Mar., 1919 NESTING O? TWO SPECIES OP PETREL 61 The nesting burrows of this petrel were in sandy soil in nearly all the drier parts of the island. They were generally from six. to ten inches in diameter at the mouth, and seven or eight feet in length; it is very probable that part of this extensive excavation is done by the Wedge-tailed Shearwater (Puffinus cuneatus), as these birds are known to use the same burrows later in the sea- son. The shallow nest cavity at the end of the burrow is generally fairly well lined with grass and leaves. An exceptional nesting site of the species was toted on January 25, when a nest and egg were found under an overturned basket near the cabin. The single egg is pure White, unmarked. Six typical eggs measure (in inches) as follows: Largest, 1.98xl.45; smallest, 1.85xl.42; average, 1.91xl.44. Heavy sandstorms during early February filled up several thousand bur- rows of this species, smothering many of the incubating birds. While ?valking among the colonies at this time, birds were frequently found imprisoned in sand at the mouths of burrows, often with their heads above the surface and still alive. The Sooty Petrel (Ocea?odroma tristrami) at the time of our visit to the islands, was considered one of the rarest of the petrels, being known from a very.few specimens. We were therefore much pleased to find a substantial breeding colony on Laysan Island, also a smaller one on Pearl and Hermes Reef. A series of the birds was secured and, as little has been previously published regarding the species, the measurements obtained may be worthy of record. It will be noted that the females are appreciably larger than the males, in. most ?nstances this being clearly perceptible in living birds. The average measurements. (in inches) of six breeding males follow. Length, 9.98; wing, 7.09; tail, 4.07. The largest measures: Length, 10.20; wing, 7.25; tail, 4.27. The smallest: Length, 9.40; wing, 6.68; tail, 3.77. Six breeding females average: Length, 10.39; wing, 7.43; tail, 4.33. The largest measures: Length, 10.92; wing, 7.61; tail, 4.58. The smallest: Length, 10.15, wing, 7.32; tail, 4.25. The nesting colony of the Sooty. Petrel on Laysan Island was situated along the shores of the shallow salt-water lagoon that lies approximately in the center of the island. A rise in the water of this lagoon, caused by heavy rainfall February 6, flooded and destroyed several hundred of the petrels' nests, as well as numerous nests of the Laysan Albatross (Diomedea immutabi- lis). One of the sand storms previously mentioned, coming two days later, also destroyed many nests by filling the burrows with sand. Probably at least half of the petrel colony was wiped out by these two catastrophes. The burrows of the Sooty Petrel were much smaller than those of the White-breasted, averaging about five inches in diameter and from two and one- half to three and one-half feet in length. In most instances they were quite crooked, resembling in this respect nesting burrows of Oceanodroma leucorhoa or O. furcata. The nest at the end of the burrow was composed of rootlets, weedstems and leaves. The eggs, deposited mostly during the first two weeks in January, are typical of the genus Oceanodroma, though, of course, larger than those .of any of the genus along our Pacific coast, being approached in size only by those of O. macrodactyla, of Guadalupe Island. They are creamy white in color, more or less faintly dotted, scrawled or wreathed, with purplish and pinkish brown, mostly around the larger end. Average measurements (in inches) of six eggs are: 1.52xl.07; largest, 1.63xl.08; smallest, 1.48xl.07. Los Angeles, California, December 6, 1918.
