I walk my dogs almost daily in a park near my house. For two years there was a crow that was clearly sick or disabled in some way, as I never saw it fly and it was missing feathers. When ever I saw him/her while I was walking with my dogs the others crows would fly over and protect the one crow and usher it away from us. I was always busy keeping my dogs away from them so did not study it as much as I wished I had. I was amazed that it was able to live so long with what ever issues it had, but clearly its family protected it.