Most seabird species nest colonially on cliffs or islands with limited terrestrial predation, so that oceanic effects on the quality or quantity of prey fed to chicks more often determine nest success. However, when predator access increases, impacts can be dramatic, especially when exposure to predators is extended due to slow growth from inadequate food. Kittlitz’s Murrelet (Brachyramphus brevirostris), a rare seabird having experienced serious declines, nests solitarily on the ground in barren, often alpine areas where exposure to predators is generally low. Nestling growth rates are exceptionally high and nestling periods very short relative to other Alcidae. This strategy reduces duration of exposure to predators, but demands adequate deliveries of high‐energy prey. In an area where foxes can access nests, we investigated whether varying energy content of prey fed to chicks could alter growth rates and resulting duration of predator exposure, and whether prolonged exposure appreciably reduced nest success. From 2009 to 2016, we monitored 139 nests; 49% were depredated (almost all by foxes) and 25% fledged. Prey fed to nestlings were 80% Pacific sand lance (Ammodytes personatus) and 19% capelin (Mallotus villosus), with capelin having 2.3× higher energy content per fish. In a year of slow chick growth, increased sand lance energy density of 31% (4.29–5.64 kJ/g, within published values), or increased proportion of capelin in the diet from 5.6% to 27.2%, would have allowed maximum chick growth. Maximum growth rates were attainable by delivering only 1.9 capelin/d versus 5.5 sand lance/d. Slow growth increased time to fledging by up to 5 d, decreasing survival by 7.7% (0.142–0.131). Breeding propensity of Kittlitz’s Murrelet averages only 20%, so even small changes in nest success could affect populations. Although nest success was limited mainly by predation, oceanic effects on prey quantity and quality had overriding impacts in one year (2015 heat wave), and small but substantive effects in other years by mediating exposure to predation. Climate warming that decreases availability of high‐energy forage fish, or increases expansion of predators into nesting habitats, may disproportionately affect this sensitive species and others with predator‐accessible nests and demands for energy‐rich prey.

中文翻译：

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海洋猎物能否对处于危险中的海鸟的生长和下垂的时间产生介导的陆地捕食者限制？

大多数海鸟物种在有限的陆地捕食中殖民地筑巢在悬崖或岛屿上，因此，海洋对饲喂雏鸟的猎物的质量或数量的影响通常决定巢的成功。但是，当掠食者的获取增加时，影响可能是巨大的，尤其是由于食物不足导致生长缓慢而使掠食者的接触时间延长时。Kittlitz的Murrelet（Brachyramphus brevirostris）是一种罕见的海鸟，经历了严重的下降，它孤零零地筑巢在贫瘠的地区，通常是高山地区，这些地区的天敌很少。相对于其他Alcidae，雏鸟的生长速度极高，而雏鸟的时期非常短。这种策略减少了被捕食者接触的时间，但是需要足够的高能猎物来运送。在狐狸可以进入巢穴的区域，我们调查了喂给雏鸡的猎物能量含量的变化是否会改变生长速度和由此导致的捕食者接触的持续时间，以及长时间的接触是否会显着降低筑巢成功率。从2009年到2016年，我们监测了139个巢穴；49％被弃用（几乎全部被狐狸捕杀），而25％被弃用。喂给雏鸟的猎物有80％的太平洋沙矛（Ammodytes personatus）和19％的毛鳞鱼（绒槌），毛鳞鱼的能量含量比每条鱼高2.3倍。在小鸡生长缓慢的一年中，喷枪能量密度增加31％（4.29–5.64 kJ / g，在公布的值内），或者日粮中毛鳞鱼的比例从5.6％增加到27.2％，将使小鸡最大程度地生长。通过仅提供1.9 capelin / d相对于5.5 sand lance / d可以获得最大的增长率。缓慢的生长使出雏时间延长了5 d，使存活率降低了7.7％（0.142–0.131）。基特利茨的穆雷莱特（Murrelet）的繁殖倾向平均仅为20％，因此即使巢窝成功的微小变化也可能影响种群。尽管筑巢成功主要受捕食限制，但海洋对猎物数量和质量的影响在一年（2015年热浪）中具有压倒性影响，而在其他年份中，通过介导捕食暴露对海洋的影响很小但具有实质性影响。