64 
THE BIRDS OF WISCONSIN. 
Buteo swainsoni Bonap. SWAINSON'S HAWK. 
Although this hawk is very common to the northwest of 
us — ■ in Minnesota and Dakota — it is not a common species 
in Wisconsin. Dr. Hoy apparently met only the young, which 
he called vulgaris, and later described as a distinct species, 
under the name of B. bairdii, a mounted specimen remaining 
so labeled in his collection to this day. Mr. J. N. Clark has 
procured but a single specimen, in December, 1896, in Dunn 
County. Grundtvig did not secure a specimen in Outagamie 
County, and Willard does not include it in his list of Brown 
County birds. King calls it a "summer resident/' on what 
authority we do not know, as he apparently did not procure 
a specimen. Thure Kumlien procured perhaps a dozen 
specimens during his long period of collecting at Lake Kosh- 
konong, and half as many more have been taken by 
L. Kumlien. Here it has been noted only during the 
autumnal migrations, in September and October. Probably 
occurs more frequently along the Mississippi River than in 
the eastern or central parts of the state. 
Buteo platypterus (VieillJ. BROAD-WI\GED HAWK. 
In eastern Wisconsin rather a common spring migrant, 
and especially common in fall. By no means a common nest- 
ing species, but is a summer resident and breeds from the 
southern tier of counties northward. In Dunn County 
Mr. Clark considers it on the whole an uncommon species, but 
has seen and taken it a number of times. According to our 
observations, this is the hawk that "flocks" in the fall, ofttimes 
in great numbers. Occasionally several hundred may be seen 
at a time, often ten to twenty in one tree. These migrations 
seldom last but a day or two and are of irregular occurrence. 
Other authorities speak of these "hawk flocks" being made up 
of all the smaller species in general and the red-shouldered in 
particular, but our observation has been that the flocks are 
invariably of this species alone. 
Avcliibuteo lagopus sancti-johannis (Gmcl.). AMERICAN ROUGH- 
LEGGED HAWK. 
Very common migrant, and, unless the weather be too 
severe, a common winter resident in southern Wisconsin An 
occasional specimen is found as late as the middle of 
April, but rarely later, although there are records of 
individuals remaining through the summer. In May. 
1ST2, a pair of these hawks was found nesting in the 
