Or the bobcat, needing rabbits and beavers and den sites.

And it need beavers to create the wetlands, and maybe some other things.

And rapidly we started to realize that beavers can be something that a bobcat needs.

So, we would read in field guides, the standard field guides that maybe you have on your shelves, you know, what beavers need is A slowly meandering stream with aspen trees and alders and willows, near the water. That's the best thing for a beaver.

So, we studied the fish and the frogs and the birds and the bees, the 85 different kinds of fish that were on Manhattan, the Heath hens, the species that aren't there anymore, the beavers on all the streams, the black bears, and the Native Americans, to study how they used and thought about their landscape.