BIRDS OF PENNSYLVANIA. 
141 
through the sides of the building communicating with it. A pair of 
doves that had mated there were attacked and killed by a pair of Sparrow 
Hawks, who took possession of their nest, laid four eggs, and com¬ 
menced incubating.” 
Incubation, which lasts for about a period of from twenty-one to 
twenty-four days, is engaged in by both birds, and while one is sitting 
its mate supplies it with food. When first hatched the young are cov¬ 
ered with a white down. The food of young, while under parental care, 
I have found to consist chiefly of insects. 
H. W. Henshaw says: “Its food consists chiefly of the various kinds 
of coleopterous insects and grasshoppers, of which it destroys multi¬ 
tudes ; in fact, this last item is the most important of all, and where 
these insects are abundant I have never seen them recourse to any other 
kind of food.” 
Allen, in his “ Ornithological Notes on the Birds of the Great Salt 
Lake Valley,” says: “ The Sparrow Hawk, however, was by far the most 
numerous of the Fcilconidce ; thirty were seen in the air at one time 
near the mouth of Weber canon, engaged in the capture of the hateful 
grasshoppers, which seems at this season to form the principal food of 
this and other birds.” Audubon mentions that he had one of these 
birds tamed. It was allowed its liberty. “ In attempting to secure a 
chicken one day, the old hen attacked him with such violence as to cost 
him his life.” Doctor Wood says: “When they cannot readily procure 
their favorite food, mice and small birds are greedily devoured; and, 
according to a writer in the American Naturalist , they are not wholly 
devoid of the piratical habits of the Bald Eagle. ‘A tame cat was cross¬ 
ing the street and bearing a large mouse in her mouth; a Sparrow 
Hawk came flying over, and seeing the mouse in her mouth, made a 
sudden swoop and tried to seize it with its talons, but did not succeed. 
The hawk continued its attempts until they reached the opposite side 
of the street, when the cat disappeared under the sidewalk.’ If it 
catches a mouse that proves to be lousy and poor, it will leave it and 
seek another.” The stomach contents of sixty-five of this species which 
I have dissected showed, in thirty-one, principally field-mice, with fre¬ 
quent traces of various insects; twenty-three, mainly grasshoppers and 
beetles; seven, small birds; two, meadowlarks; one, remains of mouse 
and small bird; one, insects and small bird. 
