Beyond the uniform: uncovering structural complexity within Adélie penguin colonies
摘要
In colonial animals, territory selection and defence are shaped by both environmental physical constraints and interactions among conspecifics. Understanding the spatial arrangement of individuals within colonies thus provides a valuable framework for assessing the forces that shape colony structure and may influence its demography. Here, we aim to determine how environmental and colonial factors jointly influence the size and shape of individual nesting territories in a colonial bird species, the Adélie penguin. We derived spatial and topographic features from drone-based digital elevation models obtained in Adélie Land (AL), the Western Antarctic Peninsula (WAP), and the Eastern Antarctic Peninsula (EAP). We show that individual territories are shaped by local slope and distance to the colony edge. On average, territory size decreases towards the centre and then stabilises, whereas shape optimisation level increases monotonically, revealing a decoupling between size and shape optimisation level. In contrast, we find no consistent effect of elevation, nor any effect of colony shape or number of nests on individual territories. Colony-specific patterns were evident at Heroína (EAP) and Petrel Island (AL), where these centre-periphery gradients in both size and shape were significant, whereas no such gradients were detected at Torgersen and Yalour Islands (WAP). These colony-level differences may reflect local variation in predation pressure, territorial behaviour, or ground conditions, although the relative contribution of each factor remains unclear. Our findings highlight the importance of considering within-colony heterogeneity and the environmental context to refine our understanding of spatial organisation.