Impact of Pesticides on Red Kite Population
Résumé
Poisoning by pesticides is reported as a main cause of Red kite decrease. Based on available data on lethal intoxication, we aim to quantify the impact of pesticide poisoning on the “German-French-Spanish” population of Red kite since 1990. According to the WWF/Adena, 435 kites were poisoned in Spain from 1990 to 2005. In France, 51 intoxicated specimens were identified from 1992 to 2002. No data were found for Germany. Using the rate of cadaver discovery of 3% proposed by WWF/Adena, this would represent 14,500 specimens poisoned in Spain and 1700 in France. An age-structured model of population dynamic (Leslie matrix) was built to project pesticide consequences on Red kite population between 1990 and 2009. Population size was estimated at 110,000 specimens in 1990 for the 3 countries. The Leslie matrix developed has a growth rate of 1. It is assumed that an individual may lived up to 15 years and reproduced from 3 years. We assumed that a pair produced 1.5 fledged young per year (0.75 female). Survival rate was 0.55 the first year and then, increased to 0.88 for adults. Results showed that pesticides would be responsible of a 22% decrease according to the scenario used here. Anticholinesterasic chemicals (i.e., organophosphorous and carbamates) would contribute to 19% and anticoagulants to 2%, respectively. The results varied dramatically according to the rate of cadaver discovery retained, this key factor has to be assessed more precisely. Present results suggest that anticholinesterasic compounds used in Spain are the main responsible of the current decline followed by anticoagulant rodenticides.