Stopover duration of Palearctic passerine migrants in the western Sahara - : independent of fat stores?
Stopover duration of Palearctic passerine migrants in the western Sahara - : independent of fat stores?
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古北区雀形目鸟类迁徙者在西撒哈拉的停留时间：与脂肪储存无关？
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发表时间：
2007
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通讯作者：
M. Schaub
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作者：
V. Salewski;M. Schaub
鸟类在迁徙途中停留的时间要比在高处停留的时间长得多，但停留时间的经验数据很少，特别是古北界跨撒哈拉移民在穿越沙漠时。以往的研究表明，肥胖鸟类在绿洲的停留时间远短于瘦鸟。在2003年和2004年捕获-再捕获数据迁移雀形目鸟类从两个内陆绿洲在春季和一个沿海网站在秋季毛里塔尼亚，西非，进行了分析，以测试是否是一个短暂的概率和停留时间取决于燃料储存在第一次捕获。捕获-再捕获模型的应用表明，在秋季迁徙期间，在海岸的短暂停留（仅停留1天的个体）的比例相对较高（77-90%），在四个物种的调查和停留时间短（1.9-4.6天）。在春季的内陆绿洲中，12个分析中只有4个检测到瞬变。停留时间比在秋季海岸，令人惊讶的是，在一些物种长达30天的持续时间长。考虑到鸟类在第一次捕获时的初始脂肪负荷的模型，除了一个例外，从来都不是最吝啬的。这表明，捕获后和捕获前在中途停留地点花费的时间并不取决于第一次捕获时的脂肪储存。因此，我们不能证实这样的假设，即到达沙漠中途停留地点的低脂肪负荷的鸟类比高脂肪负荷的鸟类停留时间更长。
Birds on migration spend much more time on stopover sites to refuel for the next migration step than aloft, but empirical data on stopover duration are rare, especially for Palearctic trans-Sahara migrants whilst crossing the desert. Previous studies suggest that stopover duration of fat birds in oases is much shorter than that of lean birds. During 2003 and 2004 capture-recapture data of migrating passerines from two inland oases in spring and from one coastal site in autumn in Mauritania, West Africa, were analysed to test whether the probability of being a transient and the stopover duration depend on fuel stores at first capture. The application of capture-recapture models revealed that during autumn migration at the coast the proportion of transients (individuals that stop over only for 1 day) was relatively high (77-90%) in three out of four species investigated and stopover duration was short (1.9-4.6 days). In the inland oases in spring, transients were detected in only four out of 12 analyses. Stopover duration was longer than at the coast in autumn and surprisingly long in some species with durations of up to 30 days. Models taking into account the initial fat load of birds on the first capture occasion were, with one exception, never the most parsimonious ones. This indicates that the time spent after and before capture at the stopover site did not depend on the fat stores at first capture. Therefore, we cannot confirm the assumption that birds arriving at stopover sites in the desert with low fat loads stay longer than birds that arrive with high fat loads.