Black skimmer parental defence against chick predation by gulls

Predation by laughing gulls, Larus atricilla, on black skimmer, Rynchops niger, chicks was observed in a Texas nesting colony. The patterns of predation differed from random in two respects: (1) significantly more attacks (both attempts and successes) were directed toward nests with two parents present than toward nests with only one parent and (2) significantly more attempts occurred when female parents were brooding than males. Differences in …