Two culvert traps outside the Churchill Polar Bear jail. The traps get their name from the culvert pipe from which they are constructed. These traps are very humane, because they do no damage to the bear. Bait is placed inside them, and when the animal enters, they trigger a sliding door on the front to close. These traps are the most common type used in bear research. The design of a culvert trap makes it easy for the scientists and researchers to inject the animal with a tranquilizer to make them docile or immobile for study.