212 BULLETIN 121, UNITED STATES NATIONAL MUSEUM. 



very Jiarsh cry, making use of their bealvs if occasion offers. Tbey are 

 singularly beautiful birds despite their vicious yellow eyes, as the white 

 plumage is set off by bright blue skin about the bill, and by coral-red foot. 



Dr. Thomas H. Streets (1877), writing of the birds of the Fanning 

 Islands, in the North Pacific Ocean, says : 



On Palmyra Island, their principal breeding-place, the period of their incuba- 

 tion was over at the time of our visit in December, but the young were not 

 yet fledged. The latter were very numerous ; they covered the trees and bushes, 

 and looked like great balls of snow-white down. The nests are rudely con- 

 structed of coarse twigs, and are built on the low trees. 



We arrived at Christmas Island one month later, in January, and there we 

 found the gannets still sitting on their eggs ; few or no young were to be seen. 

 This difference is probably induced by the physical conditions surrounding 

 them. One of the islands is situated almost directly on the Equator, exposed to 

 the fiercest rays of a tropical sun ; it is devoid of fresh water, and it rarely 

 or never rains ; the vegetation is scanty and stunted, and life in general 

 has a very unequal struggle for existence. On the other island, Palmyra, a con- 

 dition of things directly opposite to these exists. The gannets of Christmas 

 Island have a very curious habit, which, as far as our observ-ations extended, 

 is confined to those of that island. Under their nests, which were quite low on 

 account of the stunted condition of the shrubbery, were mounds one and two 

 feet high, built of twigs, and in some instances solidly cemented together by 

 their excrement. It probably affords them diversion during the monotonous 

 period of incubation to break off all the twigs within reach of tlieir bill, 

 and to drop them under their nests. These mounds furnish evidence of the 

 nests being occupied for several successive years, for the lean bushes could not 

 furnish a suflicient amount of twigs to build them up in a single breeding 

 season. 



Eggs. — The red-footed booby hays ordinarily only one ^^^^ but, 

 according to published accounts, two eggs are very often found in a 

 nest. Only a single brood of one or two young is raised in a season. 

 The shape varies from " elliptical ovate " to " elongate ovate," in 

 average specimens, but extremes are " cylindrical ovate " or " short 

 ovate." The color of the shell, where it can be seen, is pale bluish 

 Avhite, but the ^^^ is so completely covered with a thick, rough coat- 

 ing of calcareous deposit that the underlying shell is nearly or quite 

 concealed. This outer coating, which was originally Avhite, is usually 

 much nest stained and dirty; it is rough and lumpy and badly 

 scratched, cracked or peeled off in sj)ots, giving the ^^^ a far from 

 attractive appearance. 



The measurements of 38 eggs, in various collections, average 62.7 

 by 41.4 millimeters ; the eggs showing the four extremes measure 72 

 by 48.5, 59 by 40.5, and 69 by 35 millimeters. 



Plumages. — Incubation is shared by both sexes and the period of 

 its duration is said by Campbell (1901) to be 15 days. The young 

 bird is hatched naked, but soon becomes covered with a coat of white 

 down. By the time that the young bird has become fully grown the 

 down has been replaced by the first plumage ; the wings are the first 



