Granadeiro JP, Burns MD, Furness RW
Instituto da Conservação da Natureza, Lisbon
Anim Behav. 1999 Mar;57(3):663-671. doi: 10.1006/anbe.1998.0992.
We examined temporal variation in food delivery to nestling Cory's shearwaters Calonectris diomedea, by repeated periodic weighings during the night. We tested whether the magnitude and frequency of meals were influenced by the condition of chicks. In contrast to previous studies of chick provisioning in petrels and shearwaters, the evidence of feeding derived from chick weight gains was complemented by data provided by an electronic system, which logged the entry of each parent to the nest. Estimates of feed size and visiting frequency obtained from chick weighing alone differed from similar estimates obtained using the automatic logging equipment. The data obtained with the logging system combined with chick weighing also showed that, to some extent, food provisioning was regulated, chicks left in poorer condition being more likely to receive food the next night than those left in better condition. The methods based on chick weight gains alone did not detect this regulation effect. Our findings suggest that resolving parental visits to the nest is crucial to obtain accurate parameter estimates, and to address the problem of regulation of provisioning rates in Procellariiformes. Our results do not support the hypothesis that accumulation of fat is just a by-product of chronic overfeeding arising from stochastic variation in foraging success at sea. Copyright 1999 The Association for the Study of Animal Behaviour.
我们通过夜间反复定期称重，研究了为科氏鹱（Calonectris diomedea）雏鸟提供食物的时间变化。我们测试了喂食的量和频率是否受雏鸟状况的影响。与之前对海燕和鹱雏鸟喂养情况的研究不同，除了根据雏鸟体重增加得出的喂食证据外，一个电子系统提供的数据也对其进行了补充，该系统记录了每只亲鸟进入巢穴的情况。仅通过雏鸟称重获得的饲料量和探访频率估计值，与使用自动记录设备获得的类似估计值有所不同。结合雏鸟称重与记录系统获得的数据还表明，在一定程度上，食物供应是受到调节的，状况较差的雏鸟比状况较好的雏鸟更有可能在第二天晚上获得食物。仅基于雏鸟体重增加的方法并未检测到这种调节效应。我们的研究结果表明，确定亲鸟对巢穴的探访情况对于获得准确的参数估计以及解决鹱形目鸟类食物供应率的调节问题至关重要。我们的结果不支持脂肪积累仅仅是由于海上觅食成功率的随机变化导致长期过度喂养的副产品这一假设。版权所有1999动物行为研究协会。
