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 

 feedino- wild birds in winter I have noticed that Chickadees 



O 



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 swallow r ed 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 



