Page:Bird-lore Vol 03.djvu/203

 enable the birds of each species to recognize their friends, just as soldiers are uniformed so that each may know his own party. But the uniform also enables the enemy to distinguish him, so these recognition marks enable us to distinguish the birds at an otherwise impossible distance. The directive marks of the common northern birds of prey are those selected for illustration. The size, shape and general color of the birds, as well as the spots, all enter into the plan. Those shown are adults; the young in many cases are different, but have nevertheless a recognized natural uniform which usually agrees in important features with that of its parents. Thus the white rump-spot is a constant and distinctive feature of the Harrier in any plumage. So is the white collar of the Horned Owls. The mustaches of Peregrine and Broadwing, and the wrist -spot, i. e., the dark splotch on the bend of the wing in the Buteo's and in the tufted Owls, also the breast-band on Swainson's Hawk and the body-band on the Rough -leg (see plate). Late one evening as I walked through a marsh a large hawk -like bird rose before me. In the dim light I barely made out that it was a bird of prey, but as it went off I saw the white spot on the rump and that settled it beyond question as a Marsh Hawk or Harrier. On another occasion I saw a bird in a tree. Its size and upright pose said 'Hawk.' On coming nearer its mustache marks said either Peregrine or Broadwing. But when it flew, the pointed wing and swift flight made certain that it was a Peregrine. Again a young Redtail sailed over my head in an opening of the trees. I took it for a young Goshawk, but before I tried to 'collect' him I saw the wrist-spot that labeled him ' Buteo,' and so let him go. The usefulness of the color-spots is increased by another well-known law, namely, that the peculiar feature of a species is its most variable feature. Thus the greatly developed bill of the long-billed Curlew, the beak-horn of the Pelican, the neck of the Swan, the collar of the Loon, are much more variable than features that they have in common with others of their group. So, also, these markings are never twice alike. They keep the same general style but differ in detail with each individual, so that the birds can recognize each other personally, just as we do our friends by peculiarity of feature. Of course color-spots are not the only things to be considered ; pose, flight, voice, locality, probabilities and tricks of attitude all come in to help. A long reddish bird darted past me to alight in a tree that almost concealed him. I thought it a Thrasher, but the deliberate pumping of his tail (another recognition mark), taken with his size and color, told me at once that it was a Sparrowhawk.