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Bird feeders might be changing bird beaks

A great tit at a feeder. Photo: proxyminder / iStock

Bird beaks might be evolving to better fit bird feeders. A study of great tits in the UK, where feeders are common, found the bird's beaks have grown over the last 26 years, that British birds had longer beaks than those in the Netherlands, and that birds with genes for longer beaks were more likely to visit feeders, per Science News.

Why it matters: Scientists have known that environmental changes, like El Niño, can influence the evolution of animals. Now, it appears something as simple as bird feeders can do the same.

What they did: The scientists looked at the beaks of 2,322 great tits from the UK and the Netherlands, and also examined their genes. They tagged birds with gene variants for short and long beaks and tracked their feeding habits.

What they found: The British birds had longer beaks and were more likely to have genes associated with beak length. They also found that bird beak length had increased by about a tenth of a millimeter in 26 years, and that birds with longer beaks were more successful at raising offspring, showing selective pressure towards large beaks.

Why it happened: When the scientists looked at dietary difference between both groups of great tits, they found their diets were mostly the same. However, bird feeders are much more common in the UK than in the Netherlands. Birds with the long-beaked genes were also more likely to visit feeders than those without.

Sound smart: When Darwin visited the Galapagos, he encountered birds with such wildly different beak and skull structures, he assumed they were wildly different types of birds. When the specimens were examined, he learned that they were in fact all finches. The idea of adaptation in response to different food types in birds became central to his theory of evolution.