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首页> 外文期刊>Marine ecology progress series >Foraging behaviour in two Antarctic fur seal colonies with differing population recoveries
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Foraging behaviour in two Antarctic fur seal colonies with differing population recoveries

机译：在两个南极海豹种群具有不同种群回收率的觅食行为

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We compared Antarctic fur seals Arctocephalus gazella breeding at 2 contrasting sites on South Georgia: one high density colony at Bird Island and one lower density colony at Cooper Bay. The population at Cooper Bay was considerably smaller than that at Bird Island despite ample suitable breeding area being available. At Cooper Bay, female seals were longer but weighed less than those breeding at Bird Island and, whilst both maintained the same rate of female pup growth, male pups grew faster at Cooper Bay. Although Bird Island seals dived deeper, they dived less often than Cooper Bay seals so that both populations spent comparable amounts of time in the bottom phase of dives actively foraging. Longer distance oceanic foraging trips that were observed at Bird Island were almost entirely absent from Cooper Bay. Both populations fed on Antarctic krill, but there was an absence of myctophid prey in the diet of seals at Cooper Bay. Evidence suggests that the favoured myctophid prey of fur seals at South Georgia, Protomyctophum choriodon, are absent from the colder waters around the south-east of the island. We propose that, if these energy-rich prey are unavailable in this region then seals at Cooper Bay may find it hard to offset the increased costs of foraging trips with longer duration and distance. This potentially reduced niche width means that the Cooper Bay population may be less buffered against environmental variability. Although food resources appeared to be sufficient during the period of our study, the south-eastern region of South Georgia has increased variability in food resources that, coupled with a smaller area in which to forage, might explain the reduced population size compared to the north-eastern end of the island.
机译：我们比较了南乔治亚州2个形成鲜明对比的地点的南极海狗Arctocephalus gazella繁殖：伯德岛的一个高密度殖民地和库珀湾的一个低密度殖民地。尽管有足够的合适的繁殖区域，库珀湾的人口比伯德岛的人口少得多。在库珀湾，雌海豹比伯德岛（Bird Island）繁殖的海豹更长，但体重也更轻，虽然两者的雌性幼仔生长速度保持不变，但公仔在库珀湾的生长速度更快。尽管伯德岛海豹的潜水深度较深，但他们的潜水次数比库珀湾海豹的潜水次数少，因此，这两个种群在潜水的最底层阶段积极觅食的时间相当。库珀湾几乎完全没有在伯德岛观察到的远距离海洋觅食之旅。两种种群都以南极磷虾为食，但库珀湾海豹的饮食中没有食丝的食肉动物。有证据表明，在该岛东南部较冷的水域中没有南乔治亚州偏爱的海豹Myctophid捕食者Protomyctophum choriodon。我们建议，如果在该地区没有这些能量丰富的猎物，那么库珀湾的海豹可能很难用更长的持续时间和距离来弥补觅食旅行所增加的成本。生态位宽度的这种潜在减小的趋势意味着库珀湾种群可能较少受到环境变化的影响。尽管在研究期间粮食资源似乎足够，但佐治亚州东南部的东南部地区的粮食资源却增加了变异性，再加上较小的觅食面积，这可以解释与北部相比人口减少的原因。 -岛的最东端。

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