The Ostrich is the largest living species of bird, so it's no surprise that they have the largest eyes of any avian species. In fact, the eyes of an ostrich, measuring two inches in diameter, are the largest of any terrestrial species. Its large eyes help the flightless Ostrich perceive predators that share their wide open savanna habitat. When a predator is perceived, another avian extreme comes in handy: the Ostrich is the fastest land bird, able to achieve a running speed of up to 45mph! If you can't get enough of this extreme avian species, be sure to check out Birdorable's collection of cute Ostrich t-shirts & gifts.