BIRDS OF BOULDER COUNTY, COLORADO 195 



and took four eggs from a nest on the Little Thompson (probably over the county 

 line) April 30, 1889. Blanchard reported one from the county (Henderson). 

 Kellogg took one above timberline near Estes Park and Widmann saw several 

 there in July, 1910. 



Falco perigrinus anatum, Duck Hawk (356a) 



Migrant; infrequent. There are two specimens in the cabinets at the State 

 Capitol labelled "Longmont," one taken September n, 1898, by Harry Holland, 

 the other by B. Hayward. Gale observed a pair at their nesting site just north 

 of the county, April 2, 1889. Pierce (Kellogg) noted one at Estes Park in June. 

 Reported as common in migration at the Barr Lakes. 



Falco columbarius richardsoni, Richardson's Pigeon Hawk (3576) 



Migrant. The status of the Pigeon Hawks is not well determined for the 

 county. They are rather common in migration but the form which appears to be 

 the more common in the state, Falco columbarius columbarius, has not been 

 definitely recorded from the county, though Kellogg reported it from Estes Park 

 (1889). Some of the migrants are probably of this form. Richardson's Pigeon 

 Hawk has been taken near Silver Lake at 10,000 feet, in September (Henderson), 

 while Gale took one near Boulder January 5, 1885, and listed it as a winter bird 

 of the plains and mountains. 



Falco sparverius sparverius, Sparrow Hawk (360) 



Summer resident; common from the Plains to the Mountain zone. Abundant 

 as a migrant, occurring above timberline in the fall. A few sometimes remain 

 through the winter (Henderson). They arrive March 12 — April 1 (4 records), 

 and leave October 10-16 (4 records). Eggs were found by Gale in the Plains and 

 Yellow Pine zones between April 23 and June 12. 



Pandion haliaetus carolinensis, Osprey (364) 



One was seen on the Plains by the writer, April 21, 1912. Reported as not 

 uncommon during migration at the Barr Lakes. 



Order STRIGES, Owls 



Family ALUCONIDAE, The Barn Owls 

 Aluco pratincola, Barn Owl (365) 



One was found in a deserted prospect hole on the Plains by the writer, October 

 3r, 1909, and again on November 7. Though an attempt to secure the bird was 

 unsuccessful, there was every opportunity to make certain of its identity. It is 

 rare in Colorado. 



