Fine-scale foraging behaviour of a medium-ranging marine predator
Fine-scale foraging behaviour of a medium-ranging marine predator
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DOI：
10.1111/j.1365-2656.2009.01549.x
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发表时间：
2009-07-01
影响因子：
4.8
通讯作者：
Wanless, S.
中科院分区：
文献类型：
--
作者：
Hamer, K. C.;Humphreys, E. M.;Wanless, S.
捕食者的运动模式，应允许他们在不同的空间尺度，特别是通过区域限制搜索（ARS）的行为检测和响应猎物补丁。本文利用精细尺度的移动和活动数据，结合首次通过时间（FPT）分析，研究了北海西部北方塘鹅（Morus dalanus）的觅食策略，并检验了以下假设：（i）鸟类采取以嵌套ARS行为为特征的等级觅食策略;（iii）发现和追捕猎物触发ARS行为的启动;（iv）ARS行为与觅食努力的增加密切相关，特别是在嵌套ARS区域内。15次觅食旅行中的13次采用ARS行为，尺度为9.1 +/- 1.9 km，10次采用第二次，嵌套ARS尺度为1.5 +/- 0.8 km，支持上述假设1。ARS区位于离殖民地殖民地117 +/- 55 km处，超过一半位于潮汐混合前沿5 km范围内（类似于离岸50 km），支持上述假设2。ARS行为的开始通常仅在短时间间隔（通常类似于5 min）后开始潜水。塘鹅在找到猎物之前不会潜水，因此这种模式强烈表明ARS行为是由猎物探测触发的，支持上面的假设3。然而，类似于33%的潜水混合沿海水域和16%的潜水分层水没有任何可检测的ARS行为。因此，虽然ARS行为是由探测和追捕猎物引起的，但与猎物物种的相遇并不一定会引起ARS行为。ARS行为开始后，ARS区域内的潜水率几乎是其他区域的四倍，而在有嵌套ARS行为的区域内，潜水率几乎是没有嵌套ARS行为的区域的三倍。支持上述假设4，并表明鸟类觅食的成功与它们匹配猎物等级分布的能力有关。
Movement patterns of predators should allow them to detect and respond to prey patches at different spatial scales, particularly through the adoption of area-restricted search (ARS) behaviour. Here we use fine-scale movement and activity data combined with first-passage time (FPT) analysis to examine the foraging strategy of northern gannets Morus bassanus in the western North Sea, and to test the following hypotheses: (i) birds adopt a hierarchical foraging strategy characterized by nested ARS behaviour; (ii) the locations and characteristics of ARS zones are strongly influenced by physical oceanography; (iii) the initiation of ARS behaviour is triggered by the detection and pursuit of prey; (iv) ARS behaviour is strongly linked to increased foraging effort, particularly within nested ARS areas.Birds on 13 of 15 foraging trips adopted ARS behaviour at a scale of 9.1 +/- 1.9 km, and birds on 10 of these 13 trips adopted a second, nested ARS scale of 1.5 +/- 0.8 km, supporting hypothesis 1 above. ARS zones were located 117 +/- 55 km from the colony and over half were within 5 km of a tidal mixing front similar to 50 km offshore, supporting hypothesis 2 above.The initiation of ARS behaviour was usually followed after only a short time interval (typically similar to 5 min) by the commencement of diving. Gannets do not dive until after they have located prey, and so this pattern strongly suggests that ARS behaviour was triggered by prey detection, supporting hypothesis 3 above. However, similar to 33% of dives in mixed coastal water and 16% of dives in stratified water were not associated with any detectable ARS behaviour. Hence, while ARS behaviour resulted from the detection and pursuit of prey, encounters with prey species did not inevitably induce ARS behaviour.Following the initiation of ARS behaviour, dive rates were almost four times higher within ARS zones than elsewhere and almost three times higher in zones with nested ARS behaviour than in those without, supporting hypothesis 4 above and suggesting that the foraging success of birds was linked to their ability to match the hierarchical distribution of prey.