114 



NORTH AMERICAN FAUNA 73 



by 10 May (latest— 19 May 1966, Washington County). The first fall mi- 

 grants arrive in the Western Upland 1-10 September. Peak fall abundance 

 occurs 25 September to 25 October and most have departed by 20 No- 

 vember. 



Nesting Season Distribution: Uncommon and local resident, restricted pri- 

 marily to the Northern Highland, although occasionally observed in the 

 Central Plain. There is no direct evidence of nesting in the Valley. I have ob- 

 served breeding season adults along the upper St. Croix River in Douglas 

 and Pine counties in 1976 and 1977. Although I observed no nests or young, 

 these records suggest possible nesting. Intensive field work in southern 

 Douglas and throughout Pine counties during late May and June may shed 

 additional light on brown creeper breeding status. 



Winter: Brown creepers occur throughout the Valley during early winter; ob- 

 servations were made until 23 December in southern Douglas County. 

 During midwinter this species is rare or absent in the Northern Highland 

 and Central Plain, uncommon and local in the Western Upland. 



Habitat: My observations of brown creepers during the nesting season have 

 been confined to extensive stands of Northern Hardwood Forest that are 

 dominated by mixed sugar maple, basswood, white birch, trembling aspen, 

 red pine, and white pine. During the winter Lowland Deciduous Forest, 

 dominated by silver maple, American elm, and green ash, is used exten- 

 sively. Occasional use is also made of mixed-oak forest and Pine Plantations. 



FAMILY TROGLODYTIDAE: Wrens 



House Wren {Troglodytes aedon) 

 Status: Regular migrant and nesting species. 



Migration: Common migrant throughout the Valley. Spring migrants arrive 

 in the Western Upland 20-25 April (earliest— 15 April 1978, St. Croix 

 County) and reach the Northern Highland about 25 April. Peak spring 

 migration occurs 1-10 May. Peak fall migration occurs 25 August to 15 Sep- 

 tember and departure by 10 October. 



Nesting Season Distribution: Breeding Bird Survey data (Table 5) show that 

 this is the most numerous wren in the Valley during the nesting season and 

 that relative abundance is similar throughout the Valley. Jackson (1943) ob- 

 served that the house wren was a common nesting species throughout north- 

 western Wisconsin. Goddard (1972) found that house wrens were the third 

 most abundant breeding species in the Kinnickinnic River Valley, Pierce 

 County. Mean density in that area was 36.1 pairs per 40 ha. 



Habitat: A characteristic species of several deciduous forest communities in- 

 cluding Southern Deciduous Forest, Old Field Community, Northern Hard- 

 wood Forest, Lowland Deciduous Forest, and Deciduous Clear Cut. Also im- 

 portant are edge habitats including forest-agricultural field borders, brushy 

 road ditches, and brushy fencerows. Jackson (1943) found house wrens 

 "especially abundant" in burns and cut-over land. This species has adapted 



