Why Do Tawny Owls Come In Two Different Colors?

A recent genetic study reveals that the pale grey plumage of the tawny owl could be linked to the bird’s ability to survive in cold environments

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A brown-morph tawny owl (Strix aluco), also known as the brown owl, hiding on a tree. This species has two plumage color morphs: brown and grey. (Credit: Anil Öztas / CC BY-SA 4.0)

A recently published study finds that the silver plumage of the tawny owl, Strix aluco, is related to its ability to thrive in extremely cold environments. Color is an evolutionary adaptation that helps animals in a number of ways: camouflage, mate attraction and, as we’re seeing here, color can even be related to physiological abilities and behavioral traits conferred by the pigments themselves. But the presence of more than one color polymorphism, or ‘morph’, in a population is probably one of the most enigmatic of evolutionary questions.

Grey morph tawny owl (Strix aluco) in the Czech Republic. (Credit: Martin Mecnarowski / CC BY-SA 3.0)

Tawny owls commonly occur in woodlands across all of Europe and into portions of western Siberia. Tawny owls are medium-sized nocturnal birds who have two plumage color morphs, pale gray and dark brown. It has long been suspected that these two plumage color morphs are consistent with the owls’ physiological adaptations to their environment: reddish-brown individuals are found in warmer and more humid environments, mostly in…