I 9 0 THE CUCKOO’S SECRET 
and the fact is so well known to all who have 
practical field-knowledge of the Cuckoo that it needs 
no re-statement. The only qualification necessary 
is that the most successful results in this country 
have been produced by investigations into Cuckoos 
parasitic upon Meadow Pipits, Reed and Sedge 
Warblers, and in a lesser degree upon Robins, 
Hedge-sparrows, and Pied Wagtails. So far as I 
know, there is yet no one who can show a long and 
genuine series of eggs of one Cuckoo in one season 
from nests of any fosterers but the three first 
mentioned. Doubtless this is owing to the greater 
difficulties one meets with in discovering a suffi- 
ciency of the nests of other dupes in any given 
territory. That at least many Cuckoos will not 
willingly make use of the nest of any fosterer not 
belonging to the species which they are accustomed 
to victimise is well shown by the history of Cuckoo 
A, also by that of “ Mary Pickford,” and the most 
prolific birds mentioned by Scholey, Lees, and 
Pettitt — all of them, it may be noted, dominant 
Cuckoos. 
Mr. Pettitt says that though he has taken hun- 
dreds of Cuckoos’ eggs from Reed Warblers’ nests, 
he can, in this wide experience, recall very few 
instances of Cuckoos which habitually dupe that 
