Why barn owls’ plumage becomes more reddish and mottled
Keystone-SDA
Over the course of thirty years, the plumage of Swiss barn owls has become more reddish-brown and spotted. A long-term study by the University of Lausanne interprets this as a sign of rapidly advancing evolution, as it announced on Wednesday.
This content was published on
October 21, 2026 – 15:48
According to the study report, published in the journal Nature Communications, alongside owls with immaculate white plumage, the scientists had observed an increasing number of specimens with plumage ranging from golden-brown to deep red. This was neither a chance finding nor purely cosmetic in nature.
According to the long-term study, the colour change is the result of a rapidly advancing evolutionary process. It is linked to fertility and hunting strategies, and thus also to food intake.
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The scientists have identified a gene that could be linked to traits such as stress management or aggression, whilst also playing a role in pigmentation. Ultimately, however, it remains difficult to determine exactly which ecological factors account for the varying colouration.
White barn owls use moonlight to hunt their prey – mostly field mice. The red owls, on the other hand, feed predominantly on voles. The mottled plumage, in turn, is linked to immunity and the ability to cope better with stressful situations such as food shortages or parasite infestations.
Not least, the study demonstrates that evolution does not only take place over millions of years, but also within timeframes of just a few decades. Against the backdrop of climate change, this is seen as an encouraging sign. The ability to adapt quickly could help living organisms cope swiftly with environmental changes.
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Translated from German, reviewed by an English Department journalist.
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