Mikkelsen Ashlee J, Zedrosser Andreas, Sergiel Agnieszka, Hobson Keith A, Selva Nuria, Hertel Anne G
Department of Natural Sciences and Environmental Health University of South-Eastern Norway Borre Vestfold-Telemark Norway.
Department of Integrative Biology University of Natural Recourses and Applied Life Sciences Vienna Austria.
Ecol Evol. 2025 Apr 7;15(4):e71181. doi: 10.1002/ece3.71181. eCollection 2025 Apr.
The effects of climate and plant phenological changes on herbivorous species are widely recognized, yet less research has focused on predatory species, even though vegetative components can account for large proportions of their diet. The historical focus on predation through the lens of simple interactions between obligate carnivores and their prey oversimplifies many species' roles within ecological communities and minimizes other, equally important community functions. We used a long-term, individual-based dataset on an omnivorous species, the brown bear (), to identify long-term diet patterns and factors contributing to annual variation in diet. We used carbon and nitrogen stable isotopes measured in hair and Bayesian mixing models to determine annual diet among three demographic classes and then used linear mixed models to relate diet to indices of food availability. Variation in both carbon and nitrogen values were explained by bilberry () productivity. Additionally, even as the moose population increased over time, there was no increase in the proportion of moose in the diet. The variation in the proportion of moose in the diet slightly decreased throughout the study, while the proportion of bilberry became increasingly more variable. Our results highlight that even though vegetative diet components are typically considered less important to predator ecology, brown bear diet in Sweden responded to changes in berry availability, regardless of prey availability. It will be crucial to put more emphasis on the vegetative parts of diets as we predict how species and ecological communities respond to climate change because predators serve many more functions within their community besides predation alone.
气候和植物物候变化对食草物种的影响已得到广泛认可，但针对捕食性物种的研究较少，尽管植物性食物在它们的饮食中占很大比例。历史上通过专性食肉动物与其猎物之间简单相互作用的视角来关注捕食行为，过于简化了许多物种在生态群落中的作用，并将其他同样重要的群落功能降至最低。我们使用了一个关于杂食性物种棕熊（ ）的长期、基于个体的数据集，来确定长期的饮食模式以及导致饮食年度变化的因素。我们利用毛发中测量的碳和氮稳定同位素以及贝叶斯混合模型来确定三个种群类别的年度饮食，然后使用线性混合模型将饮食与食物可获得性指数联系起来。碳和氮值的变化都可以用越橘（ ）的生产力来解释。此外，即使驼鹿数量随时间增加，其在饮食中的比例也没有增加。在整个研究过程中，驼鹿在饮食中的比例变化略有下降，而越橘的比例变得越来越不稳定。我们的研究结果表明，尽管植物性饮食成分通常被认为对捕食者生态学不太重要，但瑞典棕熊的饮食会对浆果可获得性的变化做出反应，而与猎物可获得性无关。当我们预测物种和生态群落如何应对气候变化时，更加重视饮食中的植物性部分至关重要，因为捕食者在其群落中除了捕食之外还发挥着更多功能。
