Fine scale foraging habitat selection by two diving central place
foragers in the Northeast Atlantic
Abstract
1. Understanding the animal-habitat relationship at local scale is
crucial in ecology, particularly to develop strategies for wildlife
management and conservation. As this relationship is governed by
environmental features and intra and inter-specific interactions,
habitat selection of a population may vary locally between its core and
edges. 2. This is particularly true for central place foragers, such as
grey and harbour seals, whose trends in numbers vary among different
regions in the Northeast Atlantic. Here, we aimed at studying how
foraging habitat selection may vary locally with the influence of
population trends and physical habitat features 3. Using GPS/GSM tags
deployed in grey and harbour seal colonies of contrasting sizes, we
investigate spatial patterns and foraging habitat selection by comparing
trip characteristics and home range similarities, and fitting GAMM to
the seal distribution and environmental data respectively. 4. We show
that grey seal foraging habitat selection and spatial patterns differed
markedly between regions. Grey seals may select environmental
characteristics for their foraging habitat accounting for local
differences in prey consumed. Spatial patterns were different might
depend on local seal density and regional productivity, located from
inshore to offshore areas for the limit ranges and core population
respectively. Our results on foraging habitat selection reflected the
coastal and sedentary behaviour of harbour seals. We found no difference
in spatial patterns between colonies, except for the Inner Hebrides
where seals foraged further, potentially reflecting density dependence
pressure, as the number in this colony is higher. 5. These results
suggest that local conditions might have a strong influence on
population spatial ecology, highlighting as well the relevance of
studying foraging habitat selection based on foraging behaviour at fine
geographical scale, particularly if species are managed within regional
units.