Drever Mark C, Smith Adam C, Venier Lisa A, Sleep Darren J H, MacLean David A
Canadian Wildlife Service Environment and Climate Change Canada Delta British Columbia Canada.
Canadian Wildlife Service Environment and Climate Change Canada National Wildlife Research Centre Ottawa Ontario Canada.
Ecol Evol. 2018 Jun 27;8(15):7334-7345. doi: 10.1002/ece3.4244. eCollection 2018 Aug.
Insect outbreaks are major natural disturbance events that affect communities of forest birds, either directly by affecting the food supply or indirectly by changing the vegetation composition of forest canopies. An examination of correlations between measures of bird and insect abundance across different spatial scales and over varying time lag effects may provide insight into underlying mechanisms. We developed a hierarchical Bayesian model to assess correlations between counts of eight warbler species from the Breeding Bird Survey in eastern Canada, 1966 to 2009, with the presence of spruce budworm ( Clem.) at immediate local scales and time-lagged regional scales, as measured by extent of defoliation on host tree species. Budworm-associated species Cape May warbler (), bay-breasted warbler (), and Tennessee warbler () responded strongly and positively to both local and regional effects. In contrast, non-budworm-associated species, Blackburnian warbler (), magnolia warbler (), Canada warbler (), black-throated blue warbler (), and black-throated green warbler (), only responded to regional effects in a manner that varied across eastern Canada. The complex responses by forest birds to insect outbreaks involve both increased numerical responses to food supply and to longer term responses to changes in forest structure and composition. These effects can vary across spatial scales and be captured in hierarchical population models, which can serve to disentangle common trends from data when examining drivers of population dynamics like forest management or climate change.
昆虫爆发是影响森林鸟类群落的主要自然干扰事件,要么通过影响食物供应直接产生影响,要么通过改变森林树冠层的植被组成间接产生影响。考察不同空间尺度以及不同时间滞后效应下鸟类数量与昆虫数量测量值之间的相关性,或许能为潜在机制提供见解。我们构建了一个分层贝叶斯模型,以评估1966年至2009年加拿大东部繁殖鸟类调查中8种莺类的数量与云杉芽虫(Clem.)在当地即时尺度和区域尺度上的存在情况之间的相关性,后者通过寄主树种的落叶程度来衡量。与芽虫相关的物种——栗颊林莺()、赤腰林莺()和田纳西林莺(),对当地和区域效应均表现出强烈的正向响应。相比之下,与芽虫无关的物种——橙胸林莺()、木兰林莺()、加拿大林莺()、黑喉蓝林莺()和黑喉绿林莺(),仅以在加拿大东部各地有所不同的方式对区域效应做出反应。森林鸟类对昆虫爆发的复杂反应既包括对食物供应增加的数量反应,也包括对森林结构和组成变化的长期反应。这些效应在不同空间尺度上可能有所不同,并可在分层种群模型中体现出来,在研究诸如森林管理或气候变化等种群动态驱动因素时,该模型有助于从数据中梳理出共同趋势。