Montana Field Guide

Species slightly sexually dimorphic. Both sexes have a large chalky blue patch on upper wing; brighter blue in males. Males in breeding plumage have large, gray head with a large white crescent in front of eye; cinnamon under parts heavily speckled with black spots. Female body plumage mottled brown with whitish patch at base of bill; dark line through eye, small whitish crescents above and below eye; and grayish to yellow legs and feet.

The Bozeman migration occurs from April 20-May 30 and earlier and from September-October 15, with the peak May 15 and earlier. In September 1957, 300 were seen on Hebgen Lake during fall migration (Skaar 1969).

Main habitat consists of shallow ponds with adequate supplies of aquatic invertibrates. Prefers to nest in grass or herbaceous vegetation and rarely uses brushy nesting cover.

Diet consists of aquatic inveritbrates, seeds, vegetative parts of aquatic plants, duckweeds, algae, and occasional grains from agricultural crops. Animal matter dominates diet of laying females.

At Freezeout Lake, skunks were the major cause of unsuccessful nests.

In north-central Montana brood size was 5.9. Nesting records are from mid-May to August 20. At Freezeout Lake, grassland nests were more successful (18.5%) than those in other habitat types (14.3%). The average clutch size was 5.8. Hatching dates were from May 21 to August 10. In the Fortine area, egg dates were from June 13 to July 31.