In other species: chicken , ducks , domestic goose , turkey , Indian peafowl , Eurasian bullfinch , Ring-necked pheasant , rock pigeon , Japanese quail , South polar skua , swan goose , superb starling , carrion crow , hooded crow , emperor penguin , red-fronted tinkerbird , yellow-fronted tinkerbird , white wagtail , Mallard

Mendelian trait/disorder: yes

Considered a defect: no

Key variant known: no