They put up a sign "Beware of the snake!"
After a few days, they realized that the snake would have to feed, so they went to the nearby Montaignyard village, and bought two ducks to feed to the snake. The marines lifted the wire, threw the ducks in, expecting to see the snake immediately pounce upon one of the ducks and devour it. Apparently the snake was not hungry just then so it lay still. Later that night, after all had turned in, there arose a great ruckus from the snake pit, lots of quacking and thrashing about. Everybody assumed that the snake had fed.
The next morning, when they went out to see the well-fed snake, it was dead....the ducks had pecked out its eyes and killed it.
Later that day the marines made a new sign:
BEWARE OF THE DUCKS