38 



NORTH AMERICAN FAUNA 73 



populations occur 20 October to 10 November. Largest concentrations have 

 been noted at the Crex Meadows WildUfe Area, Burnett County; 1,000 indi- 

 viduals were recorded 14 November 1964, 7 November 1965, and 28 October 

 1966. In the Western Upland, greatest numbers occur in central St. Croix 

 County and along the St. Croix River and backwaters 25 October to 5 No- 

 vember. During fall migration, black ducks are usually observed in close 

 association with flocks of mallards. Departure during fall occurs 15 Novem- 

 ber to 1 December, depending on weather conditions. 



Nesting Season Distribution: Locally occurring nesting duck, primarily in 

 the Northern Highland. Green and Janssen (1975) have mapped the breeding 

 distribution of this duck in Minnesota and indicated it as a regular nesting 

 bird in northern Pine County. There are two Washington County nest rec- 

 ords: 24 May 1971, a female with 10 young was observed near Hugo, Minne- 

 sota, and nesting was reported during the summer of 1978 (Green 1979). Pair 

 counts at Crex Meadows from 1957 to 1976 revealed an average of 1.1 pairs 

 per year; broods were observed in 1957 and 1971 (WDNR files). Jackson 

 (1941) observed one black duck near Solon Springs, Douglas County, on 

 8 August 1919. In St. Croix County, one pair was observed near New Rich- 

 mond on 28 June 1975. They may have been nonbreeding birds or late 

 migrants. 



Winter: Fairly common winter resident wherever there is open water. 

 Recorded primarily along the lower St. Croix River (Hudson-Stillwater) and 

 below the dam at Taylors Falls. One midwinter record for Crex Meadows, 

 Burnett County, 12 January 1955. 



Habitat: The black duck is primarily a species of northern forested wetlands. 

 Typical habitat consists of 0.5 ha or larger permanently flooded wetlands 

 that are slightly acidic. Pairs and broods have also been noted on acid bog 

 wetlands and beaver ponds. 



Gady^^aW {Anas strepera) 



Status: Regular migrant and nesting species, casual winter resident. 



Migration: Uncommon migrant in the Western Upland and Central Plain; 

 uncommon to rare in the Northern Highland except at Crex Meadows. 

 Spring migrants arrive 25 March to 5 April in the Western Upland, reaching 

 the Northern Highland 10-15 April (earliest— 31 March 1958, Burnett 

 County). Peak spring migration occurs 15-25 April and departure of non- 

 breeders occurs 5-15 May. 



Fall migrants arrive 20-30 September reaching peak numbers 10-15 Octo- 

 ber. The largest concentration recorded at Crex Meadows, Burnett County, 

 was 400 on 3 October 1970, and the largest number on the St. Croix County 

 wetlands was 150 on 10 October 1975. Departure of fall migrants occurs 

 after mid-October and most birds have left by 10 November. 



Nesting Season Distribution: Rare and local nesting species with confirmed 

 brood records from St. Croix, Polk, and Burnett counties. Gadwalls were 

 released at the Crex Meadows Wildhfe Area, Burnett County, during 1970 in 

 an attempt to establish this prairie duck on seeded native prairie grasslands. 



