BIRDS OF THE ST. CROIX RIVER VALLEY 



177 



em Upland 5-10 September (earliest— 25 August 1977, Pierce County). 

 Peak fall migration occurs 15 September to 10 October. Departure from the 

 Northern Highland occurs 10-20 October and elsewhere by 15 November. 



Nesting Season Distribution: Common nesting species in the Northern 

 Highland (Table 8), uncommon and local in the Central Plain. Green and 

 Janssen (1975) showed that the breeding range of this sparrow extended 

 south to the Chisago- Washington County Hne. My most southerly nest 

 record was obtained on 9 June 1975, near Luck, Polk County (Sec. 19, 

 T. 36 N.,R. 17 W.). 



Winter: Rare and regular winter resident in the Western Upland. Usually 

 encountered each year on either the Afton or Suburban St. Paul CBC. One 

 remained at St. Croix Falls, Polk County, during the 1949-50 Winter. 



Habitat: The white-throated sparrow occupies both deciduous and conif- 

 erous habitats during the nesting season. There is no single habitat that can 

 be considered characteristic. Deciduous habitats that are most regularly 

 used include stands of mature Northern Hardwood Forest with sugar maple, 

 basswood, and silver maple the predominant vegetation. Nests in this 

 habitat are usually associated with lush grasses and forbs in the ground 

 layer. Deciduous Clear Cuts < 10 years old and predominantly trembUng 

 aspen with scattered patches of black raspberry are an important deciduous 

 habitat. Coniferous habitats of major importance include Lowland Conif- 

 erous Forest dominated by yellow birch, white cedar, black spruce, and 

 balsam fir. Extensive use is also made of Black Spruce-Tamarack Bogs. Use 

 of Jack Pine Barrens is very low and irregular. 



Fox Sparrow {Passerella iliaca) 



Status: Regular migrant, casual early winter resident. 



Migration: Fairly common migrant throughout the Valley. Spring migrants 

 arrive in the Western Upland 15-25 March and the Northern Highland 

 1-5 April. Peak spring migration occurs 10-25 April and departure by 

 15 May (latest— 28 May 1972, Washington County). Fall migrants arrive 

 10-15 September, peak fall migration occurs 1-20 October, and departure is 

 by 15 November. 



Winter: There are several early winter records from the Western Upland. 

 These records include 13 December 1968, Chisago County, and 2 January 

 1960, 1 January 1970, 1974, and 1976 on the Afton CBC, Washington 

 County. 



Habitat: In the Western Upland, the fox sparrow is primarily a species of 

 Southern Deciduous Forest characterized by white. Hill's, and bur oak. 

 Extensive areas of brushy understory, primarily prickly ash, hazelnut, and 

 beaked hazel are important components of that habitat. In the northern 

 regions, fox sparrows use brushy edges and heavy undergrowth in Northern 

 Hardwood Forest, primarily quaking aspen, sugar maple, basswood, white 

 birch, and green ash. 



