372 MR. J. H. GURNEY ON THE ECONOMY OF THE CUCKOO. 
The reason a Cuckoo chooses such small kinds of birds as 
Wagtails, Titlarks, etc., to palm its egg upon, is that if its egg were 
smaller than the fosterer’s eggs, it would not always receive enough 
of the warmth of the sitting bird to hatch. Yet it is a stated 
“fact” that Cuckoos have laid in Wood Pigeon’s nests, and 
“a fact” too as old as Willoughby (1G7G). That each individual 
Cuckoo lays its own type of egg, season after season, and that 
in nineteen cases out of twenty it lays that egg on the ground 
(always for that reason preferring a low nest), and taking it in its 
mouth flies (J. O. Harper) or crawls to a nest already known, is 
established, and hardly requires any further proof. The introducing 
of that egg into another bird’s nest may, very possibly, not be resented 
at all, and certainly not nearly so much as the abstraction of one of 
the fosterer’s would be, which act of spoliation often leads to a scuffle 
and even to the death of the foster-bird. Neither are the two 
acts generally simultaneous, but they are sometimes so according to 
first-hand evidence. Our Norwich birdstuffers have on two or 
three occasions taken perfect eggs out of Cuckoos, which indicates 
some latent power of retaining them in the ovarium, — a power 
long ago suspected by Montagu. 
Cuckoos Watching their own Eggs. 
Professor Newton thinks that when a Cuckoo has deposited her 
egg in a nest she takes no further interest in it, but there are many 
instances of Cuckoos being seen hanging about in the immediate 
vicinity. But most likely their motive is, as a rule, not to watch 
their own eggs, but to carry off some of the fosterer’s, lest the latter 
should bestow too much attention on hers, and not the Cuckoo’s, 
and this is generally done; yet the Cuckoo is too crafty to take all 
the fosterer’s eggs, whereby it would defeat its own ends by causing 
the fosterer to forsake. All evidence confirms the Professor’s view. 
The Cuckoo’s burglarious intention (defeated in this case) seems 
pointed to in the following memorandum of Mr. Norgate’s: — 
“ June 1st, 1881. — I saw a Cuckoo, and heard it uttering the bubbling 
noise, which I believe is peculiar to the hen, in the act of flying. It alighted 
on a Willow under which I was sitting, and near which I found a Pied 
Wagtail sitting on its nest in ivy on a wall. This nest contained one Cuckoo’s 
egg, and six Wagtail’s eggs, and was so deeply imbedded in ivy that I doubt 
if the Cuckoo could put its head in far enough to take an egg out of it.” 
