249 
all others which may perhaps be singing around him.” 
Barrington found that a young house-sparrow, taken when 
fledged, and placed with a linnet, but where it could also hear 
a goldfinch, uttered a mixture of the linnet’s and goldfinch’s 
songs. His other experiments showed “it to be very uncertain 
what notes the nestling will most attend to, and often their 
song is a mixture, as in the instance I have before stated of 
the house-sparrow.” There is not any doubt that each of his 
trained birds, if brought up by parents, would have had only 
their proper notes. : 
These experiments, and the fact that the young of certain 
wild birds, (e.g. the nightingale) acquire the idea of their 
songs while yet unfledged, proves that the receptivity of such 
fledglings must be very great: may it not be related to things 
as well as to sounds, and account for the perpetuation of modes 
of nidification ? 
Both call-notes and alarm-cries have sometimes diverged 
from common types. Particular sounds are sometimes em- 
ployed to suggest the approach of a certain kind of enemy. 
Darwin observed that when the mother turkey sees a kite 
approaching, high in air, “she shows her fears by her gesture 
and deportment; she uses a certain exclamation, ‘ koe-ut, 
koe-ut,’ and the young ones afterwards know that the presence 
of their adversary is denounced, and hide themselves as before.” 
(Syst. Nat.; D. H. B., 250). 
4 The common cock announces the arrival of a bird 
of prey overhead by uttering his loud yell of distress, 
and not by the cackle employed to tell that a dog or cat 
approaches. I have observed that in Gloucestershire the house- 
_ Sparrow announces the similar discovery of a hawk by uttering 
a cry “tourrr,” which is distinct from every other of its notes. 
When I hear starlings utter a particular cackle, which I know, 
Iam sure, from experience, that they see a hawk. This cry is 
- quiet distinct from their ordinary call, but often is uttered by 
them when fighting. However, it is probable that the sug- 
_ gested relation of alarm-cries to particular enemies is due to 
_vehemence, and that a cry may, by reason of its violence or 
