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首页> 外文期刊>Marine biology >Foraging behaviour of sympatric Antarctic and subantarctic fur seals: does their contrasting duration of lactation make a difference?
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Foraging behaviour of sympatric Antarctic and subantarctic fur seals: does their contrasting duration of lactation make a difference?

机译：同伴南极和亚南极海狗的觅食行为：哺乳期的对比时间是否有所不同？

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摘要

The duration of periods spent ashore versus foraging at sea, diving behaviour, and diet of lactating female Antarctic (Arctocephalus gazella, AFS) and subantarctic (A. tropicalis, SFS) fur seals were compared at Iles Crozet, where both species coexist. The large disparity in lactation duration (SFS: 10 months, AFS: 4 months), even under local sympatry, has led to the expectation that AFS should exhibit higher foraging effort or efficiency per unit time than SFS to allow them to wean their pups in a shorter period of time. Previous evidence, however, has not supported these expectations. In this study, the distribution of foraging trip durations revealed two types of trips: overnight (OFT, < 1 day) and long (LFT, > 1 day), in common with other results from Macquarie Island. However, diving behaviour differed significantly between foraging trip types, with greater diving effort in OFTs than in LFTs, and diving behaviour differed between fur seal species. OFTs were more frequent in SFS (48%) than in AFS (28%). SFS performed longer LFTs and maternal attendances than AFS, but spent a smaller proportion of their foraging cycle at sea (66.2 vs. 77.5%, respectively). SFS dove deeper and for longer periods than AFS, in both OFTs and LFTs, although indices of diving effort were similar between species. Diel variation in diving behaviour was lower among SFS, which foraged at greater depths during most of the night time available than AFS. The diving behaviour of AFS suggests they followed the nychthemeral migration of their prey more closely. Concomitant with the differences in diving behaviour, AFS and SFS fed on the same prey species, but in different proportions of three myctophid fish (Gymnoscopelus fraseri, G. piabilis, and G. nicholsi) that represented most of their diet. The estimated size of the most important fish consumed did not vary significantly between fur seal species, suggesting that the difference in dive depth was mostly a result of changes in the relative abundance of these myctophids. The energy content of these fish at Iles Crozet may thus influence the amount and quality of milk delivered to pups of each fur seal species. These results contrast with those found at other sites where both species coexist, and revealed a scale of variation in foraging behaviour which did not affect their effort while at sea, but that may be a major determinant of foraging efficiency and, consequently, maternal investment.
机译：在Iles Crozet比较了两个物种共存的哺乳雌性南极洲（Arctocephalus gazella，AFS）和南极洲（A.tropicis，SFS）海豹在岸上与海上觅食，潜水行为以及饮食的持续时间。即使在局部症状的情况下，哺乳期的巨大差异（SFS：10个月，AFS：4个月）也导致人们期望，AFS在单位时间内应表现出比SFS更高的觅食努力或效率，以允许他们为幼仔断奶。时间较短。但是，以前的证据并不支持这些期望。在这项研究中，觅食行程持续时间的分布揭示了两种行程：过夜（OFT，<1天）和长时间（LFT，> 1天），与麦格理岛的其他结果相同。但是，觅食旅行类型之间的潜水行为差异很大，OFT中的潜水努力要比LFT中的更大，并且海豹物种之间的潜水行为也不同。 SFS中的OFTs频率更高（48％），而AFS中的频率更高（28％）。与AFS相比，SFS的LFT和产妇出勤时间更长，但在海上觅食周期中所占的比例较小（分别为66.2和77.5％）。尽管不同物种之间的潜水努力指标相似，但在OFT和LFT中，SFS比AFS更深，更长寿。在SFS中，潜水行为的Diel变化较低，在AFS夜间大部分时间都在较深处觅食。 AFS的跳水行为表明他们更紧密地跟随猎物的夜空迁移。伴随着潜水行为的差异，以相同的猎物为食的AFS和SFS，但以代表其大部分饮食的三种Myctophid鱼类（Gymnoscopelus fraseri，G。piabilis和G. nicholsi）的比例不同为食。所消耗的最重要鱼类的估计大小在海狗种类之间没有显着差异，这表明潜水深度的差异主要是这些菌丝体相对丰度变化的结果。这些鱼在Iles Crozet的能量含量可能会影响输送到每种海狗种类幼崽的牛奶的数量和质量。这些结果与在两个物种共存的其他地点发现的结果形成对比，并揭示了觅食行为的变化规模，该变化规模并不影响他们在海上的努力，但可能是觅食效率以及因此对母体投资的主要决定因素。

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