The reason some birds in Britain have evolved bigger beaks over the past 40 years may be down to the country’s enthusiasm for feeding them in their gardens, researchers have said.

The report published on Thursday in the US journal Science compared beak length among great tits in Britain and the Netherlands, where bird feeders are less common.

“Between the 1970s and the present day, beak length has got longer among the British birds. That’s a really short time period in which to see this sort of difference emerging,” said study co-author Jon Slate, professor in the department of animal and plant sciences at the University of Sheffield.

“We now know that this increase in beak length, and the difference in beak length between birds in Britain and mainland Europe, is down to genes that have evolved by natural selection.”

The report is part of a long-term study on great tits in Britain’s Wytham Woods, along with Oosterhout and Veluwe in the Netherlands.

Researchers screened DNA from more than 3,000 birds in order to uncover genetic differences between the British and Dutch populations. Changes in specific gene sequences in the British birds were found to closely match human genes that determine face shape.

Researchers discovered that birds with genetic variants for longer beaks were more frequent visitors to feeders than birds without the genetic variation.

There was “strong similarities with genes identified with beak shape” in line with Charles Darwin’s historic study of finches, which showed how they evolved physical traits that helped them adapt to different environments in the wild.

“In the UK, we spend around twice as much on birdseed and bird feeders than mainland Europe – and, we’ve been doing this for some time,” said co-author Lewis Spurgin of the school of biological sciences at the University of East Anglia (UEA). “Although we can’t say definitively that bird feeders are responsible, it seems reasonable to suggest that the longer beaks amongst British great tits may have evolved as a response to this supplementary feeding.”

Researchers on the study came from the Netherlands Institute of Ecology and the Universities of Wageningen, Oxford, Exeter, East Anglia and Sheffield.