Integrating habitat and partial survey data to estimate the regional population of a globally declining seabird species, the sooty shearwater

Clark, T. J., Matthiopoulos, J. , Bonnet-Lebrun, A.-S., Campioni, L., Catry, P., Marengo, I., Poncet, S. and Wakefield, E. (2019) Integrating habitat and partial survey data to estimate the regional population of a globally declining seabird species, the sooty shearwater. Global Ecology and Conservation, 17, e00554. (doi: 10.1016/j.gecco.2019.e00554)

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Abstract

Many animal populations are thought to be in flux due to anthropogenic impacts. However, censusing organisms to understand such changes is often impractical. For example, while it is thought that over half of pelagic seabird populations are declining, most breed in burrows or on cliffs, in large, remote colonies, making them difficult to count. Burrow-nesting sooty shearwaters (Ardenna grisea) are abundant but declining in their core (South Pacific) breeding range, potentially due to introduced rodents and habitat loss. In contrast, Kidney Island, their largest colony in the Falkland Islands (Southwest Atlantic), purportedly grew by several orders of magnitude since the mid-1900s. This island is rodent-free, and native tussac grass (Poa flabellata) has increased following cessation of historical exploitation. To estimate the sooty shearwater population in the Falkland Islands, and its relationship with breeding habitat availability, we sampled burrow density and occupancy on Kidney Island and modeled these as functions of habitat. Both indices responded positively to a proxy for historical increases in tussac cover. We estimate that breeding sooty shearwaters occupy ∼140,000 (95% CI: 90,000–210,000) burrows on Kidney Island. Moreover, using additional survey data and Generalized Functional Response models to account for intra-island variation in habitat availability, we estimate that 25,000 (95% CI: 20,100 - 30,500) burrows could be occupied on nearby islands from which non-native rodents have been recently eradicated. Our study shows that habitat selection functions, generalized where necessary, not only improve population estimates but provide biological insights needed to reverse declines in seabirds and other species.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Wakefield, Dr Ewan and Matthiopoulos, Professor Jason
Authors: Clark, T. J., Matthiopoulos, J., Bonnet-Lebrun, A.-S., Campioni, L., Catry, P., Marengo, I., Poncet, S., and Wakefield, E.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Global Ecology and Conservation
Publisher:Elsevier
ISSN:2351-9894
ISSN (Online):2351-9894
Published Online:11 February 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Global Ecology and Conservation 17: e00554
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
685021Seabirds and wind - the consequences of extreme prey taxis in a changing climateEwan WakefieldNatural Environment Research Council (NERC)NE/M017990/1RI BIODIVERSITY ANIMAL HEALTH & COMPMED