BIRDS FROM THE FARALLON ISLANDS. 29 



when it was picked up stunned. Auks have struck persons 

 walking without a light, but always below the shoulders. 

 From the balcony of the light-tower they could be heard 

 below calling; their note is the most noticeable of the 

 night cries, seeming to predominate over all other bird 

 sounds, especially during stormy and windy nights. 



On the Farallon Islands they do not burrow, but lay in 

 natural cavities over the entire island, particularly where 

 a pile of rocks afford concealment. The inhabited places 

 may be known by the excrement accumulated about the 

 entrance. They use no nest material, laying a single un- 

 marked egg. Several young are supposed to be raised dur- 

 ing the season. Many nests were found occupied by 

 young in down and one adult bird sitting upon a fresh egg; 

 in some nests the egg was kept warm by contact with the 

 young. In no instance were two old birds found in the 

 same nest, and no birds were found at the time search was 

 made without an egg or young or both. The majority of 

 adult birds taken were females, although both sexes were 

 found sitting. If provoked, either young or old will seize 

 a finger and hold on. The old birds are silent when on 

 the nest, but the downy young make a faint peeping when 

 disturbed. When taken from the nest, they endeavor to 

 crawl out of sight, and if tossed into the air they descend 

 quickly and hide themselves from the light. They com- 

 menced flying this year as early as April 2d; and eggs have 

 been found as late as November 20tli, 1886, showing a 

 breeding time extending through eight months. 



The eggs, when held to the light, show a pale shade of 

 emerald green. 



Fifty specimens measured average 45.3 x 32.5 mm. The 

 extreme largest and smallest eggs were found to measure 

 respectively 49 X 35; 48.5x33.5; 48x36; 47.5x36; 46 x 

 32; 43 X 32.5; 43 x 32; 42.5 x 34 millimeters. 



I have taken measurements of examples of both sexes, the 

 averages of which, in millimeters, are here appended. 



