264 



USEFUL BIRDS. 



Fig. 119. — Black- 

 billed Cuckoo, one- 

 half natural size. 



cow, cow, repeated monotonously many times, and sometimes 

 preceded by a short chuckle. The bird often calls at night, 

 and toward autumn its notes may sometimes be heard in the 

 air as it passes overhead, probably in migration. Usually 



when the bird is heard at 



night in the spring and early 



summer it appears to be 



stationary. There is some 



mystery in the wakefulness and 



night flight of Cuckoos, for they are 



certainly as wide-awake at times as the 



Owl or Whip-poor-will at night, and often 



seem slow and sleepy by day. 



The Cuckoos are of the greatest service 

 to the farmer, by reason of their well-known fondness- for 

 caterpillars, particularly the hairy species. No caterpillars 

 are safe from the Cuckoo. It does not matter how hairy or 

 spiny they are, or how well they 

 may be protected by webs. Often 

 the stomach of the Cuckoo will be 

 found lined with a felted mass of 

 caterpillar hairs, and sometimes 

 its intestines are pierced by the 

 spines of the noxious caterpillars that it has swallowed. 

 Wherever caterpillar outbreaks occur we hear the calls of 

 the Cuckoos. There they stay; there they bring their 

 newly fledged young ; and the number of caterpillars they 

 eat is incredible. Professor Beal states that two thousand, 



seven hundred and seventy-one 

 caterpillars were found in the 

 stomachs of one hundred and 

 twenty-one Cuckoos, — an aver- 

 age of more than twenty-one each. 

 Dr. Otto Lugger found several hundred small hairy cater- 

 pillars in the stomach of a single bird. The poisonous, 

 spined caterpillars of the Io moth, the almost equally dis- 

 agreeable caterpillars of the brown-tail moth, and the spiny 

 elm caterpillar, are eaten with avidity. 



While the above statements may apply to either of our 



VYYT^w 



Fig. 120. — Caterpillar of the Io 

 moth. 



Fig. 121. — Spiny elm caterpillar. 



