Milder British weather brought about by the effects of global warming is attracting an array of exotic species of birds never before spotted on British soil.

Birdwatchers have recently been amazed at the arrival in Britain of several exotic species of birds from as far away as Africa.

Not all that long ago the only chance of sighting a Little Egret was by watching a wildlife film set in the tropics.

But Graham Madge from the Royal Society for the Protection of Birds (RSPB) says nowadays he can spot several of these small yellow-footed herons in permanent residence at Poole harbour in Dorset.

"Birdwatchers have now been watching the gradual arrival of Little Egrets in this country over the past 20 years. At that time, they were a great rarity and would have attracted birdwatchers from all over the country", Mr Madge says.

Southern invasion

Also in the Dorset outback, there is another immigrant, who has winged its way over from France.

The Cetti's Warbler, which is very active at this time of year, has made the southern wetlands its new breeding spot.

The Cetti's Warbler finds the wetlands an ideal breeding ground

And about 150 miles to the north in rural Norfolk, local pheasants are fighting off competition from a southern bird who never used to be seen north of Watford.

According to ornithologist Chris Meade, the Nuthatch, which has a blue back and sharp beak, is spreading northwards at the rate of around 20km every 10 years.

"All through the country you can see insects and birds moving further north and this is almost certainly down to global warming", Mr Meade says.

Warm welcome

Britain's slightly warmer weather has made going up north a far less chilling prospect not only for new African and Continental visitors.

The Stony Curlew made Britain its home last year

The Serin, the Lesser Blackbacked Gull, Dartford Warbler and Little Egret as well as growing numbers of indigenous birds like the Nuthatch who used to stay glued to the south coast, have now ventured northwards.

Our milder winters have also persuaded some foreign species to settle down and start a family instead of flying home.

According to Mr Meade, one very rare bird, the Stone Curlew, made Dorset its home and breeding ground throughout the whole of last year.

Ecological effects

Tim Sparks from the Institute of Terrestrial Ecology has a great deal of information to support the view that a recent rise in temperatures has not only changed the lives of many birds but has also upset the calendar for Britain's plants and trees.

The Nuthatch is a southern bird gone north

"With migrants arriving earlier, plants are coming into bloom and coming into leaf much earlier than they ever have done before," he says.

"Species such as Ash, Oak, Horse Chestnut and Lime for example, are coming into leaf perhaps 10 days earlier than they were in the 1970s," Mr Sparks says.

Insects too are feeling the heat with some butterfly species extending their range nearly 200km north over the last two decades and others have crossed the Channel for the first time.

Ian Maclaine of the Joint Nature Conservation Committee says: "Insects are responding quite quickly to climate change by extending their distributional ranges northward.

"One example would be the Median Wasp which colonised this country in the 1980s and is now quite widespread in eastern and southern Britain."

The climate change could all be temporary but Chris Meade fears it is all down to global warming with human beings to blame.

"If this was a natural event, obviously that is good news because birds would be able to fit in with natural events and so on.