A tranquillizer gun (also spelled tranquilizer gun or tranquilliser gun), capture gun, or dart gun, is a non-lethal gun used for capture via a special chemical. Tranquillizer guns shoot darts filled with tranquillizer that, when injected, temporarily sedates an animal, so that it may be handled (or captured) safely. The tranquillizer can be a sedative, anaesthetic, or paralytic agent. Tranquillizer guns have a long history of use for capturing wildlife without injury. (source)