EFFECTS OF AERIAL SPRAYING OF FENITROTHION ON BREEDING WHITE-THROATED SPARROWS

The effects of fenitrothion on reproduction in Zonotrichia albicollis was examined in a New Brunswick forest cutover in the context of control operations against spruce budworm Choristoneura fumiferana. Insecticide was applied aerially twice, once at 420 g ha-1 and once at 210 g ha-1, 8 days later. Behavioural responses of breeding birds to the insecticide included territory abandonment, inability to defend territory, disruption of normal incubation, and clutch desertion. The adult population was reduced by 1/3 , primarily a consequence of mortality and territory abandonment after the first spray. Clutch size and hatching success were not significantly different between the sprayed and control study populations. Almost all breeding attempts (84%) at 13 nests were disrupted by the 420 g active ingredient ha-1 spray; reproductive success in the sprayed area was only 1/3 of that in the control area. The observed effect of territory maintenance and reproductive success is compared to an earlier investigation in which mean brain acetylcholinesterase inhibition of 42% and 30%, respectively, was noted in birds exposed to the same 2 sprays. -Authors