Longer beaks may be evolving in U.K. great tits because of the widespread use of bird feeders in the country.
How to Choose the Right Kind of Bird Feeder
Are great tit beaks really getting greater? – David Bradley
Life, Page 162 of 615
Nesting Birds - 5 ways you can help – Green&Blue
How to attract birds to your feeding station - Happy Beaks Blog
Great tit - Wikipedia
Richard Collins: Why do some urban birds have paler feathers than
The Growing Of The Great Tits
Time to 'chirp' in and help annual bird spot
Garden Birds in June - Advice – Peckish UK
Evolution in your back garden – great tits may be adapting their
Beak Evolution - Science Update
Animals, Page 77 of 237
Great Tit - where they live, food, nesting and other facts - Garden Birds