What does Piggy attempt to call attention to?

When the first fire which they light on top of the mountain gets out of control Piggy is the first to notice and he tries to draw attention to the fact. He also tries to make them realise that nobody had bothered to count the littluns or check whether any of them were still picking fruit in the pocket of trees that the fire had spread to. Just afterwards he realised that the small boy with the mulberry coloured birthmark on his face was missing, he was never seen again.