BREEDING POPULATIONS OF MALLARDS, ANAS-PLATYRHYNCHOS, ON 4 URBANIZED LAKES IN MICHIGAN

Among breeding Mallard (Anas platyrhynchos) populations on four urbanized lakes in the northern lower peninsula of Michigan, maximum numbers of indicated pairs (single males or single males with single females) per km of shoreline varied from 0.59 to 0.91, other adults from 1.65 to 5.67, females with broods from 0.19 to 0.94, and individuals in broods from 1.06 to 6.15. More males occurred than females. Males occurring singly or with single females decreased during the survey period whereas males occurring in groups showed no trend. Abundance of females with and without broods increased during the survey period. Mallard production varied significantly on the four lakes. The largest number of broods appeared on the lakes during the third week in June. Brood size reached a high of 8.6 individuals in mid-June and declined to a low of 5.3 individuals at the end of the survey period. Breeding Mallards were most abundant on gently sloped urbanized shorelines. Mallards using these lakes undertook typical fall and spring migrations and at least some individuals returned in subsequent summers.