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Males or pairs of American black ducks (Anas rubripes) disturbed by the observer usually flew a short distance offshore and returned soon after the observer withdrew. If disturbed just prior to nesting, the pair flew off with the female quacking loudly and never returned to nest at that exact area. Nest-building females often flushed within 100 yd (91.4 m) and usually never returned. In 1956, 22 nesting females were trapped on their nests and marked and of those 6 deserted due to flooding or observer interference, 1 lost her nest to crows (Corvus sp.) , and 13 hatched clutches successfully. Nesting studies in 1954 resulted in the collection of many clutches by the observer and desertion of many nests by the female, and abnormal activity near nests may have caused predation by crows. In 1955, local persons collected numerous clutches of eggs from Bodkin Island. In 574 nesting attempts, 4 were abandoned because of humans, 12 were destroyed by humans, and 132 were abandoned because of the observer (a total of 3.3% of all nest losses).