BIRDS OF THE ST. CROIX RIVER VALLEY 



59 



Winter: Fairly common winter resident primarily in the vicinity of open 

 water. Wintering birds at Crex Meadows regularly occupy open prairie 

 areas. The distribution of wintering bald eagles closely follows the large 

 river systems of the Valley; birds are located primarily at Prescott (Pierce 

 and Washington counties) and St. Croix Falls (Polk and Chisago counties) 

 along the St. Croix River, the Kettle River (Pine County), and Gordon 

 Flowage (Douglas County). 



Habitat: Nesting habitat of bald eagles consists of a complex of deciduous, 

 coniferous, wetland, and shrub situations. In all instances, however, two 

 prominent features (tall pine trees and nearby lakes or large rivers) occur. 

 Unfortunately for the eagles, these are two conditions that also attract man, 

 and several nesting territories in the Valley are endangered because of 

 human encroachment. 



Marsh Hawk (Circus cyaneus) 



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



Migration: Fairly common migrant throughout the Valley, common at Crex 

 Meadows, Burnett County. Spring migrants arrive in the Western Upland 

 about 15 March; average arrival is about 20 March. Migrants arrive in the 

 Northern Highland about 25 March. Peak migration occurs 1-20 April, and 

 nonbreeders depart by 1 May. Fall migration begins in mid- August and con- 

 sists primarily of juveniles. Peak fall migration occurs 15 September to 

 15 October in the Central Plain and extends to 25 October at Crex Meadows. 

 Most birds have departed by 15 November. 



Nesting Season Distribution: Uncommon nesting species throughout the 

 Valley, with nesting records for all counties. Apparently less numerous at 

 present than earlier as evidenced by Jackson (1941), who reported them as 

 "generally distributed ... in favorable environments throughout the 

 region." Marsh hawks have been greatly reduced as a nesting bird in west- 

 ern Wisconsin since the mid- 1 960 's. 



Winter: Casual midwinter resident in the Western Upland. Two midwinter 

 records for Crex Meadows, Burnett County (9 February 1954, 25 February 

 1953). 



Habitat: Marsh hawks use a wide range of grassland habitat types for 

 nesting. Nesting birds have been recorded in retired cropland (tim- 

 othy-quackgrass), old field habitat, wetlands (primarily sedge meadows), 

 and restored prairie. In areas of intensive agriculture, nesting may regularly 

 occur in hayfields and occasionally in oat fields. 



FAMILY PANDIONIDAE: Ospreys 



Osprey [Pandion haliaetus) 



Status: Regular migrant and nesting species. The WDNR Usted the species 

 as endangered (Les 1979). Residual pesticides and loss of nesting habitat are 



