LIFE HISTORIES OF N"f)RTH AMERICAN PETRELS AND PELICANS, 199 



About 10 o'clock the following night a visit was paid to the nesting boobies. 

 The night was calm, and taking a lighted candle I walked out a short distance 

 to an opening in the bushes where there were twenty or thirty nests. The 

 females were found on their eggs with the males standing close beside them. 

 When the strange visitor appeared in their midst the birds set up a continuous 

 series of hoarse cries and, like so many moths, seemed to become fascinated 

 by the light. They started up on all sides, and trooping within the circle of 

 bright light, began to run around me in a ring about 20 feet in diameter. They 

 ran in single file from right to left and presented a most ludicrous sight. 

 Occasionally one fell on its breast, whereupon tlie others scrambled over the 

 fallen bird until it regained its feet and rejoined the procession. One of the 

 number was suddenly possessed with a desire to run around one of my legs, 

 and, although seized by the head several times and tossed out among its com- 

 panions, persisted in returning to the same place and continuing its gyrations. 



Eggs. — The blue-footed booby lays usually one or two eggs, rarely 

 three, perhaps more commonly two. In shape they are usually 

 elliptical ovate or elongate ovate. The shell is more or less rough 

 or uneven, due to its chalky covering. The color of the shell is very 

 pale blue or bluish white, which is generally mainly concealed by a 

 thin chalky coating, which is dirty white and often much nest 

 stained. 



The measurements of 62 eggs, in various collections, average 62.7 

 by 42.5 millimeters; the eggs showing the four extremes measure 

 69 by 44, 68.5 by 48, 57.8 by 41.2, and 63.5 by 38.8 millimeters. 



Young. — Incubation seems to be performed by the female alone, 

 but she is constantly attended by her mate, except when he is off 

 fishing, and is fed by him at the nest, as it is necessary for the eggs 

 to be guarded from their various enemies. Mr. Gifford (1913) says: 

 " The half-fledged young exhibited considerable pugnacity. When 

 one was shoved into a neighbor's domain a fight ensued, the birds 

 seizing each other by the beak and then having a tug-of-war for 

 perhaps a minute." 



Plumages. — The downy young is pure white. Two young birds in 

 the United States National Museum, in one of which the head and 

 neck is still covered with white down, show the development of the 

 Juvenal plumage. In this plumage the head and neck is variegated 

 or washed with " pale brownish drab " ; the variegated effect is pro- 

 duced by the paler tips of the feathers, which are long and narrow ; 

 the back and wing coverts are " sepia," with whitish edgings on all 

 the feathers, producing a whitish interscapular saddle ; the breast is 

 pale brownish, shading off gradually into the color of the neck ; the 

 under parts are variegated or mottled with dusky, particularly on 

 the flanks. How long this plumage is worn or at what age the adult 

 plumage is assumed does not seem to be satisfactorily shown by the 

 material available. 



