420 
SAVAGE SUDAN 
snow-white stern of the addra often caught my eye at a mile 
and more; indeed at distances where my eye could in no way 
define the object, though a white patch on the horizon at once 
told me it was an addra. The same applies to leucoryx 
though in less degree, its pale coat not being a perfect white.” 
As regards the ariel, my own experiences are given in the 
chapters on the Red Sea hills, and need not be repeated. 
To the above testimony, Mr A. L. Butler adds the following 
convincing remark : “ Addra are the most extraordinarily con¬ 
spicuous things I’ve ever seen wild—and they know it! A herd 
of them is just as conspicuous as a line of white linen clothes 
hung out to dry-—oryx leucoryx nearly as conspicuous, though 
not quite so. If the colour of these animals subserves any 
special purpose, I should say it was to enable them to sight 
and recognise their kind at great distances on the vast open 
expanses over which they roam. Moving or motionless, an 
addra is a white flag” (See photo, at p. 30.) 
Once more, the question is pertinent—against what enemies 
are these desert-antelopes supposed to require protection ? 
They have no natural enemies. No big beasts of prey share 
their sterile solitudes—the absence of water assures that. 
A curious exception to the assimilative rule deserves 
passing reference. On these same Saharan wastes of Kordofan, 
and alongside their desert-hued denizens, there also occurs a 
great dun-red hartebeest (Damaliscus korrigum) that on the 
neutral-tinted environment stands out like a chimney-sweep! 1 
In the Sudan we have the lechwi and the white-eared cob, 
in both of which antelopes the sexes differ in colour. The 
female in each case is tawny—by theory, she “ blends with the 
sere grass ”—the male being dark, is “ concealed by the new- 
burnt veld.” But since the two sexes naturally associate, only 
one can be protected at one time. The other, presumably, is 
“given away”? Dozens of similar instances—where the sexes 
differ essentially in colour—occur to the mind off-hand. But 
1 Discussing the poetic ingenuity of an American theorist who argued 
that a crow, by reason of the gloss on its black plumage—“its rainbow 
sheens,” to quote precisely—was thereby rendered invisible, Mr Roosevelt 
writes :—“There is no more use arguing than if it were stated that a coal¬ 
scuttle planted in the middle of a green lawn was inconspicuous.” Mr 
Roosevelt’s language was as breezy as his life ! 
