40 



NORTH AMERICAN FAUNA 73 



Migration: Fairly common migrant in all regions, locally common during 

 spring in the Western Upland. Spring migrants begin to arrive in the West- 

 ern Upland 25 March to 1 April (earliest— 15 March, St. Croix County). 

 Arrival in the Northern Highland occurs 5-10 April. Peak spring popula- 

 tions occur 15-25 April and departure of nonbreeding birds occurs by 

 15 May. In St. Croix County, Goddard (1975) found that green-winged teal 

 made up 4.6% of the spring waterfowl population and 13.6% of the dabbhng 

 ducks. 



Fall migration begins about 25 August with a slow increase of numbers in 

 the Central Plain and Northern Highland. Peak populations occur 

 1-15 October in the Northern Highland. The largest population recorded at 

 Crex Meadows, Burnett County, was 600 birds on 2 October 1971. Peak fall 

 populations in the Western Upland occur 10-25 October. Although depar- 

 ture is fairly slow, most green-winged teal have departed by 15 November. 



Nesting Season Distribution: Uncommon to rare nesting species throughout 

 the Valley. Most observations of birds during this period are made in the 

 prairie wetland region of St. Croix, Polk, and Washington counties, and at 

 Crex Meadows. Green-winged teal are the fourth most common breeding 

 duck at Crex Meadows (WDNR files). In St. Croix and Polk counties, green- 

 winged teal constitute about 0.4% of the breeding waterfowl population. 



Winter: One bird was observed on the Afton CBC on 1 January 1972. N. R. 

 Stone observed three birds at Clam Lake, Burnett County, on 13 February 

 1950 (Robbins 1950a). 



Habitat: Pairs and broods are associated with seasonally and semiperma- 

 nently flooded wetlands. Of seven green-winged teal nests that I located in 

 St. Croix County in 1976, all were in alfalfa fields. 



Blue- winged Teal {Anas discors) 



Status: Regular migrant and nesting species. 



Migration: Abundant migrant in the Western Upland, common in the 

 Central Plain, and fairly common (locally common) in the Northern High- 

 land. Goddard (1975) found that blue-winged teal made up 14,4% of all 

 waterfowl and 43% of all dabbUng ducks using St. Croix County wetlands in 

 spring. 



Blue-winged teal are among the last migrant ducks to arrive in spring; 

 average arrival date is 5 April (earHest— 23 March 1976, St. Croix County). 

 Populations build rapidly and peak numbers are usually noted 20 April to 

 10 May. The first migrants usually arrive in the Northern Highlands about 

 20 April and reach peak populations 5-15 May. 



Fall migrants begin to form large feeding aggregations in late July and 

 early August. Peak fall populations occur early; the largest number (1,200) 

 observed at Crex Meadows, Burnett County, was on 17 September 1976. 

 Typically, large numbers of blue-winged teal are observed 10-25 September 

 in St. Croix and Washington counties (1,000 on 23 September 1975). Depar- 

 ture from the region is very rapid after peak populations occur, and most 



