ORGANOCHLORINE CONCENTRATIONS IN POTENTIAL AVIAN PREY OF BREEDING PEREGRINE FALCONS IN NORTH-CENTRAL NEW-MEXICO

Despite the federal ban of DDT since 1972, some southwestern populations of peregrine falcons (Falco peregrinus anatum) still exhibit extremely low natural production and continue to accumulate high levels of DDE. During 1985, we collected 35 potential species of migrant and resident prey of peregrine falcons in north-central New Mexico to determine if local peregrine falcons are exposed to DDE on the breeding grounds. Thirteen (37.1%) of the 35 species pools contained DDE residues >1.0 ppm. Say's phoebe (Sayornis saya; 22.01 ppm), killdeer (Charadrius vociferus; 13.49 ppm), American pipit (Anthus rubescens; 11.63 ppm), western meadowlark (Sternella neglecta; 6.25 ppm), and Brewer's blackbird (Euphagus cyanacephalus; 5.28 ppm) pools had DDE residues >5.0 ppm. DDE concentrations were not significantly related to prey diet but migration status was a significant effect with DDE residues lowest in residents (geometric mean = GM = 0.08 ppm), intermediate in weakly migratory species (GM = 0.37 ppm) and highest in strongly migratory species (GM = 1.63 ppm). Based on results of this study and a review of the literature, we conclude that peregrine falcons utilizing this study area are still faced with a potential source of DDE contamination.