Data from: "Shift in habitat selection during natal dispersal in a long-lived raptor species"

Abstract

Animals select their habitat along environmental gradients, but the mechanisms that constrain the ecological requirements of an individual can differ between life stages. Dispersal is a key demographic process that determines gene flow and alters species distributions, yet few empirical studies have examined whether habitat selection in animals is changing during dispersal. In this study, we examined changes in habitat preferences during natal dispersal of red kites (Milvus milvus), a European raptor species. By deploying solar-powered GPS-GSM transmitters on nestlings, we continuously tracked individuals up to six years (2015-2020), from fledging to settlement. We applied habitat selection functions to the tracking data using hierarchical generalized additive models, a flexible method which combines individual- and population-level inference, while allowing for the contrast of the prospecting and settlement phases. During the prospecting phase (n = 204 birds), individuals were less responsive to their environment than during the settlement phase, resulting in a predicted wide distribution in Western Europe. During the settlement phase, individuals (n = 78 birds) selected a narrower range of environmental gradients, while avoiding areas of high elevation, steep topographic slopes, high human population density and highly heterogeneous landscapes. During this phase, individuals were also more philopatric, i.e., they were more inclined to choose an environment closer to their natal area, than during the prospecting phase. Suitable habitats predicted during settlement were much more spatially contrasted than during prospecting. Our study provides empirical evidence that habitat selection changes across natal dispersal phases in a long-lived species, indicating that species conservation strategies should account for different environmental constraints before and after settlement. Furthermore, our findings underscore the importance of long-term tracking data, with sufficient sample size, to study the link between habitat selection and natal dispersal.

摘要
动物会依据环境梯度选择栖息生境，但制约个体生态需求的机制会随生活史阶段发生变化。扩散是决定基因交流、改变物种分布格局的关键种群动态过程，但目前鲜有实证研究探讨动物在扩散过程中其生境选择是否会发生变化。本研究以欧洲猛禽物种红鸢（Milvus milvus）为研究对象，探究其在出生扩散过程中的栖息偏好变化。本研究通过在雏鸟身上搭载太阳能GPS-GSM追踪器，对个体从出巢到定居的过程进行了长达6年（2015-2020年）的连续追踪。本研究采用分层广义可加模型对追踪数据开展生境选择功能分析，该方法兼具灵活性，可同时实现个体与种群水平的统计推断，且能对探索阶段与定居阶段进行对比分析。在探索阶段（样本量n=204只个体），动物对环境的响应程度弱于定居阶段，由此预测其在西欧的分布范围较广。在定居阶段（样本量n=78只个体），动物选择的环境梯度范围更窄，同时会避开高海拔、地形坡度陡峭、人口密度较高以及景观异质性极强的区域。相较于探索阶段，该阶段的个体还表现出更强的恋巢倾向，即更倾向于选择距离其出生地更近的生境。定居阶段预测的适宜生境在空间分布上的分化程度远高于探索阶段。本研究为长寿物种的生境选择会随出生扩散阶段发生变化提供了实证依据，这表明物种保护策略应考虑定居前后不同的环境制约因素。此外，本研究结果凸显了具备充足样本量的长期追踪数据，在探究生境选择与出生扩散之间关联时的重要性。