1832-3.] HABITS OF THI CUCKOO. 53 
standing on the backs of cattle; it differs only in being a little 
smaller, and in its plumage and eggs being of a slightly different 
shade of colour. This close agreement in structure and habits, 
in representative species coming from opposite quarters of a great 
continent, always strikes one as interesting, though of common 
occurrence. 
Mr. Swainson has well remarked,* that with the exception of 
the Molothrus pecoris, to which must be added the M. niger, the 
cuckoos are the only birds which can be called truly parasitical ; 
namely, such as “ fasten themselves, as it were, on another living 
animal, whose animal heat brings their young into life, whose 
food they live upon, and whose death would cause theirs 
during the period of infancy.” It is remarkable that some of 
the species, but not all, both of the Cuckoo and Molothrus, 
should agree in this one strange habit of their parasitical propa- 
gation, whilst opposed to each other in almost every other habit: 
the molothrus, like our starling, is eminently sociable, and lives 
on the open plains without art or disguise: the cuckoo, as every 
one knows, is a singularly shy bird; it frequents the most retired 
thickets, and feeds on fruit and caterpillars. In structure also 
these two genera are widely removed from each other. Many 
theories, even phrenological theories, have been advanced to ex- 
plain the origin of the cuckoo laying its eggs in other birds’ 
nests. M. Prévost alone, I think, has thrown light by his obser- 
vations ¢ on this puzzle: he finds that the female cuckoo, which, 
according to most observers, lays at least from four to six eggs, 
must pair with the male each time after laying only one or two 
eg. Now, if the cuckoo was obliged to sit on her own eggs, 
she would either have to sit on all together, and therefore leave 
those first laid so long, that they probably would become addled ; 
or she would have to hatch separately each egg or two eggs, as 
soon as laid: but as the cuckoo stays a shorter time in this 
country than any other migratory bird, she certainly would not. 
have time enough for the successive hatchings. Hence we can 
perceive in the fact of the cuckoo pairing several times, and 
laying her eggs at intervals, the cause of her depositing her 
eggs in other birds’ nests, and leaving them to the care of foster- 
* Magazine of Zoology and Botany, vol. i. p. 217. 
+ Read before the Academy of Sciences in Paris. L’Iustitut, 1834, p. 418, 
