Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
Front Zool. 2010 Jan 11;7:1. doi: 10.1186/1742-9994-7-1.
Parental care often increases offspring survival, but is costly to the parents. A trade-off between the cost and benefit of care is expected, so that when care provisioning by both parents is essential for the success of young, for instance in extremely cold or hot environments, the parents should rear their young together. We investigated the latter hypothesis in a ground nesting shorebird, the Kentish plover Charadrius alexandrinus in an extremely hot environment, the Arabian Desert. Midday ground temperature was often above 50 degrees C in our study site in Abu Dhabi (United Arab Emirates), thus leaving the eggs unattended even for a few minute risks overheating and death of embryos.
Through the use of video surveillance systems we recorded incubation routines of male and female Kentish plovers at 28 nests over a full day (24 h). We show that ambient temperature had a significant influence on incubation behaviour of both sexes, and the relationships are often non-linear. Coordinated incubation between parents was particularly strong in midday with incubation shared approximately equally between the male and the female. The enhanced biparental incubation was due to males increasing their nest attendance with ambient temperature.
Our results suggest biparental care is essential during incubation in the Kentish plover in extremely hot environments. Shared incubation may also help the parents to cope with heat stress themselves: they can relieve each other frequently from incubation duties. We suggest that once the eggs have hatched the risks associated with hot temperature are reduced: the chicks become mobile, and they gradually develop thermoregulation. When biparental care of young is no longer essential one parent may desert the family. The relaxed demand of the offspring may contribute to the diverse breeding systems exhibited by many shorebirds.
亲代照顾通常会提高后代的存活率，但对父母来说是有代价的。照顾的成本和收益之间存在权衡，因此当父母双方都必须为幼鸟的成功提供照顾时，例如在极冷或极热的环境中，父母应该一起抚养幼鸟。我们在阿拉伯沙漠中一种极端炎热环境下的地面筑巢滨鸟——蛎鹬（Charadrius alexandrinus）中研究了后一种假设。在我们位于阿布扎比（阿拉伯联合酋长国）的研究点，正午的地面温度经常高于 50 摄氏度，因此即使将蛋无人看管几分钟，也有过热和胚胎死亡的风险。
通过使用视频监控系统，我们在 28 个巢中记录了 24 小时内雄性和雌性蛎鹬的孵化过程。我们表明，环境温度对两性的孵化行为有显著影响，而且这种关系通常是非线性的。父母双方的协调孵化在中午尤为强烈，雌雄双方的孵化时间大致相等。雌雄蛎鹬在环境温度升高时，雄性增加了对巢的守护，这使得增强的双亲孵化更为明显。
我们的研究结果表明，在极热环境下，蛎鹬的孵化期间，双亲照顾是必不可少的。共同孵化也可能帮助父母自身应对热应激：它们可以经常互相分担孵化任务。我们认为，一旦蛋孵化后，与高温相关的风险就会降低：雏鸟变得活跃，它们逐渐发展出体温调节能力。当不再需要双亲照顾幼鸟时，一只亲鸟可能会离开家庭。后代的需求减少可能有助于许多滨鸟表现出多样化的繁殖系统。
