illustration of this.

They were passing a wide sand-bank that shelved back from the river,
with a scarcely perceptible slope, when they saw, at a distance of about
two hundred yards from the water's edge, a crocodile making for the
river. He looked as though he had just awoke from his torpid sleep, for
his body was caked all over with dry mud, and he seemed both hungry and
thirsty. It was like enough he was coming from some inland pond, where
the water had dried up, and he was now on his way to the river.

All at once two dark shadows were seen passing over the white surface of
the sand-bank. In the heaven two large birds were wheeling about,
crossing each other in their courses, and holding their long necks
downwards, as if the crocodile was the object of their regard.

The latter, on seeing them, paused; and lowered his body into a squatted
or crouching attitude, as if in the birds he recognised an enemy. And
yet what could such a large creature fear from a pair of "king
vultures?" for king vultures they were, as was easily seen by their
red-orange heads and cream-coloured plumage. What could a crocodile,
full ten feet long, fear from these, even had they been eagles, or the
great condor himself? No matter; he was evidently frightened at them;
and each time that they drew near in their flight, he stopped and
flattened his body against the sand, as if that might conceal him. As
soon as they flew off again to a more distant point of their aerial
circle, he would once more elevate himself on his arms, and make all
haste toward the water.

He had got within about an hundred yards of the river, when the birds
made a sudden turn in the sky, and swooping down, alighted upon the sand
directly before the snout of the crocodile. The latter stopped again,
and kept his eyes fixed upon them. They did not leave him long to rest;
for one of them, making a few hops towards him, came so close, that it
might have been supposed the crocodile could have seized it in his jaws.
This, in fact, he attempted to do; but the wary bird threw up its broad
wings, and flapped to one side out of his reach. Meanwhile, the other
had hopped close up to his opposite shoulder; and while the crocodile
was engaged with the first one, this made a dash forward, aiming its
great open beak at the eye of the reptile. The crocodile parried the
thrust by a sudden turn of his head; but he had scarcely got round, when
the second vulture, watching its