Factors affecting the flight distance of the Dusky Thrush Turdus naumanni

Abstract

Flight distances were measured in the Dusky Thrush, Turdus naumanni, in winter. Predictive models relating flight distance of the thrush to environmental variables were developed and tested using stepwise multiple regression. The models, based on analyses of possible independent variables collected in 1984 and 1985, accounted for 54% and 82% of the variation in flight distance, respectively. The most important independent variables were location of the thrush (whether it was within 10 meters from the nearest shelter belt or not) and snow depth in 1984, and distances from the thrush to the nearest shelter belt and perch height in 1985. Longer flight distances were recorded further away from shelter belt. Snow fall made the flight distance shorter. Based on the multiple regression model in 1985, I predicted flight distance of thrushes and the time until they flew off for each distance from the shelter belt and showed that a thrush would stay a longer time before it flew off near shelter belts.