WETLAND USE BY BREEDING AND POSTBREEDING FEMALE MALLARDS IN THE ST-LAWRENCE-RIVER VALLEY

We examined the use of wetland habitats by female Mallards (Anas platy rhynchos from March 1990 through July 1992 in the St. Lawrence River V alley, a focus area under the North American Waterfowl Management Plan . Female Mallards spent most of their time breeding in forested-live w etlands (40%) and postbreeding in forested-dead wetlands (35%). Accord ing to wetland availability data, breeding and postbreeding females in dicated selectivity for emergent and scrub-shrub wetlands. During post breeding, they used fewer (($) over bar x = 2.6, +/- 0.2 [SE]) individ ual wetlands of larger size (($) over bar x = 192 ha +/- 30 ha) compar ed to the breeding season (($) over bar x numbers = 4.1 +/- = 0.2, P = 0.003; ($) over bar x size = 101 ha +/- = 15 ha, P = 0.001). Moreover , females typically spent the postbreeding season in the vicinity of, or within, their breeding wetlands, hence conservation must simultaneo usly address breeding and postbreeding requirements. Protection of wet land complexes that contain a diversity of habitat types of differing sizes is recommended.