That night after the miserable defeat, Bat decided enough was enough. He flew down and joined the mammals.
“What are you doing here?” roared the cougar, his paw raised to strike bat down.
Bat opened his mouth wide to show his pointy teeth. “Wait,” he said, “I am one of you! See, I have teeth in my mouth like a mammal -- not a beak like a bird.”
The mammals pondered for a few moments and then agreed that Bat did indeed belong on their side.