Fee simple possession
We're finally getting into Spring here, with most nights above freezing and daytime temps approaching 70. Animals and plants have been wildly active lately, sensing that they need to jam their mating and growth into a short period before the heat arrives.
I sometimes wonder how it would feel to have a 3-dimensional life. Birds and squirrels handle the Y axis easily, while we're stuck on X and Z unless we get into some kind of flying machine. Birds aren't stopped by fences and walls; they can go anywhere they want in a straight line. Squirrels are more restricted, but wherever power lines or dense trees form a path, they can take the high road.
The nearest power pole has a fat Comcast line below and a delicate HV electric wire on top. Squirrels prefer the fat cable for safe street crossing, and birds like to roost in rows on the HV wire, gossiping and comparing notes. But the birds don't consider the lower cable to be a different piece of territory; the Y axis doesn't create boundaries. They harass and dive-bomb every squirrel who tries to take the Comcast road under the roosting wire. Clearly a bird's territory includes a limited horizontal area, extending all the way up and down!