Habitat loss and climate change are major processes affecting biodiversity, especially in the Arctic which is experiencing rapid sea ice decline. Loss of sea ice habitat for ice-dependent species such as polar bears (Ursus maritimus) has been associated with declines in body condition, reproductive output, survival, and abundance. Monitoring habitat use can therefore provide insights into population responses to sea ice loss, especially for vulnerable demographic groups such as subadults. Here, we used resource selection functions to examine habitat selection patterns of subadult male and female (n = 21) and adult female (n = 37) polar bears in the Southern Beaufort Sea population from 2007 to 2011. We found that polar bears displayed broad similarities in seasonal habitat selection by using nearshore areas in winter/spring and ranging farther offshore into the multiyear ice in summer/autumn. However, there were differences in habitat use among age, sex, and reproductive classes. Adult females with cubs-of-the-year differed the most among classes and selected landfast ice in spring, allowing them to hunt for seal birth lairs while reducing risk of intra-specific predation. Adult females with older cubs and solitary adult females used active sea ice, which allowed them to hunt adult seals, while subadult females used a mix of active and landfast ice. Subadult males had similar selection for landfast ice as females with cubs-of-the-year, potentially as a mechanism to reduce intra-specific competition and/or kleptoparasitism. The Arctic faces continued warming and understanding variation in habitat use patterns can assist in identifying which bears are most vulnerable to loss of different sea ice habitats.

中文翻译：

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波弗特海北极熊栖息地利用的变化

栖息地丧失和气候变化是影响生物多样性的主要过程，尤其是在海冰迅速减少的北极地区。北极熊（Ursus maritimus）等依赖冰的物种的海冰栖息地的丧失与身体状况、繁殖能力、存活率和丰度的下降有关。因此，监测栖息地的使用可以深入了解人口对海冰消失的反应，特别是对于亚成体等弱势人口群体。在这里，我们使用资源选择函数来检查 2007 年至 2011 年南波弗特海种群中亚成年雄性和雌性（n = 21）和成年雌性（n = 37）北极熊的栖息地选择模式。我们发现北极熊在冬季/春季使用近岸区域并在夏季/秋季更远的离岸进入多年冰层，在季节性栖息地选择方面表现出广泛的相似性。然而，年龄、性别和生殖等级之间的栖息地利用存在差异。具有年度幼崽的成年雌性在不同等级之间差异最大，并且在春季选择陆地冰，使它们能够寻找海豹的出生巢穴，同时降低种内捕食的风险。有年长幼崽的成年雌性和独居的成年雌性使用活动海冰，这使它们能够捕猎成年海豹，而亚成年雌性则使用活动冰和陆地冰的混合物。亚成年雄性与拥有年度幼崽的雌性对陆地冰的选择相似，这可能是减少种内竞争和/或窃虫寄生的机制。