Some birds enjoy the freedom to explore the most of our world. They fly long distances, dive into the water for food, and nest on the land.
As humans we need firm ground. We make things that we rest on, or are encased within. With these we fly through the air, on or in the water, in outer space, and on land. As we make for our own desire, exploration, and need, we take far more from the world than all other life forms on this earth have ever done. Life is give and take. We get back what we put in.