Oswald H. Latter 
171 
striking as to tempt one to dally with conscious selection and deliberate choice 
on the part of the female Cuckoo : for instance, six blue Cuckoo's eggs occur in 
the series, of these three were in Red Starts' nests (Nos. 155, 158, and one not 
accessible for measurement), one (No. 159) in nest of Saxicola melanoleuca, and 
two others (not accessible) in nests of Hedge-Sparrow and Pied-Flycatcher. All 
these birds lay blue eggs, and so far as my observations go, blue Cuckoo's eggs are 
not deposited elsewhere, though Howard Saunders's statement (Manual of British 
Birds, p. 288) that " these, (sc. blue eggs), have not been invariably located in 
nests of the Hedge-Sparrow and the Red Start " leads me to suppose that they 
may have been found in the nests of birds whose eggs are not blue. Again, the 
egg of the Orphean Warbler is of a very distinct type, and yet in six cases 
out of seven the Cuckoo's egg deposited in the nest of this species resembles 
this type to a nicety, nor is this particular variety of Cuckoo's egg to be found 
in any other nest. 
Matched 
Not 
matched 
Percentage 
matched 
more or 
less 
Total 
Meadow-Pipit . . . 
56 
6 
62 
90-3 o/„ 
Wagtails 
26 
3 
29 
89-6 o/o 
5-0% 
38-8 0/, 
35-5 0/, 
Hedge-Simrrow ... 
1 
19 
20 
Eobin 
7 
11 
18 
Reed- Warbler ... 
7 
13 
20 
Tree-Pipit 
11 
4 
15 
73-3 o/o 
Wren 
0 
17 
17 
0-0 o/o 
0-0 o/o 
50-0 o/o 
85-7 0/0 
Yellow-Aniraer ... 
0 
12 
12 
Garden-AVarbler 
4 
4 
8 
Orphean-Warbler 
6 
1 
7 
Perhaps the most striking point in connection with colour-matching is its 
entire absence from the eggs of Wren-Cuckoos, which, though closely resembling 
one another, in no case match those of the Wren itself The Wren is the only 
bird of those dealt with in this paper that constructs a nest of such a character 
as to render a view of the eggs impossible alike to the Wren and the Cuckoo ; 
hence failure in colour-matching cannot possibly reveal the intruder to the lawful 
owner and discrepancy in size becomes of more importance. It is very remarkable 
that, in both length and breadth, as already pointed out, the eggs of Wren-Cuckoos 
show a far wider variation from the average Cuckoo and in the direction of the 
Wren's egg than is the case with any other species. It is too a well known 
fact that the Wren is peculiarly intolerant of interference with her nest — at 
any rate at the hands of human beings. 
To sum up, we note that there are three cases of practically no colour- 
matching, the Hedge-Sparrow-Cuckoo, the Wren-Cuckoo and the Yellow- Amraer- 
Cuckoo ; in the first two of these cases there is an attempt both as to length 
and breadth at size-matching. In the third case no significant size-difference 
is to be found from our data, but these are too scant to be really conclusive. 
In spite then of the criticisms expressed above and of the absence of actual 
14—2 
