PETRELS. 249 
many writers. The Fork-tailed Petrel is known 
to breed on North Rona, and at some other spots 
in the Outer Hebrides, as well as on the Blaskets 
off the coast of Kerry. There can be little doubt 
that many other breeding stations of this Petrel 
remain to be discovered. This species, readily dis- 
tinguished from the Stormy Petrel by its larger size 
and deeply-forked tail, is rarely seen near the land 
unless during the breeding season, or when driven 
thence by boisterous weather. I have known it 
to be caught in the flight-nets on the mud-banks 
of the Wash; whilst it is of tolerably frequent 
occurrence elsewhere off our eastern and southern 
coasts. In its habits generally it very closely 
resembles its better known ally, the Stormy Petrel. 
During the non-breeding season it wanders vast 
distances from land, sleeping and resting on the 
sea when tired, following ships for miles, fluttering 
along close to the ocean, now down into the trough 
of the wave, anon skimming over the crest to half- 
fly, half-run, with patting feet, down the smooth 
surface of the next. Except during the breeding 
- season this Petrel is not very gregarious; it may 
often be seen in parties of perhaps half-a-dozen, 
scattered over a considerable surface of water. The 
exact nature of the food of this species is apparently 
unknown. It is said, in a vague and general way, 
to feed on crustaceans and small molluscs, and the 
scraps of refuse cast from passing vessels, but birds 
which I have dissected contained similar substances 
