Specimens exhibiting beak overgrowth characteristic of avian keratin disorder: (A) Mew Gull 993 (Larus canus), (B) American Crow 674 (Corvus brachyrhynchos), (C) Black-billed Magpie 992 (Pica hudsonia), (D) Blackpoll Warbler 1020 (Setophaga striata), (E) Hairy Woodpecker 969 (Picoides villosus), and (F) Red-breasted Nuthatch 929 (Sitta canadensis). Images are not to scale.