We have a lot of these little guys running around our backyard:
This Squirrel is one of many who love to hang out below our bird feeder and get anything that falls to the ground. I snapped this from our deck, which is about 25 feet away from the feeders. I used my Canon EF-S 55-250mm lens to get this shot. Even with the 1.6 crop factor of the T3i (making this a 370mm or so effective focal length) and some cropping I could still use some more reach. I'd like to get a 400mm lens at some point but for now 250 is all I got.