Whose Limb is it Anyway?

I happened upon a Red-tailed Hawk sitting on a tree limb earlier today. The bird spent about a half hour preening in the same place. Unfortunately, there was a thick limb between the bird and I so there wasn't really an opportunity for a nice "portrait."

But, an Eastern Gray Squirrel happened to climb the trunk of the tree and head out onto the limb where the bird was sitting. Clearly, the hawk is higher up on the food chain and I can only imagine what went through the squirrel's mind at that moment.

The two sat there for a minute or so and then the squirrel backed off and headed to safety.

Canon EOS 5D, EF300mm f/4L IS USM +1.4x, ISO 800, f/5.6, 1/30 sec.