46 PETRELS, SHEARWATERS, ETC. 



During boisterous weather they (as well 

 as most other members of the group) fly along 



Fig. 32. 



Audubon Shearwater. 



the hollows of the ever-moving billows, and 

 as they roll under them, the birds cross their 

 crests diagonally. Thus by shearing the wa- 

 ter, they allow the spray, which is driven 

 violently from the wave tops b3 T - the fierce 

 ocean winds, to strike on one side of their tu- 

 bular nostrils. They nest on islands, plac- 

 ing the egg in rock cavities, or beneath loose 

 slabs of stone. 



21. GREATER SHEARWATER. 



Rather large, about the size of the Ring- 

 billed Gull, but differs from any gull in hav- 



