Forest thinning on public lands in the Pacific Northwest USA is an important tool for restoring diversity in forest stands with a legacy of simplified structure from decades of intensive management for timber production. A primary application of thinning in young (< 50-year-old) stands is to accelerate forest development to mitigate loss of late-seral habitat to decades of logging. However, thinning may have short-term negative effects for some species associated with mature forest that are expected to benefit from the practice over the long term. An increased risk of nest predation is a primary concern to managers charged with stewardship of habitat for the federally threatened Marbled Murrelet (Brachyramphus marmoratus), a species that nests in older forests. Predation by corvids is the greatest cause of nest failure for the Marbled Murrelet, and corvids are known to respond positively to forest disturbance, but quantitative information is lacking on the potential impacts of thinning on risk of nest predation. We investigated the response of two common corvid nest predators, Steller’s Jay (Cyanocitta stelleri) and Canada Jay (Perisoreus canadensis), to variation in thinning intensity in young forest (< 50 years old) using data from a long-term silviculture experiment. We used a Before-After-Control-Impact (BACI) design, linear mixed modeling, and occupancy modeling to quantify differences in corvid observation rates among varying levels of thinning intensity, and to assess changes in jay response over more than a decade following thinning. We found an increase in observation rates of both species in the heavily thinned treatment during the first 5 to 7 years following thinning, and some evidence of a short-term increase in Steller’s Jay activity in the thinning-with-gaps treatment. Neither jay species responded to the least intensive thinning treatment, which reduced average canopy cover by < 30%. By approximately a decade after thinning, observation rates of jays did not differ between unthinned controls and any of the thinning treatments. Incorporating our quantitative information into landscape-level planning can help managers balance short- and long-term conservation goals.

The post Response of corvid nest predators to thinning: implications for balancing short- and long-term goals for restoration of forest habitat first appeared on Avian Conservation and Ecology.

美国西北太平洋地区公共土地上的森林疏伐是恢复林分多样性的重要工具，几十年来木材生产的集约化管理留下了简化的结构。对幼林（< 50 年）进行间伐的主要用途是加速森林发展，以减轻数十年伐木造成的晚期群栖地的丧失。然而，间伐可能会对某些与成熟森林相关的物种产生短期负面影响，而这些物种预计将长期受益于这种做法。巢穴被掠食的风险增加是负责管理受到联邦威胁的大理石海雀（Brachyramphus marmoratus）栖息地的管理人员的主要担忧，该物种在古老的森林中筑巢。鸦科鸟类的捕食是大理石斑斑雀鸟巢穴失败的最大原因，众所周知，鸦科鸟类会对森林干扰做出积极反应，但缺乏关于间伐对巢穴捕食风险的潜在影响的定量信息。我们利用长期造林实验的数据，研究了两种常见的鸦科鸟类巢穴捕食者虎头鸦 ( Cyanocitta stelleri ) 和加拿大鸦 ( Perisoreus canadensis ) 对幼林（< 50 岁）间伐强度变化的反应。我们使用了前后控制影响（BACI）设计、线性混合模型和占用模型来量化不同疏伐强度水平下鸦雀观察率的差异，并评估疏伐后十多年来松鸦反应的变化。我们发现，在间伐后的前 5 至 7 年内，在严重间伐处理中，这两个物种的观察率均有所增加，并且有一些证据表明，在有间隙间伐处理中虎头松鸦的活动短期内有所增加。两种松鸦物种都对强度最低的间伐处理没有反应，这种处理使平均树冠覆盖率减少了 < 30%。到间伐后大约十年，松鸦的观察率在未间伐对照和任何间伐处理之间没有差异。将我们的定量信息纳入景观规划中可以帮助管理者平衡短期和长期保护目标。

鸦科鸟类巢穴捕食者对稀疏化的反应：平衡森林栖息地恢复的短期和长期目标的影响首次出现在鸟类保护和生态学上。