Vol. XX"j Qf^ij^^^i^j^ ^yiDDxGGKTT, Birds o/ Coronados /slc/fids. 7 1 



without any more definite locality than "California" being indicated ; but 

 as many of Delattre's birds are stated to have come from San Diego, it 

 seems probable that the type of O. melania was from this vicinity. 



5. Oceanodroma socorroensis. Socorro Petrel. — The Socorro 

 Petrel was found breeding commonly on both North and Middle Islands, 

 but on the latter they were most accessible, and here on the afternoon of 

 August 6, we secured by continuous hard work twenty-four adults, with 

 many young and eggs. This island presents two jagged peaks about a 

 hundred feet high, with a sag between the two. To one side of this saddle 

 is a basin perhaps two hundred feet across unevenly edged with ragged 

 ledges. The bottom of the basin farthest from the saddle has been under- 

 mined by a subterranean channel connecting with the surf on the outside 

 of the wall. Here one can look down thirty feet or more and see the 

 water surging back and forth with the swell. The rest of the basin sloping 

 up to the saddle is covered by disintegrated rock from the surrounding 

 walls, and supports a scanty growth of dwarfed 'buck-thorn' bushes. 

 Where this bush is thickest a few inches of peaty soil has accumulated 

 and this we found to be a favorite burrowing place for the petrels. Other 

 parts of the island were also occupied, but in those places the burrows 

 usually ended underneath or between heavy fragments of rock and so 

 were mostly impossible to reach. We were first made aware of the 

 presence of the colony by the strong and characteristic odor of petrel oil, 

 for of course not a bird is to be seen above ground during daylight. 

 Following the scent we soon found the openings, generally more or less 

 hidden by weeds or stones. A cursory survey showed that the basin was 

 honey-combed with burrows. In the loose talus of the slopes they extended 

 directly down into the ground, turning aside here and there to avoid pieces 

 of rock, and ending, where further excavation had become impossible, in 

 a cavity about twice the diameter of the main burrow. Those in the more 

 level ground were often entirely concealed by wide spreading bushes which 

 had to be cut away before the entrance could be reached. Otherwise 

 these latter were easy of access, for the peaty, fibrous nature of the soil 

 rendered shallow burrows possible, and such were easily uncovered by 

 sliding the hand in and lifting up the top soil. The terminal chambers 

 were larger here than in the burrows among the rock fragments. Often 

 two burrows crossed or united, but always the occupants were in sep- 

 arate terminal cavities. The shortest burrow did not exceed twelve 

 inches in length, the first lifting up of the top disclosing a Socorro Petrel 

 and egg. The longest observed was in stoney ground, and zigzagged 

 about so that in all its windings it extended fully six feet. The nest 

 cavities sometimes showed a sparse flooring of fine twigs and grass, but 

 just as often they were altogether bare of any lining. Most of the nests 

 contained downy young, from newly hatched ones to individuals in which 

 the wing and tail feathers were more than half grown. The juvenals 

 were uniformly smoke gray in color not obviously different from corre- 

 sponding ages of the Leach Petrel. Perhaps some of these belonged to 



