Fear in Birds. 99 
never seen any bird of prey attempt the pursuit of 
a swallow. The question then arises, how did this 
unnecessary fear, so universal in swallows, origi- 
nate? Can it be a survival of a far past—a time 
when some wide-ranging small falcon, aérial in 
habits as the swallow itself, preyed by preference on 
hirundines only ? 
[Nore.—Herbert Spencer, who accepts Darwin’s inference, ex- 
plains how the fear of man, acquired by experience, becomes instince- 
tive in birds, in the following passage : ‘‘ It is well known that in 
newly-discovered lands not inhabited by man, birds are so devoid 
of fear as to allow themselves to be knocked over with sticks ; 
but that, in the course of generations, they acquire such a dread 
of man as to fly on his approach: and that this dread is mani- 
fested by young as well as by old. Now unless this change be 
ascribed to the killing-off of the least fearful, and the preservation 
and multiplication of the most fearful which, considering the 
comparatively small number killed by man, -is an inadequate 
cause, it must be ascribed to accumulated experience; and each 
experience must be held to have a share in producing it. We 
must conclude that in each bird that escapes with injuries in- 
flicted by man, or is alarmed by the outcries of other members 
of the flock (gregarious ereatures of any intelligence being neces- 
sarily more or less sympathetic), there is established an association 
of ideas between the human aspect and the pains, direct and in- 
direct, suffered from human agency. And we must further con- 
clude, that the state of consciousness which compels the bird to 
take flight, is at first nothing more than an ideal reproduction of 
those painful impressions which before followed man’s approach ; 
that such ideal reproduction becomes more vivid and more massive 
as the painful experiences, direct or sympathetic, increase; and 
that thus the emotion, in its incipient state, is nothing else than 
an aggregation of the revived pains before experience. 
“* As, in the course of generations, the young birds of this race 
begin to display a fear of man before yet they have been injured 
by him, it is an unavoidable inference that the nervous system 
of the race has been organically modified by these experiences, 
we have no choice but to conclude, that when a young biid is led 
