Trophic niche overlap between sympatric harbour seals (<i>Phoca vitulina</i>) and grey seals (<i>Halichoerus grypus</i>) at the southern limit of their European range (Eastern English Channel)

Planque, Yann; Spitz, Jérôme; Authier, Matthieu; Guillou, Gaël; Vincent, Cécile; Caurant, Florence

doi:10.1002/ece3.7739

Cited by 4 publications

(2 citation statements)

References 117 publications

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“…This offshore behavior is in accordance with our results for the FoT. Gray seals in the EEC performed their trips mostly in specific areas along the coast, as the EEC is known to be a major ground for flatfish (Carpentier et al., 2009 ; Riou et al., 2001 ; Selleslagh et al., 2009 ), which are observed in gray seal diet (Planque et al., 2021 ). In the ICS and Iroise Sea, gray seals made shorter trips.…”

Section: Discussionsupporting

confidence: 90%

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

Huon

Planque

Jessopp

et al. 2021

Ecology and Evolution

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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.

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Section: Discussionsupporting

confidence: 90%

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

Huon

Planque

Jessopp

et al. 2021

Ecology and Evolution

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“…There have been several detailed studies of the coexistence of marine predators in productive environments, such as those found in temperate and polar regions (Rosenzweig 1995 ; Pigot et al 2016 ). At these latitudes, some co-nesting seabirds appear to have similar feeding niches (Dehnhard et al 2020 ; Planque et al 2021 ), while others show niche differentiation through a range of mechanisms including: feeding in different areas (Hamilton et al 2019 ), at different depths (Hoskins et al 2017 ) or at different times (Clewlow et al 2019 ). In addition, species often specialise on different kinds or sizes of prey (Barger and Kitaysky 2012 ).…”

Section: Introductionmentioning

confidence: 99%

Marked differences in foraging area use and susceptibility to predation between two closely-related tropical seabirds

Fayet,

Sanchez,

Appoo

et al. 2023

Oecologia

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Ecological theory predicts that closely-related species must occupy different niches to coexist. How marine top predators achieve this during breeding, when they often gather in large multi-species colonies and are constrained to central-place foraging, has been mostly studied in productive temperate and polar oceans with abundant resources, but less so in poorer, tropical waters. Here, we track the foraging movements of two closely-related sympatric seabirds—the white-tailed and red-tailed tropicbirds Phaethon lepturus and P. rubricauda—breeding on Aldabra Atoll, Seychelles, to investigate potential mechanisms of niche segregation and shed light on their contrasting population trends. Combining data from GPS, immersion, depth and accelerometry loggers, we show that the two species have similar behaviour at sea, but are completely segregated spatially, with red-tailed tropicbirds flying further to feed and using different feeding areas than white-tailed tropicbirds. Using nest-based camera traps, we show that low breeding success of both species—which likely drives observed population declines—is caused by high nest predation. However, the two species are targeted by different predators, with native avian predators mainly targeting red-tailed tropicbird nests, and invasive rats raiding white-tailed tropicbird nests when they leave their eggs unattended. Our findings provide new insight into the foraging ecology of tropicbirds and have important conservation implications. The extensive range and spatial segregation highlight the importance of considering large-scale protection of waters around tropical seabird colonies, while the high level of nest predation provides evidence in support of rat eradication and investigating potential nest protection from native avian predators.

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Deciphering Eurasian otter (Lutra lutra L.) and seal (Phoca vitulina L.; Halichoerus grypus F.) diet: Metabarcoding tailored for fresh and saltwater fish species

et al. 2022

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Long‐lived top predators shape biodiversity structure in their ecosystems and predator–prey interactions are critical in decoding how communities function. Studies on the foraging ecology of seals and Eurasian otters in Western Europe are outdated and most studies solely performed traditional hard part analysis. Molecular metabarcoding can be used as an innovative noninvasive diet analysis tool, which has proven efficient and complementary to hard part analysis, however, lacking application in the wider North Sea area. In this study, DNA from digesta, collected between 2014–2020, were used to identify fish species in the diet of 47 Eurasian otters, 54 harbour seals and 21 grey seals by applying a next‐generation metabarcoding approach. A newly designed 16S rRNA primer, providing the best coverage of >130 local marine and freshwater fish species, was used to amplify prey DNA from seal scats and otter gut content sampled from the North Sea and regional freshwater bodies. Frequent fish species included tench, ninespine stickleback and white bream in otters; hooknose and common roach in grey seals and Pleuronectidae and sand gobies in harbour seals. Bipartite network analysis showed a strong overlap of harbour and grey seal diets. Otter diet intersected with both seal species in terms of freshwater species. This study provides new knowledge about dietary composition and community assemblage of fish prey in otters and seals in the North Sea and regional freshwaters, and a new molecular tool to elucidate predator–prey interactions and interspecies competition in complex and changing ecosystems under pressure from anthropogenic activities.

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Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel)

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 4 publications

References 117 publications

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

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

Marked differences in foraging area use and susceptibility to predation between two closely-related tropical seabirds

Deciphering Eurasian otter (Lutra lutra L.) and seal (Phoca vitulina L.; Halichoerus grypus F.) diet: Metabarcoding tailored for fresh and saltwater fish species

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