ECOLOGISTS are working with the owners of the UK's deepest mine to encourage wildlife on its land.

Already a survey has revealed significant numbers of rare butterflies living on countryside surrounding Boulby Mine, near Loftus, on the east Cleveland coast.

Mine operator Cleveland Potash recently became a member of the Industry Nature Conservation Association (Inca), which helps companies promote wildlife on their sites.

After the company joined, Inca ecologists examined the large expanse of woodland and meadow which Cleveland Potash owns around its main industrial operations at Boulby.

Although a wide variety of flora and fauna was found, the main discovery was eight species of butterflies, including speckled wood.

The speckled wood butterfly has been heading steadily northwards with the UK's warming climate - it was first recorded in Cleveland in the late 1990s - but remains rare in the region.

Inca ecologist Jonathan Gibson said: "During our survey, speckled wood was the most common one seen, even more so than more common species such as red admirals and peacocks.

"Speckled wood is very rare in the North-East and the survey showed that Boulby is the premier site for this species in the county."

The survey also revealed other butterflies, including common blue, comma and ringlet, and Mr Gibson said that the site produced important wildflowers, including wood sorrel, giant bellflower, common figwort, pendulous sedge and wood vetch, which are characteristic of old woodland, a rare habitat in Cleveland.

The nature of the woodland also meant that the surveyors found the cardinal beetle, which tends to occur in pockets around the region.

Birds found included the wood warbler and great spotted woodpecker, and a kingfisher was seen on the stream running through the site. Roe deer tracks were recorded and stoat have been seen.

To improve the habitats, the company is putting up a barn owl box in a disused building - the bird is thought to exist in the surrounding area.

Anne Forbes, company environment officer, said other measures being considered were the erection of kestrel boxes, bat boxes in a disused ironstone workings tunnel and the creation of a pond. Swallow boxes around the main offices were also suggested by Inca.

She said: "We do not do a lot of management of the habitats, preferring to leave them alone for the wildlife.

"However, it shows that through simple measures such as bird and bat boxes, which do not cost much, we can encourage wildlife. A lot of people do not know the wildlife is there and this survey allows us to show people that we may be a heavy industry but we can live alongside the wildlife.

"We are also promoting the wildlife to the workforce so that they know what is living on our land."

Mr Gibson said: "Cleveland Potash Ltd is one of the few industrial members of Inca to have large areas of woodland on their site. We are very pleased to have Cleveland Potash on board and look forward to working with the company in the future."

The company employs 850 people plus contractors at the site. Potash can be used in products including fertiliser.