BIRDS OF THE ST. CROIX RIVER VALLEY 



61 



Nesting Season Distribution: Formerly a rare and local nesting bird along 

 the St. Croix River. Roberts (1932) reported that fewer than six pairs nested 

 along the upper St. Croix River in the late 1920's. Surber (1919) reported a 

 pair of peregrine falcons along the St. Croix River near the mouth of the 

 Tamarack River (Pine County) during July 1918. Jackson (1941) did not 

 report this species during the 1919 nesting season in northwestern Wis- 

 consin. Apparently the last known nesting attempt occurred along "the 

 upper St. Croix River" in 1945 (Green and Janssen 1975). 



Habitat: Roberts' (1932) description of peregrine falcons nesting "along the 

 bluffs" of the St. Croix River is all that is known of their nesting habitat in 

 the Valley. Peregrine falcons presumably nested on the relatively inacces- 

 sible rock ledges on the sides of the steepest bluffs. During migration, most 

 peregrine falcons are observed in association with mudflats on large natural 

 and man-made wetlands. Open mudflats support migrant shorebirds and 

 waterfowl and provide excellent hunting for falcons. 



Merlin {Falco columharius) 



Status: Regular migrant and casual summer resident. 



Migration: Rare migrant throughout the Valley. Spring migrants arrive in 

 the Western Upland about 5-10 April and the Northern Highland 

 10-15 April. During spring migration the merlin is most frequently ob- 

 served 1-15 May and departs by 25 May (latest— 28 May 1977, St. Croix 

 County). Fall migrants arrive 25 August to 5 September and are most fre- 

 quently observed 10-25 September. Departure from the Northern Highland 

 occurs 1-10 October and elsewhere by 20 October. 



Nesting Season Distribution: Casual summer resident, restricted to the 

 Northern Highland. Jackson (1941) mentioned the observation of an adult at 

 Gordon (Douglas County) on 28 July 1919. I observed an adult merlin near 

 Moose Junction (Douglas County, Sec. 14, T. 44 N., R. 15 W.) on 30 June 

 1975 and 8 July 1977. Both observations were of lone birds. These dates pro- 

 vide speculation of possible nesting, although neither nests nor young have 

 been observed. 



Habitat: My Douglas County observations were made in a large stand of 

 Lowland Coniferous Forest. Predominant vegetation included trembling 

 aspen, green ash, black spruce, and balsam fir. These vegetative characteris- 

 tics are usually associated with merlin breeding habitat in their normal 

 breeding range in the boreal forest region of southern Canada. During 

 migration, merlins regularly use a variety of both open and forested 

 habitats. 



American Kestrel {Falco sparverius) 



Status: Regular migrant, nesting species, and winter resident. 



Migration: Abundant migrant in the Western Upland and Central Plain, 

 common in the heavily forested regions of the Northern Highland. Spring 



