Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.
J Anim Ecol. 2013 Jan;82(1):245-55. doi: 10.1111/j.1365-2656.2012.02026.x. Epub 2012 Sep 3.
Animals commonly steal food from other species, termed interspecific kleptoparasitism, but why animals engage in kleptoparasitism compared with alternate foraging tactics, and under what circumstances they do so, is not fully understood. Determining what specific benefits animals gain from kleptoparasitism could provide valuable insight into its evolution. Here, we investigate the benefits of kleptoparasitism for a population of individually recognizable and free-living fork-tailed drongos (Dicrurus adsimilis) in the southern Kalahari Desert. Drongos engaged in two foraging behaviours: self-foraging for small insects or following other species which they kleptoparasitized for larger terrestrial prey that they could not capture themselves. Kleptoparasitism consequently enabled drongos to exploit a new foraging niche. Kleptoparasitism benefitted drongos most in the morning and on colder days because at these times pay-offs from kleptoparasitism remained stable, while those from self-foraging declined. However, drongos engaged in kleptoparasitism less than expected given the overall high (but more variable) pay-offs from this behaviour, suggesting that kleptoparasitism is a risky foraging tactic and may incur additional foraging costs compared with self-foraging. This is the first study to comprehensively investigate the benefits of facultatively engaging in kleptoparasitism, demonstrating that animals may switch to kleptoparasitism to exploit a new foraging niche when pay-offs exceed those from alternate foraging behaviours.
动物通常会从其他物种那里偷取食物，这种行为被称为种间盗食寄生，但与其他觅食策略相比，动物为什么会选择盗食寄生，以及在什么情况下会这样做，目前还不完全清楚。确定动物从盗食寄生中获得的具体好处，可以为其进化提供有价值的见解。在这里，我们调查了南部卡拉哈里沙漠中可识别个体的自由生活的叉尾卷尾（Dicrurus adsimilis）种群进行盗食寄生的好处。卷尾鸟从事两种觅食行为：自己觅食小型昆虫，或跟随其他物种，它们会盗食较大的陆地猎物，而这些猎物是它们自己无法捕捉到的。因此，盗食寄生使卷尾鸟得以开发一个新的觅食生态位。盗食寄生对卷尾鸟最有利的时间是早上和较冷的天气，因为在这些时间里，盗食寄生的回报保持稳定，而自我觅食的回报则下降。然而，考虑到这种行为的整体高回报（但更具波动性），卷尾鸟的盗食寄生行为却低于预期，这表明盗食寄生是一种有风险的觅食策略，与自我觅食相比，可能会产生额外的觅食成本。这是第一项全面调查盗食寄生好处的研究，表明当回报超过其他觅食行为时，动物可能会转而选择盗食寄生来开发新的觅食生态位。
