Factors affecting winter distribution and migration distance of wood ducks from southern breeding populations

We used direct band-recovery records of Wood Ducks (Aix sponsa) banded 1 April-15 September (1960-1987) in the southern and southeastern reference areas of Bowers and Martin (1975) to test whether winter distribution and migration distance were age- and sex-specific. Effects of variation in early-autumn temperature and precipitation conditions on winter distribution patterns also were studied. Latitude and longitude of winter band recoveries did not differ by age and sex in the southern reference area; but adult Wood Ducks tended to migrate shorter distances than young. In the southeastern reference area, recovery distributions of males and females also did not differ; but adults were distributed north and east of young birds, and migrated shorter distances. We predicted that Wood Ducks would move farther south in winter when early-autumn (October-November) temperature and spring-summer (April-September) precipitation were below normal. Adults were recovered farther south when precipitation was below average, but deviations from average temperatures were not associated with winter distribution. Young Wood Ducks occurred farther south when rainfall in spring-summer was less than normal and when average November temperature was colder than normal. We conclude that winter distributions of male and female Wood Ducks did not differ, but that adults migrated shorter distances than young. Variation in winter distribution was associated with early-autumn habitat suitability.