70 Life History of Common Cuckoo. 



nest that had a cuckoo's egg in it '* was high and had 

 to be cHmbed for ; " and (5) that the number of 

 cuckoo's eggs laid in a season is five. Mr. Bidwell 

 is very careful and exact usually, but here there are 

 a great number of mere assumptions : (i) the cuckoos' 

 eggs laid in low nests would be more exposed to many 

 enemies — bird-nesting boys and collectors, not to 

 speak of vermin ; (2) he admits the possibility of 

 other grounds that he could examine being used by 

 the assumed identical cuckoo, and thus he has simply 

 to suppose certain things ; and (3) after all, the iden- 

 tification of the one cuckoo is mere inference from 

 egg-markings and is an assumption — no more. I 

 should like to know if Mr. Bidwell pursued these 

 same investigations on that area, as I do not find any 

 record of them in the Zoologist for 1884 ; and if he 

 did, then, unfortunately, I have missed his report of 

 it, and would be glad to know his later specific results 

 in this httle area ; but, so far as this writing of his 

 goes, 1 do not regard either his assumed facts or his 

 inferences as so entirely convincing as he seems to 

 think them. 



VIII. 



Various theories have been advanced to account for 

 the origin of these habits in the cuckoo. It is a very 

 voracious feeder, and the food which it favours, hairy 

 caterpillars — more especially those of the tiger-moth 

 (Arctin cajaj, commonly known as the "woolly bear," 

 — has become so scarce very often, through woods 

 cut down and other changes, argue one set of natu- 

 ralists, that it would not be able to satisfy itself and 



