The Ostrich is the biggest bird in the world and also the fastest bird on the ground. They are able to run for short periods of time of up to 50 miles per hour! Though the ostrich is large and able to run quickly, they are unable to fly. They have a very powerful kick they can use to defend themselves. The ostrich mostly eats grubs and insects, often found in the ground, which is why they are known for putting their head in the ground.