White David J, Ho Lucy, Freed-Brown Grace
University of Pennsylvania, Philadelphia, PA 19104, USA.
Psychol Sci. 2009 Sep;20(9):1140-5. doi: 10.1111/j.1467-9280.2009.02418.x. Epub 2009 Jul 29.
Here we show that demands associated with brood parasitism have favored sophisticated cognitive abilities in female brown-headed cowbirds. We discovered that cowbirds can use the rate at which eggs are added to a nest across days to assess the readiness of the nest for incubation, which would allow them to synchronize laying with the host and avoid nests where incubation has most likely commenced. In three experiments, cowbirds investigated and laid eggs in artificial nests that differed in the number of eggs they contained. Across days, we added eggs to nests at different rates to simulate differences in the timing of reproduction of the hosts. Cowbirds avoided a nest if the number of eggs that had been added was less than the number of days that had elapsed. The ability of females to remember egg number and compare changes in egg number across days allows them to select nests most suitable for parasitism.
我们在此表明，与巢寄生相关的需求促使雌性褐头牛鹂具备了复杂的认知能力。我们发现，牛鹂能够利用数天内巢中新增卵的速度来评估巢是否准备好孵化，这使它们能够与宿主同步产卵，并避开那些很可能已经开始孵化的巢。在三个实验中，牛鹂对所含卵数不同的人工巢进行了调查并在其中产卵。数天内，我们以不同速度向巢中添加卵，以模拟宿主繁殖时间的差异。如果添加的卵数少于过去的天数，牛鹂就会避开该巢。雌性牛鹂记住卵数并比较数天内卵数变化的能力，使它们能够选择最适合寄生的巢。
