MacAulay Kara M, Spilker Eric G, Berg Jodi E, Hebblewhite Mark, Merrill Evelyn H
Department of Biological Sciences University of Alberta Edmonton Alberta Canada.
Wildlife Biology Program Department of Ecosystem and Conservation Sciences W. A. Franke College of Forestry and Conservation University of Montana Missoula Montana USA.
Ecol Evol. 2022 Feb 14;12(2):e8589. doi: 10.1002/ece3.8589. eCollection 2022 Feb.
There is growing evidence that prey perceive the risk of predation and alter their behavior in response, resulting in changes in spatial distribution and potential fitness consequences. Previous approaches to mapping predation risk across a landscape quantify predator space use to estimate potential predator-prey encounters, yet this approach does not account for successful predator attack resulting in prey mortality. An exception is a prey kill site that reflects an encounter resulting in mortality, but obtaining information on kill sites is expensive and requires time to accumulate adequate sample sizes.We illustrate an alternative approach using predator scat locations and their contents to quantify spatial predation risk for elk ) from multiple predators in the Rocky Mountains of Alberta, Canada. We surveyed over 1300 km to detect scats of bears (/. ), cougars (), coyotes (), and wolves (. ). To derive spatial predation risk, we combined predictions of scat-based resource selection functions (RSFs) weighted by predator abundance with predictions that a predator-specific scat in a location contained elk. We evaluated the scat-based predictions of predation risk by correlating them to predictions based on elk kill sites. We also compared scat-based predation risk on summer ranges of elk following three migratory tactics for consistency with telemetry-based metrics of predation risk and cause-specific mortality of elk.We found a strong correlation between the scat-based approach presented here and predation risk predicted by kill sites and ( = .98, < .001). Elk migrating east of the Ya Ha Tinda winter range were exposed to the highest predation risk from cougars, resident elk summering on the Ya Ha Tinda winter range were exposed to the highest predation risk from wolves and coyotes, and elk migrating west to summer in Banff National Park were exposed to highest risk of encountering bears, but it was less likely to find elk in bear scats than in other areas. These patterns were consistent with previous estimates of spatial risk based on telemetry of collared predators and recent cause-specific mortality patterns in elk.A scat-based approach can provide a cost-efficient alternative to kill sites of quantifying broad-scale, spatial patterns in risk of predation for prey particularly in multiple predator species systems.
越来越多的证据表明，猎物能够感知被捕食的风险并相应地改变其行为，从而导致空间分布的变化以及潜在的适应性后果。以往在景观中绘制捕食风险的方法是通过量化捕食者的空间利用情况来估计潜在的捕食者与猎物相遇的概率，但这种方法没有考虑到成功的捕食者攻击导致猎物死亡的情况。一个例外是猎物死亡地点，它反映了导致死亡的一次相遇，但获取有关死亡地点的信息成本高昂，且需要时间来积累足够的样本量。我们展示了一种替代方法，利用捕食者粪便的位置及其内容物来量化加拿大艾伯塔省落基山脉中多种捕食者对麋鹿的空间捕食风险。我们调查了超过1300公里的区域，以检测熊（/）、美洲狮（）、郊狼（）和狼（.）的粪便。为了得出空间捕食风险，我们将基于粪便的资源选择函数（RSF）的预测结果（按捕食者丰度加权）与某个地点特定捕食者的粪便中含有麋鹿的预测结果相结合。我们通过将基于粪便的捕食风险预测与基于麋鹿死亡地点的预测进行关联，来评估基于粪便的捕食风险预测。我们还比较了采用三种迁徙策略的麋鹿夏季活动范围内基于粪便的捕食风险，以使其与基于遥测的捕食风险指标以及麋鹿的死因特异性死亡率保持一致。我们发现，这里提出的基于粪便的方法与死亡地点预测的捕食风险之间存在很强的相关性（=0.98，<0.001）。在亚哈廷达冬季牧场以东迁徙的麋鹿面临美洲狮的捕食风险最高，在亚哈廷达冬季牧场度夏的常住麋鹿面临狼和郊狼的捕食风险最高，而向西迁徙到班夫国家公园度夏的麋鹿遭遇熊的风险最高，但在熊的粪便中发现麋鹿的可能性低于其他区域。这些模式与先前基于佩戴项圈的捕食者遥测数据得出的空间风险估计以及麋鹿最近的死因特异性死亡率模式一致。基于粪便的方法可以为死亡地点提供一种成本效益高的替代方法，用于量化猎物被捕食风险的广泛空间模式，特别是在多种捕食者物种系统中。
