Shrub encroachment is transforming arid and semiarid grasslands worldwide. Such transitions should influence predator–prey interactions because vegetation cover often affects risk perception by prey and contributes to their landscape of fear. We examined how the landscape of fear of two desert lagomorphs (black‐tailed jackrabbit, Lepus californicus; desert cottontail, Sylvilagus audubonii) changes across grassland‐to‐shrubland gradients at Jornada Basin Long Term Ecological Research site in the Chihuahuan Desert of southern New Mexico. We test whether shrub encroachment shapes risk differently for these two lagomorphs because of differences in body size and predator escape tactics. We also examine whether an ecosystem engineer of grasslands (banner‐tailed kangaroo rat, Dipodomys spectabilis) mediates risk perception through the creation of escape refuge and whether trade‐offs exist between shrub encroachment and the local reduction of banner‐tailed kangaroo rats caused by shrub expansion. We measured perceived predation risk with flight initiation distances (FIDs) and then used structural equation modeling to tease apart the hypothesized direct and indirect pathways for how shrub encroachment could affect perceived risk. A total negative effect of shrub cover on FID was supported for jackrabbits and cottontails, suggesting both species perceive shrubbier habitat as safer. Increases in fine‐scale concealment also reduced risk for cottontails, but not jackrabbits, likely because cottontails rely on crypsis to avoid predator detection whereas jackrabbits rely on speed and agility to outrun predators. Perceived risk was reduced when individuals were near kangaroo rat mounds only for cottontails because the smaller species can use banner‐tailed kangaroo rat mounds as refuge. Shrub encroachment greatly reduced the availability of mounds. Thus, a trade‐off exists for cottontails in which shrub encroachment directly reduced perceived risk, but indirectly increased perceived risk through the local extirpation of an ecosystem engineer. Our work illustrates how the expansion of shrub encroachment can create a dynamic landscape of fear for populations of prey species involving direct and indirect pathways contingent on prey body size, escape tactics, and activities of an ecosystem engineer.

中文翻译：

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灌木侵蚀通过多种途径创造了对沙漠兔形恐惧的动态景观

灌木丛的侵蚀正在改变全世界的干旱和半干旱草原。这种过渡应该影响食肉动物与猎物之间的相互作用，因为植被的覆盖通常会影响猎物对风险的感知，并加剧其恐惧感。我们研究了在新墨西哥州南部奇瓦瓦沙漠的Jornada盆地长期生态研究站点，两种荒漠象形文字（黑尾长尾小野兔，狼疮californicus；沙漠棉尾鱼，西尔维拉古斯audubonii）的恐惧景观如何在草地到灌木丛的梯度上变化。 。我们测试了由于体型和捕食者逃避策略的差异，这两种兔形灌木的侵占形状风险是否有所不同。我们还研究了草原的生态系统工程师（旗尾袋鼠，壮观的两栖动物）通过建立逃生避难所以及灌木入侵和灌木扩张引起的袋鼠尾鼠局部减少之间是否存在折衷关系来介导风险感知。我们用飞行起始距离（FID）测量了感知到的捕食风险，然后使用结构方程模型梳理了假设的直接和间接途径，以了解灌木丛入侵如何影响感知到的风险。灌木覆盖对FID的总体负面影响得到了兔子和棉尾草的支持，表明这两种物种都认为灌木丛生境更安全。细密隐蔽性的增加也减少了棉尾虫而不是野兔的风险，这很可能是因为棉尾虫依靠低温昆虫来避免捕食者的发现，而野兔则依靠速度和敏捷性来超越捕食者。当个体靠近袋鼠鼠丘只用棉尾时，可知的风险降低了，因为较小的物种可以使用横幅尾袋鼠鼠丘作为避难所。灌木丛的侵占大大减少了土丘的可用性。因此，存在着权衡棉尾的情况，其中灌木入侵直接降低了感知风险，但通过局部灭绝生态系统工程师而间接增加了感知风险。我们的工作说明了灌木丛侵害的扩大如何为猎物种群带来动态的恐惧景观，其中涉及直接和间接的路径，这些路径取决于猎物的体型，逃避策略和生态系统工程师的活动。灌木丛的侵占大大减少了土丘的可用性。因此，存在着权衡棉尾的情况，其中灌木入侵直接降低了感知风险，但通过局部灭绝生态系统工程师而间接增加了感知风险。我们的工作说明了灌木丛侵害的扩大如何为猎物种群带来动态的恐惧景观，其中涉及直接和间接的路径，这些路径取决于猎物的体型，逃避策略和生态系统工程师的活动。灌木丛的侵占大大减少了土丘的可用性。因此，存在着权衡棉尾的情况，其中灌木入侵直接降低了感知风险，但通过局部灭绝生态系统工程师而间接增加了感知风险。我们的工作说明了灌木丛侵害的扩大如何为猎物种群带来动态的恐惧景观，其中涉及直接和间接的路径，这些路径取决于猎物的体型，逃避策略和生态系统工程师的活动。