It's not on its own. Mom is near by. At this age baby deer don't have any scent and their too weak to follow mom very far or run away from dogs and other preditors. So mom drops them off some place and they lay still as death, until she picks them up to feed. Since preditors can't smell them and instinct tells them to lay still, not even moving when a truck is started and backed off of them or dog walks within feet there safe from critters that there not strong enough to run away from. In another week or two it will be stronger and act more deer like and run from danger.