BIRDS OF THE ST. CROIX RIVER VALLEY 



109 



erous habitats. In the Western Upland, blue jays are common in Southern 

 Deciduous Forest and in remnants of oak savannah. This species appears to 

 be partial to oak forest. During years of poor acorn production, the migra- 

 tion of this species is heavy. In years of high acorn production, large win- 

 tering populations occur. 



Black-billed Magpie {Pica pica) 



Status: Casual, two fall records and one hypothetical record. 



Records: K. H. Dueholm observed a black-billed magpie at the McKenzie 

 Creek W^ildlife Area, Polk County, on 25 October 1973. C. Strehlow observed 

 one in St. Croix County on 12 November 1921 (Milwaukee PubUc Museum 

 files). Bernard (1967) described a specimen in the University of Wiscon- 

 sin-Superior bird collection that was "said to have been taken at Solon 

 Springs in the 1930's. Unfortunately, however, no label is attached to the 

 specimen." Roberts (1932) stated that in Minnesota, the black-billed magpie 

 occurs "as far east as Pine and Goodhue counties, both bordering on the 

 Wisconsin line." 



Common Raven {Corvus corax) 

 Status: Regular permanent resident. 



Migration: Uncommon spring and fall migrant in the Northern Highland 

 and Central Plain, accidental elsewhere. Definite migratory movements 

 begin about 15 October, reaching a peak by 1 December. Spring migration 

 begins in late February with dispersal from winter territories. Most ravens 

 have reached their breeding territories by 1 April. 



Nesting Season Distribution: Breeding Bird Survey data suggest that the 

 common raven is a rare breeding bird in the Central Plain and uncommon in 

 the Northern Upland (Table 5). Documented nest records exist only for 

 Burnett and Polk counties. Jackson (1942) failed to record ravens during his 

 research in northwestern Wisconsin in 1919. Bernard (1967) considered 

 common ravens uncommon in summer, but cited no evidence of breeding. 



Winter: Fairly common to common winter resident in the Northern High- 

 land, uncommon to fairly common in the Central Plain. The largest concen- 

 trations have been recorded near Solon Springs, Douglas County; 192 were 

 recorded on 23 December 1974. 



Habitat: Common ravens are not characteristic of any one habitat during 

 the breeding season. The Burnett County nest was found in an oak savannah 

 that was invaded by jack pine. The Polk County nest was in mixed aspen- 

 maple forest. Observations of apparent territorial common ravens indicate 

 an attraction to Northern Hardwood Forest during the nesting season. 

 Large numbers of common ravens are usually associated with garbage 

 dumps during the winter. 



