Organochlorine residue levels in livers of birds of prey from Spain: Inter-species comparison in relation with diet and migratory patterns Barend van Drooge a , Rafael Mateo b ,I ´ ngrid Vives a , Iris Cardiel b , Raimon Guitart a, * a Laboratory of Toxicology, Faculty of Veterinary, Universitat Auto `noma de Barcelona, 08193 Bellaterra, Spain b Instituto de Investigacio ´n en Recursos Cinege ´ticos, IREC (CSIC-UCLM), Ronda de Toledo s/n, 13071 Ciudad Real, Spain Received 6 March 2007; received in revised form 24 July 2007; accepted 27 July 2007 The contribution of bird biomass in the diet is a determining factor for the accumulation of organochlorines in raptors. Abstract Livers from 130 specimens corresponding to 18 species of raptors from Spain were analysed for persistent organochlorine (OC) residues. In all species, p,p 0 -DDE was the most abundant individual OC compound detected, with geometric means ranging from 61 to 40,086 ng/g ww. The geometric mean for P PCB ranged from 225 to 9184 ng/g ww. Migration to Africa, south of Sahara, where p,p 0 -DDT is still in use, was not associated with higher liver concentrations of its metabolite, p,p 0 -DDE. The presence of birds in the diet of the species was an important spe- cies-specific factor determining the mean liver concentrations of p,p 0 -DDE and P PCB. The effect of the diet on OC concentrations in liver is explained by the lower metabolising capacity of OC compounds in birds, especially for p,p 0 -DDE. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Raptors; Organochlorine pesticide; PCB; Diet; Migration 1. Introduction Persistent organochlorine compounds (OCs), including pesti- cides such as p,p 0 -DDT, hexachlorocyclohexane (b-HCH, g- HCH), aldrin, hexachlorobenzene (HCB) and industrial products such as polychlorinated biphenyls (PCBs), have been detected in all environmental compartments, as well as in birds. In diurnal raptor species, some studies have reported OC levels in eggs (Ma~ nosa et al., 2003; Mateo et al., 2000; Wiesmu ¨ller et al., 2002) and tissues (Hela et al., 2006; Kenntner et al., 2003; Lo ´pez-Lo ´pez et al., 2001; Wienburg and Shore, 2004). Predatory birds are highly susceptible to the accumulation of persistent OC pollutants, due to the fact that they are lo- cated at the top of the food web (Furness, 1993; Newton et al., 1993). Moreover, the risk on the effects of these contam- inants increases when it is considered that these birds of prey exist in relatively small numbers have slow reproduction rates, and have low enzyme activity to degrade the OCs (Fossi et al., 1995; Furness, 1993; Joiris and Delbeke, 1985; Walker, 1990). OCs can produce reproductive failure in birds (Blus, 1995), and have been blamed for the population decline of several birds of prey around the world (Newton et al., 1993). For these reasons, birds of prey are sensitive bioindicators of environ- mental quality (Furness, 1993). Although most OC compounds were banned in Spain in the late seventies, their negative effects on birds of prey may still be of concern in that country (Ma~ nosa et al., 2003; Mateo et al., 2000; Negro et al., 1993), due to their long persistence in the environment and to the relevance of the Spanish coun- tryside for the conservation of endangered raptor species. In the present study, the high diversity of raptors present in Spain permitted us to explore the relationships between OC residues and species-specific variables, such as migratory pattern or diet. Some of the studied species winter south of the Sahara in Africa, where p,p 0 -DDT is still in use after the ban in * Corresponding author. Tel.: þ34 93 5811299; fax: þ34 93 5812006. E-mail address: raimon.guitart@uab.cat (R. Guitart). 0269-7491/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2007.07.029 Available online at www.sciencedirect.com Environmental Pollution 153 (2008) 84e91 www.elsevier.com/locate/envpol