Wildlife Infometrics Inc, Mackenzie, British Columbia, Canada.
Department of Biology, University of British Columbia, Kelowna, British Columbia, Canada.
Ecol Appl. 2022 Jul;32(5):e2580. doi: 10.1002/eap.2580. Epub 2022 Jun 5.
Recovering endangered species is a difficult and often controversial task that challenges status quo land uses. Southern Mountain caribou are a threatened ecotype of caribou that historically ranged in southwestern Canada and northwestern USA and epitomize the tension between resource extraction, biodiversity conservation, and Indigenous Peoples' treaty rights. Human-induced habitat alteration is considered the ultimate cause of caribou population declines, whereby an increased abundance of primary prey-such as moose and deer-elevates predator populations and creates unsustainable caribou mortality. Here we focus on the Klinse-Za and Quintette subpopulations, part of the endangered Central Group of Southern Mountain caribou in British Columbia. These subpopulations were trending toward immediate extirpation until a collaborative group initiated recovery by implementing two short-term recovery actions. We test the effectiveness of these recovery actions-maternity penning of adult females and their calves, and the reduction of a primary predator, wolves-in increasing vital rates and population growth. Klinse-Za received both recovery actions, whereas Quintette only received wolf reductions, providing an opportunity to test efficacy between recovery actions. Between 1995 and 2021, we followed 162 collared female caribou for 414 animal-years to estimate survival and used aerial counts to estimate population abundance and calf recruitment. We combined these data in an integrated population model to estimate female population growth, total population abundance, and recovery action effectiveness. Results suggest that the subpopulations were declining rapidly (λ = 0.90-0.93) before interventions and would have been functionally extirpated (<10 animals) within 10-15 years. Wolf reduction increased population growth rates by ~0.12 for each subpopulation. Wolf reduction halted the decline of Quintette caribou and allowed them to increase (λ = 1.05), but alone would have only stabilized the Klinse-Za (λ = 1.02). However, maternity penning in the Klinse-Za increased population growth by a further ~0.06, which when combined with wolf reductions, allowed populations to grow (λ = 1.08). Taken together, the recovery actions in these subpopulations increased adult female survival, calf recruitment, and overall population growth, more than doubling abundance. Our results suggest that maternity penning and wolf reductions can be effective at increasing caribou numbers in the short term, while long-term commitments to habitat protection and restoration are made.
恢复濒危物种是一项艰巨且常具争议的任务，它挑战了现状下的土地利用方式。南方山地驯鹿是一种受到威胁的驯鹿生态型，历史上分布在加拿大西南部和美国西北部，体现了资源开采、生物多样性保护和原住民条约权利之间的紧张关系。人类导致的栖息地改变被认为是驯鹿数量下降的最终原因，因为主要猎物（如驼鹿和鹿）的增加会导致捕食者数量上升，从而造成驯鹿无法承受的死亡率。在这里，我们关注的是不列颠哥伦比亚省濒危的中央组南方山地驯鹿的 Klinse-Za 和 Quintette 亚种群。这些亚种群的数量一直在减少，直到一个合作小组通过实施两项短期恢复行动来启动恢复计划。我们测试了这些恢复行动——成年雌性和其幼崽的产犊围栏，以及减少主要捕食者狼的数量——提高关键增长率和种群增长的效果。Klinse-Za 同时接受了这两项恢复行动，而 Quintette 只接受了减少狼的数量，这为测试两种恢复行动的效果提供了机会。在 1995 年至 2021 年期间，我们跟踪了 162 只佩戴项圈的雌性驯鹿，记录了 414 个动物年的生存情况，并使用空中计数来估计种群数量和幼鹿的补充情况。我们将这些数据结合到一个综合种群模型中，以估计雌性种群的增长、总种群数量和恢复行动的效果。结果表明，在干预之前，亚种群的数量正在迅速减少（λ=0.90-0.93），并且在 10-15 年内将功能性灭绝（<10 只）。每一个亚种群减少狼的数量都会使种群增长率提高约 0.12。减少狼的数量阻止了 Quintette 驯鹿的数量下降，并使它们的数量增加（λ=1.05），但单独行动只会使 Klinse-Za 的数量稳定（λ=1.02）。然而，Klinse-Za 的产犊围栏进一步提高了种群增长率约 0.06，当与减少狼的数量相结合时，使种群数量得以增长（λ=1.08）。综上所述，这些亚种群的恢复行动提高了成年雌性的存活率、幼鹿的补充率和整体种群增长率，使数量增加了一倍以上。我们的研究结果表明，产犊围栏和减少狼的数量可以在短期内有效地增加驯鹿的数量，同时也需要长期致力于保护和恢复栖息地。
