Abiotic, bottom‐up, and top‐down influences on recruitment of Rocky Mountain elk in Oregon: A retrospective analysis
Abiotic, bottom‐up, and top‐down influences on recruitment of Rocky Mountain elk in Oregon: A retrospective analysis
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非生物、自下而上和自上而下对俄勒冈州落基山麋鹿招募的影响：回顾性分析
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发表时间：
2013
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影响因子：
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通讯作者：
R. Green
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作者：
B. Johnson;P. Coe;R. Green
了解可能影响有蹄类动物招募的许多因素的相对影响，对于管理它们的种群是至关重要的。在过去的40年里，美国俄勒冈州一些麋鹿种群（Cervus elaphus）的平均招募数量从每100只雌鹿50只下降到20只以下，一些相互竞争的假说解释了这些下降。我们建立了先验模型并构建了1977-2005年间的协变量，这些协变量包括被猎杀的麋鹿、麋鹿种群估计、美洲狮收获量和天气统计数据，以评估非生物、自下而上和自上而下的因素，这些因素可能解释了每年的变化和长期趋势，晚秋幼鹿和春季幼鹿的招募。在怀孕状态模型中，8月降水量、年龄和美洲狮指数对麋鹿的生长有正向影响，而前一年（t−1）冬季严重度或冬季降水量（t−1）和麋鹿密度对麋鹿的生长有负向影响。在晚秋幼鹿跟鹿模型中，8月降水量、8月降水量（t−1）、美洲狮指数×麋鹿密度（t−1）和年龄对幼鹿跟鹿有正向影响，而美洲狮指数、麋鹿密度（t−1）和冬季降水量（t−1）对幼鹿跟鹿有负向影响。8月降水量（t−1）、泌乳率和美洲狮指数×麋鹿密度（t−1）的正效应和美洲狮指数和麋鹿密度（t−1）的负效应是幼鹿招募的最佳解释。冬季严重度、降水和温度对麋鹿招募的变化解释不显著。怀孕、幼崽和招募的年变化受8月降水的影响最大，而招募的长期趋势受美洲狮密度的影响最大，而麋鹿密度的影响相对较小。这些结果有助于深入了解驼鹿复育的年度原因和长期趋势，并为更严格地评估影响驼鹿复育的因素提供依据。©2012野生动物协会。
Understanding the relative effects of the many factors that may influence recruitment of ungulates is fundamental to managing their populations. Over the last 4 decades, average recruitment in some populations of elk (Cervus elaphus) in Oregon, USA declined from >50 to <20 juveniles per 100 females, and several competing hypotheses address these declines. We developed a priori models and constructed covariates spanning 1977–2005 from hunter-killed elk, elk population estimates, cougar harvest, and weather statistics to evaluate abiotic, bottom-up, and top-down factors that may explain annual variation and long-term trends of pregnancy, juveniles-at-heel in late autumn, and recruitment of juvenile elk in spring. In models of pregnancy status, August precipitation, age, and cougar index had positive effects, whereas previous year (t − 1) winter severity or winter precipitation(t−1) and elk density had negative effects. In models of juvenile-at-heel in late autumn, August precipitation, August precipitation(t−1), cougar index × elk density(t−1), and age had positive effects, whereas cougar index, elk density(t−1), and winter precipitation(t−1) had negative effects. Juvenile recruitment was best explained by positive effects of August precipitation(t−1), lactation rate, and cougar index × elk density(t−1) and negative effects of cougar index and elk density(t−1). Winter severity, precipitation, and temperature were not significant in explaining variation in elk recruitment. Annual variation in pregnancy, juvenile-at-heel, and recruitment was most influenced by August precipitation, whereas long-term trends in recruitment were most influenced by cougar densities with relatively weak effects of elk density. These results provide insight into causes of year-to-year and long-term trends of elk recruitment and provide a basis for more rigorous evaluation of factors affecting recruitment of elk. © 2012 The Wildlife Society.