Effects of Aerial Applications of Fenitrothion on Bird Populations of a Scottish Pine Plantation

Abstract

(1) Fenitrothion, an organophosphorus insecticide, has been used in Scotland to control outbreaks of pine beauty moth (Panolisflammea D. & S.) in lodgepole pine (Pinus contorta Loud.) plantations. Fenitrothion is applied at 300 g ha' from helicopters using ultra-low-volume techniques. This study (1982-84) investigated the effects of spraying on five species of passerine birds in two 70 ha plots, which were compared with two neighbouring unsprayed plots. (2) Annual changes in breeding-bird populations, as measured by Common Bird Census techniques, were not affected by fenitrothion. (3) Changes in the numbers of singing birds from 5 days before until 5 days after spraying were either not significantly different or were inconsistent between sprayed and unsprayed plots. (4) There were no differences in coal tits (Parus ater L.) breeding in nestboxes between sprayed and unsprayed plots, nor in the proportion of broods hatched or fledged, clutch size, or brood size at hatching or fledging. (5) Residues of fenitrothion were detected in two coal tit nestlings found dead within 4 days after spraying, but not in six others found 10-16 days later. (6) Regression analyses of nestling growth in weight, wing and tarsus measurements did not reveal significant effects of spraying, although a non-significant trend for slower growth resulting in a lower final weight was indicated for nestlings in sprayed plots. (7) Visiting rates by parent coal tits to their nests and the diets of their nestlings were examined using camera nestboxes. The differences between nests in unsprayed and sprayed areas were complex and could have been caused by factors other than spraying.