The British obsession for feeding birds is causing their beaks to grow longer so they can reach into bird feeders, scientists suspect. In an extraordinary example of rapid evolution, researchers have discovered that the UK tit has a beak up to 0.3mm longer than its European counterparts.
Although it sounds like a tiny difference, scientists believe even such a small advantage could aid survival, ensuring those with longer beaks live long enough to lay eggs, and pass on their genes.
Researchers at Oxford University have been studying the Wytham Woods great tit population in Oxfordshire for 70 years and recently spotted that British great tits’ beaks have been getting longer since the 1970s.
Scientists at Oxford also teamed up with researchers from Sheffield University, the University of East Anglia and Dutch experts to also examine whether genes have changed to allow for the longer beaks. They found significant differences in the DNA of British tits compared with those in the Netherlands.
The new findings, published in Science, have led scientists to speculate that the changes in beak length and DNA are linked to the relatively recent practice of putting out food for garden birds.
“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 Professor Jon Slate, of 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.”
For the study, researchers measured beak length, and screened the DNA of more than 3,000 birds in Wytham Woods and Oosterhout and Veluwe, in the Netherlands.
The specific gene sequences which had evolved in the British birds were found to closely match human genes known to determine face shape.
According to The British Trust for Ornithology, British gardeners now spend £200 million each year feeding the birds.
“In the UK we spend around twice as much on birdseed and birdfeeders than mainland Europe – and, we’ve been doing this for some time,” said Dr Lewis Spurgin, of the School of Biological Sciences at the University of East Anglia.
“In fact, at the start of the 20th century, Punch magazine described bird feeding as a British national pastime,” “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.”
In the 1980s, only 18 species of birds had been recorded feeding on seed left out by householders, but now that has risen to 130.
Woman hand feeds wild birds
Garden bird feeding was already thought to have reversed the fortunes of the goldfinch, which was in serious decline until the introduction of sunflower hearts and nyjer seeds into feeders. Farmland birds who have suffered through habitat loss are also increasingly foraging in urban gardens during the winter time.
Martin Fowlie, of the RSPB, said: “Great tits numbers have increased fairly steadily since the 1960s and this new study may shed light on why and how this has happened.”
The team carried out further investigations into the gene with the strongest association with beak length and confirmed that British birds with the longer-beaked gene variants were more successful at reproducing in the UK but not in the Netherlands.
Electronic tags also showed that birds with the genetic variants for longer beaks were more frequent visitors to feeders than those birds which did not have that genetic variation.
“It’s certainly true that birds who have adapted to better access food will be in better condition generally, and so better able to reproduce and outperform others without that adaptation,” added Dr Spurgin.