A ptarmigan (Lagopus mutus) in both summer and winter plumage. Colour lithograph, ca. 1875. https://www.rawpixel.com/image/13954691/image-animal-public-domain-birdFree Image from public domain licenseRock ptarmigan (Lagopus mutus) illustrated by the von Wright brothers. Digitally enhanced from our own 1929 folio version of… https://www.rawpixel.com/image/325994/free-illustration-image-von-wright-brothers-wright-birdFree Image from public domain licenseRock ptarmigan (Lagopus mutus) illustrated by the von Wright brothers. Digitally enhanced from our own 1929 folio version of… https://www.rawpixel.com/image/326329/premium-illustration-psd-america-ancient-animalView license