Groups of hardy workers were busy on our reserves during the Christmas and New Year holidays, completely unpaid and enjoying every minute!

Their significant attributes include four legs, a thick skin and a good set of grinding molars to tackle rough vegetation — these ‘volunteers’ are our livestock.

Your average farm animal won’t survive on a nature reserve. The forage is often prickly and contains limited goodness, especially in winter. Only the hardiest of breeds can thrive on this diet, and we choose our suitable candidates carefully.

Last year, four Dexter heifers joined our herd grazing Oxfordshire reserves, and a large group of dark brown Hebridean sheep are now nibbling the chalk turf of the Chilterns.

The newest arrivals are four Welsh Mountain ponies from Carneddau in Snowdonia. These tough little ponies have a pedigree running back to Celtic times, and they mostly live wild on the mountains. We visited the annual round-up to choose the youngsters that are now acclimatising at Chimney Meadows, before going to Parsonage Moor in June. What do we hope to achieve with this grazing? Is not nature best left to her own devices?

We live in a country with only fragments of its wildlife habitats left, and most of these are the products of many centuries of productive farming. Modern farming techniques introduced in the latter half of the 20th century, based on chemicals and cheap fossil fuel, radically affected the landscape. Hedgerows were grubbed up, wet meadows drained, and creatures that were once commonplace, such as the corncrake and marsh fritillary butterfly, became increasingly rare or disappeared altogether.

Looking after the remaining fragments of natural wildlife habitat is the Trust’s highest concern, and the grazing effects of traditional breeds of cattle, ponies and sheep are one of the tools that help to achieve this. Without their positive action controlling invasive brambles and tree seedlings, our flower-rich fields and fens would quickly be covered in young scrub and trees.

The animals’ ability to chew down tussocks of grasses and sedges leaves spaces for wild flowers to grow. Cattle tear at taller clumps, creating an uneven ragged sward. Sheep and ponies tend to nibble closely which maintains a close-cropped turf.

Even their dung attracts insects and worms that provide food for badgers, hedgehogs, birds and bats. More than 250 species (mainly beetles and flies) live, eat and breed in cowpats.

Our livestock are well worth the effort of looking after them, and add an interesting dimension to a walk around a BBOWT reserve. Their welfare is ensured by our volunteer stock watchers who regularly walk our sites, checking the animals are healthy.

You can see what a great job our ruminating reinforcements are doing on these reserves: Hartslock and Aston Clinton Ragpits in the Chilterns: where close nibbling and the dainty hooves of Hebridean sheep keep the turf short and enable thousands of orchids to flower in June.

The Cothill Fen project, near Abingdon —Parsonage Moor, Lashford Lane and Dry Sandford Pit — are so close together you can visit all three in a few hours. These reserves are grazed by ponies and cattle from June to November. The special fen habitat has rare plants, and insects such as the southern damselfly, which thrives on the little pools and puddles caused by the Dexters’ hooves.

If you would like to visit any of our nature reserves, become a volunteer stock watcher, or find out about becoming a member of the Wildlife Trust, visit www.bbowt.org.uk or call 01865 775476.