Density and Habitat Relationships of Blue-Winged Teal Nesting in Northwestern Iowa

Abstract

Blue-winged teal (Anas discors) were censused on a 136-ha study area from 1962 to 1974 by use of pair counts and nest numbers. Populations fluctuated between 20 and 111 pairs. Numbers showed a significant, positive correlation with water depth for the years 1968 to 1974, possibly because deeper water created additional feeding and loafing sites for territorial pairs in flooded grasses and sedges of temporary wetlands and around perimeters of deeper wetlands. Nest success was inversely related to both number of pairs and number of nests. Nest losses resulted almost entirely from predators, but reliable data were not available on predator numbers so correlation with nest success was not possible. Nest and pair numbers were sufficiently well correlated that pair counts can be used on this area to estimate nesting effort when time does not permit nest surveys or when data on nest-site selection or nest success are