2 20 Mr, Jenner’s Obfervations on the 
with a hope that they may tend to illuftrate a fubjeft hitherto 
not fufficiently inveftigated ; and Ihould what is here offered 
prove, in your opinion, deferving the attention of the Royal 
Society, you will do me the honour of prefenting it to that 
learned Body. 
The fir ft appearance of Cuckoos in Gloucefferlhire (the part 
of England where thefe obfervations were made) is about the 
17th of April. The fong of the male, which is well known* 
foon proclaims its arrival. The fong of the female (if the 
peculiar notes of which it is compofed may be fo called) is 
widely different, and has been fo little attended to, that I be- 
lieve few are acquainted with it. I know not how to convey 
to you a proper idea of it by a comparifon with the notes of 
any other bird ; but the cry of the Dab- chick bears the neareffc 
refemblance to it. 
Unlike the generality of birds, Cuckoos do not pair. When 
a female appears on the wing, fhe is often attended by two or 
three males, who feem to be earneftly contending for her 
favours. From the time of her appearance, till after the mid- 
dle of fummer, the nefts of the birds felefled to receive her 
egg are to be found in great abundance ; but, like the other 
migrating birds, the does not begin to lay till fome weeks after 
her arrival. I never could procure an egg till after the middle 
of May, though probably an early- coming Cuckoo may pro- 
duce one fooner *. 
* What is meant by an early-coming Cuckoo, I fhall more fully expiain in a 
Paper I intend to lay before you on the Migration of Birds j but it may be 
neceflary to mention here, that migrating birds of the fame fpecies arrive and 
depart in fucceifion. Cuckoos, for example, appear in greater numbers on the 
thefecond than on the week of their arrival, and they difappcar in the fame 
gradual manner,. 
The 
