BIRDS OF BOULDER COUNTY, COLORADO 193 



Order RAPTORES, Birds of Prey 



Suborder Sarcorhamphi, American Vultures 

 Family CATHARTIDAE, The American Vultures 

 Cathartes aura septentrionalis, Turkey Vulture (325) 



Summer resident; infrequent. Nearly all the county records are from near 

 Lyons, at the lower edge of the Yellow Pine zone. Birds were seen at this place 

 by Gale in 1888, by Markman in 1907 and by Henderson in 1908. Gale recorded 

 their nests in trees occupied also by Great Blue Herons. A few have been seen 

 near Boulder and in the Yellow Pine zone. They have been noted between April 

 16 and October 2. 



Suborder Falcones, Falcons, Hawks, Eagles, etc. 



Family BUTEONIDAE, The Hawks, Eagles, etc. 

 Circus hudsonius, Marsh Hawk (331) 



Migrant; common on the Plains. It has been noted as early as February 22 

 and as late as December 26. There appear to be no definite summer records except 

 one on August 13, though Gale observed it building a nest in May just north of 

 the county. Common summer resident at the Barr Lakes. Gale listed it as a 

 winter bird for Boulder Valley without further data. 



Accipiter velox, Sharp-shinned Hawk (332) 



Migrant; probably rather common and occurring throughout the county. 

 Dates for arrival and departure are April 6 and October 12. One was taken at 

 Goose Lake, in the upper part of the Mountain zone, September 3, 1905. There 

 are no definite summer or winter records, though Gale listed it as a winter bird. 



Accipiter cooperi, Cooper's Hawk (333) 



Summer resident; probably infrequent; the records are from the lower part 

 of the Mountain zone. It is more common as a migrant on the Plains in Sep- 

 tember. There are no definite winter records, the latest fall date being October 21 

 (in the Yellow Pine zone). Gale found nests with eggs in the upper part of Left 

 Hand Creek, May 29 and June 10, 1890, and June 28, 1889. Widmann reported 

 one from Estes Park in July, 1910. 



Astur atricapillus atricapillus, Goshawk (334) 



Visitant; probably rare. H. G. Smith saw one in a taxidermist's shop killed 

 at Sugarloaf (Yellow Pine zone), February 21, 1888. One was reported by Sprague 

 in his notes many years ago (Henderson): Two were killed in 1908, one of which 

 is iir the University collection (Henderson). One was seen by Mr. and Mrs. 

 McHarg near Boulder, December 26, 1912. 



