BIRDS OF THE ST. CROIX RIVER VALLEY 



137 



doubtedly breeds in the Valley. Northern parula observations during the 

 breeding season consist of birds using Lowland Coniferous Forest domi- 

 nated by a mixture of white cedar, balsam fir, and black spruce. Also typical 

 of their breeding habitat is Unsea moss which is used in nest construction. 



Yellow Warbler {Dendroica petechia) 

 Status: Regular migrant and nesting species. 



Migration: Common spring migrant in all regions; fairly common during fall. 

 Spring migrants arrive in the Western Upland 1-5 May and reach the 

 Northern Highland by 10 May. Peak spring abundance occurs 10-20 May. 

 Fall migration begins with dispersal from breeding areas in late July. The 

 first large fall movement of yellow warblers occurs 1-5 August. Peak fall 

 movements are noted 10-25 August and departure by 5 September. 



Nesting Season Distribution: Common breeding species throughout the 

 region with confirmed breeding records from all counties. Jackson (1943) re- 

 ported that yellow warblers were uncommon breeding birds at the head- 

 waters of the St. Croix River in 1919. Breeding Bird Survey data (Table 6) 

 suggest that the center of yellow warbler abundance in the Valley is in the 

 Central Plain. Goddard (1972) reported a breeding density of 3.4 pairs per 

 40 ha in the Kinnickinnic River Valley, Pierce County. 



Habitat: This warbler appears to use a wide range of habitats, including 

 second-growth deciduous and coniferous woodland. Deciduous Clear Cuts, 

 Black Spruce-Tamarack Bogs, Alder Thicket, Shrub Carr, and edge of 

 various natural basin wetlands. Although seemingly ubiquitous in breeding 

 habitat use, it appears that the yellow warbler demonstrates a strong pref- 

 erence for wetland and wetland-associated habitats. 



Magnolia Warbler {Dendroica magnolia) 

 Status: Regular migrant and summer resident. 



Migration: Fairly common nugrant in all regions. Spring migrants arrive in 

 the Western Upland 5-10 May (earliest— 1 May 1969, Washington County) 

 and reach the Northern Highland about 15 May. Peak spring migration 

 occurs 15-25 May but stragglers remain until 1 June. Fall migrants arrive 

 in the Northern Highland 15-20 August and the Western Upland about 

 20 August (earUest— 15 August 1976, Washington County). Peak fall migra- 

 tion occurs 5-20 September and departure by 1 October (latest— 21 October 

 1955, Polk County; Foster 1956). 



Nesting Season Distribution: Rare and local summer resident, restricted to 

 the Northern Highland. Several summer records (16 June 1973, 28 June 

 1974, and 12 June 1977 from along the St. Croix River in Douglas County, 

 and 10 June 1977 along the St. Croix in Pine County) suggest the possibility 

 of nesting. Bernard (1967) considered the magnolia warbler a rare summer 

 resident in Douglas County, but provided no evidence of nests. 



