Habitat use, survival, and causes of mortality among mallard broods hatched near the James River in North Dakota

Habitat use and survival by nine mallard (Anas platyrhynchos) broods from nests on the James River floodplain and adjacent drift plain were monitored during summer 1987. Radio-marked broods were relocated an average of 22% of the time in the river channel, 22% in oxbow ponds, 43% in a large sewage lagoon complex, and 13% in basin wetlands. Four of the six broods hatched on the floodplain stayed primarily in riverine wetlands throughout the brood-rearing period. Seven of nine broods fledged at least one young; a total of 27 ducklings survived to fledging of the 82 that hatched. The seven hens that fledged young used an average of two wetlands each from hatching to fledging. Mink and raptor predation and adverse weather conditions were the principal identified causes of mortality. Potential effects on waterfowl production of planned downstream irrigation, a part of the Reformulated Garrison Diversion Unit, are discussed and recommendations are made to reduce adverse impacts to wildlife.