42 



NORTH AMERICAN FAUNA 73 



Nesting Season Distribution: Nest records of American wigeon have been 

 confirmed only at Crex Meadows: two broods (eight each) in July 1967 (first 

 brood observed on 14 July); one brood observed in 1970 and 1971; one brood 

 of four observed on 21 July 1975, and two broods during 1976. Elsewhere, 

 summering pairs are regularly observed in St. Croix and Polk counties. The 

 only evidence suggestive of nesting was a female acting "broody" on a pond 

 1.6 km northwest of New Richmond on 20 July 1977. Although summering 

 pairs are regularly observed in Washington County near Lake Elmo, no evi- 

 dence of nesting has been obtained. 



Habitat: Breeding pairs at Crex Meadows are typically associated with large 

 man-made impoundments. In St. Croix and Washington counties summer- 

 ing American wigeon pairs are associated with semipermanently flooded 

 wetlands. 



Northern Shoveler {Anas clypeata) 

 Status: Regular migrant and nesting species. 



Migration: Fairly common spring migrant in the Western Upland, uncom- 

 mon to rare elsewhere. Rare throughout the Valley during fall migration. 

 Goddard (1975) found that the northern shoveler made up 2.2% of the water- 

 fowl population and 6.4% of the dabbUng duck population in St. Croix 

 County during spring migration. 



Spring migrants arrive 1-5 April (earliest— 24 March 1976, St. Croix 

 County). Peak spring migration in the Western Upland occurs 20 April to 

 5 May and departure occurs 15-20 May. Elsewhere, arrival occurs 10-20 

 April (average 15 April at Crex Meadows). Peak spring populations occur 

 about 10 May and departure by 20 May. Fall migrants begin to arrive 

 10-20 August. Peak fall populations cannot be determined because of the 

 small number of birds usually observed. Departure from the Valley occurs 

 by 15 November. 



Nesting Season Distribution: Regular nesting species at Crex Meadows, 

 Burnett County, where up to eight pairs per year have been recorded on 

 breeding waterfowl survey transects (WDNR files). Elsewhere, northern 

 shovelers are encountered irregularly during the breeding season in St. 

 Croix, southern Polk, and Washington counties. 



Habitat: Soft-bottomed semipermanently and permanently flooded wet- 

 lands supporting populations of macroinvertebrates are usually occupied 

 during the nesting season. During spring migration, extensive use is made 

 of temporarily flooded wetlands. 



Wood Duck (Aix sponsa) 



Status: Regular migrant and nesting species, casual in early winter. 



Migration: Common migrant throughout the VaUey. Spring migrants arrive 

 in the Western Upland 15-20 March (earUest— 6 March 1975, Pierce 

 County). Spring migration progresses according to the opening of river sys- 



