3 
7 a) 
ON THE NOTES OF BIRDS. 
the power, and being willing to remove every cir- 
cumstance on which the most fastidious inquirer 
could fix a doubt, I placed the eggs of a Redbreast 
in the nest of a Chaffinch, and removed the eggs of 
the Chaffinch to that of the Redbreast, conceiving 
that if I was fortunate in rearing the young, I should, 
by this exchange, insure an unexceptionable experi- 
ment, the result of which must be deemed perfectly 
conclusive by all parties. In process of time these 
eggs were hatched, and I had the satisfaction to find 
that the young birds had their appropriate chirps*. 
When ten days old they were taken from their 
nests, and were brought up by hand, immediately 
under my own inspection, especial care being taken 
to remove them to a distance from whatever was 
likely to influence their notes. At this period an un- 
fortunate circumstance, which it is needless to relate, 
destroyed all these birds except two (a fine cock 
Redbreast and a hen Chaffinch), which, at the expi- 
ration of twenty-one days from the time they were 
hatched, commenced the calls peculiar to their species. 
This was an important point gained, as it evidently 
proved that the calls of birds, at least, are instinctive ; 
and that, at this early age, ten days are not sufficient 
to enable nestlings to acquire even the calls of those 
* Mr. Barrington defines the chirp to be the first sound a 
young bird utters as a cry for food. It consists of a single note. 
repeated at short intervals. and is common to nestlings of both 
scXes. 
