Breeding density, fine-scale tracking and large-scale modeling reveal the regional distribution of four seabird species

• Published in: Ecological Applications
• Main Authors: Wakefield, Ewan D., Owen, Ellie, Baer, Julia, Carroll, Matthew J., Daunt, Francis, Dodd, Stephen G., Green, Jonathan A., Guilford, Tim, Mavor, Roddy A., Miller, Peter I., Newell, Mark A., Newton, Stephen F., Robertson, Gail S., Shoji, Akiko, Soanes, Louise M., Votier, Stephen C., Wanless, Sarah, Bolton, Mark
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2017
• Subjects: Alca torda; rissa tridactyla; Uria aalge; uria
• Online Access: https://eprints.gla.ac.uk/143430/; https://eprints.gla.ac.uk/143430/1/143430.pdf

Population-level estimates of species’ distributions can reveal fundamental ecological processes and facilitate conservation. However, these may be difficult to obtain for mobile species, especially colonial central-place foragers (CCPFs; e.g. bats, corvids, social insects), because it is often impractical to determine the provenance of individuals observed beyond breeding sites. Moreover, some CCPFs, especially in the marine realm (e.g. pinnipeds, turtles and seabirds) are difficult to observe because they range 10s to 10,000s km from their colonies. It is hypothesized that the distribution of CCPFs depends largely on habitat availability and intraspecific competition. Modeling these effects may therefore allow distributions to be estimated from samples of individual spatial usage. Such data can be obtained for an increasing number of species using tracking technology. However, techniques for estimating population-level distributions using the telemetry data are poorly developed. This is of concern because many marine CCPFs, such as seabirds, are threatened by anthropogenic activities. Here, we aim to estimate the distribution at sea of four seabird species, foraging from approximately 5500 breeding sites in Britain and Ireland. To do so, we GPS-tracked a sample of 230 European shags Phalacrocorax aristotelis, 464 black-legged kittiwakes Rissa tridactyla, 178 common murres Uria aalge and 281 razorbills Alca torda from 13, 20, 12 and 14 colonies respectively. Using Poisson point process habitat use models, we show that distribution at sea is dependent on: (i) density-dependent competition among sympatric conspecifics (all species) and parapatric conspecifics (kittiwakes and murres); (ii) habitat accessibility and coastal geometry, such that birds travel further from colonies with limited access to the sea; and (iii) regional habitat availability. Using these models, we predict space use by birds from unobserved colonies and thereby map the distribution at sea of each species at both the colony and regional ...