WORK on reducing heath fires in Dorset has led to increasing numbers of rare birds including the Dartford warbler being spotted in the county.

Research by the Rare Breeding Birds Panel has shown that species such as little egrets, firecrests, cranes and Mediterranean gulls all chalked up their highest numbers since monitoring began in 1973.

The panel, which conducts an annual survey, suggests the warmer climate is helping the birds reach record numbers, but Borough of Poole’s nature conservation officer Jez Martin said there were other factors.

He said: “It’s a bit early to say for this year because they’ve only just started breeding.

“One of the things we are still not sure about is whether that cold spell we had earlier on has affected them.

“Dartford warblers in recent years have increased in numbers. Some of it may be about the weather but they are crucial birds of heathland and a lot of work has been done on heathland to make it better for them.

“I think it’s more likely it’s due to management of the site and reduction in arson and fires.”

Mr Martin said the early signs were that numbers would be good this year, with at least 40 pairs of Dartford warblers on Canford Heath.

Mark Holling, secretary of the Rare Breeding Birds Panel, said warmer weather may be having a negative impact on some northerly species, including the purple sandpiper and Temminck’s stint, which each recorded just one bird in 2006.

He added that some species of birds which might be expected to benefit from warming temperatures have actually seen numbers decline, including the golden oriole, marsh warbler and the wryneck, which had no records at all in 2006.

But he said the decline of golden orioles may be linked to changes in the availability of habitat, for example the felling of poplar plantations they favour.