BIRDS OF THE ST. CROIX RIVER VALLEY 



101 



draw conclusions on the range of these two species in Wisconsin (Robbins 

 19746). Because this work was not carried out in Minnesota, only general- 

 ized distribution can be provided for that State. 



Status: Regular nesting species. 



Migration: Most records of this species are of breeding pairs on territory. 

 Consequently, dates of first occurrence are nearly impossible to determine. 

 The earhest record I have of a singing willow flycatcher is 20 May 1974 in 

 St. Croix County. This date is near the usual range of 10-20 May for the 

 arrival of most Empidonax flycatchers in the Valley. Fall departure 

 probably begins in early August and most birds have left by 15 September. 

 Because nearly all Empidonax flycatchers are silent in the fall, few data 

 exist on their migration. 



Nesting Season Distribution: Robbins (19746) cited summer records of this 

 species in St. Croix County in 1961-67 and 1970. There are Polk County 

 records in 1965-67 and 1970 and Pierce County records for 1965-78. S. D. 

 Robbins (personal communication) found a singing male willow flycatcher 

 near Fish Lake, Burnett County, on 17 June 1978 and 22 June 1977. I ob- 

 served male willow flycatchers on territory in W^ashington County near Still- 

 water on 6 July 1978. Breeding Bird Survey data were not separable to 

 species until 1975. Consequently, only recent survey data from the Loraine 

 transect in Polk County provide information on relative abundance 

 (Table 3). One nesting record exists for the region. I found a nest with four 

 eggs along Black Brook, Cylon Township, St. Croix County, on 9 July 1978. 



Habitat: Willow thickets and Shrub Carr associations are the primary 

 habitats of this bird. The St. Croix County nest was placed in a young black 

 willow located in an extensive Shrub Carr. Observations of singing males are 

 invariably associated with these wetland types. 



Alder Flycatcher {Empidonax alnorum) 

 Status: Regular migrant and nesting species. 



Migration: Observations of alder flycatchers during spring are usually pairs 

 on presumed breeding territories. Song dates of first observation usually 

 occur 15-20 May in the Western Upland and about 20 May in the Northern 

 Highland. Alder flycatchers are apparently most numerous 20 May to 

 5 June. Fall migration begins in mid- August, reaching peak numbers 

 1-10 September. Departure of this species occurs 15-20 September. 



Nesting Season Distribution: Fairly common to locally common nesting 

 species north of the Tension Zone. Within this zone of overlap, observations 

 of breeding pairs have been made in southern Washington and northwestern 

 Pierce counties. Breeding Bird Survey data (Table 3) indicate that the 

 largest breeding populations occur north of the Tension Zone. Documented 

 nesting records exist for Polk and Douglas counties. Faanes and Goddard 

 (1976) cited observations of singing males 15-20 June in northern St. Croix 

 County. 



Habitat: Aider tiycaLchers use a greater diversity ot habitat types than is 



