When I first observed a particular Tufted Titmouse land on a feeder pole, I thought he had a leaf snagged on his right foot.  As he flitted in and out, it became clear this was a bird foot deformity.  A brief Google search indicates deformities among wild birds is rare.  This rarity is undoubtedly attributable, in large part, to reduced survivability.

As you will see in the video, he (or she) appears to function quite well in spite of the excess tissue.  He has no trouble perching.  He moves freely through the cage protecting the mealworm feeder from the larger birds.  In fact, I just saw him again this morning.  So, he’s hanging in there!