HOW YOUNG BIRDS BREAK THE EGG SHELL. 



249 



drops off after a few days, but in some birds it wears off. This is true of 

 the young of Audubon's sheerwater, a bird allied to the petrels which live in 

 tropics, spending most of its time at sea. The nests of this species are usu- 

 ally made under rocks in the Bermudas and Bahamas. At fig. 120 I give a 

 cut of a newly hatched young. 



In certain species of birds which have long bills, the egg tooth is more 

 developed. An example of a species of this kind may be seen in Wilson's 

 plover, a bird which inhabits our southern coast in summer. The diameter 

 of the egg of this species is about one inch and this is also about the length 

 of the head and bill taken together. The tip of the bill is hard, and judg- 

 ing from the position in which the young bird lies in the egg, this tip comes 

 in contact nith the shell, and by moving it slightly, bits of the shell are 



Fig. 121. 



Head of Einged Murre. 



forced outward. In all cases the breaking of the egg shell is rendered more 

 easy by the fact that, as the period of hatching draws nigh, the shell becomes 

 more and more brittle through losing its moisture. At fig. 122 I have giv- 

 en a life-sized" cut of Wilson's plover when two hours old, and at fig. 12(3, 

 the head; of the adult male, also life size. As will be seen upon compari- 

 son, there is really very little difference between the two heads. 



It is probable that the young kingfisher also breaks the shell much as 

 does the plover. At fig. 124 maybe seen a cut of a young kingfisher which 

 was removed from the egg just before hatching, and as will be seen there is 

 no indication of an egg tooth. 



