150 BULLETIN 121, UNITED STATES NATIONAL MUSEUM. 



Concerning the number of birds in the colony it is difficult to form a judg- 

 ment. We dug out fifty nests representing a hundred birds from tlie least 

 populous portion of the colony, yet the area affected was no sensible portion 

 of the whole, certainly not a hundredth, probably not a five-hundredth. Based 

 upon this estimate alone the number of resident birds would run from ten 

 to fifty thousand, and it might easily be much greater. I think the birds in 

 the air simply represented the newcomers as they came in from the ocean 

 to feed their mates, and who took a few turns about the island preparatory to 

 settling down to business. Certainly the majority of the birds wei-e at all times 

 below ground, while the number in transition may be judged from the fact that 

 at 1 o'clock, when I left the bed and crawled along the ground on hands and 

 knees, I put my hands on two birds in the darkness. 



At 4 o'clock the volume of sound had subsided, and not above a dozen flitting 

 forms were seen, while at 6 o'clock there was no sign again to betray the 

 presence of the sleeping myriad. 



Prof. Lynds Jones (1908) has also visited this island and adds the 

 following observations : 



Many nests of both Kaeding's petrel and Cassin's auklet were uncovered by 

 overturning the sod as the burrows were followed. While the burrows of the 

 auklet were usually a litle farther from the surface and a little longer, the 

 plan was the same. The mouth of the burrow extended almost vertically down 

 6 inches or more, until stones were encountered, then the burrow turned and 

 ran parallel to the surface of the sod. Very few burrows were straight for 

 any distance, but usually angled here and there apparently to avoid obstruc- 

 tions. Several feet from the nest end of the burrow there was always a side 

 burrow branching off at a sharp angle, ending in an unused enlarged space. 

 Nothing was ever found in this false burrow. The nest burrow of the auklets 

 contained a bed of dry grass, but that of the petrel often contained nothing but 

 fish bones. Very few of the auklets were at home on this island, possibly 

 because there were no young in the nests, but at Alexander Island most of the 

 burrows contained young birds and one parent. Unoccupied nests were few. 

 In every petrel burrow there was at least one bird. If there was an egg the 

 male bird was with it, but if there was no egg both birds occupied the nest 

 burrow. We were unable to determine whether the office of incubation is 

 assumed wholly by the male or whether it is shared by the female. Only 

 males were found iu the burrows with eggs. When either of these species was 

 taken from the burrow and tossed into the air they took the shortest course 

 to the water, usually vacillating somewhat as if confused by the sudden day- 

 light. It seemed to us significant that the presence of these two species any- 

 where in this region would not be suspected away from their nesting burrows. 

 None at all were seen during daylight on any part of the trip. 



Only a few Beal petrels breed on the Farallon Islands. Mr. Daw- 

 son (1911) relates his experience with them, as follows: 



Near us were several half-ruined stone walls, the relics of occupation by 

 the eggers, or possibly by their predecessors, the Russian sea-otter hunters. 

 These walls resounded nightly to the incessnnt cries of petrels as did every 

 other wall on the island. On the evening of May 30, Leon Garland, one of the 

 wireless operators, secured a white rumped petrel in his tent, whither it had 

 been attracted by the light. On the morning of the 3d of June, Mr. Garland 

 brought in another Kaeding petrel, which he had secured in one of these old 



