CUCKOO NOTES. 145 



touching its history have been gathered. It 

 would indeed fill quite a volume if one should 

 give only a compendium of cuckoo literature, 

 most of which refers to the European bird. 

 Quite a discussion was precipitated into scien- 

 tific circles when, some thirty years or more 

 ago, a distinguished gentleman propounded 

 the statement that a cuckoo invariably colored 

 her egg to coincide with those in the nest 

 chosen as the place of deposit. A cabinet of 

 eggs, claimed to be those of the cuckoo and 

 those of the birds in whose nests they had 

 been found, was arranged for the purpose of 

 demonstrating the apparent truth of the start- 

 ling theory ; but notwithstanding many curi- 

 ous facts, it could not be maintained. 



It remains pretty well settled, however, that 

 the eggs of Cuculus canorus may now and 

 then vary in color, somewhat in accordance 

 with the hereditary individuality of the partic- 

 ular bird, and that each female cuckoo may 

 instinctively choose, as a rule, to deposit her 

 egg in a nest with those of a bird laying eggs 

 of nearly or quite the same color. 



So eccentric and variable is the Yellow-bill 

 in its habits, that it is not at all wonderful 

 that much doubt has existed as to whether it 

 is parasitic ; but I am convinced that it does, 

 irregularly, under stress of over-fecundity, slip 

 an egg occasionally into the nest of another 

 bird, and this habit and others characteristic 

 of the genus, appear to be imperfectly formed 

 as yet, or else they are being gradually aban- 

 doned. 



This apparent tendency towards sloughing 

 hereditary habits, or acquiring new ones, is 

 noticeable in several of our American birds, 



