The term 'land-bound bird' can be summarized by the crossword solution EMU, which is a three-letter word. An EMU is a large, flightless bird native to Australia that is closely related to the ostrich. It is the second-largest living bird by height, after the ostrich. Emus are known for their long legs and neck, and they can reach speeds of up to 30 mph. They are omnivorous, eating a variety of plants, insects, and small animals.