Fine-scale movement decisions of tropical forest birds in a fragmented landscape
Fine-scale movement decisions of tropical forest birds in a fragmented landscape
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DOI：
10.1890/09-2090.1
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发表时间：
2011-04-01
影响因子：
5
通讯作者：
St Clair, Colleen Cassady
中科院分区：
文献类型：
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作者：
Gillies, Cameron S.;Beyer, Hawthorne L.;St Clair, Colleen Cassady
在破碎化生境中，依赖森林的物种的存续从根本上与个体在亚种群之间的移动相关。扩散个体所采取的路径可被视为由个体路径选择构成的一系列步骤。尽管这些精细尺度的移动决策很重要，但收集能揭示森林鸟类如何在新环境中移动的数据却很困难。我们收集了哥斯达黎加热带干性森林高度破碎地区两种森林鸟类迁移的前所未有的路径信息。在这片以牧场为主的生境中，森林以斑块或河岸走廊的形式存在，还有少量的活篱笆、单株树木或“踏脚石”。我们使用步选函数来量化这些生境要素对路径选择的影响。我们发现这些鸟类愿意穿越开阔生境所承担的风险程度取决于环境。森林特化物种——横斑蚁鵙（Thamnophilus doliatus）在远离其领地的新环境中移动时，相较于靠近其领地的位置，对有林路径表现出更强的选择性。当它的一步起始于森林生境时，它也会选择有林路径。当可用路径的森林覆盖率较低时，它更喜欢以踏脚石为终点的步骤，但当路径的森林覆盖率较高时则会避开。森林广适性物种——棕颈鹪鹩（Campylorhynchus rufinucha）更喜欢包含更多牧场的步骤，但仅当从非森林生境出发时如此。我们的研究结果表明，有林走廊（即河岸走廊）最有利于敏感的森林特化物种在这片破碎化生境中移动。研究结果还表明，在森林覆盖率极低的高度破碎化森林中，踏脚石可能很重要。我们预计，自然扩散的鸟类以及对森林依赖程度更高的物种，相较于我们实验中的鸟类，会对有林路径表现出更强的选择性。
The persistence of forest-dependent species in fragmented landscapes is fundamentally linked to the movement of individuals among subpopulations. The paths taken by dispersing individuals can be considered a series of steps built from individual route choices. Despite the importance of these fine-scale movement decisions, it has proved difficult to collect such data that reveal how forest birds move in novel landscapes. We collected unprecedented route information about the movement of translocated forest birds from two species in the highly fragmented tropical dry forest of Costa Rica. In this pasture-dominated landscape, forest remains in patches or riparian corridors, with lesser amounts of living fencerows and individual trees or "stepping stones." We used step selection functions to quantify how route choice was influenced by these habitat elements. We found that the amount of risk these birds were willing to take by crossing open habitat was context dependent. The forest-specialist Barred Antshrike (Thamnophilus doliatus) exhibited stronger selection for forested routes when moving in novel landscapes distant from its territory relative to locations closer to its territory. It also selected forested routes when its step originated in forest habitat. It preferred steps ending in stepping stones when the available routes had little forest cover, but avoided them when routes had greater forest cover. The forest-generalist Rufous-naped Wren (Campylorhynchus rufinucha) preferred steps that contained more pasture, but only when starting from non-forest habitats. Our results showed that forested corridors (i.e., riparian corridors) best facilitated the movement of a sensitive forest specialist through this fragmented landscape. They also suggested that stepping stones can be important in highly fragmented forests with little remaining forest cover. We expect that naturally dispersing birds and species with greater forest dependence would exhibit even stronger selection for forested routes than did the birds in our experiments.