ABSTRACT
Canvasbacks and redheads are diving ducks native to North America. Canvasbacks winter in the southern and eastern US and in Mexico, and redheads winter in the southern US and Mexico, principally along the coast of Texas. Comparatively low numbers of both species and deteriorating breeding habitats necessitate regular population monitoring to determine numerical status and to provide indexes of productivity. Make counts of pairs after spring migration when birds are dispersed on the breeding habitat and before most of the females are incubating clutches. This period, which varies with latitude and local weather, ranges from the first to the third week of May in the northern prairies and parklands. Recruitment estimates usually imply fledged young and are based on brood size and density, sampled in the same way as pairs. Canvasbacks and to a lesser extent, redheads, are relatively mobile species, with large home ranges.
