Great tit

Clive Knight has photographed a great tit at its nest site in one of the reserve’s oaks.

For several reasons, the great tit (Parus major) is a popular subject of ornithological studies, in fact it is the most intensely studied of all birds. While the species covers a wide geographical range, individual birds rarely move far from where they were raised, which is often conveniently near human habitation, so that a ringed bird can easily be tracked throughout its life.

The longest-running study began in Wytham Wood near Oxford in the 1940s and continues to this day.

And great tits are more than happy to use nest boxes; on April 27th 1947, the year’s first great tit egg in Wytham Wood, Oxfordshire, was counted in a nest box erected by researchers from Oxford University. That survey has become the world’s longest-running study of individually tagged animal behaviour and continues to this day. Its findings have been key to our understanding of how bird populations change in response to the environment, in particular in response to the changing climate.

This year, 75 years later, the first great tit egg in Wytham Wood was counted on March 28th, almost exactly a month earlier.