EGG-EATING BY FEMALE BROWN-HEADED COWBIRDS
EGG-EATING BY FEMALE BROWN-HEADED COWBIRDS
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DOI：
10.2307/1369242
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发表时间：
1992-08-01
期刊：
影响因子：
3.1
通讯作者：
ANKNEY, CD
中科院分区：
文献类型：
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作者：
SCOTT, DM;WEATHERHEAD, PJ;ANKNEY, CD
我们根据(1)雌性褐头牛鹂（Molothrus ater）从寄主巢穴中取出的卵和雏鸟的比例（n = 36）和(2)北红雀（Cardinalis Cardinalis）寄生巢穴下方未被吃掉的取出的卵和雏鸟的比例（n = 69）估算了雌性褐头牛鹂（Molothrus ater）从寄主巢穴中取出的卵和雏鸟的比例。雌性牛鹂只在中午之前或下午晚些时候和傍晚时分才会产卵。卵从被寄生和未被寄生的巢中以及从产蛋到孵化后期的任何筑巢阶段取出。虽然卵、卵内物和壳经常被吃掉，但没有观察到被移走的雏鸟被吃掉。然而，多达40%的被移除的卵子是正常的。不吃，尽管吃鸡蛋有明显的能量益处。我们提供了六种解释来解释牛郎鸟不吃很多蛋的原因，并建议用实验来阐明牛郎鸟这一令人困惑的行为。我们的结论是，将鸡蛋作为食物可能不是褐头牛头鸟脱蛋的主要原因。
We estimated the proportions of eggs and nestlings, removed from hosts' nests, that were eaten by female Brown-headed Cowbirds (Molothrus ater) from (1) a compilation of published and unpublished observations (n = 36) of egg or nestling removal and egg-eating by female cowbirds and (2) the proportion of removed eggs that were found uneaten below parasitized nests (n = 69) of Northern Cardinals (Cardinalis cardinalis). Female cowbirds were seen removing eggs only before midday or in late afternoon and early evening. Eggs were removed from both parasitized and unparasitized nests and at any nesting stage from laying to late incubation. Although eggs, contents and shell, were frequently eaten, removed nestlings were not observed to be eaten. However, as many as 40% of removed eggs were.not eaten, despite the apparent energetic benefits of egg-eating. We offer six explanations to account for the failure of cowbirds to eat many eggs, and suggest experiments to elucidate this puzzling behavior of cowbirds. We conclude that the use of eggs as food may not be the primary cause of egg removal by Brown-headed Cowbirds.