66 BIRDS IX THEIR RELATIONS TO MAN. 



day. Had it been at liberty it would probably have eaten 

 some insects of other species and fewer cutworms, but this 

 shows about what each young robin requires for its main- 

 tenance when growing ; the adult birds require much less, of 

 course. The average number of young raised by a robin is 

 four, and there are usually two broods in the season. A very 

 simple calculation will give a good idea of the number of 

 insects destroyed while the young are in the nest.' 1 



Five young goldfinches which we watched were from the 

 beginning fed by their parents almost exclusively upon seeds 

 of the bull-thistle (Cnicus pumilus, Torr.). At the age of one 

 week rather more than the product of one thistle-head was 

 divided among them at each meal. They were fed every 

 half-hour on an average, the old birds feeding independently. 

 Not less than thirty thistle-heads were thus consumed in a 

 day by these young birds when they were scarcely more than 

 half-grown. 



A family of four song-sparrows seven days old received 

 seventeen grasshopper nymphs, from five-eighths to three- 

 fourths of an inch long, and two spiders between 1.55 and 

 3.02 P.M. sixty-seven minutes. As they were out of the 

 nest the next day, it may be accepted that they are hearty 

 eaters. Eight days is a short time for the accomplishment of 

 so great a change. 



A brown thrasher at ten visits made in one hundred and 

 twenty-six minutes delivered to one of her young just out of 

 the nest one spider, one earthworm, one hairy caterpillar an 

 inch and a half long, two Carolina locusts, seven red-legged 

 locusts, and three other insects which were not identified. 



A bobolink brought to two fledglings between 5.13 and 

 5.33 one afternoon, twenty minutes, nine grasshoppers. 

 The next morning between 9.18 and 10.05, forty-seven 

 minutes, ten grasshoppers were brought. About that time 

 one of the young birds escaped. To the remaining one he 

 fed eleven grasshoppers in two hours. Of the thirty 'hoppers 



