50 NORTH AMERICAN FAUNA 61, FISH AND WILDLIFE SERVICE 



holes, in a weakened condition. He says that they were found 

 on the lower Yukon, and that one was found about 75 miles 

 up the Tanana River, near an air hole in the ice, late in November. 

 These petrels are also recorded from the Pribilofs (Preble and 

 McAtee 1923). Cahn (1947) reports from Unalaska: "Seen 

 abundantly in the fall and winter far out in Bering Sea." 



The Aleutians must be considered to be the stronghold of this 

 petrel. We found them on most of the islands. Experience taught 

 us that wherever we found petrel wings left by blue foxes, or 

 petrel remains in fox droppings, it was safe to assume that the 

 birds nested on the island. 



The following islands were specifically noted as being nesting 

 places for these petrels: Sanak group, Egg Island (in Akutan 

 Pass), Uliaga, Kagamil, Chuginadak, Herbert, Yunaska, Chagulak, 

 Amukta, Amlia (reported by natives), Atka (on Korovin 

 Volcano, reported by L. M. Turner), Salt (until destroyed by 

 fox raising), Kasatochi, Igitkin, Ulak, Bobrof, Tanaga, Ilak (re- 

 ported by natives, but now destroyed by blue foxes), Gareloi, 

 Semisopochnoi, Little Sitkin, Chugul (reported by natives), Kiska, 

 Buldir, Agattu, and Attu. It is almost certain that the birds nest 

 also on most of the other islands — on the Shumagins, and probably 

 on other islands off the Alaska Peninsula. This list serves to 

 show the uniform distribution of these birds. 



It is well known that the forked-tailed petrel nests underground. 

 It may make its own burrow, often as a side tunnel from the 

 wall of the tufted puffin's burrow, or it may nest in natural 

 cavities, such as those found in lava beds. Amukta Island fur- 

 nishes a typical example, where the moss-covered lava formation 

 had neat round holes through the vegetative crust leading in to 

 irregular cavities beneath. 



Food Habits 



The forked-tailed petrel is said to skim the oil from the surface 

 of the water near a wounded seal or whale, but we do not have 

 extensive data on its food habits. Preble and McAtee (1923) 

 record one stomach from the Pribilofs that contained a few 

 fish bones. Scheffer made interesting observations at Kagamil 

 Island on August 30, 1938, when about 25 forked-tailed petrels 

 and 3 Leach's petrels were picked up on the deck of the ship. 

 Six piles of regurgitated material on the deck contained broken 

 remains of small fish — the largest was about the size of a man's 

 little finger 



Mortality Factors 



The principal enemy of the petrel, so far as our observations 



