Feeding garden birds in the UK could be causing great tits to grow longer beaks, according to a new study.


Researchers comparing the morphology and genetics of great tits in the UK and the Netherlands have discovered that great tit beak lengths in the UK are longer.

By analysing the data, they were able to establish that the change in beak lengths had occurred in a short time period between the 1970s and present day.

“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,” says Prof Jon State from the University of Sheffield.

The results are part of long-term study of great tit populations in Wytham Woods near Oxford and in Oosterhout and Veluwe in the Netherlands.

For the study, the DNA of more than 3000 birds was screened to highlight the genetic differences between the British and Dutch populations.

Birds with the longer beak genetic variation were found to visit birdfeeders more regularly than those without the genetic variation.

“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,” says Dr Lewis Spurgin from the University of East Anglia.

“Although we can’t say definitively that birdfeeders are responsible, it seems reasonable to suggest that the longer beaks amongst British great tits may have evolved as a response to supplementary feeding.”

Further investigations by the team confirmed that British birds with longer beaks were more successful at reproducing and were generally in better condition.

A follow-up study is looking at DNA samples from great tit populations around Europe to determine whether the long beak adaption is specific to the UK.

Read the paper in Science


Main image: Garden bird feeders could be changing the morphology of British great tits © Tom Meaker / EyeEm / Getty