Reproductive vulnerability: Parental attendance around hatching in roseate (Sterna dougallii) and common (S. hirundo) terns

Presence of one or both members of a pair at the nest site during the incubation and early chick stage reduces reproductive losses due to predation and weather stresses. The authors monitored the presence of pair members by the temporary removal of one member of several pairs of Roseate (Sterna dougallii ) and Common (Sterna hirundo ) Terns at nests at Cedar Beach, New York, to determine if vulnerability varies by reproductive stage, to compare species differences that might partially account for declines in Roseate Tern populations, and to examine their response to trapping. There were significant differences between species in the time to return to the nest following an initial disturbance, and Roseate Terns that were trapped and released took longer to return to the nest and resume incubating than did Common Terns. The nests of Roseate Terns were vulnerable (neither adult in attendance) for longer time than were the nests of Common Terns.