OBSERVATIONS ON THE CUCKOO. 65 
153,176,320,000. This, divided by 3,301,816 square 
yards (the area of the township of Crumpsall), and the 
quotient multiplied by 3 (the mean number of hen 
Cuckoos for every 3,301,816 square yards), gives 
139,173 (the mean annual number of female Cuckoos 
that visit England and Wales), which, multiplied by 5 
(the mean number of eggs laid by the Cuckoo), gives 
695,865, the number of nestlings produced annually 
by the mean number of females; and this product 
multiplied by 5 (the mean number of eggs laid by 
those birds to whose care Cuckoos usually intrust 
their offspring) gives 3,479,325, the mean annual 
number of nestling birds destroyed by young Cuckoos 
in England and Wales. Enormous as this destruc- 
tion appears to be, it is probably rather under than 
overrated, and ‘when compared with that occasioned 
by Cuckoos in general, or by our British species alone 
in the various countries in which it breeds, it sinks 
into absolute insignificance. 
The injuries which so frequently happen to the 
eggs of those birds in whose nests Cuckoos lay are 
occasioned, as I have often proved experimentally, by 
the sitting bird in attempting to accommodate herself 
to eggs of different sizes. If comparatively large and 
small eggs are placed in the same nest, some of the 
smaller ones are generally thrown out, or rendered 
addle, by the hen bird in endeavouring to arrange 
them so that she may distribute nearly an equal de- 
gree of warmth and pressure to all; but the larger 
F 
