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, 
Io 
