British birds have evolved longer beaks in order to more easily get food from birdfeeders!

Most of the time natural selection works on an extremely large time scale, and it takes thousands of years to see any development in the species. However, when the pressure or benefit that comes with an evolved adaptation is high, evolution can happen rather quickly, which is the case in the study I want to talk about today.

A great tit. Image by Francis Franklin, posted with the Creative Commons Attribution-Share Alike 4.0 International license.

What happened is that researchers University of Oxford measured the major tit (Parus major) population in Wytham Woods in Oxfordshire for several decades. This gave them a huge amount of data, and the data clearly shows that the beak length has increased during these decades. This of course raised a lot of questions, and hypotheses were formed and tested.

At the same time data from other parts of the world, and in this case The Netherlands, showed no increase in beak length during the same time. What a puzzling phenomenon! In order to make sense of it, the scientists looked at the DNA of over 3,000 great tits, and found a major different in the gene that affects the face of the bird. So the DNA supports the theory that the faces of the population in Oxfordshire and The Netherlands is different, in this case the first one having longer beaks.

More visits to the birdfeeder leads to higher fitness

The next piece of the puzzle comes from tagged birds, that showed that birds that visits birdfeeders have a higher fitness than those who visits less frequently. Fitness, as most have probably heard about from Darwin himself, is a measure of how much an individual contributes to the genetic pool. In other words, it tells how many offspring or relatives an individual is able to help create or nurture into adulthood. Genetic traits that leads to a higher fitness will spread in the population, and over time tend to become the common trait found in the population. This is basic natural selection.

What happened with the great tits in the United Kingdom is that those with longer beaks were able to get food from the birdfeeder more easily, and this in turn ended up giving the long-beaked bird an advantage in survival, and increased their fitness. Over the 40 years that the scientists made the measurements, they saw a clear trend that the long-beaked ones became more abundant, and they pretty much witnessed natural selection and evolution happening in real-time!

Why don’t the beak length increase all over the world?

If a longer beak would lead to increased fitness, then you are probably wondering why not all great tits have long beaks. Well, the thing is that they generally don’t get increased fitness by it. The different between the ones in Oxfordshire (and most likely most of the United Kingdom) get the fitness increase because having birdfeeders is extremely popular. According to the published paper, the UK have more than double the amount of bird feeders per inhabitant than most other parts of Europe, so it is safe to assume that there is no (or very little) fitness gain by having a long beak in the other parts of Europe!

I find this to be a great example of regional adaptation, where a species is able to change its physical appearance to fit the local environment in a matter of only 40 years!

Thanks for reading!

Thanks for reading my post! Make sure to leave a comment below with any questions or comments.

If you want to take a look at the research paper, it is available at Science. If you attend a university you might be able to get access to it for free, but everyone else have to pay to be able to read it. Well, the abstract is free at least.

About the author

Hi, I’m @valth! I live in Norway with my wife, our baby, and our two dogs; one of which is seen wearing a bow tie in the profile picture!

I am very passionate about nature and biology, and have been studying ecology for a few years now. My passions are mostly within conservation biology, mycology (the studies of mushrooms), botany, animal behavior and general microbiology. I really enjoy both the theoretical aspect, as well as the more practical aspect of biology, and I spend about as much time in front of biology textbooks as I do spend on finding and identifying plant, mushroom and animal species in the forests.