Flying in the desert while being transformed into a Corgan was a very very bad idea. The desert is a very very cruel place. Not every animal or bird is meant to survive in this place. Arvin knew that the Corgans were not made in such a way that they could survive the hot climate of a desert. And it was his foolishness to fly in the desert despite that.
While flying Arvin's body would get heated up from time to time so he had to take a break often. He would transform back into his human form to decrease his body temperature. And he would drink a lot of water while cooling down his body. He was drinking water at a very fast rate. Although the amount of water that he had was enough for the 15 people and would last for at least a month. But that didn't mean that he should just waste it like that.
