Reboreda J C, Clayton N S, Kacelnik A
Instituto de Biologia y Medicina Experimental-CONICET, Buenos Aires, Argentina.
Neuroreport. 1996 Jan 31;7(2):505-8. doi: 10.1097/00001756-199601310-00031.
To test the hypothesis that selection for spatial abilities which require birds to locate and to return accurately to host nests has produced an enlarged hippocampus in brood parasites, three species of cowbird were compared. In shiny cowbirds, females search for host nests without the assistance of the male; in screaming cowbirds, males and females inspect hosts' nests together; in bay-winged cowbirds, neither sex searches because this species is not a brood parasite. As predicted, the two parasitic species had a relatively larger hippocampus than the non-parasitic species. There were no sex differences in relative hippocampus size in screaming or bay-winged cowbirds, but female shiny cowbirds had a larger hippocampus than the male.
对空间能力的选择（这种能力要求鸟类准确找到并返回宿主巢穴）导致巢寄生鸟类的海马体增大，研究人员对三种牛鹂进行了比较。在辉亮牛鹂中，雌性在没有雄性协助的情况下寻找宿主巢穴；在栗翅牛鹂中，雄性和雌性一起检查宿主巢穴；在湾翅牛鹂中，两性都不进行搜索，因为该物种不是巢寄生鸟类。正如预测的那样，这两种寄生性牛鹂的海马体相对比非寄生性牛鹂的更大。在栗翅牛鹂或湾翅牛鹂中，海马体相对大小没有性别差异，但雌性辉亮牛鹂的海马体比雄性的更大。
