BIRDS OF THE ST. CROIX RIVER VALLEY 



151 



grants arrive 25 April to 1 May, reaching northern areas by 10 May. Peak 

 spring migration occurs 10-20 May. Fall migration begins in late July in the 

 Northern Highland and 10-15 August elsewhere. Peak abundance occurs 

 20-30 August and departure from the Northern Highland by 20 August and 

 15 September elsewhere. 



Nesting Season Distribution: Common to locally abundant nesting species 

 in Western Upland and Central Plain. Rare to uncommon and local in the 

 Northern Highland. Breeding Bird Survey data (Table 7) indicate that a uni- 

 formly large breeding population occurs in the Western Upland and Central 

 Plain. Documented breeding records exist for Pierce, St. Croix, and Polk 

 counties. There are inferred breeding records for the remainder of the region. 

 In Douglas County, Bernard (1967) referred to the bobolink as a "common 

 summer resident." Jackson (1943) found this species to be "distributed . . . 

 where meadow environment suitable for them prevails"; however, he pro- 

 vided no data for the Valley. 



Habitat: Characteristic species of grassland communities including retired 

 cropland, alfalfa fields, tame pasture. Managed Grasslands, and remnant 

 prairies. Occasionally found using Northern Sedge Meadow and Shrub Carr; 

 however, these habitats apparently receive higher use during migration. 



Eastern Meadowlark {Sturnella magna) 



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



Migration: Fairly common migrant east of the St. Croix River, uncommon 

 west of the river. Spring migrants arrive 5-15 March, reaching peak abun- 

 dance 1-15 April. Fall migration begins in early September in the Northern 

 Highland and by 10 September elsewhere. Peak abundance occurs 25 Sep- 

 tember to 15 October and departure by 1 November. 



Nesting Season Distribution: Fairly common nesting species throughout the 

 Valley; most numerous in eastern segments of the Western Upland and 



Table 7. Mean number of bobolinks, meadowlarks and blackbirds recorded 

 on western Wisconsin Breeding Bird Survey transects, 1966-78. 



Western 

 Upland 



Central Plain 



Northern Highland 



Species 



Hudson Dresser 



Loraine 



Union 



Minong 



Bobolink 



Eastern meadowlark 

 Western meadowlark 

 Yellow-headed blackbird 

 Red-winged blackbird 

 Northern oriole 

 Brewer's blackbird 

 Common grackle 

 Brown-headed cowbird 



133.7 



4.1 

 50.0 

 7.3 

 0.0 

 43.8 

 11.2 



31.0 

 3.4 



30.7 

 10.7 

 73.7 



3.4 

 184.4 

 16.3 



0.6 

 84.6 

 36.1 



37.0 

 22.7 

 32.2 



1.2 

 203.2 

 12.2 



1.7 

 61.2 

 33.5 



0.1 

 0.0 

 0.1 

 0.1 

 8.7 

 3.7 

 0.2 

 0.4 

 24.4 



0.5 

 0.4 

 0.2 

 0.5 

 36.0 

 8.3 

 2.7 

 10.5 

 37.9 



