Nest sites and nest webs for cavity-nesting communities in interior British Columbia, Canada: Nest characteristics and niche partitioning
Nest sites and nest webs for cavity-nesting communities in interior British Columbia, Canada: Nest characteristics and niche partitioning
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作者：
Martin, K;Aitken, KEH;Wiebe, KL
加拿大不列颠哥伦比亚省内陆的混交林孕育着丰富的空巢鸟群落，约占森林脊椎动物物种的三分之一。对于 20 种空洞筑巢鸟类和 6 种空洞筑巢哺乳动物（代表挖掘机和次生空洞筑巢者），我们测量了 8 年来在内陆花旗松 (Pseudotsuga menziesii) 森林生态系统中的巢洞和巢树特征。颤木（Populus tremuloides）的选择是压倒性的。 1692 个空洞巢穴中的 95% 位于白杨树中，而白杨树仅占可用树木的 15%。使用了各种活树和死树，但我们观察到人们强烈偏爱腐烂的活树（45％的巢）或死树（45％的巢）。基于树木和洞穴特征的聚类分析将群落分为五个类群，其中包括大中型啄木鸟和主要由弱挖掘机组成的类群。第四组包括北方闪烁鸟（Colaptes auratus），数量最多的挖掘鸟，以及较大的次生洞筑巢鸟。最后一组包含最具攻击性和最丰富的次生洞筑巢者。欧洲椋鸟 (Sturnus vulgaris) 是最具攻击性的次生空巢筑巢者，相对于其体型而言，占据较窄的巢穴（在腐烂程度较低、入口较小的树木中）。就树木腐烂类别和空腔尺寸而言，竞争力较弱的挖掘机和二次空腔筑巢者占据了更广泛的巢穴生态位。我们为群落结构构建了一个巢网，表明大多数空洞资源的使用通过白杨树和北方闪烁树挖掘的空洞向上流动。因此，白杨是关键的筑巢树，而北方闪烁树是这个社区的基石挖掘机。
The mixed forests of interior British Columbia, Canada, support a rich community of cavity nesters, accounting for about one-third of forest vertebrate species. For 20 cavity-nesting bird and six cavity-nesting mammal species, representing excavators and secondary cavity nesters, we measured nest-cavity and nest-tree characteristics over 8 years in Interior Douglas-fir (Pseudotsuga menziesii) forest ecosystems. There was overwhelming selection for quaking aspen (Populus tremuloides); 95% of 1692 cavity nests were in aspen, which comprised only 15% of trees available. The full range of live and dead trees were used, but we observed a strong preference for live trees with decay (45% of nests) or dead trees (45% of nests). A cluster analysis based on tree and cavity characteristics divided the community into five groups, including large- and medium-sized woodpeckers and a group comprised mostly of weak excavators. A fourth group included Northern Flickers (Colaptes auratus), the most abundant excavator, and the larger secondary cavity nesters. The final group contained the most aggressive and most abundant secondary cavity nesters. European Starling (Sturnus vulgaris), the most aggressive secondary cavity nester, occupied a narrower nest niche (in less-decayed trees with smaller entrances) relative to their size. Less-competitive excavators and secondary cavity nesters occupied wider nest niches in terms of tree decay class and cavity size. We constructed a nest web for community structure that showed most cavity resource use flowed up the community through aspen trees and cavities excavated by Northern Flickers. Thus, aspen was the critical nesting tree and Northern Flickers were the keystone excavators in this community.