Institute of Integrative and Comparative Biology, University of Leeds, Leeds, LS2 9JT, UK.
J Exp Biol. 2010 Apr;213(Pt 7):1018-25. doi: 10.1242/jeb.037390.
Species of bird that use their wings for underwater propulsion are thought to face evolutionary trade-offs between flight and diving, leading to the prediction that species with different wing areas relative to body mass (i.e. different wing loadings) also differ in the relative importance of flight and diving activity during foraging trips. We tested this hypothesis for two similarly sized species of Alcidae (common guillemots and razorbills) by using bird-borne devices to examine three-dimensional foraging behaviour at a single colony. Guillemots have 30% higher wing loading than razorbills and, in keeping with this difference, razorbills spent twice as long in flight as a proportion of trip duration whereas guillemots spent twice as long in diving activity. Razorbills made a large number of short, relatively shallow dives and spent little time in the bottom phase of the dive whereas guillemots made fewer dives but frequently attained depths suggesting that they were near the seabed (ca. 35-70 m). The bottom phase of dives by guillemots was relatively long, indicating that they spent considerable time searching for and pursuing prey. Guillemots also spent a greater proportion of each dive bout underwater and had faster rates of descent, indicating that they were more adept at maximising time for pursuit and capture of prey. These differences in foraging behaviour may partly reflect guillemots feeding their chicks single large prey obtained near the bottom and razorbills feeding their chicks multiple prey from the water column. Nonetheless, our data support the notion that interspecific differences in wing loadings of auks reflect an evolutionary trade-off between aerial and underwater locomotion.
被认为用于水下推进的鸟类物种在飞行和潜水之间面临着进化权衡，这导致了这样的预测，即相对于体质量而言翅膀面积不同（即不同的翼载荷）的物种在觅食过程中飞行和潜水活动的相对重要性也不同。我们通过使用鸟载设备在单个繁殖地检查三维觅食行为，为两种大小相似的海雀（普通海鸠和刀嘴海雀）检验了这一假说。海鸠的翼载荷比刀嘴海雀高 30%，符合这一差异，刀嘴海雀在一次觅食过程中飞行的时间占比是海鸠的两倍，而海鸠潜水的时间则是刀嘴海雀的两倍。刀嘴海雀进行了大量的短而相对浅的潜水，在潜水的底部阶段花费的时间很少，而海鸠的潜水次数较少，但经常达到表明它们接近海底（约 35-70 米）的深度。海鸠潜水的底部阶段相对较长，表明它们花费了相当多的时间寻找和追逐猎物。海鸠在每次潜水期间水下停留的比例也更大，下降速度也更快，这表明它们更擅长最大限度地延长追逐和捕获猎物的时间。这些觅食行为的差异可能部分反映了海鸠给雏鸟喂食的是靠近底部获得的单个大型猎物，而刀嘴海雀则从水柱中给雏鸟喂食多个猎物。尽管如此，我们的数据支持了这样的观点，即鸥科物种之间翼载荷的差异反映了空中和水下运动之间的进化权衡。
