The ____ in the Tree

Today while hauling trash to the community dump I saw a large bird flying in front of the car. I slowed down and watched it swoop up to a branch overlooking the road. Instantly I thought it was a hawk or an eagle. Turns out I was wrong.

Instead, it was an animal I had previously only seen in zoos. It was large for its species, and watched me with piercing eyes until I slowly drove away.

Until today, I never knew such an animal lived in this part of Mississippi.

Your job is to fill-in-the-blank above. What did I see?