栖木在越冬红隼（Falco tinnunculus）的觅食地与捕食方式选择中的作用

栖木是重要的生境因子，对于鸟类生境选择和利用具有重要意义。2003年9月-2004年3月，采用固定样地对照观测的方法，分析研究栖木在越冬红隼（Falco tinnunculus）的栖息地选择与捕食方式选择中的作用。研究结果表明，增加了栖木的试验区（下称试验区），红隼的出现频率远大于未增加栖木的对照区（下称对照区）;试验区红隼个体平均停留时间显著长于对照区;在试验区红隼栖停捕食占捕食次数的77.24%，而在对照区红隼只进行飞行捕食，红隼捕食方式和样地中是否增加栖木具有极显著相关性;试验区，红隼栖停行为时间占51.8%，大于对照区（30.1%），对照区中，红隼在空中的行为如飞行、翱翔、悬停等行为时间所占比例为34.8%，远高于试验区（12.1%）。这些结果表明，栖木在越冬红隼的栖息地选择和捕食方式选择中具有重要的作用，栖木的存在是栖停捕食的先决条件，冬季红隼偏好于具有较好栖木条件的栖息地，并且偏向于采取低消耗低收益的栖停捕食。

Foraging area and hunting technique selection of Common Kestrel (Falco tinnunculus) in winter: the role of perch sites

In winter, Common Kestrel minimizes energy expenditure by using the low-cost, low-profit technique of perch hunting. Existence of the perch sites is the precondition of perch hunting. Therefore, one can predict that the kestrels would prefer a habitat with more perch sites, and perch sites should have an important role in the kestrels' hunting technique use, habitat selection and habitat use in winter. To test this prediction, the authors manipulated two areas in a grassland. They increased the potential perch sites in one area with bamboo poles (hereafter test area) and kept another as control (hereafter control area). They observed and compared the kestrels' use and their behaviors in these two areas. Far more kestrels appearing in the test area with increasing perch sites than in the control area were recorded. The kestrels stayed in the test area with more perch sites significantly longer than in the control area. And in the test area with more perch sites, kestrels hunted 77.24% of the total hunting with the technique of perch hunting. In the control area, kestrels hunted only with the technique of flight-hunting. There was a significant correlation between the technique used by kestrels and the areas with or without perch sites. In the test area with increasing perch sites kestrels spent 51.8% of their time in perching and 12.1% in air, which were 30.1% and 34.8%, respectively, in the control area. There was no significant difference in hunting profit between areas. The results suggest that perch sites play an important role in the selection of hunting technique and foraging habitat for kestrels in winter, and kestrels appear to prefer the habitat with suitable perch sites in winter.