Post-fledging movements in an elusive raptor, the Eurasian Goshawk (Accipiter gentilis): scale of dispersal, foraging range and habitat interactions in lowland England

Abstract

Studies of the response of high-trophic-level predatory species to environmental gradients contribute to our understanding of adaptation, dependency and risk, both to the predator and its prey. Many such species are of high conservation concern because of a slow life history and a greater susceptibility to threats, not least in organized anthropogenic landscapes that have the propensity to modify or even distort predator–prey dynamics. There are, however, observational difficulties in studying species that are wide-ranging and furtive in their behaviour. All the above characteristics are shared by the Eurasian Goshawk Accipiter gentilis, a highly elusive species for which the movements and habitat associations are poorly quantified at large geographical scales. In Great Britain, this species is of further interest because the population is recovering from the historical impacts of persecution. Here we used remote tracking methods to gather spatially accurate accumulations of data for reliable depictions of movement scale and habitat use in Eurasian Goshawks during the early months of independence from the nest environment (termed ‘first-winter’). The data were taken from two regions of England for good geographical representation of lowland habitats. First-winter Eurasian Goshawks exhibited strongly philopatric characteristics with low levels of natal dispersal once settled. They adopted sedentary and localized foraging patterns, averaging less than 5 km in diameter for approximately 90% of the time, located on the periphery of breeding habitat and centred on farmland or farmland edge, unlike the more forest-centric adults. The use of farmland was especially the case for the first-winter males compared with females, which we speculate may be driven by competitive exclusion or hunting advantages. The results are discussed in the context of future population recovery and colonization, while recognizing existing and emerging threats, including diseases such as highly pathogenic avian influenza and trichomonosis. The study also serves as a methodological demonstration of the capacity for tracking technology to contribute more to our understanding of predators and, by extension, predation as a response to change (such as land-use practice), that can shape observed patterns of conflict.