This is the time of year when ewe hoggs return to their hills from the low-ground farms where they have spent the winter.

Lambs are called hoggets or hoggs after January 1st and ewe hoggs become gimmers in late summer when their first two incisor teeth have fully emerged.

The practice of sending hoggs away to better pasture for the winter allows them to grow out to their full potential as well as conserving precious grazing on the hill for pregnant ewes and gimmers. A flock of 1,000 breeding ewes needs at least 250 replacement ewe hoggs, which are a lot of extra mouths competing for scarce winter rations.

Nowadays, low-ground farmers charge about £17 per head for the full, six-month grazing period, or about 70p per head per week for shorter wintering, so it's a nice little earner for grass that would otherwise go to waste. When you add another £4 per head to pay for transporting the sheep to and from the wintering, the total bill for sending 250 hoggs away for a six-month wintering comes to a hefty £5,250.

Traditionally hoggs went to their wintering on October 1st and returned on April 1st, but many modern dairy farmers want them away by mid-February so that pastures are lush enough for their cows to graze in early April, or grow heavy crops of silage ready to be cut in May.

While hoggs undoubtedly grow out well when wintered away, they can also learn some very bad habits. Sheep are born with a wanderlust and their ability to stray has justifiably earned them their reputation as the Houdinis of farm animals.

It's one of life's mysteries that, if a lamb starts squeezing through a hole in a hedge when it's very small, it can still squeeze through the same hole when it's about five times the size. They always leave a piece of wool hanging from barbed wire or hawthorn that acts as a beacon to the rest of the flock, highlighting the newly-discovered escape route.

Young lambs love to crawl under gates. Part of the spring ritual is to waste valuable time catching sprightly lambs and then returning them to their anxious mothers. Such lambs grow up to be ewes that think they are limbo dancers and prove it by the way they can sashay under the bottom wire on a fence or gate.

Worst of all are the jumpers and there are some nimble-footed brutes that can clear a six-foot dyke in one bound. Snag with jumpers is that others see them doing it and attempt the same trick. Those that can't jump properly end up knocking off top stones and before you know it there's another hole in the dyke.

Dairy cows on the other hand are more content with their lot and tend not to stray. As a result, badly-maintained fences and low dykes will contain them, unlike hill-bred hoggs that use such field boundaries for training purposes.

Straying sheep are a real nuisance. Apart from the time wasted looking for them, there's also the ill-will that is created when a neighbour's fields or crops are grazed by strays.

On returning home, hoggs undergo routine medication such as vaccinations or dosing for stomach worms and liver fluke. Many farmers also apply insecticide to their fleeces either by pouring small quantities of a concentrated form on their back, or by plunge-dipping them in a solution. That insecticide controls things like sheep scab mite, lice and ticks which transmit dreadful diseases such as tick fever and louping ill.

The rest of the flock are also gathered in from the hill at this time of year to undergo similar treatment as part of the preparations in the run up to lambing.

Ultra-sound pregnancy scanning results have revealed there are more barren hill sheep than usual, with some farmers reporting significantly more. That may be as a result of the good grazing conditions last summer and autumn.

Sheep farmers improve the fertility of their ewes by having them gaining condition in the run up to mating. Flushing as it is called, also encourages ewes to produce more embryos and is achieved by putting ewes onto better grazing so that they are on an improving plane of nutrition.

Sadly, hill ewes were already in big order last autumn and many were losing condition when the rams went out in late November, which explains why there are more barren ones.