Spur-winged Jacanas[23] in loud cackling pairs were everywhere, showing conspicuously against the green reeds—dark chocolate when at rest and flashing pale yellow in flight. Guiana Cormorants[47] and Snakebirds[48] rose or dived ahead of the launch, twenty of the former taking refuge in one small tree as we passed. Hawks were abundant and one of the most numerous was the Cream-headed Hawk,[54] which soared low over the savanna or perched on the shrubs along the bank. Small birds showed no fear of it, often alighting in the same tree. From almost every bush along the river bank little Guiana Green Herons[38] flew up from their nests, built close to the surface of the water. These herons “froze” like Bitterns when they alighted, standing motionless with the bills at an angle of 45°. Along the railroad they were semi-domesticated, flying fearlessly in and out of the coolie yards, and snatching bits of food from the very door-ways of the huts. About eleven o’clock, on rounding a sharp turn in the river, we saw what appeared to be great expanses of burnt marsh. On and on we went and at last we realized that we were looking at vast phalanxes of Ducks. Suddenly, without warning, a living sheet of birds rolled up from the ground, hung a moment, then gained momentum and wheeled upward. Thousands began to rise at once, until for fifty or a hundred yards on each side of the river, there was an almost unbroken wave of birds, flying upward and backward. From this mass of life, giving forth a medley of shrill whistles which soon deepened into a perfect roar of wings, single lines of ducks detached themselves, shooting out in all directions, passing up and across the river, or right and left out over the savanna. They were Gray-necked Tree-ducks[45] with a plentiful scattering of the Rufous[44] and a very few White-faced.[46] The great curving wave never ceased for a moment as we approached, but widened and thickened and wheeled over and behind us until the sky was pitted with their bodies. I took picture after picture with my Graflex, the ground glass reflecting a myriad of swiftly moving forms. Then the Ducks which had first arisen, having flown in a great circle over the savanna, returned, and intersecting the newly arisen host, formed a crisscrossing maze which carpeted the heavens with a close warp and woof of living birds. Even in Mexico, where we had watched the vast flocks of Ducks and Geese on Lake Chapala, there was nothing to equal this. The Ducks looked dark against the sunlight but whenever they veered, the white wing-bands flashed like mirrors. [Illustration: FIG. 145. GRAY-NECKED TREE-DUCKS RISING FROM THE SAVANNA.] We counted the birds in one short line near us and found there were four hundred and twenty individuals. No one could count those in even one of the flocks but there must have been at least twenty thousand in the first phalanx we encountered.