LIFE HISTORIES OF NORTH AMERICAN GULLS AND TERNS. 215 



efjgs have been recorded, though these were probably laid by two 

 birds. Often only one egg is laid, and where the first set has been 

 destroyed, only a single egg is laid for the second set. Two eggs are 

 more often found in northern colonies, but in the southern portion 

 of its range this tern usually, or at least frequently, lays only one 

 egg for the first set. Only one brood is raised in a season, so far 

 as I know. 



EggH. — The eggs of the royal tern are usually quite characteristic 

 and are not likely to be mistaken for anything else. They are quite 

 different from those of the Caspian tern. In shape they vary from 

 ovate to elongate ovate or even cylindrical ovate, but average about 

 elongate ovate. Tlie shell is smooth but without luster until it 

 becomes worn by incubation. The common types have a very light 

 ground color, practically white, varying from " light buff " or " ivory 

 yellow " to pure dull white. Darker shades are rare, but I have a 

 few in my collection which vary from " clay color " or " cinnamon 

 buff " to " light buff." The greener types, " olive buff " or " 3'ellowish 

 glaucous," are still rarer. The eggs are usually quite evenly spotted 

 with small, dark-colored spots, sometimes with fine dots and some- 

 times with large, bold, heavy blotclies ; very rarely they are marked 

 with irregular scrawls. The markings include only the darkest 

 shades of brown, " chestnut brown," " bister," or " clove brown," and 

 often they are practically black. The spots have a washed-out 

 appearance on the edges. On many eggs there are underlying spots 

 of " lavender gray " or " pale violet gray," often in washed-out 

 splashes. Sparingly spotted or even immaculate eggs are occasion- 

 ally found. The measurements of 54 eggs, in the United States Na- 

 tional Museum, average 63 by 44.5 milimeters; the eggs showing the 

 four extremes measure 74.5 by 48.5, 57.5 by 43, and 63.5 by 40.5 

 millimeters. 



Plumages. — In a series of 10 downy young royal terns, in the 

 author's collection, no two are alike, and there are, at least, three dis- 

 tinct types of coloration. In the palest type the color of the upper 

 parts varies from " light pinkish cinnamon " to " pale pinkish buff," 

 which becomes paler on the throat and sides and almost white on the 

 belly. Some specimens are nearly immaculate, but there are always 

 a few small black-tipped filaments of down on the rump and often 

 a few on the head. The character of the down is peculiar; on the 

 head is rather stiff and hair-like, but on the back and flanks each 

 filament stands out by itself, round and soft like chenille at the base 

 and tapering to a fine point at the end. The bill and feet are light 

 yellowish flesh color in the dried skin. 



In the mottled type the color varies from " light pinkish cinna- 

 mon" to "cartridge buff" above, shading off to the latter or to 

 nearly white below. This is more or less heavily spotted with ])lack, 



174785—21 15 



