REPRODUCTION AND NEST BEHAVIOR OF TENNESSEE WARBLERS VERMIVORA-PEREGRINA IN FORESTS TREATED WITH LEPIDOPTERA-SPECIFIC INSECTICIDES

1. This study was designed to test the hypothesis that food reductions caused by forest spraying with Lepidoptera-specific insecticides woul d affect Tennessee warbler behaviour and reproduction. 2. Tennessee wa rbler nests and parental behaviour were monitored in two spray blocks, one treated with Bacillus thuringiensis (Bt) and the other with tebuf enozide (MIMIC), and in an untreated control area. 3. Nestling surviva l and growth were unaffected by the insecticide treatments. Nests in t he treated blocks had smaller clutches, smaller broods and lower hatch rates than nests in the control block, but these differences were not statistically significant. 4. Nestling diets were similar in the MIMI C and control blocks. 5. There were slight differences in the behaviou r patterns of female Tennessee warblers in the MIMIC and control block s. MIMIC females spent less time at the nest and more time foraging. 6 . The results of this study suggest that the indirect effects of fores t spraying with Lepidoptera-specific insecticides pose little risk to forest songbirds.