Why Do Animals Need to Move Around So Much?

Why do animals need to move around so much? Why don't they just sit on their bird couches for the rest of their life, just lounging in one spot? It looks as if they do that because it enables them to get access to food resources and may be better weather conditions. David's favorite example is a really cool critter uses a whole bunch of navigation tools the desert. Anyou got to imagine it's living in this god forsaken desert environment. I mean, salt pans, flat salt pans in the sahara desert,. So hot that the desert will die of heat if it doesn't move quickly enough and get back into its nest fast enough.