Many of the rodents betray themselves by squeaking during territorial disputes if only they learnt to settle their differences in silence, their chances of survival would greatly improve

It is one thing to enjoy a walk through woods on your own: quite another to spend a morning in the company of expert foresters. Hearing them discuss management plans takes you down to an altogether deeper level of understanding and appreciation.

So it was when I joined Rod Leslie, the Forestry Commission's acting regional director for the south and west of England, and Ben Lennon, his Bristol beat forester, in Stockhill Plantation, 900ft up on the Mendips. The fourth member of the party was Chris Sperring, from the Hawk and Owl Trust - one important point on the agenda being to discuss the well-being of the rare, resident long-eared owls.

When the commission planted this 500-acre wood in the late 1940s, it did so with a lack of finesse typical at that time, slapping down a solid mass of conifers. But nature took a hand with the great storm of 1990, which flattened 40 per cent of the trees, in several different patches.

These areas of wind-blow have now been cleared and replanted, so that today the forest is an attractive mixture of mature conifer and open spaces - and it is these clear glades that are the key to the owls.

When trees are removed and light is let in, grass then starts to grow. Grass is the primary food of bank and field voles, and voles are the primary food of long-eared owls. Grass, voles, owls: it is as simple as that.

As we surveyed one clearing, discussion turned on field voles' amazing productivity. According to Chris, a female can give birth to as many as 12 young, and every female is ready to mate by the time she is three weeks old.

On the other hand, mortality rates are phenomenal, and the appetites of predators are voracious. A study carried out in 1992 showed that a single pair of barn owls got through 2,451 field voles in the course of rearing one family. Many of the rodents betray themselves by squeaking during territorial disputes: if only they learnt to settle their differences in silence, their chances of survival would improve greatly.

Chris also described his plan to introduce artificial nests for the long- eared owls, in the form of hanging baskets. The owls normally use old crows' nests, but, being idle builders, they do little to repair them from year to year, so that the centres sometimes give way, taking eggs or chicks with them - a mishap which baskets would prevent.

The bird-men are naturally keen that the wood should be managed so as to maintain as many grassy areas as possible. The trouble is, nature never stands still. After four or five years, in any cleared area, young trees, brambles and other shrubs suffocate much of the grass, and the habitat becomes much less good, or even useless, for voles.

In these days of enlightenment, the commission positively encourages management for wildlife, and accepts some loss of revenue provided other benefits accrue. To have long-eared owls breeding is seen as a definite benefit: hence some concessions can be made.

Nevertheless, this is essentially an upland production forest, and must pay its way. Conservation work such as weeding and grass-cutting is now so expensive that little can be afforded.

As we walked from block to block, the experts discussed alternatives. The ideal solution, Rod Leslie pointed out, would be to clear-fell and replant the whole wood block by block, in rotation, so that it would always comprise a mixture of high trees and open spaces, providing the owls with both nesting and hunting areas. The main problem in Stockhill is a shortage of fellable material: too much went down in the gale, and the remaining stands are mostly of moderate quality.

One possibility is to widen the rides, removing a few young trees from the edges of re-stocked areas; another, not to replant a circular patch where most of the seedlings failed: in other words, to watch for opportunities, and make the most of them.

All this is a far cry from the bad old days, when the commission planted every square yard of its ground and turned its back on any creature that might think of taking up residence. Today the owls are more than welcome; and they, I like to think, have showed their appreciation by moving in.