Hemborg Christer, Lundberg Arne, Siikamäki Pirkko
Department of Zoology, Villavägen 9, S-752 36 Uppsala, Sweden e-mail:
Department of Biological and Environmental Science, PO Box 35, FIN-40351 Jyväskylä, Finland, , , , , , FI.
Oecologia. 1998 Dec;117(3):374-380. doi: 10.1007/s004420050670.
Organisms that reproduce at high latitudes are assumed to have evolved several adaptations to the short summer. For birds, and especially for long-distance migrants, there is a time constraint because both reproduction and moult must be completed before autumn migration. It has therefore been assumed that birds at northern latitudes must initiate their moult during reproduction more often than birds at low latitudes. To investigate how passerine birds breeding at different latitudes allocate their time between reproduction and moult, we compared timing of these activities during three consecutive breeding seasons in three widely separated populations of the pied flycatcher Ficedula hypoleuca. Our results show that the frequency of individuals with moult-breeding overlap, and moult initiation in relation to breeding stage, varied considerably among populations and years. In all three populations, female moult initiation was restricted to the late nestling period. The males had a more pronounced moult-breeding overlap than the females, but its duration was similar in all three study areas. Thus, there was no evidence for a more pronounced moult-breeding overlap at high compared with low latitudes. These results suggest that pied flycatchers sometimes accept a moult-breeding overlap, but that the time gained by having too extensive an overlap between reproduction and moult does not outweigh the associated costs. Long-distance migrants breeding at northern latitudes apparently experience a trade-off between reproduction and somatic investment during moult. We therefore suggest that a pronounced moult-breeding overlap is not a typical strategy used by long-distance migrants to adjust to the short breeding season at northern latitudes.
在高纬度地区繁殖的生物被认为已经进化出了几种适应短暂夏季的特征。对于鸟类，尤其是长途迁徙的鸟类来说，存在时间限制，因为繁殖和换羽都必须在秋季迁徙之前完成。因此，人们认为高纬度地区的鸟类比低纬度地区的鸟类更常在繁殖期间开始换羽。为了研究在不同纬度繁殖的雀形目鸟类如何在繁殖和换羽之间分配时间，我们比较了在三个广泛分布的斑姬鹟（Ficedula hypoleuca）种群中，连续三个繁殖季节这些活动的时间安排。我们的结果表明，换羽与繁殖重叠的个体频率以及换羽开始时间与繁殖阶段的关系，在不同种群和年份之间有很大差异。在所有三个种群中，雌性换羽开始时间都局限于雏鸟后期。雄性换羽与繁殖的重叠比雌性更明显，但在所有三个研究区域中其持续时间相似。因此，没有证据表明高纬度地区与低纬度地区相比，换羽与繁殖的重叠更明显。这些结果表明，斑姬鹟有时会接受换羽与繁殖的重叠，但繁殖与换羽之间过度重叠所获得的时间并不超过相关成本。在高纬度地区繁殖的长途迁徙鸟类显然在繁殖和换羽期间的身体投资之间面临权衡。因此，我们认为明显的换羽与繁殖重叠并不是长途迁徙鸟类适应高纬度地区短暂繁殖季节的典型策略。
