314 BIRDS OF NEW ENGLAND AND EASTERN NEW YORK 



parents were found in the burrow if the egg was not yet 

 laid. The presence of the birds on the island would not 

 be suspected during the daytime, for one bird keeps close 

 within the burrow and the other is presumably feeding far 

 out at sea. At night, however, the air is filled with the 

 twittering of birds, coming and going to and from the 

 burrows. 



Petrels are attracted to vessels that pass across the Bay 

 of Maine, and also follow trans- Atlantic liners far out over 

 the ocean ; they may be observed from the stern of the 

 boat, but it is very difficult to see the tail clearly enough 



Fig. 89. Leach's Petrel 



to distinguish between the forked tail of this species and 

 the square tail of Wilson's Petrel. Wilson's Petrel is 

 darker, almost black, but it is also difficult to see this dif- 

 ference in color on the water. Both species have the bright 

 white rump, contrasting with the dark back, wings, and 

 tail, and both hover over the water, often with legs down, 

 as if walking upon it. Leach's Petrel is occasionally found 

 on inland waters, apparently blown in by a storm. (See 

 preceding species.) 



