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The lethal 23%: predator demography influences predation risk for threatened prey
Animal Conservation ( IF 2.8 ) Pub Date : 2020-08-02 , DOI: 10.1111/acv.12623
K. E. Moseby 1, 2 , H. McGregor 2, 3 , J. L. Read 4
Affiliation  

Globally, wildlife managers often control predator populations to protect biodiversity, livestock or other valued resources. Most assume that the predation impact of each individual predator is the same and that removing any individual predator produces a benefit to the target species. However, research suggests predation efficacy can vary within a predator species according to phenotypic characteristics. Understanding these individual differences may be critical for managing predation impacts on particular categories of prey including small populations where predation effects are amplified. We used dietary data from 1748 feral cats euthanized over 30 years during a control programme in arid Australia to determine whether any predator attributes could predict their effect on different prey weight classes. Feral cats in our study ate a wide range of prey including reptiles, mammals, birds and invertebrates. Demography (body mass) was a highly significant predictor of diet. Cats weighing 3 kg fed predominantly on prey <50 g increasing to >500 g when cats attained a body mass of 6 kg. Of more significance was that diet varied between demographic groups but also within a single demographic group (adult males) based on body mass, with results having significant implications for threatened prey. Modelling indicated that for a fixed predator population size, the predation rate on prey in a >500 g weight class increased by 28% when the ratio of large (>4.2 kg) to small adult males varied according to its natural range (12%–80% over the 30‐year study). Results suggest that variations in predator demography can significantly impact predation rates on prey species and should be included in predator–prey models for small prey populations. On average, large male cats comprised 23% of the population and our findings suggest that targeting this ‘lethal demographic’ and manipulating predator demography should be prioritized along with lowering predator density to reduce predation impacts on prey weighing more than 500g.

中文翻译:

致命的23%:捕食者的人口统计学影响受威胁猎物的捕食风险

在全球范围内,野生动植物管理者经常控制捕食者的种群,以保护生物多样性,牲畜或其他有价值的资源。大多数人假设每个捕食者的捕食影响是相同的,并且消除任何一个捕食者都会对目标物种产生好处。但是,研究表明,根据表型特征,捕食效果在捕食物种内可能会有所不同。了解这些个体差异对于管理捕食对特定种类的猎物(包括捕食效应被放大的小种群)的影响可能至关重要。在干旱澳大利亚的一项控制计划中,我们使用了30年内对1748只野猫实施安乐死的饮食数据,以确定是否有任何掠食者属性可以预测它们对不同体重的猎物的影响。在我们的研究中,野猫吃了各种各样的猎物,包括爬行动物,哺乳动物,鸟类和无脊椎动物。人口统计学(体重)是饮食的重要预测指标。体重3千克的猫主要摄食<50克,而体重达到6千克时则增加到500克以上。更重要的是,饮食根据人群的不同而有所不同,但在一个人口群体(成年男性)中,饮食也因体重而异,结果对受威胁的猎物具有重要意义。模型表明,对于固定的捕食者种群规模,体重大于500 g的类别中的猎物捕食率会根据其自然范围的变化(大于4.2千克)与成年小型成年雄性的比率增加28%(12%–在30年的研究中占80%)。结果表明,捕食者人口统计学的变化会显着影响捕食物种的捕食率,应将其纳入小型捕食者种群的捕食者-猎物模型中。平均而言,大型雄猫占总人口的23%,我们的研究结果表明,针对这种“致命人口统计”和操纵捕食者人口统计学应优先进行,同时降低捕食者密度,以减少捕食对体重超过500g的猎物的影响。
更新日期:2020-08-02
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