IOWA ACADEMY OP SCIENCE 
195 
A REMARKABLE PLIGHT OP BROAD WINGED HAWKS. 
BY B. H. BAILEY. 
On Friday a. m., September 22, 1911, a flock of Broad Winged Hawks (Buteo 
latissimus Wils.), remarkable for its size and compact character, passed about 
two miles north of Cedar Rapids, Iowa. 
The birds were moving in a westwardly direction on a light breeze blowing 
from the east. 
The day was clear, and we first saw the flock some four miles up the river from 
the city. 
From our launch we could see large birds circling at varying heights in the 
air above the bluffs on the east bank of the river, and moving toward us as 
we came down stream. 
We were soon close enough to make out the species and, although the flock 
was mainly composed of Broad Wings, while watching them four other species 
were identified, viz.. Red Tailed Hawk (Buteo borealis), Harlans Hawk (Buteo 
borealis harlani). Coopers Hawk (Accipiter cooperi), and Marsh Hawk (Circus 
hudsonius). 
After landing, Mr. S, N. Harris and the writer climbed the bluffs to the east- 
ward and from the heights observed hawks circling in and out among their 
fellows far up the ravines, and both east and west as far as we could see. A 
bird which was shot seemed Immature. The stomach contained insect re- 
mains, chiefly beetles. 
For nearly an hour the birds continued passing to the westward and up the 
river. 
From an unfavorable point on the river bank which afforded no view of the 
great numbers of birds beyond the bluffs and in the ravines. Professor J. H. 
Scott counted over eight hundred individuals. 
It is conservative to estimate the flock at from two to three thousand birds, 
as, viewed from a distance, at times they sailed so close together as to remind 
one of a swarm of gnats. 
Returning later in the morning to a point farther up the river, we found 
hawks scattered through the timbered bottom lands. 
One was frightened from a willow covered sand bar where grasshoppers 
were plentiful. 
The presence of such an unusual number of these birds in Linn County may 
be explained by the extraordinary abundance of such food as these birds sub- 
sist upon. 
During the fall insect life was unusually abundant in this locality, especially 
grasshoppers. ,, 
