THE mating call of a song thrush echoes through the trees and a squirrel scuttles across the ground where the red stain of raspberry berries has been trampled into the ground.

Trouble is, it's December, and this is more of a scene to be seen in spring.

In Bristol's Stoke Park mother nature has been tricked into thinking spring has come early and despite the recent cold snap there are few signs of winter.

While local families could be enjoying one of the warmest Christmases on record, rising temperatures could mean trouble for the city's wildlife.

Steve England, chair of Stoke Park Action, said: "This all revolves around rising temperatures – a soil temperature of above 16C stimulates plants to grow.

"At the moment the soil temperature is warming up so quickly it is causing all sorts of things to grow out of season."

Temperatures are a far cry from last year's snowy spell and earlier this month the Evening Post featured a story on daffodils growing in Portishead.

In Stoke Park, where Mr England has found fossils dating back millions of years, dozens of plants are flowering out of season.

He said: "The lesser celandine, a member of the buttercup family, is usually the first flower to arrive in spring and that's out already. We have wood anemone out and that usually grows at the end of February.

"Yesterday I took a group on a walking tour and we came across wild raspberries growing – they were delicious but it's worrying to see them now. They are summer plants."

Father-of-three Mr England said he has also seen blackberries in flower, wild geranium growing and lady ferns sprouting new fronds. Even the festive-sounding elf cup fungus, which usually heralds the start of spring, is in blossom.

And the warmth is having a knock-on effect for animals in the woods.

Mr England said: "In the heart of the woods the hazel trees have full summer leaf and this has an implication on the food chain. There are still insects on there and this stimulates breeding.

"The jackdaws are building their nests, the nuthatches are singing their spring mating calls along with the song thrushes. Wood pigeons are so confused they are already mating. In Stoke Park we have a small population of goldcrest that stay in the park while the rest migrate for the winter. This year there is a massive group that have stayed which is really unusual.

"I'm worried because if the temperatures do drop then the food source for all these animals will dry up. If they lay eggs then these eggs will freeze and some of these plants will not flower again for another year.

"Hibernating creatures such as slow worms and grass snakes will also think spring has come early and then get caught out if it freezes."

Mr England said he was hoping for a prolonged period of cold to send plants into suspended animation or the slowing down of life.

He said: "I don't know if this is related to human intervention and us burning fossil fuels or just the natural cycle of the earth but you can walk through the woods now and think it was the middle of March. It's incredible."