Nature's clock goes awry as birds, bees and flowers celebrate spring three weeks early

Winters in Britain are moving into spring earlier, according to a survey of wildlife's response to climate change.

Warmer temperatures are sparking a range of early activity, including insects emerging, trees, shrubs and plants coming into leaf and flowering, and birds nesting.

The changes were logged by 16,500 volunteers from the Woodland Trust's award- winning UK Phenology Network, which records the way that wildlife behaviour is influenced by changing weather patterns.

Every aspect of this year's spring was earlier than in 2001, Nick Collinson, the Trust's conservation policy adviser, said. "How early varied across the species range and in different regions.

"But on average insects were three weeks early, while plants were a fortnight ahead in terms of leafing and flowering. For spring migrant bird arrivals it was about a week."

He said this followed a period in which average temperatures were consistently higher than those recorded during the same months by the Meteorological Office during 1961-90.

January was 2 degrees Celsius warmer than average, February 3.2 degrees, March 2.5 degrees and April 1.3 degrees. Although the weather over the next two months might have been perceived as poor, May still finished 0.7 degrees above average and June 0.1 degrees.

"It seems the weather during the earliest months is the deciding factor in how soon natural events begin in the spring," Mr Collinson said.

"Once the process is set in motion it seems to continue. For instance, dog rose and ox-eye daisy were both in bloom about two weeks early, despite the fact temperatures during their flowering period – May and June – were closer to average.

"Earlier in the spring, hazel flowered 23 days earlier than last year and blackthorn by 22 days, while the earliest hawthorns in leaf were 17 days ahead. The number of days varied, but the pattern was similar with other species."

It was the same with insects. Butterflies such as small tortoiseshells, red admirals, commas, peacocks and painted ladies were on show much earlier than usual and bumble bees buzzed into action about 15 days ahead of schedule.

Common birds were also behaving abnormally. The 1,300 blackbird early nesting records showed the average was nine days earlier than last year, while for blue tits it was eight days.

* Exotic fish are being found off Britain's shores in growing numbers, according to the first systematic study of how marine fish have been affected by global warming. Biologists at the Plymouth Marine Laboratory have linked the arrival of tropical and semi-tropical fish off the coast of Cornwall to rises in temperature in the North Atlantic Ocean.