Long-term population trends of breeding Kentish PloversCharadrius alexandrinusin north-west Spain under the effects of a major oil spill

Abstract

SummaryThe Kentish PloverCharadrius alexandrinusis the only wader that nests on the beaches of Galicia, north-west Spain. In November 2002, much of that habitat was heavily affected by thePrestigeoil spill, considered one of the largest spills ever experienced in Europe. We used a 23-year dataset (1988–2010) tracking the abundance and distribution of Kentish Plover breeding pairs along the Galician coast to evaluate population trends and identify the underlying effects of an oil spill. A TRIM linear trend model classified the population trend as a moderate increase; the main trend exhibited a decline in the population from 2002 to 2004 (the second reproductive period after the catastrophe), followed by a moderate increase to the present. The results showed that the variation in annual population trends can be explained by considering the characteristics and location of breeding beaches. In the most parsimonious model, three covariates were significant: the beach position: inner (located in the interior part of the estuaries), or outer (exposed to the open sea), the beach length, and the location of the stretch of coastline in relation to thePrestigewreck. The variation was obvious both with regard to population size and habitat use, with an increase in the number of birds and breeding locations and changes in distribution along the entire Galician Coast after 2004. The birds reacted to the catastrophe by avoiding the most affected areas and moving to new breeding beaches, suggesting that conservation plans must take into account the correct management of currently unoccupied beaches that could provide potential habitat for the species.