The Panamanian golden frogs live near a noisy mountain stream, so croaking does it no good. So it has evolved a clever way to communicate to rivals and mates: it waves to them!
Hilary Jeffkins, senior producer of Life In Cold Blood, said the semaphoring behaviour of the Panamanian golden frog was very unusual.
"Normally, frogs would croak to get their message across but it's too noisy," she said. "An extra mechanism they've evolved is to wave to each other."
Sadly, right after the BBC One Series Life in Cold Blood crew filmed the frogs, a fungus infection wiped out the entire frog population. The film thus captured the Panamanian golden frog's last wave.