CUCKOO. 383 
extreme voracity of the young bird is an additional reason why the care 
of the five nestlings should be entrusted to as many pairs of birds. What- 
ever may have been the cause of this apparently unnatural habit, the 
result has been remarkably successful in the case of the Common Cuckoo, 
which must be regarded as a common bird with a very wide distribution, 
and scattered over almost every variety of country within its range. 
In its choice of a foster-parent for its offspring it exercises more 
discrimination than might be supposed, from the long lists which have 
been published of birds in whose nests its egg has been found. An 
insectivorous bird is generally chosen. The Pipits and the Wagtails are 
perhaps the greatest favourites; and in our islands Cuckoos’ eggs are 
most often found in the nests of the Meadow-Pipit and Pied Wagtail. 
In gardens the Hedge-Sparrow is most frequently entrusted with the 
charge, and in the fens the Reed-Warbler. In some districts Redstarts 
have the preference, and in others, curiously enough, the Common Wren. 
There is probably no insectivorous bird which breeds in the districts where 
the Cuckoo spends the summer in whose nest its eggs are not occasionally 
deposited, though preference is given to such as build open nests. Some- 
times the Cuckoo is unable to find the nest of a suitable bird, and is 
obliged to deposit its egg in the nest of a granivorous bird, such as the 
various species of Finches, Buntings, &c.; and occasionally Cuckoos’ eggs 
have been found in the nests of such totally unsuitable birds as Magpies, 
Jays, Shrikes, Pigeons, and even the Little Grebe. The Cuckoo’s egg is 
remarkably small in proportion to the size of the bird, and it is generally 
placed amongst eggs which are smaller than itself; so that the young 
Cuckoo is usually much larger than its foster-brothers or sisters, and 
monopolizes the attention of the parents to the exclusion of the other 
inhabitants of the nest, who die or are eventually expelled by the young 
Cuckoo. It has been said, on what appears to be incontestable evidence, 
that the young Cuckoo soon after it is hatched ejects the young or eggs 
from the nest by hoisting them on its back ; but one feels inclined to class 
these narratives with the equally well-authenticated stories of ghosts and 
other apparitions which abound. 
_ The eggs of the Cuckoo are subject to great variation of colour, and 
they very frequently resemble closely the eggs amongst which they have 
been placed, so much so that Cuckoos’ eggs are often supposed to be 
double-yolked eggs of the same species. This fact has given rise to the 
extravagant theory that the Cuckoo possesses the power of determining 
the colour of her eggs, so as to make them resemble the other eggs in the 
nest. The explanation probably is that the eggs of each individual Cuckoo 
vary very slightly. A Cuckoo which lays blue eggs always lays blue eggs, 
and its descendants will continue to lay blue eggs; it was probably 
hatched in a nest containing blue eggs, and will, to the best of its ability, 
