172 BIRDS 



below, can scarcely be distinguished from that of the 

 black-billed species which has a similar unmusical gut- 

 tural, kr-r-ruck, kr-r-ruck rattle and some cow, cow, 

 cow notes run together. It is not until you get close 

 enough to note the yellow biU, reddish brown wings, and 

 black tail feathers with their white "thumb-nail" marks, 

 that you know which cuckoo you are watching. If you 

 were to dip your thumb in white paint, then pinch the 

 outer quills of the yellow-billed cuckoo's dark tail feathers, 

 you would leave similar marks. 



Most birds will not touch the hairy, fuzzy caterpillars 

 — very disagreeable mouthfuls, one would think. But 

 happily cuckoos enjoy them as well as the smooth, sUp- 

 pery kind. "I guess they like the custard inside," said a 

 httle boy who had stepped on a fat caterpillar on the 

 garden path. "Cuckoos might well be called caterpillar 

 birds," wrote Florence Merriam Bailey, "for they are so 

 given to a diet of the hairy caterpillars that the walls of 

 their stomachs are actually permeated with the hairs, 

 and a section of stomach looks like the smoothly brushed 

 top of a gentleman's beaver hat." When you see the 

 webs that the tent caterpillar, toward the end of summer, 

 stretches across the ends of the branches of fruit and nut 

 trees, especially wild cherry trees — watch for the cuckoo's 

 visits. Orioles, also, tear open the webs to get at the 

 wiggling morsels inside, but they leave dead and mutilated 

 remains behind them, showing that their appetite for 

 web worms is less keen than that of the cuckoos, who eat 

 them up clean. Fortunately the caterpillar of the terribly 

 destructive gypsy moth is another favorite dainty. 



Perhaps you have heard that the cuckoo, like the cow- 

 bird, builds no nest and lays its eggs in other birds' 



