Use of Perches as Vantage Points During Foraging By Male and Female Stonechats Saxicola Torquata
Use of Perches as Vantage Points During Foraging By Male and Female Stonechats Saxicola Torquata
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雄性和雌性石鳖在觅食时使用栖息处作为有利位置 Saxicola Torquata
DOI：
10.1163/156853983x00372
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发表时间：
1983
期刊：
影响因子：
1.3
通讯作者：
P. Greig
中科院分区：
文献类型：
--
作者：
P. Greig
研究了石斑羚(Saxicola Torquata)个体在刺地生境中的觅食行为，以揭示栖息高度对觅食效率的可能影响。对雄性和雌性鸟类在繁殖前和繁殖期的摄食率、猎物捕获方法、栖息时间和栖息高度进行了量化；此外，还检查了觅食与繁殖前雄性鸣叫行为的整合。猎物捕获率变化很大，没有明显的季节趋势或性别差异。春季栖息高度平均为1.0m，夏季平均为1.6m，尽管性别差异不大，但春季雄性栖息高度更高，更接近植被顶端。与随机遇到的栖息地进行比较表明，鸟类选择的栖息地高于平均可用栖息地。在三种主要的捕食技术中，春季只使用俯冲到地面，但在夏天也使用捕捉苍蝇和从树叶上抓取猎物。这种变化与白桦树和蕨类植物叶片上出现新的猎物类型有关。栖息时间短，平均25次S，没有明显的性别或季节差异，但在较高的栖息地往往更长，可达2分钟。这些数据结合在一起，评估了不同栖息高度觅食的盈利能力。对于俯冲到地面的觅食，最低的高度提供了最大的捕获率，但对于捕蝇和抓取，非常高的栖息地更成功。这些鸟在春季观察到的栖息地偏好与每次访问的捕获机会最高相对应，而不是每单位时间。在夏天，没有通信。鸟类离开栖息地的时候，它们的捕获前景仍然很高，因此，不成功的访问时间不能被视为“放弃”时间。在春季，短观察期内觅食次数与歌唱次数呈负相关，不同的海拔高度(觅食平均为0.9m，歌唱平均为1.8m)表明活动不相容。雄性和雌性(不唱歌)的春季觅食行为没有差异，这表明雄性将觅食和鸣叫分开成不同的回合。这显然是通过在稳定条件下的战术分配时间来实现的，而不是将歌唱降级到觅食条件较差的时候。
The behaviour of individual stonechats (Saxicola torquata) foraging in heathland habitats was studied, to reveal possible influences of the height of the perches used as vantage points on feeding efficiency. Feeding rates, methods of prey capture, time spent on perches, and perching heights were quantified for male and female birds in a pre-breeding, and breeding periods; in addition, the integration of foraging with pre-breeding male song behaviour was examined. Rates of prey capture were highly variable, showing no clear seasonal trends or sex differences. Perching heights averaged 1.0 m in spring, and 1.6 m in summer, and although sex differences were small, males tended to perch higher, and closer to the top of the vegetation, in spring. Comparison with randomly encountered perches showed that birds selected higher perches than the average available. Of three principal prey-capture techniques, only diving to the ground was used in spring, but flycatching, and snatching prey off foliage, were also employed in summer. The change correlated with the appearance of new prey types on the foliage of birch and bracken. Visits to perches were short, averaging 25 s, and showed no clear sex or seasonal differences, but tended to be longer on higher perches, up to 2 min. These data were combined to assess the profitabilty for foraging of different perching heights. For feeding by diving to the ground, the lowest heights provided the greatest capture rates, but for flycatching and snatching, very high perches were more successful. The birds' observed preferences for perches in spring corresponded to those allowing the highest chance of capture per visit, rather than per unit time. In summer, there was no correspondence. Birds departed from perches when their prospects of capture were still high, and thus the lengths of unsuccessful visits cannot be regarded as 'giving-up' times. In spring, the frequencies of foraging attempts and song-phrases were inversely related in short observation periods, and incompatibility of the activities was suggested by the different heights chosen (averaging 0.9 m for foraging, 1.8 m for singing). The lack of differences in the spring foraging behaviour of males and females (who do not sing) suggests that males separated their foraging and singing into discrete bouts. This was apparently accomplished by tactical allocation of time in stable conditions, rather than relegation of singing to times when foraging conditions were poor.