The Christmas Island red crab (Gecarcoidea natalis) lives on a small set of Islands in the Indian Ocean. Every year, at the beginning of the rainy season, they migrate from the forests to the shoreline, millions of them, to mate and lay eggs. This migration clashes with the residents of the island, but in recent years, islanders try to take care not to interfere with the migration.
In order to study the red crabs up close, conservationists rigged up a robotic crab with a spy camera to blend in with the crabs without disrupting their natural behavior. You can see the whole sequence at YouTube. We assume there was more one than one crab robot in order to film the other. Like the real crabs, the robot had to negotiate fences, cross busy roads, and avoid being eaten. This footage is part of the BBC/PBS series -via Spy in the Wild 2. -via Laughing Squid