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ON THE NESTING OF CERTAIN HAWKS, ETC. 597 
noticed an interesting variation from the usual mode of nesting, 
necessarily brought about by the entire absence of trees. In 
Montana, as in most of Dakota, Swainson’s buzzard occurs in 
great numbers over large areas of almost unbroken, arid and cac- 
tus-ridden prairie, where, even along the water-courses, there may 
be no trees or bushes for many miles. Several of the northern 
tributaries of the Milk river, which we have crossed this season, 
are entirely unwooded ; the streams cut their sinuous course deep 
into the loose soil of the prairie, making on the convexity of 
almost every turn a bold perpendicular earth-bank a hundred feet, 
more or less, in height. To these ‘‘cut-banks” as they are called, 
Swainson’s and some other hawks, to be presently mentioned, re- 
sort to breed. The nest is composed of small sticks—the stems 
of sage brush and other rank weeds—with grasses, etc., and is of 
the usual size and shape; it rests directly on the earth of some 
little projecting shelf of ground, generally near the top of the 
embankment. The eggs of this bird I have taken, fresh and in 
various stages of incubation, from the latter part of June till the 
middle of July. No one of the numerous sets contained more 
than two eggs; this is obviously the usual complement, in this lat- 
ttude at least, though presumably not the maximum. In one in- 
stance, I found but a single egg in the nest, so far advanced in 
incubation that I was satisfied no other would have been laid. 
These eggs differ, furthermore, from what I believe to be the rule 
in this genus, in being nearly colorless and unmarked. They are 
quite like hens’ eggs in general appearance, as well as in size and 
shape. Most of my specimens are uniform dull white, with no 
more evident markings than such obsolete grayish spots as are 
frequently observed in the eggs of the marsh hawk (Cireus cya- 
neus Hudsonicus) ; a few have some obvious dirty-brown scratchy 
spots, in every instance at the small end; none are marked all 
Over, nor are any of them strongly blotched at all. It would have 
been impossible to predicate the normal character of these eggs 
Spon any rule which might be supposed to hold in this genus. 
Plain Colorless eggs, the well-known exceptions in the cases of 
Many or most species of Buteo, are here the rule. 
) It may not be generally known that the ferrugineous buzzard 
(Archibuteo ferrugineus) which is accredited, and properly so, with 
a decidedly western range, is a common species of eastern Montana 
and the adjoining portions of Dakota, in latitude 49°. I have 
