ORGANOCHLORIDE PESTICIDE CONTAMINATION IN 3 SPECIES OF RAPTOR AND THEIR PREY IN SOUTH AUSTRALIA

This study investigates the degree of organochlorine pesticide contami nation in three species of raptor from the central regions of South Au stralia. Levels of residue in both eggs and tissue, as well as measure ments of shell thickness, were obtained for peregrine falcon (Falco pe regrinus), osprey (Pandion haliaetus) and white-bellied sea eagle (Hal iaeetus leucogaster). Organochlorine residues in some prey species wer e also measured. Residue levels of DDE and DDT in the raptors were fou nd to be low to moderate. Levels of total DDT were highest in the pere grine falcon (mean 1.82 mg kg-1), followed by the white-bellied sea ea gle and osprey (mean 1.07 and 0.11 mg kg-1 respectively). A comparison of peregrine falcon eggs collected before and after 1947 showed signi ficant eggshell thinning (mean 16%). DDT residue levels of concern wer e recorded for several prey species commonly found in the diet of whit e-bellied sea eagle and peregrine falcon, particularly in feral pigeon s (37.46 mg kg-1) and silver gulls (3.06 mg kg-1). These levels are we ll above those known to cause reproductive failure in falcons. DDT was also found in high levels in pelican eggs (mean 2.04 mg kg-1). Dieldr in was present in most samples, but at low levels. The level of pestic ide contamination detected is considered sufficient to interfere with the reproduction of peregrine falcons in South Australia.