Fine‐scale foraging habitat selection by two diving central place foragers in the Northeast Atlantic

Abstract

Habitat selection and spatial usage are important components of animal behavior influencing fitness and population dynamic. Understanding the animal–habitat relationship is crucial in ecology, particularly in developing strategies for wildlife management and conservation. As this relationship is governed by environmental features and intra‐ and interspecific interactions, habitat selection of a population may vary locally between its core and edges. This is particularly true for central place foragers such as gray and harbor seals, where, in the Northeast Atlantic, the availability of habitat and prey around colonies vary at local scale. Here, we study how foraging habitat selection may vary locally under the influence of physical habitat features. Using GPS/GSM tags deployed at different gray and harbor seals’ colonies, we investigated spatial patterns and foraging habitat selection by comparing trip characteristics and home‐range similarities and fitting GAMMs to seal foraging locations and environmental data. To highlight the importance of modeling habitat selection at local scale, we fitted individual models to colonies as well as a global model. The global model suffered from issues of homogenization, while colony models showed that foraging habitat selection differed markedly between regions for both species. Despite being capable of undertaking far‐ranging trips, both gray and harbor seals selected their foraging habitat depending on local availability, mainly based on distance from the last haul‐out and bathymetry. Distance from shore and tidal current also influenced habitat preferences. Results suggest that local conditions have a strong influence on population spatial ecology, highlighting the relevance of processes occurring at fine geographical scale consistent with management within regional units.

Sympatric Seals, Satellite Tracking and Protected Areas: Habitat-Based Distribution Estimates for Conservation and Management

“…More generally, our study highlights the importance of considering regional variation in habitat preference. Regional habitat preference models have been shown to be favourable to global models for marine predator populations occupying different sides of an ocean basin (Torres et al, 2015;Mannocci et al, 2020), or discrete regions within shelf seas (Huon et al, 2021). However, few studies have combined predictions from different regional habitat preference models to generate large scale distribution estimates.…”

“…Indeed, recent research suggests that in such cases regional habitat preference models are more appropriate than single models (Torres et al, 2015;Mannocci et al, 2020). Nevertheless, species distribution estimates across multi-region study areas are generally restricted to predictions from single models (Wakefield et al, 2017;Fauchald et al, 2021), or predictions for discrete areas from regional models (Huon et al, 2021), and no framework exists to combine predictions from regional models into a continuous distribution map.…”

“…Hotspots of important foraging habitat are likely to be heterogeneously distributed offshore, and if none of the tracked seals visited a certain foraging patch, this approach would underestimate or overlook density in that area. Other studies have modelled tracking data in a habitat preference framework and predicted seal distribution in specific discrete areas of the UK and Ireland (Aarts et al, 2008;Bailey et al, 2014;Jones et al, 2017;Huon et al, 2021), but no study has used habitat preference to generate distribution estimates for the whole of the UK and Ireland. Given the regional differences in habitat characteristics (Huon et al, 2021), population dynamics (Thomas et al, 2019;Thompson et al, 2019), diet (Gosch et al, 2019;Wilson and Hammond, 2019), and foraging trip characteristics (Huon et al, 2021) of both seal species, a single habitat preference model would likely produce unrealistic results when used to generate predicted distributions across multiple regions.…”

“…Other studies have modelled tracking data in a habitat preference framework and predicted seal distribution in specific discrete areas of the UK and Ireland (Aarts et al, 2008;Bailey et al, 2014;Jones et al, 2017;Huon et al, 2021), but no study has used habitat preference to generate distribution estimates for the whole of the UK and Ireland. Given the regional differences in habitat characteristics (Huon et al, 2021), population dynamics (Thomas et al, 2019;Thompson et al, 2019), diet (Gosch et al, 2019;Wilson and Hammond, 2019), and foraging trip characteristics (Huon et al, 2021) of both seal species, a single habitat preference model would likely produce unrealistic results when used to generate predicted distributions across multiple regions. Therefore, updated distribution estimates are required for the entire populations for both species, based on regional habitat preference.…”

Static Acoustic Monitoring of Harbour (Phoca vitulina) and Grey Seals (Halichoerus grypus) in the Malin Sea: A Revolutionary Approach in Pinniped Conservation

“…Both harbour and grey seals are generalist and benthic feeders [62], preying on a wide variety of taxa [63]. Nevertheless, differences in their diets can be found at regional and seasonal scales [24,[64][65][66], subject to prey availability, distribution and abundance as well as additional factors in the surroundings of the haul-out sites [67,68].…”