BIRDS OF THE ST. CROIX RIVER VALLEY 



55 



juveniles from nesting areas. Peak fall movements occur 20 September to 

 10 October in the Northern Highland and throughout October elsewhere. 

 Nonwintering birds have departed by 1 December. 



Nesting Season Distribution: Common nesting species in all regions, most 

 conspicuous in agricultural areas. Nest records have been obtained for all 

 counties except Chisago. Analysis of Breeding Bird Survey data indicate 

 that the red-tailed hawk is the most frequently encountered breeding hawk 

 in the Western Upland and Central Plain. 



Winter: Fairly common to uncommon winter resident in the Western 

 Upland. Uncommon to rare in the Central Plain and rare to absent in the 

 Northern Highland. Birds normally depart the northern regions by mid-Jan- 

 uary. In open agricultural areas along the lower St. Croix River, red-tailed 

 hawks are the most frequently encountered hawk during the winter. 



Habitat: Red-tailed hawks use a large variety of habitats during the nesting 

 season. In agricultural areas this hawk will use brushy field margins, small 

 woodlots, and woods edge situations. In the Northern Highland, the species 

 is usually associated with field borders of extensive Northern Deciduous 

 Forest and Coniferous Forest. Jack Pine Barren and Lowland Deciduous 

 Forest probably receive the lowest frequency of use by nesting red-tailed 

 hawks. 



Red-shouldered Hawk {Buteo lineatus) 



Status: Regular migrant, nesting species, and winter resident. The Wis- 

 consin DNR has Usted this species as threatened (Les 1979). Habitat 

 destruction is considered the primary reason for their decline. 



Migration: Uncommon to rare migrant in the Western Upland and Central 

 Plain; rare to absent in the Northern Highland. Spring migration begins in 

 mid-February with a gradual movement into the Western Upland along the 

 St. Croix River. Migrants have reached the Central Plain by 25 March (ear- 

 liest— 11 March 1950, 16 March 1975; Polk County). Red-shouldered hawk 

 migration is rather diffuse, consisting primarily of movements of sohtary 

 individuals. Consequently, determination of peak dates is difficult. Most 

 birds have reached nesting territories by mid- April. Fall migration is equally 

 diffuse, consisting of a gradual movement from nesting areas. During fall, 

 red-shouldered hawks are most conspicuous throughout October and non- 

 wintering birds have departed by 1 December. 



Nesting Season Distribution: Uncommon and local nesting species in the 

 Western Upland and Central Plain, rare and local in the Northern Highland. 

 A. C. Rosenwinkel found young in a nest along the Willow River, Pine 

 County, on 7 April 1949 (Mierow 1949). EstabUshment of the red-shouldered 

 hawk as a nesting bird in the Valley is apparently very recent. Roberts 

 (1932) mentioned no nests from Minnesota, and cited only one summer 

 record (3 July 1927, at Marine-on-St. Croix, Washington County). Behavior 

 and plumage of that bird suggested nesting. Since that time, however, the 

 red-shouldered hawk has been recorded regularly, and there are presently 

 nest records for all the counties except Douglas. 



