 A Flock of Sheep
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July 21, 2003 — Former military satellites are being used to track flocks of sheep on a government-owned farm in the west of Ireland as part of a research project aimed at sustaining grazing and controlling soil erosion on the country's scenic mountainsides.
The government's agricultural research and advisory body, Teagasc, hopes the study will lead to a blueprint for farmers to protect the environmentally sensitive areas.
Traditional black-faced mountain sheep have grazed the mountains for centuries but from 1980-97 their numbers increased by almost 110 percent.
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Overgrazing resulted in some of the steeper and drier sections of mountainsides suffering particularly badly. In some cases the sheep eroded peat and soil to bare rock and vegetation would not grow again.
Gerry Scully, chief sheep advisor for Teagasc, said that, following concern at the European Union and national level, about 150,000 sheep were removed from mountain grazing in a compulsory de-stocking.
To try and draw up a scheme for grazing the mountains while still protecting the environment, special satellite tracking collars from Canada and Scotland have been fitted to sheep on an experimental farm at Erriff in County Mayo.
Scully said the study had as much to do with changing lifestyles as the sheep.
"There has been huge social change in these areas. Previous generations farmed full-time and moved their sheep around to areas where there was grazing. The present generation farm part-time. If they are working in other jobs they don't have time to do that," he said.
Dummy collars have had to be fitted to some sheep as the researchers found those wearing the real satellite collars were treated as outcasts by other members of the flock.
"The sheep wearing the collars became persona non grata. It is like wearing a uniform. As far as the sheep are concerned if you are in the army you wear the uniform," Scully said.
"The collars allow us to follow the sheep 24 hours a day and track their grazing behavior — where they go, when they sleep, what effect wind and rain has and so on."
Scully said that in January the sheep walked an average of two kilometers per day, mostly in daylight. This increased to over three kilometers as the year progressed and days got longer.
The satellite readings have shown the sheep are mainly grazing in specific areas and have a clear preference for particular parts of the farm.
Sheep learn grazing behavior from their parents and become territorial, a phenomenon known in highlands of Scotland as "hefting."
Scully said fencing to protect the sheep's favorite areas was not practical over huge tracts of mountainside. But all-weather blocks of supplementary feedstuff could coax the sheep to stay in areas for up to two weeks.
"With selective overgrazing, just removing 50 percent of the sheep won't work as it just means the other half will still concentrate on those preferred areas," he said.
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