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Platte River Status: An abundant migrant, common and widely distributed breeding species, and local winter resident. Mallard is the most numerous waterfowl species breeding in the study area. Tout (1947) considered mallard the most common duck in Lincoln County, present throughout the year. Rosche (1979) found mallard a permanent resident, nesting in the lower North Platte River Valley.

Breeding Range: A common breeding species in Platte River Valley, in the Rainwater Basin area of the Eastern Plain, and in the Sandhills. Fairly common and locally distributed on the Dissected Plain, Western Plain, and elsewhere on the Eastern Plain.

Breeding Population: The population in 1979-1980 was estimated at 5,743 breeding pairs. Mallard was the most abundant and widespread waterfowl species, making up 0.2% of the total bird population those years. Mallard made up 27% of the waterfowl population nesting on Waterfowl Production Areas in the Rainwater Basin area in 1983.

Habitat: We found the highest mean breeding densities in prairie wetlands (13.8 pairs/km²), followed by river channel island (0.5 pairs/km²), and wet prairie (0.2 pairs/km²). Faanes (1982) found mallard occupying all wetland classes present on a central North Dakota study area, although highest densities occurred on semipermanent wetlands. Kantrud and Stewart (1977) reported that highest densities in North Dakota were associated with temporary (66.7 pairs/km²) and seasonal (44.9 pairs/km²) wetlands.

Effect of Habitat Alteration: Loss of natural wetland habitat, particularly in the Rainwater Basin area, and the conversion of native grasslands to crop production have negatively affected mallard production within the study area. Overall habitat impacts have been less severe in the Sandhills. Modern agricultural techniques have provided waste grain as a food source for winter. That factor, combined with the maintenance of open water areas along the Platte and North Platte rivers, has resulted in the recent establishment of wintering mallards throughout the study area.

Nesting Data: We have found nine active nests at the Mormon Island Crane Meadows, Hall County, which contained 7 to 11 eggs (_X=8.9). Egg dates extend from 19 May to 17 June. Onset of incubation would normally be from late April to mid May. Tout (1947) found a nest with 11 eggs along a drainage ditch 16 km west of North Platte on 2 May 1937. Faanes found a nest with 6 eggs in Lincoln County on 3 May 1979. Mallard brood records include the following: a brood of 6 on Lake Maloney, Lincoln County on 3 June 1979; an uncounted brood in Phelps County on 14 June 1979; a brood of 7 in Buffalo County on 30 May 1979; a brood of 7 on the North Platte sewage lagoon on 21 June 1979. Egg dates in Kansas extend from 1 April to 10 June (Johnsgard 1979).