IT is a traditional picture of rural charm sheep peacefully nibbling grass on moorland roadside verges.

But a more sinister side to the woollies of the Durham Dales has been revealed - as ruthless killers.

A sharp-eyed ornithologist has discovered that the sheep, thought to be exclusively herbivores, have developed alarming carnivorous tendencies.

British Trust of Ornithology's Dr Niall Burton described how he saw one sheep reveal its taste for red grouse chicks.

Dr Burton was watching a brood of eight-week-old chicks foraging in a patchwork of heather and close-cropped turf on Muggleswick Common, Weardale.

As the grouse became visible as they moved on to the short turf, one of three nearby sheep "ran forward, picked up a chick and ate it whole". Dr Burton said: "The alarmed female grouse quickly removed her remaining chicks into the heather, but the sheep was prevented from taking a second only by my intervention."

The discovery backs up earlier reports from the Shetlands of sheep eating live tern and skua chicks. This was thought to be a means of alleviating a mineral deficiency in their diet.

Dr Burton said: "The behaviour may also occur in nutrient-poor moorland where there are high densities of breeding grouse or waders.

"I am unaware of other reports of sheep eating grouse chicks, but over extensive moorland with many sheep and ground-nesting birds, it could well happen regularly, without being noticed."

It is another example of "simple-minded" sheep not being all they seem. Far from being dumb, they have been reported, in Wales, to have learned to roll over cattle grids.