162 HABITS OF BIRDS. 
summer nutriment of our soft-billed birds, and the 
great distances gone over by such as have young 
ones, in their numerous trips from hedge to tree in 
the hours specified, when they have full broods to 
support. <A climate of mossture and temperature 
like ours is peculiarly favourable for the production 
of insect food, which would in some seasons be 
particularly injurious, were we not visited by such 
numbers of active little friends to consume it.”* 
From similar observations, Mr. Bradley, in his 
“Treatise on Husbandry,” calculated that a pair of 
sparrows, during the time they have their young to 
feed, destroy every week about 3360 caterpillars. 
The basis of this calculation was, that he had ob- 
served the two sparrows carry to their young 40 
caterpillars within an hour, and thence making a 
supposition that they are employed in this manner 
during twelve hours in the day, he finds the daily 
consumption to be 480 caterpillars, which, mutiplied 
by 7, the days in a week, gives 3360. We should 
be disposed, however, to consider this perhaps dou- 
ble the real number; for, in a case so uncertain, the 
result of one hour cannot be accurately predicated 
of twelve successive hours, inasmuch as the spar- 
rows could not be certain of meeting with the re- 
quisite supply of caterpillars in their immediate 
vicinity, and if they did one day, they would proba- 
bly have afterward to forage at some distance. 
A more recent observer has with due caution con- 
sidered such calculations too vague, though they 
are literally copied not only by all the compilers, 
but by Bonnet and Smellie. ‘1 have observed,” 
says Mr. Knapp, ‘‘a pair of starlings for several 
days in constant progress before me, having young 
ones in the hole of a neighbouring poplar-tree, and 
they have been probably this way in action from 
the opening of the morning; thus persisting in this 
* Journal of a Naturalist, p. 171, 3d edit. 
