Organochlorine Pesticide Contamination in Three Species of Raptor and Their Prey in South Australia.

The extent of organochlorine pesticide contamination in 3 species of predatory birds from the central regions of South Australia was investigated. Residues in both eggs and tissue, as well as measurements of shell thickness, were obtained for Falco peregrinus (peregrine falcon), Pandion haliaetus (osprey) and Haliaeetus leucogaster (white-bellied sea eagle). Organochlorine residues in some prey species were also measured. Residues of DDE and DDT in the predatory birds were found to be low to moderate. Concn of total DDT were greatest in F. peregrinus (mean 1.82 mg/kg), followed by the H. leucogaster and P.haliaetus (mean 1.07 and 0.11 mg/kg, resp.). A comparison of F. peregrinus eggs collected before and after 1947 showed significant eggshell thinning (mean 16%). DDT residue levels of concern were recorded for several prey species commonly found in the diet of H. leucogaster and F. peregrinus, particularly in Columbia livia (feral pigeons) (37.46 mg/kg) and Larus novaehollandiae (silver gulls) (3.06 mg/kg). These concn were well above those known to cause reproductive failure in falcons. DDT was also found at high concn in eggs of Pelecanus conspicillatus (pelican) (mean 2.04 mg/kg). Dieldrin was present in most samples, but at low concn. The degree of pesticide contamination detected was considered sufficient to interfere with the reproduction of F. peregrinus in South Australia.