Predation risk drives long‐term shifts in migratory behaviour and demography in a large herbivore population
Predation risk drives long‐term shifts in migratory behaviour and demography in a large herbivore population
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捕食风险驱动大量食草动物迁徙行为和人口结构的长期变化
DOI：
10.1111/1365-2656.14022
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发表时间：
2023
影响因子：
4.8
通讯作者：
Merrill, E. H.
中科院分区：
文献类型：
--
作者：
Williams, S.;Hebblewhite, M.;Martin, H.;Meyer, C.;Whittington, J.;Killeen, J.;Berg, J.;MacAulay, K.;Smolko, P.;Merrill, E. H.
迁移是一种跨类群的适应性生活史策略，可以帮助个体通过获取饲料和避免捕食风险来最大限度地提高适应性。驱动迁徙变化的机制知之甚少，迁徙行为，空间利用和人口后果之间的联系很少。在这里，我们使用了近20年的大型食草动物麋鹿个体监测记录。（Cervus canadensis）来检验在班夫国家公园（BNP）的一个大型保护区内和附近的迁移模式变化的假设，加拿大我们测试自下而上（草料质量）或自上而下（捕食风险）因素解释了以下趋势：（i）使用5种不同迁移策略的个体比例，（ii）迁移期间和夏季范围内迁移策略的存活率差异，（iii）狼和灰熊的特定原因死亡率，和（iv）人口丰富度。我们发现迁移的戏剧性变化与个人选择年度迁移路线的行为可塑性一致。这种变化与自下而上的移民利益不一致。相反，暴露于保护区外的开发造成的捕食风险的景观梯度推动了迁徙的转变。保护区外的食肉动物开发导致雌性麋鹿留在保护区外或迁移到保护区外的存活率更高。特定原因的死亡率与沿着迁移路线和夏季范围暴露于捕食风险一致。狼捕食风险较高的迁徙路线比夏季范围的山地迁徙策略，但狼捕食风险权衡与灰熊在夏季范围的风险增加。一种新的东部迁徙策略出现在一场大的森林火灾之后，这场火灾增加了保护区外捕食风险较低的地区的饲料。迁徙行为的变化转化为种群丰度，随着时间的推移，山地迁徙策略的丰度下降。与种群中只有一种迁徙策略的情况相比，不同迁徙生活史的存在维持了更高的总种群丰度。我们的研究表明，由于个体平衡捕食风险和饲料权衡，迁徙种群通过行为可塑性和相关的人口后果随时间变化的复杂方式。
Migration is an adaptive life‐history strategy across taxa that helps individuals maximise fitness by obtaining forage and avoiding predation risk. The mechanisms driving migratory changes are poorly understood, and links between migratory behaviour, space use, and demographic consequences are rare.Here, we use a nearly 20‐year record of individual‐based monitoring of a large herbivore, elk (Cervus canadensis) to test hypotheses for changing patterns of migration in and adjacent to a large protected area in Banff National Park (BNP), Canada.We test whether bottom‐up (forage quality) or top‐down (predation risk) factors explained trends in (i) the proportion of individuals using 5 different migratory tactics, (ii) differences in survival rates of migratory tactics during migration and whilst on summer ranges, (iii) cause‐specific mortality by wolves and grizzly bears, and (iv) population abundance.We found dramatic shifts in migration consistent with behavioural plasticity in individual choice of annual migratory routes. Shifts were inconsistent with exposure to the bottom‐up benefits of migration. Instead, exposure to landscape gradients in predation risk caused by exploitation outside the protected area drove migratory shifts. Carnivore exploitation outside the protected area led to higher survival rates for female elk remaining resident or migrating outside the protected area.Cause‐specific mortality aligned with exposure to predation risk along migratory routes and summer ranges. Wolf predation risk was higher on migratory routes than summer ranges of montane‐migrant tactics, but wolf predation risk traded‐off with heightened risk from grizzly bears on summer ranges. A novel eastern migrant tactic emerged following a large forest fire that enhanced forage in an area with lower predation risk outside of the protected area.The changes in migratory behaviour translated to population abundance, where abundance of the montane‐migratory tactics declined over time. The presence of diverse migratory life histories maintained a higher total population abundance than would have been the case with only one migratory tactic in the population.Our study demonstrates the complex ways in which migratory populations change over time through behavioural plasticity and associated demographic consequences because of individuals balancing predation risk and forage trade‐offs.