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 (RI). 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）是专性巢寄生鸟类。仅雌性个体搜寻寄主鸟巢，且会在产卵前1天或更早的时间找到寄主巢。过往研究表明，雌性褐头牛鹂的海马体（hippocampus）大于雄性，但空间认知的性别差异尚未得到广泛深入的研究。本研究通过设置具有生态相关性的保留间隔（retention interval, RI）的觅食任务，检测了牛鹂在空间记忆上的性别与季节差异。实验中，受试鸟需经过训练，在24小时后从25个候选位置中找到被赋予奖励的目标位置。结果显示，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；而雌雄个体的搜寻时长无显著差异，说明二者的觅食动机不存在性别差异。本研究观测到的空间认知性别差异与部分多配偶哺乳动物的相关结果相反，同时契合“该巢寄生物种的空间认知存在适应性特化”这一假说。