Radford A N, Blakey J K
Edward Grey Institute of Field Ornithology, Department of Zoology, University of Oxford, UK.
Proc Biol Sci. 2000 Mar 22;267(1443):535-8. doi: 10.1098/rspb.2000.1033.
Nest-defence behaviour of passerines is a form of parental investment. Parents are selected, therefore, to vary the intensity of their nest defence with respect to the value of their offspring. Great tit, Parus major, males were tested for their defence response to both a nest predator and playback of a great tit chick distress call. The results from the two trials were similar; males gave more alarm calls and made more perch changes if they had larger broods and if they had a greater proportion of sons in their brood. This is the first evidence for a relationship between nest-defence intensity and offspring sex ratio. Paternal quality, size, age and condition, lay date and chick condition did not significantly influence any of the measured nest-defence parameters.
雀形目鸟类的巢防御行为是亲代投资的一种形式。因此，自然选择会使亲鸟根据后代的价值来调整其巢防御的强度。对大山雀（Parus major）雄性个体进行了测试，观察它们对巢捕食者以及大山雀雏鸟求救叫声回放的防御反应。两项试验的结果相似；如果雄性个体育有较大的一窝雏鸟，或者雏鸟中雄性的比例更高，它们就会发出更多的警报叫声，并且更多地变换栖木位置。这是巢防御强度与后代性别比例之间存在关联的首个证据。父本质量、体型、年龄和身体状况、产卵日期以及雏鸟状况均未对所测量的任何巢防御参数产生显著影响。
