In Chapter 3 of Lord of the Flies, Jack yells "Got it!" What does Ralph think might have caused Jack's excitement?

By Chapter 3 in Lord of the Flies,
Jack has already become single-mindedly addicted to hunting the wild pigs on the island.
While Ralph is trying to stress the importance of keeping the signal fire going in the
hope that a plane or ship will see the smoke, Jack can barely "remember what rescue
was." Both Ralph and Jack were looking skyward, but for very different reasons. While
Ralph was looking to see how far the smoke could be seen, Jack was eyeing the shady,
downward slope of the mountain. As always, he was thinking of pigs. When he cried out,
"Got it!" it was because he had just come to the realization that the shade was where
the pigs could be found.

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"Of course! They'll lie up there--they must, when
the sun's too hot--"

Ralph,
thinking of rescue first, hoped that Jack's cry was
because

"I
thought you saw a ship!"