FOSTERERS OF THE CUCKOO 195 
Linnet’s nest which was found in A’s territory on 
May 15, 1920. Now the Linnet’s nest, very low 
down in the gorse, was only four yards away from 
the Meadow Pipit’s nest which contained the first 
egg of A. It is more than likely that B had 
intended her egg for the Meadow Pipit’s nest, 
beginning almost before A had started. It is most 
likely that, on flying down to lay, B mistook the 
Linnet’s nest, which she found the more readily, 
for the Meadow Pipit’s in which she intended to 
lay. But it is also possible that A resented her 
presence, flustering and perturbing B to the extent 
that she became careless in her choice. 
The numerical list of Cuckoo fosterers is a very 
long one and embraces almost every species of 
small bird breeding where Cuckoos range. But 
as the great majority have only been recorded in 
rare instances, it is good negative evidence that it is 
foreign to the nature of Cuckoos to make use of 
any but their natural fosterers. Eggs of Cuckoos 
are comparatively rarely found away from the nests 
of the common run of hosts, and it is at least open 
to doubt whether in many instances uncommon 
fosterers, especially unsuitable ones, succeed in 
rearing the young interloper to maturity. And 
there is not much doubt that the percentage of 
