BIRDS OF THE ST. CROIX RIVER VALLEY 



45 



ever, most ring-necked duck breeding activity in St. Croix and Polk counties 

 occurs west and north of Peterson's study area. 



Winter: One male was observed on the Afton CBC 1 January 1975. 



Habitat: Ring-necked ducks are primarily a species of permanently flooded 

 wetlands in the forested areas of the Valley. Typical brood habitat consists 

 of shghtly acidic water and scattered growths of pond Uly, bulrush, and cat- 

 tail. Beaver ponds are commonly used in the northern counties and acid bogs 

 are occasionally used. 



Canvasback {Ay thy a valisineria) 



Status: Regular migrant and casual summer resident, one nesting record 

 and one winter record. 



Migration: Uncommon spring and fall migrant in the Western Upland and 

 Central Plain, rare in the Northern Highland. Spring migrants arrive in late 

 March (earUest— 16 March). Peak abundance occurs 10-25 April and depar- 

 ture occurs 10-20 May .Goddard (1975) found that the canvasback made up 

 0.4% of the total spring waterfowl population and 1.0% of the diving duck 

 population in St. Croix County. Fall migration begins in mid-September 

 with arrival of small flocks on the larger lakes and the St. Croix River. Peak 

 fall populations occur 15 October to 1 November and departure by 30 No- 

 vember. 



Nesting Season Distribution: Casual summer resident in St. Croix County 

 and at Crex Meadows, Burnett County. The only nesting record is my obser- 

 vation of a hen with a brood of eight on Oakridge Lake, St. Croix County, on 

 8 July 1976. Summering pairs are occasionally observed on other prairie 

 wetlands although no evidence of nesting is available. Elsewhere, summer- 

 ing pairs were observed at Crex Meadows in 1950, 1962, 1975, and 1978. 



Winter: A male canvasback was observed on the Afton CBC, Washington 

 County, on 1 January 1975. 



Habitat: The nesting record was obtained on a large permanently flooded 

 wetland. Dominant vegetation included softstem bulrush, cattail, and river 

 bulrush. Most additional summer records are the birds on semi-open perma- 

 nent wetlands. During migration, canvasbacks utiHze most wetland types, 

 although a preference is shown for semipermanently and permanently 

 flooded wetlands. 



Greater Scaup {Ay thy a marila) 



Status: Regular migrant. 



Migration: Rare migrant throughout the Valley. Spring migrants arrive 

 5-15 April and are most regularly observed 25 April to 5 May. First 

 migrants are usually observed on the St. Croix River, followed by an in- 

 crease of observations away from the river. Departure from the Valley 

 occurs by 15 May (latest— 29 May 1968, Burnett County). Goddard (1975) 

 failed to record the greater scaup during four spring field seasons in St. 



