Great tits cope well with warming

At least one of Britain's birds appears to be coping well as climate change alters the availability of a key food.

Researchers found that great tits are laying eggs earlier in the spring than they used to, keeping step with the earlier emergence of caterpillars.

Writing in the journal Science, they point out that the same birds in the Netherlands have not managed to adjust.

Understanding why some species in some places are affected more than others by climatic shifts is vital, they say.

The Royal Society for the Protection of Birds (RSPB) commented that other species are likely to fare much worse than great tits as temperatures rise.

Perfect timing

The research uses a long record of great tits in a breeding site at Wytham Woods near Oxford, where observations began in 1947.

"We think it’s the longest running population study of wild animals anywhere in the world where animals are marked (ringed)," said Ben Sheldon of Oxford University, who led the new research.

"The population contains about 400 breeding pairs, and they produce between them 2,000 or more offspring each year - so over the course of the study about 80,000 birds have been ringed and studied," he told BBC News.

The current work used records going back only to 1961, when a standard methodology was adopted.

The great tits are laying eggs now about two weeks earlier in the year than they were 47 years ago.

The timing is crucial, because for the two-week period after they hatch, the chicks have to gobble down huge quantities of winter moth caterpillars which only emerge for a short period.

"Winter moth larvae can make up up to 90% of the biomass of insects on oak trees at that time," said Professor Sheldon.

"Great tits have eight or nine babies in a brood, and each of them will eat about 70 caterpillars a day.

[link to news.bbc.co.uk]