Tits of the 2020s are breeding three weeks earlier than their 1940s forebears thanks to climate change, a study of the birds in an Oxford woodland has found.

University of Oxford researchers have spent the last 75 years studying the behaviour of Great Tits in Wytham Woods, around three miles north west of the city.

Now, they monitor more than 1,200 nest boxes set up across the woodland.

READ MORE: Oxford college becomes first to sign gagging clause pledge

Prof Ben Sheldon, who leads the Wytham Great Tit study, said: “One of the most striking changes [since 1947] is that the average Great Tit breeds three weeks earlier now than it did at the start of the study.

Oxford Mail: Prof Ben Sheldon of the University of OxfordProf Ben Sheldon of the University of Oxford

“This shift is a clear signal of the effects of climate change on one of our most familiar woodland and garden birds, and it is studies of this kind that allow us to work out what the consequences of such changes have been, and what they may be in the future.”

When the Wytham Great Tit study was launched in 1947, two years after the end of the Second World War, the first egg of the year was counted on April 27.

This year, the first Great Tit egg was recorded on March 28 – almost exactly a month earlier than 75 years ago.

READ MORE: Six figure makeover for Jericho pub

Researchers say the timing of the laying of Great Tit eggs is influenced both by large and small-scale factors, including climate, social interactions and the health of nearby trees.

By studying the behaviour of the birds over three-quarters of a century, the academics have been able to note long term trends in the creatures’ behaviour and response to factors like climate change.

Oxford Mail: A great tit Picture: KEITH MCMAHON/OXFORD UNIA great tit Picture: KEITH MCMAHON/OXFORD UNI

The Oxford project, which has spawned more than 70 PhD theses, is the longest continuous study of an individually-marked animal population in the world.

And the milestone anniversary has been welcomed by naturalist Sir David Attenborough, who said he was ‘delighted’ by the news.

“Having visited several times, I know how fundamental this study, and others like it, have been for our understanding of the impacts of climate change on the natural world,” the veteran broadcaster added.

“Long-term studies like this require long-term commitment, and I wish the study – and its practitioners – a long and productive future.”

Prof Lord John Krebs, Emeritus Professor of Zoology at Oxford, and a member of the House of Lords Science and Technology Committee spent several years researching tits in Wytham Woods while studying for a doctorate on the subject half a century ago.

Oxford Mail: Great tit chicks Picture: ELLA COLE/OXFORD UNIGreat tit chicks Picture: ELLA COLE/OXFORD UNI

"In the late 1960s, when I started my DPhil on the Great Tits in Wytham, there was a remarkable 'long-term' record of the population, which I analysed to understand what factors determined the number of birds in the population," he said.

‘At that time 'long-term' meant about 20 years. Now, thanks to the foresight of those who started the study, and many generations of field workers, there is a truly unique record which will continue to yield novel and important insights into the ecology and behaviour of bird populations in the wild."

Keep up to date with all the latest news on our website, or follow us on Facebook, Twitter and Instagram

For news updates straight to your inbox, sign up to our newsletter here

Have you got a story for us? Contact our newsdesk on news@nqo.com or 01865 425 445.