90 



NORTH AMERICAN FAUNA 73 



Nesting Season Distribution: A common nesting species in cities and towns, 

 less common and more localized in areas away from human habitation. 



Habitat: This species has adapted well to expanding human population. In 

 cities and towns, an abundance of flat roofs and gravel roadways provide 

 excellent breeding habitat. Although nesting habitat away from human 

 habitation is poorly known, most birds are found associated with mixed 

 deciduous-coniferous forest with sandy soils and open (or barren) under- 

 story. 



FAMILY APODIDAE: Swifts 



Chimney Swift (Chaetura pelagica) 

 Status: Regular migrant and nesting species. 



Migration: Chimney swifts are common to locally abundant in the Western 

 Upland and Central Plain, fairly common in the Northern Highland. Because 

 of their relationship with human settlements, this species is most frequently 

 observed near villages and cities. Spring migrants begin to arrive about 

 30 April and peak abundance occurs 10-20 May. Fall migrants begin to 

 form loose flocks during late July. Peak fall migration occurs between 

 25 August and 10 September and departure by 20 September (latest— 

 5 October 1947). 



Nesting Season Distribution: Breeding chimney swifts have been recorded 

 in all counties of the VaUey. Largest breeding populations occur in the 

 Western Upland and Central Plain, where human habitation provides an 

 abundance of nesting sites. Jackson (1942) reported that chimney swifts 

 occurred regularly in the northern regions, even in areas removed from 

 human settlement. 



Habitat: Chimney swifts are most numerous in villages and cities where 

 they nest in chimneys and abandoned buildings. Populations of breeding 

 chimney swifts occur in the forested regions where they occupy hollow trees 

 (Jackson 1942) and other natural cavities for nesting. 



FAMILY TROCHILIDAE: Hummingbirds 



Ruby-throated Hummingbird {Archilochus colubris) 

 Status: Regular migrant and nesting species. 



Migration: Fairly common migrant throughout the Valley. Spring migrants 

 arrive during the second week of May (earUest— 13 April 1953, Burnett 

 County) and peak abundance occurs 20 May to 1 June. Peak fall abundance 

 occurs 10-25 August and departure by 20 September (latest— 1 October 

 1947, St. Croix County; Robbins 1948a). 



Nesting Season Distribution: The ruby-throated hummingbird is a fairly 

 common nesting species throughout the Valley; positive or inferred breeding 



