New birds and mammals to Norfolk are likely to be spotted in the county and off its coastline over the next few years as a result of climate change, according to wildlife experts.

Species of bats and birds rarely, if ever, seen in Norfolk are likely to become more commonplace, while whales and dolphins could also be sighted more frequently.

Birds such as the great white egret, glossy ibis, black kite, penduline tit and fan-tailed warbler are also likely to colonise the UK over the next 50 years and could be seen in Norfolk.

Dr Dave Leech, Norfolk mammal recorder for the Norfolk and Norwich Naturalists' Society (NNNS), said: 'This is a period of rapid change in environmental conditions, which is likely to impact on the diversity of plant and animal species throughout the UK, including Norfolk.

'Some species from warmer climes may benefit and move into the country, but equally, others that prefer wetter, more temperate conditions may be forced out.

'As an increasing number of people are interested in wildlife these days and as technology - binoculars, telescopes, bat detectors) and identification guides develop, so the ability to discover previously overlooked populations increases.'

Sam Philips from Norwich Bat Group said an increase in mean temperature in Britain could mean the range of our resident bat species may increase northwards.

'It may also result in some species spreading into Britain, such as Kuhl's pipistrelle, a species recently discovered on Jersey. The fortunes of bat species are, however, heavily dependent on those of their insect prey, which themselves will change in distribution and number as the climate changes,' he said.

'Agri-environment schemes may help to create better foraging habitat; but realistically we really don't know what the potential impacts of climate change will be.'

And Dr Peter Evans, director of the Sea Watch Foundation, said that common dolphin and Risso's dolphin were occurring much more regularly in the North Sea, probably as a result of climate change affecting the ranges of particular prey species.

Most sightings had been in the northern North Sea, mainly off north-east Scotland, he said, with just seven records of the common dolphin off Norfolk and no sighting of the Risso's.

In August last year, a Sowerby's beaked whale - only Norfolk's second - was found beached on Blakeney Point. A team of birdwatchers, wardens and tourists were on hand to carry it to the sea where it swam back to deeper waters.

The species usually lives in water more than 1,000m deep, such as that found in the Rockall Trough, between Shetland and the Faroes; in the Bay of Biscay and around the Azores. The only previous record in Norfolk was a beaching of one creature at Happisburgh in August 1952.

Details of the beaching are included in the newly-published Norfolk Bird and Mammal Report, which summarises sightings of every bird and mammal species recorded in Norfolk in 2009.

Another rarity noted in the book is the black-winged pratincole, a Russian visitor that appeared at Titchwell in May. Other highlights include a barn owl, seen hunting in broad daylight, and otters glimpsed in a Norfolk stream. Both species, once threatened, are now making a comeback.

The report also notes the spread of Chinese water deer. The species was first reported in Norfolk in 1968, but have now expanded rapidly in their Broads habitat and are now spreading along the North Norfolk coast.

Rare birds spotted so far this year in Norfolk include a flycatcher, believed to be an alder flycatcher but unconfirmed, at Blakeney Point last month; a Wilson's phalarope at Welney in September; a river warbler in July at Thorpe and a trumpeter finch at Blakeney / Cley in May.

The Norfolk Bird and Mammal report is free to all NNNS members and costs �12, including postage and packing, to non-members. It is available by sending a cheque payable to Norfolk and Norwich Naturalists' Society, to Tony Leech, NNNS Publications, 3 Eccles Road, Holt, Norfolk NR25 6HJ.