Data from: Female cowbirds have more accurate spatial memory than males

Brown-headed cowbirds (Molothrus ater) are obligate brood parasites. Only females search for host nests and they find host nests one or more days before placing eggs in them. Past work has shown that females have a larger hippocampus than males, but sex differences in spatial cognition have not been extensively investigated. We tested cowbirds for sex and seasonal differences in spatial memory on a foraging task with an ecologically relevant retention interval. Birds were trained to find one rewarded location among 25 after 24 h. Females made significantly fewer errors than males and took more direct paths to the rewarded location than males. Females and males showed similar search times, indicating there was no sex difference in motivation. This sex difference in spatial cognition is the reverse of that observed in some polygynous mammals and is consistent with the hypothesis that spatial cognition is adaptively specialized in this brood-parasitic species.

褐头牛鹂（Molothrus ater）为专性巢寄生鸟类。仅雌性个体搜寻寄主巢穴，且会在产卵前1天及以上提前定位寄主巢址。既往研究显示，雌性个体的海马体（hippocampus）较雄性更大，但空间认知的性别差异尚未得到广泛深入的研究。本研究通过一项具备生态学相关性保留时长的觅食任务，对牛鹂空间记忆的性别差异与季节差异展开检验。实验对象经训练后，需在24小时后从25个位置中寻找到带有奖励的目标位置。结果表明，雌性个体的犯错次数显著少于雄性，且前往奖励位置的路径更为直接；雌雄个体的搜寻时长无显著差异，说明二者的行为动机不存在性别差异。此种空间认知的性别差异与部分多配偶哺乳动物中观测到的结果恰好相反，且契合"该巢寄生鸟类的空间认知已发生适应性特化"这一假说。