Montana Field Guide

Redhead - Aythya americana

Medium-sized diving duck. Adult male in breeding plumage has rufous head and neck, black breast, gray body, black hindquarters, yellowish eye, and blue-gray bill with black tip and white subterminal band. Non-breeding male resembles female, but with reddish-brown head and yellowish eye. Female, at all times, is entirely plain brownish with whitish belly, grayish secondaries, whitish chin and eye-ring, dark eye, and bill similar to male (Woodin M. C. and Michot, T. C., The Birds of North America, No. 695, 2002).

Montana Range

In the Bozeman area, migration occurs from March 28 to May 20 and from September 15 to November 15, with peaks on April 20 and October 15. Dates for the Libby area are about 1 month later (Skaar 1969).

Habitat generalist; opportunistic in use of wetlands (Woodin and Michot 2002). In Flathead valley, small, shallow potholes with dense emergent vegetation is preferred for nesting. Comments on habitat can be found in Holm 1984. In the Bozeman area, they are confined to lakes and ponds at all seasons (Skaar 1969).

Vegetative parts and tubers of submerged aquatic plants; seeds, achenes and oogonia of muskgrass; and aquatic invertebrates. Highly adaptable in matching feeding tactics to available foods and environmental conditions: diving, tipping, dipping or gleaning foods from water surface, depending mostly on water depth (Woodin and Michot, 2002).

The sex ratio of the breeding population was 122:100, male to female. Home ranges were all less than 2600 feet. The main cause of nest failure was desertion (26%), then mammalian predation (21.7%); Skunk predation was the main cause at Freezeout Lake.

Overwater nests constructed in relatively tall, dense emergent vegetation of deeper semipermanent and permanent marshes. About 1/2 of nests possess cupolas, and about 2/3 have ramp constructed of vegetation extending from rim of nest to water surface. Elliptical to subelliptical eggs; usually creamy white to pale, olive buff, smooth and glossy. Clutch size (of an unparasitized nest) is 7 to 8 eggs (Woodin and Michot, 2002). In the Flathead valley, nest dates were late April to July and the success rate was 15.2%. Broods move to nearby potholes or Ninepipe National Wildlife Refuge after hatching. At Freezeout Lake the average clutch size of successful nests was 8.1.