Montana Field Guide

Medium sized dabbling duck with stocky build. Length: 50-65cm; mass: 1000-1300 g. Strongly sexually dimorphic. Adult male in breeding plumage has dark-green head, narrow white neck-ring, chestnut-brown breast, brownish-gray upperparts, grayish underparts, black rump and under tail-coverts, white outer tail-feathers and strongly recurved black central tail-feathers. In basic plumage, held briefly in late summer, the male retains its solid dark-greenish crown, warm-brown breast, darker upperparts, and slight upturned central tail-feathers.. Female plumage is similar year-round. Has broken streaky pattern of buff, white, gray, or black on brown feathers, white outer tail-feathers, contrastingly pale belly and under tail-covets and prominent dark eyeline. Juvenal plumage similar to female but averages darker, with notched tail feathers. (Drilling, N., Tittman, R. and McKinney, F. The Birds of North America, No. 658, 2002).

In the Bozeman area, normal migration occurs from February 25 to April 20 and from October 15 to January 1, with peaks on March 20 and December 1 (Skaar 1969).

In North America, the Mallard is the most abundant duck species. Its success in the wild reflects its adaptability to varied habitats, its hardiness in cold climates, and tolerance of human activities. Usual nest site is in uplands close to water. Nests in wide variety of situations with dense cover, including grasslands, marshes, bogs, riverine floodplains, dikes, roadside ditches, pastures, cropland, shrubland, fence lines, rock piles, forests, and fragments of cover around farmsteads (Drilling, Tittman, and McKinney 2002). Comments on habitat are in Holm 1984.

Omnivorous. Very flexible in food choice; diet composition depends on stage of annual cycle, hydrological conditions, invertebrate behavior, and crop-harvesting schedule (Drilling, Tittman, and McKinney 2002).

At Freezeout Lake, the most common cause of nest failure was skunk predation. Brood movements in southeast Montana tended to be from bare ponds to those with emergent vegetation, from small to larger ponds, and to ponds with a lower water loss rate.

Active nests have been found from April 15 to July 21, and hatching dates have been reported for May 10 to Aug 10. Clutch size averages about 7 for Freezeout Lake and the Fortine area; brood size averages 5.4 on pastures in north-central Montana.