15 April 2005news.telegraphCharles Clover
A horse chestnut in leaf and blue tits starting to nest in January are among the most recent signs that spring is getting earlier.
A record number of unseasonal events has been submitted by members of the public for a database that monitors the times of annual events in the natural world.
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| Spring will advance rapidly after only a few unusually warm days |
Frogspawn was sighted as early as last October, and by January there were 43 sightings across Britain, from the Scillies to south Lancashire.
In January - which was two degrees centigrade warmer than the long-term average for 1961 to 1990 - there were 3,000 records of bumblebees feeding on nectar rather than hibernating, according to the UK Phenology Network.
The monitoring project, run by the Monks Wood laboratory and the Woodland Trust, reports that lesser celandine was seen flowering in December and daffodils on Christmas Day. As in recent years, the white dead-nettle flowered throughout the winter.
Dr Tim Sparks, an ecologist at Monks Wood, said: "The bumblebee records are the most pronounced. Some are not going to bed, and winter has almost disappeared, so it is difficult to record the first one of spring.
"It is the same with the blackcap and chiffchaff. We can't record the first migration if the birds are here all winter."
Dr Sparks says nearly everything stopped growing from February until mid-March, when winter finally arrived. But even February was still half a degree centigrade above the 1961-90 average.
"What surprises me is how easily people have got used to warm weather," he said. "If we ever get a winter like 1963 again, people will be horrified. But that is becoming increasingly unlikely."
The phenology (timing of natural events) project uses the public to record the timing of 100 events among wildlife, from the leafing of oaks - now three weeks earlier than in the 1950s - to the flowering of snowdrops and the breeding of amphibians and birds.
The project's scientists say in this month's BBC Wildlife magazine that a rough rule of thumb is that the timing of spring is approximately six days earlier for every one degree centigrade rise in temperature.
It takes only a few days with temperatures above 10C to see spring advancing rapidly.
Some species show more temperature response than others. Oaks have changed more than ash and the timing of sand martin migration has advanced more than that of swallows.
This suggests that there will not be a smooth progression to a warmer climate, if predictions of global warming are borne out. Butterflies, bats and dormice, with limited reserves of fat to live on, could be caught out by early periods of warmth followed by cold spells.
At Kew Gardens, where the rhododendrons are now in flower, Tony Kirkham, head of the arboretum, said that this year the first time of flowering was around the natural average for the past 25 years - having been up to two weeks earlier in some years.
• Kew Gardens is calling for volunteers to save its 40 acres of bluebells from being smothered by an invading African weed.
The yellow-flowered Alexanders perfoliate grows up to 5ft tall and flowers at the same time as the bluebells. "We don't know how they arrived here, but things are very serious," said Simon
Cole, manager of the natural areas. A purge of the weed is planned for late May, after the bluebells have flowered.
Anyone wishing to volunteer should visit the website www.yearofthevolunteer.org.
