Energy and time allocation in seabirds differ between consecutive stages of breeding given various requirements of particular phases of the reproductive period. Theses allocations may also be sex-specific considering differential energetic or nutritional requirements of males and females and/or sexual segregation in foraging niches and/or areas. In this study we investigated the foraging ecology of an Arctic, zooplanktivorous seabird, the little auk Alle alle during the pre-laying period using remote sensing of the environment and GPS-TDR loggers deployed on birds. We compared foraging trips range and habitats of birds with other stages of the breeding period and between sexes. We found that little auks during the pre-laying period foraged exclusively in cold sea surface temperature zones (with temperatures < 5 ºC) but in various sea depth zones. They dived to similar depths ranging from -4.0 to -10.9 m, exploring various thermal microhabitats (with mean temperatures values ranging from 2.2 °C in Shelf sea depth zone to 5.9 °C in Deep sea depth zone). The majority of foraging trips and dives characteristics were similar to subsequent phases of breeding. However, home ranges during the pre-laying trips were wider compared to the incubation period. As expected, females exhibited wider foraging niches compared to males (wider range of sea surface temperature and sea depth in foraging locations), which could be explained by sex specific energetic and/or nutritional requirements (females producing an egg). We also delineated local foraging areas important for little auks during their whole breeding season. Protection of these areas is crucial for sustaining the local marine biodiversity. We found that little auks females during the pre-laying period explored wider foraging niches compared to males. These differences may be attributed to sex-specific nutritional or/and energetical constraints at this stage of breeding. The results of this study also emphasize the importance of shelf Arctic-type water masses as the foraging areas for little auks during successive stages of breeding.

中文翻译：

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产蛋前浮游动物食性小海雀 Alle alle 觅食生态的性别差异：遥感和动物追踪的见解

鉴于繁殖期特定阶段的不同需求，海鸟的能量和时间分配在连续的繁殖阶段之间有所不同。考虑到雄性和雌性不同的能量或营养需求和/或觅食生态位和/或区域中的性别隔离，这些分配也可能是针对性别的。在这项研究中，我们利用环境遥感和部署在鸟类身上的 GPS-TDR 记录仪，研究了北极浮游动物海鸟（小海雀 Alle alle）在产蛋前的觅食生态。我们将鸟类的觅食行程范围和栖息地与繁殖期的其他阶段以及性别之间进行了比较。我们发现，小海雀在产卵前阶段只在寒冷的海面温度区（温度< 5 ℃）觅食，但也在不同的海深区觅食。他们潜入-4.0至-10.9 m的相似深度，探索各种热微生境（平均温度值范围从陆架海深度区的2.2°C到深海深度区的5.9°C）。大多数觅食旅行和潜水特征与随后的繁殖阶段相似。然而，与孵化期相比，产蛋前的活动范围更广。正如预期的那样，与雄性相比，雌性表现出更广泛的觅食生态位（觅食地点的海面温度和海深范围更广），这可以通过性别特定的能量和/或营养需求（雌性产卵）来解释。我们还划定了对小海雀在整个繁殖季节都很重要的当地觅食区。保护这些地区对于维持当地海洋生物多样性至关重要。我们发现，与雄性相比，雌性小海雀在产蛋前探索了更广泛的觅食环境。这些差异可能归因于这一育种阶段性别特异性的营养或/和能量限制。这项研究的结果还强调了北极陆架水团作为小海雀在连续繁殖阶段的觅食区的重要性。