Abstract. During 1987-89, organochlorine contaminant levels were measured in American kestrel (Falco sparverius) eggs and in other components of the terrestrial ecosystem in Ontario, Canada. The extent to which these samples were contaminated with DDE varied geographically. Wet weight levels of DDE were greater in eggs from American kestrels (10.8 mg/kg), American robins (Turdus migratorius) (17.3 mg/kg), European starlings (Sturnus vulgaris) (8.8 mg/kg), and eastern bluebirds (Sailia sailis) (7.6 mg/kg) and in samples of earthworms (Lumbricus sp.) (0.6 mg/kg), soil (0.3 mg/kg) and vegetation (8