Climate change has broad ecological implications for species that rely on sensitive habitats. For some top predators, loss of habitat is expected to lead to cascading behavioral, nutritional, and reproductive changes that ultimately accelerate population declines. In the case of the polar bear (Ursus maritimus ), declining Arctic sea ice reduces access to prey and lengthens seasonal fasting periods. We used a novel combination of physical capture, biopsy darting, and visual aerial observation data to project reproductive performance for polar bears by linking sea ice loss to changes in habitat use, body condition (i.e., fatness), and cub production. Satellite telemetry data from 43 (1991–1997) and 38 (2009–2015) adult female polar bears in the Baffin Bay subpopulation showed that bears now spend an additional 30 d on land (90 d in total) in the 2000s compared to the 1990s, a change closely correlated with changes in spring sea ice breakup and fall sea ice formation. Body condition declined for all sex, age, and reproductive classes and was positively correlated with sea ice availability in the current and previous year. Furthermore, cub litter size was positively correlated with maternal condition and spring breakup date (i.e., later breakup leading to larger litters), and negatively correlated with the duration of the ice‐free period (i.e., longer ice‐free periods leading to smaller litters). Based on these relationships, we projected reproductive performance three polar bear generations into the future (approximately 35 yr). Results indicate that two‐cub litters, previously the norm, could largely disappear from Baffin Bay as sea ice loss continues. Our findings demonstrate how concurrent analysis of multiple data types collected over long periods from polar bears can provide a mechanistic understanding of the ecological implications of climate change. This information is needed for long‐term conservation planning, which includes quantitative harvest risk assessments that incorporate estimated or assumed trends in future environmental carrying capacity.

中文翻译：

---

气候变化对顶点食肉动物的相关生态影响。

气候变化对依赖敏感栖息地的物种具有广泛的生态影响。对于某些顶级掠食者而言，栖息地的丧失预计会导致行为，营养和生殖等方面的连锁反应，最终加速人口下降。在北极熊（Ursus maritimus），北极海冰的减少会减少捕食的机会，并延长季节性禁食期。通过将海冰损失与栖息地使用，身体状况（即脂肪）和幼崽生产的变化联系起来，我们使用了物理捕获，活组织检查和视觉空中观测数据的新颖组合来预测北极熊的繁殖性能。巴芬湾亚种群中43只（1991–1997）和38只（2009–2015）成年雌性北极熊的卫星遥测数据显示，与1990年代相比，2000年代熊现在在陆地上花费了额外的30 d（总共90 d） ，这一变化与春季海冰破裂和秋季海冰形成的变化密切相关。在所有性别，年龄和生殖类别中，身体状况均下降，并且与本年度和上一年的海冰供应量呈正相关。此外，幼崽的产仔数与产妇状况和春季解体日期呈正相关（即，后期解体导致更大的产仔数），与无冰期的持续时间呈负相关（即，更长的无冰期导致产仔数减少）。基于这些关系，我们将未来三个北极熊世代（约35年）的生殖性能预测出来。结果表明，随着海冰流失的继续，以前为常态的两立方英尺垃圾可能会从巴芬湾大量消失。我们的发现表明，从北极熊长期收集的多种数据类型的并发分析如何能够提供对气候变化的生态含义的机械理解。长期保护规划需要此信息，