaethetus) have only recently been discovered breeding in New Caledonia, the previous nearest breeding colonies being in Eastern Australia. Bridled Tern breeding biology was investigated in a single, small (c. 100 pairs) colony during the 2003 and 2004 breeding seasons. Of 93 nests monitored, 82 were tinder cover (70 under rock and twelve under vegetation). Nesting location did not predict hatching success. Almost half (49%) of the 37 nests monitored in 2003 were reused in 2004. Egg-laying took place between late October and mid-January; egg volumes did not vary between the two breeding seasons. Chicks reached their asymptotic weight (132 g) at 37 d, faster than chicks in Australia (40-53 d). Wing length was the most reliable predictor of chick age. An equation based on density was generated to age eggs, and graphs to age chicks. An estimated 81% of clutches produced fledglings. Predation of tern nests by Silver Gull (Larus novaehollandiae) was not observed, but Peregrine Falcons (Falco peregrinus) were observed hunting and catching adult terns. Received 12 August 2009, accepted 17 February 2010.