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Title: Modelling terrestrial and marine foraging habitats in breeding Audouin's gulls Larus audouinii: timing matters
Author: Bécares, Juan
García-Tarrasón, Manuel
Villero, Dani
Bateman, Santiago
Jover Armengol, Lluís de
García Matarranz, Víctor
Sanpera Trigueros, Carola
Arcos Pros, José Manuel
Keywords: Gavines
Ocells aquàtics
Gestió de la pesca
Ebre, Delta de l' (Catalunya)
Water birds
Fishery management
Issue Date: 14-Apr-2015
Publisher: Public Library of Science (PLoS)
Abstract: Although the breeding ecology of Audouin's gull has been widely studied, its spatial distribution patterns have received little attention. We assessed the foraging movements of 36 GPS-tracked adult Audouin's gulls breeding at the Ebro Delta (NW Mediterranean), coinciding with the incubation period (May 2011). This also coincided with a trawling moratorium northwards from the colony. We modelled the distribution of the gulls by combining these tracking data with environmental variables (including fishing activities from Vessel Monitoring System, VMS), using Maxent. The modelling range included both marine and terrestrial areas. Models were produced separately for every 2h time interval across the day, and for 2 fishing activity scenarios (workdays vs. weekends), allowing to assess the spatio-temporal distribution patterns of the gulls and the degree of association with fisheries. During workdays, gull distribution at sea fully matched with fishing activities, both trawling (daylight) and purse-seining (nightime). Gulls tended to avoid the area under trawling moratorium, confirming the high influence of fisheries on the distribution patterns of this species. On weekends, gulls made lesser use of the sea and tended to increase the use of rice fields. Overall, Audouin's gull activity was more intense during dailight hours, although birds also showed nocturnal activity, on both workdays and weekends. Nocturnal patterns at sea were more disperse during the latter, probably because these gulls are able to capture small pelagic fish at night in natural conditions, but tend to congregate around purse-seiners (which would enhance their foraging efficiency) in workdays. These results provide important insight for the management of this species. This is of particular relevance under the current scenario of European fisheries policies, since new regulations are aimed at eliminating discards, and this would likely influence Audouin's gull populations.
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It is part of: PLoS One, 2015, vol. 10, num. 4, p. e0120799
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ISSN: 1932-6203
Appears in Collections:Articles publicats en revistes (Biologia Evolutiva, Ecologia i Ciències Ambientals)
Articles publicats en revistes (Fonaments Clínics)

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