LIFE HISTORIES OF NORTH AMERICAN PETRELS AND PELICANS. 133 



incubating bird was caught. Apparently they were just beginning 

 to breed, but further search was impossible for lack of time. 



Dr. Leonhard Stejneger (1885) found a small colony of forked- 

 tailed petrels breeding on Copper Island, in the Commander group, 

 on July 12, 1883, where " the eggs, a single one in each nest, were 

 deposited in deep holes in the steep basaltic rocks, 3 feet or more 

 deep, and it was only with great difficulty that a few could be se- 

 cured." This was apparently a departure from the usual custom 

 of the species, for it usually closely resembles the Leach petrel in 

 its nesting habits and is often intimately associated with it. Dr. 

 Joseph Grinnell and Mr. Joseph Mailliard found these two species 

 breeding abundantly together on St. Lazaria Island, a long narrow 

 rock lying in the mouth of Sitka Bay, Baranoff Island, Alaska. They 

 estimated that the Leach petrels outnumbered the forked-tailed by 

 about four to one. Doctor Grinnell (1897) in describing the island, 

 says : 



It is irregularly shaped, approximately a quarter of a mile in length, by 

 three hundred yards In width at its widest portion. It has the general outline 

 of a huge rocli with steep sides, but in the main it is crowned by a heavy 

 growth of large flrs and hemloclis. There is a rank growth of tall grass on 

 those parts where there are few trees or none at all, and among the trees there 

 are scattered clumps of galmonberry bushes, while the porous sod is carpeted 

 by deer's feet and other low plants. 



This island is the one in the vicinity of Sitlsa chosen by thousands of sea- 

 birds for a breeding ground. The exposed, broken precipitous sides of the 

 island are the resorts of violet green cormorants, pigeon guillemots and Cali- 

 fornia murres, while the glaucous-wingedi gulls and tufted puffins select the 

 grassy banks and promontories above the cliffs. But the petrels, to be con- 

 sidered in the present paper, seem to prefer the dark forest, although their 

 burrows are abundant wherever there is enough soil to hold them. 



Mr. Mailliard (1898) describes their nesting habits as fc)llows: 



The burrows seemed to run in any and every direction except directly down- 

 wards. The area that I worked in was covered with bunch grass and low 

 salmonberry bushes, the roots of the latter being greatly in the way. The peat 

 was so loose and wet that it was difficult to clearly define the burrows, but it 

 seemed certain that they frequently intersected when on the same level, and also 

 that tihere were tiers of them on different planes and running diverse ways. 

 I could, however, form no idea of the length of any particular one. Their 

 depth varied from four to 18 inches from the surface of the ground. The diam- 

 eter of the burrows was from about 2 J to 3 J Inches, but frequently they were 

 hollowed out in the interior to a greater size. The nests were merely small 

 hollows in slightly enlarged portions of the galleries, with sometimes a little 

 dry grass on the bottom, and were placed at irregular distances apart — fre- 

 quently an O. furcata within a foot of a nest of 0. leucorhoa, and then again 

 perhaps several of one species in a succession at varying intervals. It was diffi- 

 cult to discern much removed material at the entrances to the burrows, the 

 same ones being in all probability used year after year, the excavated earth 

 having in the course of time become assimilated with the surrounding surface. 

 It seemed as if one could dig down and strike burrows anywhere, and, in fact, 

 83960—22 10 



