40 Nesting Habits of Cuckoo. 
another in 1864, and the third in 1865. It appears also from 
Mr. Dressers’ list that there is only one other recorded instance 
of the use by the cuckoo of the nest of the Blackcap, Yellow 
Wagtail, or Linnet; all these nests were found by Smithers, the 
Blackcap’s in 1860, the Yellow Wagtails’ in 1860, and the 
Linnets’ in 1863, 1866, and 1869. The nest of the Yellow Bunt- 
ing is one which is very rarely used by the Cuckoo, the two 
nests of this species which are in Mr. Crowley’s collection, 
were both found by Smithers in the summer of 1864. 
As will be seen from the specimens here this evening, the 
eggs of the Cuckoo differ very much in color, and in the number 
and character of their markings, as well as in size. As far as is 
known, however, it would appear that all the eggs laid by any 
particular female are alike. Some females have even been 
known to lay blue eggs. It will be seen, too, that the eggs of 
the species of birds to which the cuckoo entrusts its eggs also 
differ very widely. Strange as it may appear, it has been 
proved, in many instances, that the egg of the Cuckoo bears a 
remarkable general resemblance to the eggs of the bird in whose 
nest it is placed; and it would appear from this, that the Cuckoo 
does not deposit its egg at random in the first nest that comes, 
but that, as a rule, each female selects a nest the eggs in 
which resemble its own. Some very remarkable instances are 
on record of this resemblance, the best of which perhaps is in 
the case of the Redstart (R. phcenicurus). The eggs of this 
species are blue, and in several instances, blue Cuckoo’s eggs 
have been found in the nest of the redstart. How far this 
resemblance goes is a matter of controversy. Some authors 
maintain that it is the rule for the eggs of the Cuckoo to 
resemble the eggs of the bird to which it is entrusted, whilst 
others maintain that this is exceptional. This difference of 
opinion may, perhaps, to some extent, be due to the fact that 
the authors would not, in all probability, agree as to what con- 
stitutes a resemblance. The object of this assimilation in 
color must be to render the egg of the cuckoo less easily 
recognized as a substituted one by the foster parents, and for 
this and other reasons it would seem probable that it is the rule 
for the eggs to agree in colour, and not the exception. Cer- 
tainly this collection seems to favour this view, for, of the 46 
nests, in twenty-nine cases the eggs agree fairly well in colour 
and markings, and in seventeen cases they differ. The seven- 
teen exceptions are Red Backed Shrike, one; Hedge Sparrow, 
two; Redbreast, three ; Dartford Warbler, two; Tree Pipit, 
one; Meadow Pipit, two; Yellow Bunting, one; Greenfinch, 
two; and Linnet, three. 
In one or two instances the resemblance between the two 
eggs is very striking, as, for instance, in the nest of the Yellow 
