242 FIELD-STUDIES OF EARER BIRDS 



quite rare occasions where two eggs of a " set " 

 have been in contact, I am positive that it has 

 always been the result of the sitting bird having 

 kicked them against one another in her frantic 

 hurry to be gone when suddenly disturbed. Any- 

 how, I have seen the thing happen when an 

 exposed eyrie has been fully commanded from 

 above. This curious fact of the eggs never touch- 

 ing except accidentally must surely owe its 

 origin to some formation of the Peregrine's under- 

 parts. Certainly there is no chance about it, not 

 only by reason of the bird making a shallow 

 ' cup " though not so shallow as to prevent their 

 all lying together for the reception of its eggs, 

 but also because I have examined so many " sets ' 

 in situ, and because best ' because" of all I 

 have even troubled to descend to eyries in the 

 morning and place all the eggs touching, only to 

 find a few hours later that their owner had just 

 as surely separated them. No other bird I know 

 of lays its eggs apart intentionally. 



Moreover, the Peregrine incubates in a 

 decidedly curious fashion. Instead of keeping the 

 head up and the neck curved, it extends the 

 latter almost in a line with the body ; indeed it 

 must, I think, be actually resting on the ground, 

 while the head is pointed slightly upwards, though 

 occasionally I have seen it tucked down beneath 

 the breast, the beak then almost, if not quite, 

 touching the soil. The wings are either somewhat 



