SHERWOOD Pines Park's new workers bounded over at the sound of cars. Sidling up to a fence in an isolated section of the park, they eyed the people who'd come out to watch them work.

They've been brought up from the South and given jobs that involve protecting some of Notts', and Britain's, most important and jeopardised natural habitats.

That's a big job for a little pony.

But a handful of wild New Forest ponies have been brought to the park, where they will be given the job of ... well, of doing what they do. By grazing in fields around the park, they will help manage areas of endangered heath.

"These ponies specialise in grazing on lowland heath," said Notts Wildlife Trust Community and Wildlife Officer Andrew Lowe.

Land they're grazing on needs their help. Lowland heather is as much a part of the historical landscape as the tall trees that give Sherwood Pines Park its name. If Robin Hood actually existed, he would have recognised the scrubby open fields of Sherwood Forest as much as the dense trees.

But in recent years, the heath has come under increased threat from forest encroachment, as thick grass and small trees have threatened to overwhelm it. So conservation groups have gone to work to protect the heather.

That used to mean manpower, sending out crews to clear the land. But that's more expensive and intrusive. Grazing animals are the cheaper and more natural option.

Cows and sheep are used on the heather. But ponies are better. For one thing, they're picky eaters. Cows will chomp at everything on the ground, including the heather. Sheep are more selective, which would be more helpful if they didn't often select the heather. But the finicky ponies can't stand the stuff and eat all around it.

Then there's the ponies' size and proclivity towards going off on their own.

"Sheep will flock, and because they're lighter they don't break up the ground as much," Forestry Commission ecology and biodiversity officer Adrienne Bennett said.

Heavy cattle break up the ground more, which is a good thing as it allows smaller plants to break through while keeping little trees down. But like sheep, cows tend to mill around in groups. Ponies, on the other hand, not only break up the ground but cover more of it by going off on their own.

All this may sound a bit odd. Protecting Sherwood Forest by getting rid of grass and trees?

In fact, that balance of dense trees and open heath is crucial to the area's natural balance. Lowland heath, which according to the Forestry Commission is rarer and more endangered than rainforest, is home to birds, lizards and insects.

This particular stretch of heather is home to birds like the nightjar and the woodlark.

"This area of Notts has got over one per cent of the British population of those birds, so it's important we maintain that habitat for them," Mr Lowe said.

Seven New Forest ponies have now been moved into their new Sherwood Pines digs. Conservation officials plan to have four more.

erik.petersen@nottinghameveningpost.co.uk