Minot on Colorado Birds. 
223 
color is a peculiar pale olive-buff, not matched by one of more than 
five hundred eggs of the Royal Tern with which they have been 
compared, and the markings, distributed nearly equally over the 
entire surface, consist of small spots (roundish on the smaller egg, 
irregular on the larger) of deep sepia-brown and pale lavender. In 
every respect except size they quite closely resemble some eggs of 
the Oyster-catcher, but are, of course, very much larger. 
As regards the abundance of the species along the Virginia coast 
in summer, our experience is the same as that of last year, not more 
than one pair being observed ; and the fact that this pair was 
isolated from all other birds, while an immense colony of the Royal 
Tern was breeding on a remarkably restricted area not more than a 
quarter of a mile distant, induces us to believe that this is a normal 
habit of the bird, although we have no other evidence that the spe- 
cies may not sometimes breed in colonies. 
The Caspian Tern when seen flying may be distinguished, by a 
careful observer, from the Royal Tern by its more robust build, 
shorter, much less deeply forked tail, and by the uniform blackish 
appearance of the end-half of the wing, the greater part of the inner 
webs of the quills being white in the Royal, while the whole sur- 
face is dark slaty in the Caspian. The two are so much alike in 
appearance, however, that it requires the closest observation to dis- 
tinguish them. 
NOTES ON COLORADO BIRDS. 
BY H. D. MINOT. 
Boulder, where many of the following observations were made, 
lies just below the foot-hills, about thirty miles northwest of Den- 
ver, and 5,500 feet above the sea. Here I stayed from May 12 to 
19, and from May 24 to June 1, inclusive. Eighteen miles west- 
ward, among the hills, is Nederland, over 8,000 feet up. Colorado 
Springs is almost a degree south of Denver, with a season that 
among the birds is at least a week in advance of Boulder, and which 
this year (1880) has corresponded to that of Boston. Five miles 
back from this city of the plains, along Fountain Creek, and among 
the scrub-oaks that mark the latitude, is Manitou, over 6,000 feet 
