POSSIBLE EVIDENCE OF DOUBLE-BROODING IN COMMON TERNS (STERNA-HIRUNDO) AT ONEIDA LAKE, NEW-YORK

Double-brooding is not common in the Laridae. Only three species in this family have been reported to double-brood: Silver Gull (Larus novaehollandiae), Common Black-headed Gull (Larus ridibundus), and Common Tern (Sterna hirundo). I present seven instances of double-brooding by Common Terns at Oneida Lake, New York, in 1988 and 1989. Ten chicks hatched from six of the second broods, and six of them survived greater-than-or-equal-to 10 days. The higher frequency of double-brooding in 1988 may have been due to abundant food supply and fair weather. Each double-brooded pair except one had their second brood on a different island than their first brood. I think this is because vegetation on the first island became tall and dense, and was not suitable for nesting late in the breeding season. My results support the idea that double-brooding may be a viable reproductive strategy for Common Terns.