by counter shading, color, and near-ground markings.* (See the young gulls 

 in Fig. 75.) Mottled brown, dusky and gray costumes of various degrees of 

 darkness are worn for two or three years by the young of the larger gulls, 

 and it is a noteworthy fact that during this period they are more addicted to 

 living on and about mud-flats, marshes, and muddy lagoons, than are their 

 white and free-sea-ranging parents. 



Among the other groups of long-winged sea birds, there is a good deal of 

 diversity in coloration, but at the same time a persistent tendency toward 

 whiteness and the lack of small markings. Sky-matching costumes, indeed, 

 reach high and simple development among the gannets, tropic birds, alba- 

 trosses, fulmars, and others. 



The smaller jaegers or robber gulls {StercorarincE) have in the usual adult 

 plumage full obliterative shading, being fuscous brown or slaty gray above, 

 and white below, sometimes with small markings (dusky flecks) on the breast 

 and sides ; and their young wear a heath- and grass-picturing pattern of brown 

 and dusky. But the symmetry of these facts is marred by the existence in at 

 least two of the three or four white-breasted species of a second adult color- 

 phase, in which the costume consists of sooty brown with a comparatively slight 

 counter shading. Here, as in the case of the black leopards and jaguars (see 

 Chapter XXI, p. 133), there may be something to discover in the way of cor- 

 responding varietal peculiarities of habits. But jaegers are parasitic harriers 

 of other birds, and prodigiously swift of wing, so that, except during the 

 nesting time, they doubtless have comparatively small need of disguising- 

 coloration. Strange as it may seem, however, a good many other aerial sea 

 birds are colored much like the melanistic jaegers — i. e., almost uniformly 

 dark brown or black above and below. Such are several of the Tubinares, — 

 shearwaters, petrels, albatrosses. But almost all these birds, in addition to 

 being largely nocturnal, nest in dark earth-burrows or rock-fissures, and this 

 habit has doubtless a significant connection with their queer coloration. 

 Many other species of the same families, as well as various long-winged sea 



* See Chapter XIV, pp. 82 and 83. 



75 



