Observations on the display flights of male Brown Songlarks (Cincloramphus cruralis Vigors and Horsfield 1827) before and after the application of fenitrothion, an organophosphorous pesticide for locust control, in a semi-arid grassland in south-western New South Wales and suggestions for further research

Abstract

ABSTRACT Exposure of songbirds to organophosphorous pesticides has been shown to affect a range of behavioural characteristics including singing, displaying and flying that consequently can have significant impacts on the viability of free-living individuals and populations. In the current study, display flights of male Brown Songlarks (Cincloramphus cruralis Vigors and Horsfield 1827) before and after the application of fenitrothion (O,O-dimethyl-O-[3-methyl-4-nitrophenyl]-phosphorothioate) during locust spray operations around Conargo, south western New South Wales, were monitored incidentally for number, duration and the presence of song during flight. The duration of display flights undertaken by male C. cruralis showed a statistically significant increase after exposure to fenitrothion (t0.05, 398 = 1.97; p = 0.0085, analysed using log10 transformed flight duration data), despite the mean number of flights undertaken decreasing from 5.7 pre-spray to 4.7 post-spray during 10 min survey periods. The proportion of display flights in which the male was calling, however, did not differ between pesticide-exposed and unexposed male C. cruralis (χ2(0.05, 1) = 0.323; p = 0.570). To better understand the impacts of pesticide exposure on C. cruralis behaviour and ecology, the observations presented here require further study and validation with the addition of other variables such as territory mapping, assessment of reproductive success and the quantification of enzymatic biomarkers indicative of exposure to organophosphorous insecticides, undertaken concomitantly.