Did the Prestige oil spill compromise bird reproductive performance? Evidences from long-term data on the Kentish Plover (Charadrius alexandrinus) in NW Iberian Peninsula

Abstract

The NW Iberian Kentish Plover population inhabits sparsely vegetated beaches for foraging, roosting, nesting and rearing young. The lifestyle of this population makes them particularly vulnerable to oil spill pollution. We analyzed long-term data on breeding success, egg structure, female condition and breeding effort to ascertain the effects of Prestige oil on reproductive performance and length of time of reproductive disruption. The results showed temporal variation to A-egg volume and a change in the pattern of intraclutch egg-size. Eggshell thickness declined in the years following the oil spill and slightly recovered eight years later. A similar decline was observed in female mass and condition. Egg fertility was significantly different before and after the Prestige oil spill, although the low hatching success could have caused this parameter to be underestimated. Nest desertion, which is rare in this population, occurred only in the post-Prestige period. Our study revealed that exposure of the Kentish Plover to the Prestige oil spill adversely affected their reproductive performance by altering the condition of individual members of the population and by changing egg quality for more than just the immediate years after the spill event. The extent of the effects of the spill event on population dynamics could be underestimated due to low hatching and fledging success.