DUCK HAWK. Falco peregrinus anatum Bonaparte

Field characters.—Smaller than Red-tailed Hawk, with long slender wings and narrow, relatively short tail. Whole coloration very dark appearing; a broad black band down each side of head below eye. Upper surface dark bluish or brownish black; lower surface heavily barred with black on a light ground in adults, and heavily streaked with black on buff in immatures.

Occurrence.—Resident on Negit Island, Mono Lake, where observed May 27, 1916. Lives about rocky cliffs in vicinity of bodies of water inhabited plentifully by water birds.

The Duck Hawk is the largest and by far the darkest colored of the four falcons in the Yosemite region. Its bodily proportions are similar to those of the Sparrow Hawk, but it is a bird of audacious appearance and behavior, gaining its livelihood by preying almost exclusively on other birds, particularly those which live on or near the water.

Our only first-hand experience with the Duck Hawk was at Negit Island, Mono Lake, where, at the time of his visit on May 27, 1916, Mr. Dixon found a pair living. Concerning these his notebook reads:

Soon after landing on the island a shot roused a male Duck Hawk, and he circled over our party, ki-yi-ing loudly, but being careful to keep out of gunshot range. When we arrived at the top of the crater, after a tiresome climb over the loose talus-strewn slope, the female flushed from a nearby boulder and joined the male in his noisy circling. Both of them left the island before we did. We searched for a nest but were unable to find one, although it seemed certain that the hawks must be nesting in one of the numerous pot-holes in the black volcanic rock.

The skeletons of many Eared Grebes, a species common at most seasons on Mono Lake, were found about the hawks' vantage points, clear evidence of the havoc the hawks had wrought among the water birds that visit the lake.

On the floor of Yosemite Valley close to Rocky Point, on November 15, 1915, a single feather was picked up at the roadside. A comparative study of this feather subsequently, in the Museum, showed that it was one of the secondary flight feathers from the right wing of an adult male Duck Hawk. The features by which it was distinguished from the corresponding feathers of other hawks are the following: actual size, outline, curvature of whole feather, tone of color of outer web (with slaty gray 'bloom') and pattern of barring on inner portion of inner web. We can only surmise that this feather had been lost through molt or accident by a bird casually visiting or flying over the Yosemite.