Saltwater crocodiles are by nature violent and territorial, and tend to migrate away from home following particularly gruesome disputes. The migration is risky, but only 1% of saltwater crocodiles survive to adulthood so it's a risk worth taking. The long migration is made possible due to the crocodile’s unique physiology. They can travel up to 10 miles a day and go without eating for weeks. And when they need a rest, one side of the brain sleeps while the other stays alert for potential threats. This is called unihemispheric sleep, a feature saltwater crocodiles share with other reptiles, dolphins, and some birds.