Opposing effects of spatiotemporal variation in resources and temporal variation in climate on density dependent population growth in seabirds

Searle, Kate R.; Butler, Adam; Waggitt, James J.; Evans, Peter G.H.; Bogdanova, Maria I.; Thompson Hobbs, N.; Daunt, Francis ORCID:; Wanless, Sarah. 2022 Opposing effects of spatiotemporal variation in resources and temporal variation in climate on density dependent population growth in seabirds. Journal of Animal Ecology, 91 (12). 2384-2399.

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1. Understanding how ecological processes combine to shape population dynamics is crucial in a rapidly changing world. Evidence has been emerging for how fundamental drivers of density dependence in mobile species are related to two differing types of environmental variation—temporal variation in climate, and spatiotemporal variation in food resources. However, to date, tests of these hypotheses have been largely restricted to mid-trophic species in terrestrial environments and thus their general applicability remains unknown. 2. We tested if these same processes can be identified in marine upper trophic level species. We assembled a multi-decadal data set on population abundance of 10 species of colonial seabirds comprising a large component of the UK breeding seabird biomass, and covering diverse phylogenies, life histories and foraging behaviours. 3. We tested for evidence of density dependence in population growth rates using discrete time state-space population models fit to long time-series of observations of abundance at seabird breeding colonies. We then assessed if the strength of density dependence in population growth rates was exacerbated by temporal variation in climate (sea temperature and swell height), and attenuated by spatiotemporal variation in prey resources (productivity and tidal fronts). 4. The majority of species showed patterns consistent with temporal variation in climate acting to strengthen density dependent feedbacks to population growth. However, fewer species showed evidence for a weakening of density dependence with increasing spatiotemporal variation in prey resources. 5. Our findings extend this emerging theory for how different sources of environmental variation may shape the dynamics and regulation of animal populations, demonstrating its role in upper trophic marine species. We show that environmental variation leaves a signal in long-term population dynamics of seabirds with potentially important consequences for their demography and trophic interactions.

Item Type: Publication - Article
Digital Object Identifier (DOI):
UKCEH and CEH Sections/Science Areas: Biodiversity (Science Area 2017-)
UKCEH Fellows
ISSN: 0021-8790
Additional Information. Not used in RCUK Gateway to Research.: Open Access paper - full text available via Official URL link.
Additional Keywords: climate, density dependence, population dynamics, population growth rate, resource heterogeneity, spatiotemporal variation
NORA Subject Terms: Ecology and Environment
Date made live: 03 Nov 2023 17:30 +0 (UTC)

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