192 BULLETIN 121, UNITED STATES NATIONAL MUSEUM. 



surface but require a drop of a few feet to give them an impetus. One tliat 

 had an unusually tight tail I lifted up and held in the air by that appendage, 

 and it flapped in my hand until the feathers gave way, when it flew off, but 

 having left a young one behind, returned almost to ray feet in two minutes or 

 so as if nothing had happened. They do not appear at all particular in the 

 choice of a place to deposit their single egg. They make no nest, but the shelter 

 of an overhanging rock or the protection of the arched roots of the Vacoa (a 

 species of Pandaniis) seems preferred. On one occasion I found an old lady 

 asleep on her egg, and she was extremely indignant at being stirred up and 

 having her tail stolen. It is curious that I did not see a single egg without its 

 owner sitting on it, and perhaps one may hence presume that they feed at night. 

 In some places their nests were excessively numerous, their eggs or young 

 occurring every few yards. There were to be found about as many young as 

 eggs, some of the former almost as large as their mothers, and nearly able to 

 fly, but I did not see a single immature bird that had started in life on its own 

 account, though I have no doubt many had already done so. Most of the eggs 

 had been incubated some time; in fact on blowing fifty or so of them I hardly 

 think that I found half a dozen fresh, the majority being withhi a few days of 

 hatching. I was rather short of baskets for carrying eggs, and consequently I 

 did not get as many as I might have done. Certainly I had been told that the 

 eggs might be picked up by the thousand, but 1 had not believed the statement. 

 This species is much finer- and larger than the yellow-billed one (P. fldvirostris, 

 Brandt). Of this there were a few about the island, but I did not find a single 

 egg or see a bird on the ground. 



Eggs. — The single egg of the red-tailed tropic-bird is similar to 

 that of the foregoing species, but it is somewhat distinctly spotted, 

 speckled, or scrawled on a clearer background, producing a hand- 

 somer effect. I can not improve on the following description by 

 Doctor Fisher (1906) : 



The egg is particularly handsome, being thickly sprinkled with specks, spots, 

 and even blotches of reddish brown (liver brown), in most of the specimens 

 rather evenly distributed over the egg, but with an irregular dark area at the 

 larger pole in some specimens. The ground color is a dirty white, almost 

 obscured by the fine marks. Some examples have few spots, only fine sprin- 

 kling, so that the general tone of the egg at a distance is vinaceous. One 

 specimen is almost white, while two others are very heavily washed at the 

 blunt end with deep reddish chocolate. The eggs are ovate and a typical 

 specimen measures G7 by 4.5 millimeters. 



The measurements of 36 eggs, in various collections, average 65.5 

 by 46.6 millimeters ; the four eggs showing the four extremes measure 

 73.5 by 46.5, 67 by 51, 59 by 43, and 64 by 41 millimeters. 



Plumages. — I have never seen the downy young. What few im- 

 mature birds I have seen would seem to indicate that the adult 

 plumage, including the red tail, is acquired during the second winter. 

 Gould (1865) describes the immature bird as follows : 



The young birds for the first year are very different from the adults, being 

 of a silky white without the roseate blush, with the whole of the upper surface 

 broadly barred with black and with the black of the shafts of the primaries 

 expanded into a spatulate form at the tips of the feathers. 



