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首页> 外文期刊>Polar biology >Predation by New Zealand sea lions and Brown Skuas is causing the continued decline of an Eastern Rockhopper Penguin colony on Campbell Island
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Predation by New Zealand sea lions and Brown Skuas is causing the continued decline of an Eastern Rockhopper Penguin colony on Campbell Island

机译：新西兰海狮和布朗贼鸥的捕食活动导致坎贝尔岛上的东部凤冠企鹅殖民地持续减少

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摘要

Identification of factors causing population declines is a critical prerequisite for conserving threatened species. The most likely cause of dramatic decreases in numbers of the 'Vulnerable' Southern Rockhopper Penguin (Eudyptes chrysocome) in the twentieth century is oceanographic change reducing food availability. For example, the massive decline of the Eastern sub-species (E. c. filholi) on Campbell Island, New Zealand (94.6 %, 1942-2012), has been attributed to climate change. This decline reversed in the mid-1990s after a shift to favourable conditions, but a localized decline continued at a small, fragmented population in Penguin Bay, where one of five sub-colonies went extinct in 2010, and the number of breeding pairs fell from 7360 in 1984 to 3012 in 2012. Emerging concerns for Eudyptes penguins are the effects of increased predation from native predators. At Campbell Island, monitoring demonstrated that penguin eggs and chicks in smaller sub-colonies were most vulnerable to predation by Brown Skuas (Catharacta antarctica lonnbergi), so that average reproductive success was 25 % lower at the smallest sub-colony than at the largest. 'Endangered' New Zealand sea lions (Phocarctos hookeri) were estimated to depredate 6 % of the adult penguin population each year, which modelling identified as the most important driver of the population's negative exponential growth rate (lambda = 0.905, -9.5 % per year). Although occasional years of very poor food availability may exert a larger 'bottom-up' effect on penguin demographic rates, the 'top-down' effects of high avian and pinniped predation rates can be sufficient to drive the decline of small penguin populations.
机译：查明造成种群减少的因素是保护濒危物种的关键先决条件。二十世纪“脆弱的”南部Rockhopper企鹅（Eudyptes chrysocome）数量急剧减少的最可能原因是海洋学的变化减少了食物的供应。例如，在新西兰坎贝尔岛上的东部亚种（E. c。filholi）的大量减少（94.6％，1942-2012年）是气候变化造成的。在转为有利条件后，这种下降在1990年代中期发生了逆转，但是局部下降仍在企鹅湾的一小块零散的种群中继续发生，2010年，五个亚殖民地之一灭绝了，繁殖对的数量从从1984年的7360到2012年的3012。Eudyptes企鹅的新担忧是本地捕食者捕食增加的影响。在坎贝尔岛（Campbell Island），监测表明，较小的亚殖民地的企鹅卵和小鸡最容易受到棕贼（Catharacta antarctica lonnbergi）的捕食，因此，最小的亚殖民地的平均繁殖成功率比最大的低25％。据估计，“濒临灭绝的”新西兰海狮（Phocarctos hookeri）每年会淘汰成年企鹅种群的6％，该模型被确定为该种群负指数增长率的最重要驱动因素（lambda = 0.905，每年-9.5％） ）。尽管偶尔几年食物供应极差，可能对企鹅的人口统计率产生较大的“自下而上”的影响，但高禽和夹足捕食率的“自上而下”的影响足以推动小企鹅种群的减少。

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