An Explanation of a Seeming Discrepancy
An Explanation of a Seeming Discrepancy
My attention has been called to a seeming discrepancy between the descriptions given respectively by Dr. Joseph Grinnell and myself of the nesting of the Forked-tailed Petrel (Oceanodroma furcnta) on St. Lazaria Island, Alaska, as quoted by Mr. Arthur C. Bent in his Life Histories of North American Petrels and Pelicans and their Allies (Bulletin 121, II. S. National Museum): Dr. Grinnell speaks of only one egg in a burrow of this species, while I mention the presence of more than one and note also the joint occupation of many burrows by two species of petrels, the Forked-tailed and the Leach Petrel (O. Leucorhoa).
This apparent contradiction lies in the fact that we worked in different parts of St. Lazaria Island, in different associations. Dr. Grinnell speaks of being in the woods, where conditions apparently did not suit the Leach Petrel, while my work was done in open land only sparsely covered with bushes, where, in the loose soil, the two species frequently occupied the same burrow.
In 1897, the year after my visit to this island, M. A. Brace, a marine who had accompanied me at the time, sent me a box filled with petrel eggs of the two species, taken from St. Lazaria Island, with a letter in which he stated that he had not been particular about identifying the eggs by means of the parent birds, but that I could pick them out myself. The contents showed that the two species were breeding in the same burrow, and in the same spot as during my own visit.
Joseph Mailliard
California Academy of Sciences, San Francisco, California, December 12, 1922
