Recommendations for cowbird management in recovery efforts for the southwestern willow flycatcher

S.I. Rothstein; B.E. Kus; M.J. Whitfield; S.J. Sferra

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USGS · 1008355

Recommendations for cowbird management in recovery efforts for the southwestern willow flycatcher

S.I. Rothstein·B.E. Kus·M.J. Whitfield·S.J. Sferra

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Abstract

Three generations of mallard ducks (Anas platyrhynchos) were fed either a control diet or a diet containing 0.5 ppm mercury in the form of methylmercury. The levels of mercury in adult tissues and eggs remained about the same over 3 generations. The methylmercury diet had no effect on adult weights or weight changes during the reproductive season. Females fed a diet containing 0.5 ppm mercury laid a greater percentage of their eggs outside their nestboxes than did controls, and also laid fewer eggs and produced fewer ducklings. Methylmercury in the diet appeared to result in a small amount of eggshell thinning. Ducklings from parents fed methylmercury were less responsive than, controls to tape-recorded maternal calls, but were hyper-responsive to a frightening stimulus in avoidance tests; there were no significant differences in locomotor activity in an open-field test.

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S.I. Rothstein, B.E. Kus, M.J. Whitfield, S.J. Sferra. 2003. Recommendations for cowbird management in recovery efforts for the southwestern willow flycatcher. https://pubs.usgs.gov/publication/1008355

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