160 



NORTH AMERICAN FAUNA 73 



Black-headed Grosbeak (Pheucticus melanocephalus) 

 Status: Casual spring migrant. 



Records: This western grosbeak has been recorded in the Valley on four occa- 

 sions. The first record was a male on 27 May 1970 in Washington County 

 (Huber 1974a). A female was observed in Washington County 11 May to 

 1 June 1974, and a male was noted in the same location on 13 May 1974 

 (Savaloja 1974). I observed a singing male in Glen Park at River Falls, Pierce 

 County, on 25 May 1979 (Eckert 1979). 



Indigo Bunting (Passerina cyanea) 

 Status: Regular migrant and nesting species. 



Migration: Common migrant in the Western Upland and Central Plain, un- 

 common (locally common) in the Northern Highland. Spring migrants arrive 

 in the Western Upland 1-5 May (earliest— 26 April 1976, Pierce County) and 

 reach the Northern Highland 5-10 May. Peak spring migration through the 

 Valley occurs 15-30 May. Fall migration begins about 10-15 August. Peak 

 fall migration occurs 1-15 September and departure 20 September to 5 Oc- 

 tober. 



Nesting Season Distribution: Common and well-distributed nesting species 

 in the Western Upland and Central Plain. Fairly common in the Northern 

 Highland, except in regions of extensive coniferous forest. Jackson (1943) 

 considered the indigo bunting an uncommon nesting bird in the Northern 

 Highland in 1919. In the Western Upland, Goddard (1972) found the indigo 

 bunting was the 12th most numerous breeding bird (X = 21.8 pairs per 

 40 ha) along the Kinnickinnic River Valley, Pierce County. Breeding Bird 

 Survey data (Table 8) suggest that lowest populations occur in the heavily 

 farmed regions of the Central Plain but increase northward into the North- 

 ern Highland. 



Habitat: The indigo bunting is a characteristic breeding bird of shrubby 

 "edge" habitat types. In the Central Plain and Northern Highland, Decid- 

 uous Clear Cuts under 10 years old receive heavy use by nesting indigo bunt- 

 ings. Important vegetation associated with their breeding habitat includes 

 trembling aspen, box elder, basswood, choke cherry, hazelnut, and prickly 

 ash. 



Dickcissel (Spiza americana) 



Status: Regular migrant and nesting species. 



Migration: Common migrant in the Western Upland and Central Plain, rare 

 and local in the Northern Highland. Populations of this bird experience tre- 

 mendous variations between years and they appear to be cychc. In adjacent 

 years, dickcissels can vary from among the most numerous migrants in 

 grassland habitats to virtually absent. Spring migrants arrive in the 

 Western Upland and Central Plain 20-30 May and are widespread 



