BIRDS OF BOULDER COUNTY, COLORADO 1 87 



Erismatura jamaicensis, R.TJDDY DUCK (167) 



Migrant; common on the Plains. 

 [Chen hyperboreus hyperborens, Snow Goose (169)] 



Of regular occurrence though not common in migration at the Barr Lakes. 

 Branta canadensis canadensis, Canada Goose (172) 



Migrant; common on the Plains. Cooke found it nesting in the county in 

 1897. Gale records it on March 18 and also lists it as a "summer visitant." 



[Branta canadensis hulchinsi, Hutchins' Goose (172a)] 



Of regular occurrence though not common at the Barr Lakes in migration. 

 Olor columbianus, Whistling Swan (180) 



There are two specimens in the University collection taken on March 27, 1906; 

 three birds were brought in to Professor Henderson for identification by hunters 

 in the spring of 1907. Sclater regards the species as an occasional straggler on 

 migration in Colorado. 



Order HERODIONES, Herons, Storks, etc. 

 Suborder Herodii, Herons, Bitterns, etc. 

 Family ARDEIDAE, The Herons, Bitterns, etc. 

 Botaurus lentiginosus, Bittern (190) 



Summer resident; common in the marshes of the Plains zone. It has been 

 noted between April 28 and September 30. Full-grown young observed July 27, 

 1912. 

 Ixobrychus exilis, LEAST BITTERN (191) 



Summer resident; probably occurs regularly though easily overlooked. A 

 pair found by the writer nesting in a marsh on the Plains near Boulder June 5, 

 1910, and July 9, 1911. These are the only county records (and apparently the 

 second and third nesting records for Colorado). 

 Ardea herodias herodias, Great Blue Heron (194) 



Summer resident ; common in the Plains zone. It has also been recorded from 

 the lower part of the Yellow Pine zone. The St. Vrain colony near Hygiene is 

 well known locally. Arrives, March 20-30 (3 records); leaves, September 25 — 

 October 16 (3 records). Gale found it nesting May 12, 1888. It was also noted 

 occupying nests May 5, 191 2. 

 Egretta candidissima candidissima, Snowy Egret (197) 



One was taken in the county by Hersey May 4, 1876; two were collected in 

 the spring of 1908 (one of which is now in the University collection) ; one was seen 

 by the writer May 12, 1912. While rare in Colorado, the species appears to reach 

 the state regularly in its northward wanderings. 



