Duck Brood Behavior at the Seney National Wildlife Refuge

Daily observations of duck broods living undisturbed in their natural environment and unaware of an observer's presence were made during the summer of 1950 and 1951 at a 20-acre marsh in the Seney National Wildlife Refuge on the Upper Peninsula of Michigan. Observations were made of duck broods of the following species: blue-winged teal ( A m discors), black duck ( A m ~ubripes) , wood duck (Aix sponsa), mallard (Anas platyrhynchos), hooded merganser (Lophodytes cucullatus), ring-necked duck ( Aythya collaris), and American widgeon (Mareca americanu). The latter two species were the most numerous, with the others represented by one or two broods only. Favorable loafing spots were so much in demand that competition existed among broods for their use. Although these spots were defended by the hen occupying them, she and her ducklings were sometimes driven off by other brood hens. No instance was ever observed of a widgeon hen driving a ring-necked duck family off a mound, but several instances of the reverse were seen. The female and her brood usually left the loafing mound together after completing their period of sleep, although sometimes the hen left while the ducklings were still asleep, to return either before they had awakened or after they had gone. Similarly, hens often left their broods while they were feeding, to return after an absence of 15-75 minutes. While thus temporarily abandoned, the young usually continued their leisurely foraging through the marsh. The duck broods exercised a considerable degree of mobility in their movements into and out of the study area; the overall length of time individual duck broods used the marsh varied widely. Methods of escape used by duck broods when frightened varied among the different species observed. With the exception of the widgeon, most brood hens usually tolerated the close approach of other adult ducks, provided they made no threatening move toward the young. The widgeons were conspicuous for their belligerence toward all ducklings that attempted to join their broods. In contrast was the behavior of the ring-necked duck and wood duck, which either tolerated or adopted young of other species into their broods. Loafing sites were extremely important in the daily activities of duck broods: it is quite probable that the number of such loafing spots in a marsh, suitable in all other respects for brood rearing, has a limiting influence on both the number of broods using the marsh and on the length of time they remain in it. Although no duck nests were found in the area immediately surrounding the study marsh, many of the broods first appeared there as downy young, indicating that rearing habitat need not necessarily include nesting sites. When existing rearing marshes become overcrowded, confusion prevails among broods, resulting in lowered duckling survival. Under such conditions, establishment of additional small rearing marshes is recommended. For the study area, the maximum concentration of broods occurred July 18, 1950, when 15 broods, representing 0.75 brood/acre, were tallied; and 9 widgeon broods was the highest number of broods of a single species seen there during 1 day. There appeared to be no conflict between the ducks and the deer ( Odocoileus virgiluianus ) , beaver ( Castor canadensis), and muskrats (Ondutra zfbethicus) which also inhabited the marsh. The mink m mu stela vison), however, was shown to be a potentially important predator. This paper is the outcome of two suminterference or experiments, and (2 ) to mers of field work devoted to a study of show how knowledge of brood behavior of waterfowl behavior in a 20-acre marsh the various species can be translated into during the brood-rearing period. Its puruseful waterfowl management practices. poses are (1) to record the normal daily The writer is greatly indebted to the activities of duck broods in their natural School of Natural Resources, University of environment when undisturbed by human Michigan, for the generous research grants that made this field study possible and is l Present address: Elizabeth B. Losey, High Hill Farm, Germfask, Michigan. especially grateful to Samuel T. Dana, DUCK BROOD BEHAVIOR Beard 493 Fig. 1. Aerial view looking south of 20-acre study marsh showing its location between E Pool in the foreground and C Pool in the middle background. Note how the marsh is a topographically self-contained unit, encircled by a dike, tree-covered ridges, and two old beaver dams. Circles mark location of two tree platforms. Fig. 2. Aerial view of study marsh looking north. E Pool is in the background. Circles mark location of the two