Habitat availability is insufficient to explain regional variations in white stork breeding habitat preference

Understanding species-habitat associations is key for making predictions of species distributions of relevance to ecology and conservation. Regional differences in species habitat preferences can hinder the transferability of habitat models in space and time, but our ability to account for these differences will depend on the mechanisms underlying them (differences in habitat availability, genetics, culture). Here, we modelled the large-scale breeding distribution of an expanding species, the white stork Ciconia ciconia in France, applying machine-learning algorithms to an extensive dataset of the distribution of nests spanning the whole country. Specifically, we assessed the transferability of the models across different geographic zones and contrasted the modelled nesting habitat preferences of the species across these zones. Finally, we assessed whether local differences in model transferability were related to habitat availability in each zone. Our models generally had good calibration performances, but were not equally transferable to all zones. Additionally, environmental variables did not have the same effects in the different zones, with particularly striking differences between Alsace and the rest of France. This included a certain preference for urban areas in Alsace – absent from other zones - that was consistent with their tendency to nesting on buildings in that zone. Differences in habitat availability between Alsace and the rest of France, as well as connectivity within the French white stork metapopulation appeared to be insufficient to explain the lack of transferability of models to this zone, suggesting some possible local historical and cultural effects on habitat selection.

阐明物种与生境的关联，是开展与生态学及保护生物学相关的物种分布预测的核心所在。物种生境偏好的区域差异，会阻碍生境模型在空间与时间维度上的迁移适用性；而我们解析这类差异的能力，取决于其背后的作用机制（如生境可获得性、遗传特征与文化行为差异）。本研究以法国境内正在种群扩张的白鹳（Ciconia ciconia）为研究对象，针对覆盖全国范围的大量鸟巢分布数据集，结合机器学习算法构建了其大规模繁殖分布预测模型。具体而言，本研究评估了模型在不同地理区域间的迁移适用性，并对比了该物种在各区域内的巢址生境偏好模拟结果。最后，本研究探讨了模型迁移适用性的区域差异是否与各区域的生境可获得性相关。研究结果显示，本研究所构建的模型整体校准性能良好，但在不同区域间的迁移适用性并不均衡。此外，环境变量在不同区域的作用效应存在显著差异，其中阿尔萨斯与法国其他区域的差异尤为显著。具体表现为，阿尔萨斯区域的白鹳对城市生境存在一定偏好，而该偏好并未出现在其他区域，这与该区域白鹳倾向于在建筑物上筑巢的观测结果一致。阿尔萨斯与法国其他区域的生境可获得性差异，以及法国白鹳集合种群内部的连通性，均不足以解释模型在该区域迁移适用性不佳的现象，这暗示当地可能存在历史与文化因素对生境选择产生了影响。