BIRDS OF THE ST. CROIX RIVER VALLEY 135 



31 May 1967 in St. Croix County. Olyphant (1973) banded a Brewster's 

 warbler in Washington County on 13 July 1973. 



Habitat: In this region, breeding blue-winged warblers are characteristic of 

 extensive stands of mature Lowland Deciduous Forest. Typical vegetation 

 of their breeding habitat includes cottonwood, American elm, and green ash 

 as dominants. Ground-layer vegetation in many situations is usually wood 

 nettle and various grasses. Along the lower Willow River near Hudson, a 

 small group of breeding blue-winged warblers use a savannah-like asso- 

 ciation of Hill's oak and little bluestem. Brushy fields with invading saplings 

 or scattered trees are also used. 



Tennessee Warbler (Vermivora peregrina) 

 Status: Regular migrant. 



Migration: Common migrant throughout the Valley. Mean date of spring 

 arrival in the Western Upland is 4 May (earliest— 25 April 1948, Polk 

 County; Robbins 1948c). Arrival in the Northern Highland occurs 

 10-15 May. Peak spring migration through the Valley occurs 10-25 May. 

 Departure of spring migrants in the Western Upland and Central Plain 

 occurs 25-30 May. In the Northern Highland, stragglers can still be found 

 until 10 June. Several mid- June records that suggest possible breeding exist 

 for the Solon Springs area. However, there are no known breeding records of 

 this bird in Wisconsin. 



The Tennessee warbler is among the earliest fall migrants of this family, 

 usually arriving in the Northern Highland 15-20 July, reaching the Central 

 Plain and Western Upland 25 July to 1 August. Peak fall migration occurs 

 20 August to 15 September. This warbler has departed the Northern High- 

 land by 25 September and elsewhere by 5 October (latest— 12 October 1961, 

 St. Croix County). 



Habitat: Migrant Tennessee warblers regularly use both deciduous and 

 coniferous woods. Perhaps because of its abundance, this warbler is also 

 regularly encountered in residential shrubbery. At the peak of migration, 

 this species congregates in tall trees in residential areas. Six to 10 males per 

 block is not unusual on a peak day. Most mid-June records have been of 

 birds in Northern Hardwood Forest, Lowland Coniferous Forest, and Black 

 Spruce-Tamarack Bogs. 



Orange-crowned Warbler (Vermivora celata) 

 Status: Regular migrant. 



Migration: Fairly common migrant in the Western Upland and Central 

 Plain, uncommon in the Northern Highland. Spring migrants arrive in the 

 Western Upland 25 April to 1 May (earliest— 22 April 1949, Burnett 

 County), reaching the Northern Highland 5-10 May. Peak spring migration 

 occurs 10-20 May and departure by 25 May. Fall migrants arrive 1-5 Sep- 

 tember. Peak fall migration occurs 20 September to 5 October and de- 

 parture by 10 October (latest— 18 October 1976, St. Croix County). 



