BIRDS OF THE ST. CROIX RIVER VALLEY 171 



tion is similar to spring in that no well-defined movements have been ob- 

 j: served. Most fall observations have been made during August (latest— 

 12 September 1977, St. Croix County). 



Nesting Season Distribution: Rare and local nesting species, restricted pri- 

 marily to the Western Upland and Central Plain (Table 8). The secretive be- 

 havior of Henslow's sparrow and its short and nondescript song make this 

 bird one of the most difficult breeding birds in the VaUey to observe. 



Habitat: Restricted during the breeding season to several grassland com- 

 I muni ties. Primary use is made of retired agricultural fields that have de- 

 veloped a rank growth of vegetation, primarily timothy and various forbs. 

 Managed Grasslands maintained for duck production provide important 

 nesting habitat, especially when vegetation height exceeds 0.5 m. Occa- 

 sional use is made of alfalfa fields and tame pastures or thick grassland 

 vegetation associated with the periphery of seasonally and semipermanently 

 flooded wetlands. 



Sharp- tailed Sparrow (Ammospiza caudacuta) 

 Status: Casual migrant and summer resident. 



Migration: Three spring and one fall migration records exist for the Valley 

 including 19 May 1964, St. Croix County; 8 May 1974, Pierce County 

 (Faanes and Goddard 1976); and 23 May 1976, Burnett County (Crex 

 Meadows). One bird was observed in St. Croix County on 18 August 1977. 

 Because of the secretive habits of this species, and its extremely high- 

 pitched song, the sharp-tailed sparrow is probably more common than 

 records indicate. 



Nesting Season Distribution: The sharp-tailed sparrow has been recorded at 

 Crex Meadows, Burnett County, on at least five occasions during the 

 nesting season. The first record was of one singing male on 21-22 July 1969. 

 On 31 July and 1 August 1970, one singing male was recorded in the same 

 area. It was not until 13 August 1975 that T. C. Baptist again recorded this 

 sparrow in the same marsh. Tessen (1978) reported observing at least three 

 singing males on 28 and 29 May 1977. Later, on 10 June 1977, I recorded 

 one singing male at the sartie location. All Crex Meadows observations 

 during the breeding season were made in a large sedge meadow in Sec. 15, T. 

 39 N., R. 18 W. Because of the territorial behavior exhibited by these birds, 

 sharp-tailed sparrows can be considered a probable breeding species at Crex 

 Meadows. 



Habitat: The area that sharp-tailed sparrows occupy at Crex Meadows is an 

 extensive Northern Sedge Meadow that is characterized by manna grass, 

 bluejoint grass, and water sedge. Although habitat similarities exist be- 

 tween sharp-tailed and LeConte's sparrow at Crex Meadows, apparently 

 sharp-tailed sparrows choose moister areas in the meadow. 



Vesper Sparrow {Pooecetes gramineus) 



Status: Regular migrant and nesting species. 



