62 USEFUL BIRDS. 
a Goshawk in winter to kill a domestic Cock of more than 
its own weight, and devour the greater part at two meals. 
I have learned, by following certain Warblers and Titmice 
through the woods, that their search for and consumption of 
insects are almost continuous during most of the forenoon. 
As the noon hour approaches they become less active, and 
on warm days devote some time to resting and bathing. In 
the afternoon their activity increases, until toward night 
their quest for food is almost as strenuous as in the early 
morning. They are, therefore, actually engaged for the 
larger part of the day in capturing and eating insects. In 
feeding wild birds in winter I have noticed that Chickadees 
come to the food supplied for them about three times an hour 
all day long, and that in the intervals they are mainly occu- 
pied in finding their natural food. On May 28, 1898, Mr. 
Mosher watched a pair of Northern Yellow-throats eating 
plant lice from the birches in the Middlesex Fells Reserva- 
tion, where these insects swarmed. He was equipped with 
a good glass, and concealed close to the spot where the birds 
were feeding, and so was able to count in turn the number 
of times each bird picked up an insect. One of these War- 
blers apparently swallowed eighty-nine of these tiny insects 
in one minute. The pair continued eating at this rate for 
forty minutes. Mr. Mosher states that they must have eaten 
considerably over seven thousand plant lice in that time. It 
would seem impossible for the birds to crowd that number 
of insects into their stomachs; but we must remember that 
the insects were infinitesimal in size, soft-bodied, easily com- 
pressed in the stomach, and quickly digested, so that by the 
time a part were eaten those first taken would be well dis- 
posed of, leaving room for more. Mr. Mosher is a very 
careful, painstaking, and trustworthy observer ; undoubtedly 
his statement is accurate; but, to eliminate any possibility 
of error, we will assume for purposes of calculation that 
they ate only thirty-five hundred in an hour. 
A pair of Yellow-throats (presumably the same) were seen 
to come daily and many times each day to the birch trees 
which were infested with these aphids. Probably they spent 
at least three hours each day feeding on these insects. If 
