Diurnal Visibility and Activity of Blue-Winged Teal and Mallard Broods

Abstract

Activities of blue-winged teal (Anas discors) and mallard (A. 1>latyrhynchos) broods were recorded continuously from sunrise to sunset in South Dakota during 1976. Observations totaling 255 brood-days were evaluated by species and age-class. Morning and evening feeding peaks became more pronounced, and visibility increased, with brood age. Swimming activity decreased, and visihle loaflng, sleeping, and depth of subsurface feeding increased in older broods. Behavior of class-I ducklings was similar in both species. Class-II and -III mallard broods loafed more and fed less in open water than did teal broods of the same age. Wind speeds in excess of 24 kmlhour and air temperatures above 23 C were associated with decreased brood visibility. Recommendations are made for increasing the accuracy and efficiency of brood inventories.