106 



NORTH AMERICAN FAUNA 73 



Barn Swallow {Hirundo rustica) 



Status: Regular migrant and nesting species. 



Migration: Common spring and faU migrant throughout the Valley. Spring 

 migrants arrive in the Western Upland during 15-20 April reaching the 

 Northern Highland about 25 April (earHest— 11 April 1953, Burnett 

 County). Peak abundance during spring migration occurs 5-10 May. Fall 

 migration begins about 1 August. Peak fall abundance occurs 25 August to 

 10 September and departure by 10-15 October. 



Nesting Season Distribution: Common nesting species in the Western 

 Upland and Central Plain, uncommon and local in the Northern Highland. 

 Breeding Bird Survey data (Table 3) suggest that the barn swallow is the 

 most numerous breeding swallow in the Western Upland and Central Plain. 



Habitat: Primarily a species of open habitats, usually associated with 

 human habitation. Most nests are found under bridges or on buildings. 



Cliff Swallow {Petrochelidon pyrrhonota) 

 Status: Regular migrant and nesting species. 



Migration: Common migrant throughout the Valley, occasionally abundant 

 near the St. Croix River. Spring migrants arrive in the Western Upland 

 1-5 May and peak abundance occurs 10-20 May. Fall migration begins in 

 mid- August. Peak fall abundance occurs 1-10 September and departure by 

 25 September (latest— 18 October 1974, Pierce County). 



Nesting Season Distribution: Fairly common breeding species throughout 

 the Valley. Breeding Bird Survey data (Table 3) suggest that the abundance 

 of the nesting population increases northward across the Valley. 



Habitat: Primarily a colonial or semicolonial nesting species, utilizing barns, 

 sheds, and bridges extensively for nest placement. Occasional groups are 

 found nesting in natural settings, including Umestone cliffs. 



Purple Martin {Progne subis) 



Status: Regular migrant and nesting species. 



Migration: Common to abundant migrant throughout the Valley. Spring 

 migrants arrive 5-10 April and peak abundance occurs 1-10 May. FaU 

 migration begins about 1 August. Peak abundance occurs 25 August to 

 1 September and departure by 20 September (latest— 6 October 1966, Wash- 

 ington County). 



Nesting Season Distribution: Common nesting species throughout the 

 Valley. Jackson (1942) referred to the purple martin as "the most generally 

 distributed" among the swallows in northwestern Wisconsin. Breeding Bird 

 Survey data (Table 3) suggest that the largest densities occur in the Central 

 Plain. 



Habitat: The purple martin is one of few species benefiting from expanding 



