The National Wildlife Federation offices in Reston are right next to Lake Fairfax Park, so we get lots of visitors in the back patio area. So far I've seen deer, woodchuck, and even a couple of snakes. And the Washington Post recently reported bobcats have been seen and heard in and around Reston.
But the other day at lunchtime, a much less menacing sight -- two turtles totally going at it right in front of everybody. The cell phone camera picture isn't the best, but you should be able to see them at the foot of the stairs.