No 4.] BIRDS AND CATERPILLARS. 



325 



On June 12, 1899, Mr. Mosher watched the nest of a pair 

 of rose-breasted grosbeaks from early morning till 5 p.m. 

 The nest was about fifteen feet from the ground, in a slender 

 white birch. The ground was covered with hazelnut 

 bushes, in which he found partial concealment ; but for the 

 first half hour the old birds were so excited by his presence 

 that the feeding of the young birds was interrupted, so that 

 no notes were taken until 6 a.m., and none were taken after 



5 P.M. 



The old birds visited the nest, — 



Between 6 and 7, 52 times. 

 Between 7 and 8, 47 times. 

 Between 8 and 9, 43 times. 

 Between 9 and 10, 30 times. 

 Between 10 and 11, 36 times. 

 Between 11 and 12, 27 times. 



Between 12 and 1, 32 times. 

 Between 1 and 2, 38 times. 

 Between 2 and 3, 41 times. 

 Between 3 and 4, 22 times. 

 Between 4 and 5, 58 times. 



making altogether 426 visits during the portion of the day 

 that they were watched. The food was mainly caterpillars 

 of one kind or another, and there were only four visits made 

 by a parent bird when but one insect was fed to the young ; 

 they usually brought three or more. A bird often carries in 

 this way from three to eleven or twelve small caterpillars in 

 its mouth and beak at one time Owing to the height 

 of the nest above the ground, it was impossible to determine 

 accurately the species of caterpillars brought to the young. 

 A considerable proportion of them were certainly leaf 

 rollers from the oak trees. It seems probable, then, that 

 these two birds must have fed their young on that day at 

 least one thousand insects, mostly caterpillars. This cer- 

 tainly is a very moderate estimate of the number of insects 

 destroyed in one day by the family, when we take into 

 consideration the food required by the old birds. It is im- 

 possible to estimate how many of these insects were hairy 

 caterpillars. 



It will be noted that the grosbeaks made many more visits 

 to the nest and carried much more food than the vireos. 

 This is accounted for by the age of the young, the vireos 

 being just from the egg and the grosbeaks being nearly ready 

 to fly and very much larger. 



