BIRDS OF THE ST. CROIX RIVER VALLEY 



25 



week of April (earliest— 4 April 1964, St. Croix County; Soulen 1965) and the 

 Northern Highland 10-15 April. Peak spring abundance occurs 20 April to 

 1 May. During this period flocks of 5 to 10 birds are common and flocks 

 totahng 15 to 20 are occasional on larger lakes. Spring departure from the 

 southern one-third of the Valley occurs by 15 May. Fall migrants arrive in 

 the Western Upland during the first week of October and remain until water 

 on the larger lakes freezes in late November. No major common loon staging 

 areas exist in this region, resulting in relatively small numbers observed dur- 

 ing the fall. 



Nesting Season Distribution: Uncommon nesting bird on larger lakes and 

 marshes of the Northern Highland, rare and local in the Central Plain. 

 Casual summering birds near Roberts, St. Croix County, indicate possible 

 nesting although no broods have been observed. Longley (1949) reported a 

 pair with one young in Washington County on 17 June 1949. Additional 

 Washington County brood records were obtained in 1970 and 1971 (Eckert 

 1971). 



Habitat: Common loons are primarily a species of large permanently flooded 

 wetlands, particularly those containing small islands. Most wetlands used 

 for nesting are bordered by deciduous forest, chiefly trembUng aspen and 

 maple, and contain peripheral zones of emergent aquatic vegetation. At the 

 Crex Meadows Wildhfe Area in Burnett County, common loons nest on 

 semipermanently and permanently flooded wetlands. The vegetation con- 

 sists primarily of cattail and various species of sedge. Evrard et al. (1978) 

 found that common loons at Crex Meadows occupied wetlands that ranged 

 from 6.9 to 324 ha. 



Concern has been expressed recently about the population status of this 

 species in Wisconsin, Minnesota, and other northern States. The primary 

 threat to the nesting habitat of this species is shoreline development sur- 

 rounding nesting lakes. 



Red-throated Loon (GaL'ia s^e//ata) 

 Status: Casual migrant; one summer record. 



Records: Spring records include Pierce County— 10 May 1967; St. Croix 

 County— 25 April 1962 and 17 May 1965; Burnett County— 15 May 1950 

 (Robbins 19506). During the summer of 1953 a nonbreeding red- throated 

 loon was observed on 11 June and 17 July at Crex Meadows WildUfe Area, 

 Burnett County. 



FAMILY PODICIPEDIDAE: Grebes 

 Red-necked Grebe {Podiceps grisegena) 

 Status: Regular migrant and nesting species. 



Migration: Rare spring and fall migrant in the Western Upland, casual or 

 absent elsewhere. Spring migrants arrive during the second week of April 

 (earhest— 8 April 1959, Burnett County). Dates of peak abundance cannot 



