466 Observations on the Cuckoo. 
from inability to continue their songs, as is 
manifest from their unavailing efforts to pro- 
long them, whatever occasions their silence, 
most probably occasions that of the cuckoo 
also, and L conceive that an efficient cause 
will be found in the propagation of their spe- 
cies, and in the decrease of their food, which, 
by relaxing the vocal organs, renders them 
incapable of obeying the dictates of the will. 
The well known ery. of the male cuckoo is 
frequently heard in the night. 
Various are the modes of accounting for 
the peculiarities of the cuckoo adopted by 
different writers on the subject. Some, who 
have turned their attention particularly to the. 
anatomy of this bird, think they have dis- 
covered a satisfactory reason for its not hatch- 
ing its own eggs, in the largeness and pro= 
tuberance.of its stomach, which they hastily 
conclude must render the act of meubation 
difficult, if not impracticable; but when we 
consider that several birds, as the owl, g’oat- 
sucker, &c., whose stomachs are, in these 
respects, similar to that of the cuckoo, do 
incubate their own eggs, the insufficiency of 
this imaginary cause will be very apparent. 
Buffon supposes that female cuckoos: lay 
their eggs in the nests of. other: birds, to pre- 
vent the males, which he states occasionally 
