Mar., 1911 
57 
notp:s on the nesting of the forster and black terns in 
COLORADO 
By R()BI<;rT B. RoCKWIBJ. 
WITH SKVKK PHOTOS 
FORSTER TERN 
T he most beautiful and graceful bird with which our studies of bird life in the 
Barr Lake region brought us in contact, was the Forster Tern {Sterna 
forsteri). Their clear pearl-gray backs, snowy breasts, black crowns and 
brilliant orange feet and bills, coupled with the slender wings, deeply forked tail. 
Fig. 2.3. FOUR “FT0.\TING” NESTS OF THE FORSTER TERN IN THE BARR TAKE REGION 
OF COEORADO 
and graceful easy flight, all set off by a back-ground of deep-blue sky made a 
never-to-be-forgotten picture. Furthermore the striking contrast between their 
charming manners when unmolested and their screaming frenzy when excited, 
made them especially interesting examples of bird temperament. Their peculiar 
modes of nesting, and the many problems arising from their erratic habits lent fur- 
ther interest to our field work among them; and on the whole these charming birds 
furnished us with some of our most delightful days afield.* 
That these birds nested in Colorado was recognized as early as 187.1 by Ridg- 
way (Bull. E.ssex Institute V, Nov. 187.8, 174) who stated that “a few breed in the 
state, but most of them are merely migrants,” and Prof. W. W. Cooke in his 
“Birds of Colorado” (March 1897) classes them as “Summer Resident, rare.” 
Both of these statements were no doubt true at the time they were written, which 
was before the day of extensive irrigation projects in Colorado. But through the 
* All of the notes on which this p.-iper is based were taken in company with Mr. 1,. .1. Hersey. 
