A NATURAL HISTORY OF THE CUCKOO. 61 
tail, which it dropped at my firing a gun at it. On examining the 
nest, the Cuckoo had only made an exchange, leaving its own for 
the one taken.” 
Instances occur sometimes of two Cuckoo’s eggs being found in 
the same nest; and I have credible information of a case of this 
kind, in which a couple were found, unaccompanied by any others, 
in that of a Blackbird. Accordingly, therefore, the Cuckoo must 
instinctively recognise the egg of its own species, and refrain from 
touching it. It can be readily shown that she does not destroy those 
of her dupe previously to introducing her own, inasmuch as, when 
disturbed in her operations, and compelled to retreat precipitately, 
her egg is found together with the others ; and she is often thus in- 
terrupted by the rightful owners of the nest, who may be seen to 
follow her, and attack her furiously in the air, as she hurriedly tries 
to escape from them. Indeed, it is not unusual to observe small 
birds, of various kinds, eagerly giving chace to the Cuckoo; and 
woe betide her if she happen to approach the breeding-place of a 
troop of Swallows! 
A favourite resting-place of this bird is upon an isolated tree, 
which commands a wide prospect around ; and, in such situations, 
the female Cuckoo, quietly sitting among the foliage, attentively 
observes the operations of the numerous smaller birds scattered 
around her; more particularly noticing those which are carrying 
about building materials, and marking the place of deposit. Hence 
it is that its egg is so generally met with in the nests of ground- 
building birds. ‘A pair of Wagtails,” narrates Mr. Hoy, “ fixed 
their nest, early in April, among the ivy which covers one side of 
my house, and reared and took off their young. A few days after 
the young birds had left the nest I observed the old ones apparently 
collecting materials for building, and was much amused at seeing 
the young running after the parent birds, with imploring looks and 
gestures, demanding food ; but the old birds, with roots or pieces of 
grass in their bills, seemed quite heedless of them, and intent on 
their new habitation. Their motions were narrowly watched by a 
female Cuckoo, which I saw constantly near the place; but the 
Wagtails had placed their second nest within a yard of the door, 
and so well concealed amongst some luxuriant ivy, that the Cuckoo, 
being often frightened away, was not able to discover it. The in- 
truder being thus thwarted in its design, the birds hatched their 
second brood, which was accidently destroyed a few days after. In 
about ten days they actually commenced a third nest within a few 
feet of the situation of the second, with safety.” Mr. Hoy conti- 
