The full title of an article in the BBC Wildlife magazine is, "Outfox the fox: leave it alone". It claims that farmers who want to cut losses of lambs by foxes should try killing fewer foxes. It sounds odd, but research has found that the more foxes killed on a farm, the more lambs are lost to them. (Long ago James Fairley wrote in An Irish Beast Book that a bounty scheme for killing foxes in Northern Ireland was a waste of time and money, for, as foxes were killed, they just bred more.)
Now Rebecca Moberley, a postgraduate researcher of the University of York, gives three explanations, "possibly contradictory". First, where fox populations are high, more foxes are killed but they also kill more lambs; so farmers who lose more lambs may blame foxes and so kill more of them. And so on. But, point number two; foxes are very conscious of territory, and empty territories are quickly occupied. Some farmers have told her that if you kill one fox, another just moves in to replace it. Then, the third explanation: Trevor Williams, director of a fox project which advises on control, suggests that new foxes moving into a vacant territory have less knowledge of prey populations and go for the "more visible" targets such as lambs, rather than easier victims such has voles. Basically, the article says, killing foxes also upsets the fox hierarchies, leading vixens to produce more. "Constant killing of foxes in an area is stupid," he says. "Farmers are bringing it on themselves."
Research suggests, too, that farmers could reduce losses through killing by improved husbandry. Ewes lambed indoors are less likely to lose their lambs, and the drive by sheep-farmers to produce twins and triplets is also to blame. The ewe is three times the size of the fox and has a strong maternal instinct, but she shouldn't be expected to defend two or three young. Nearly half of sheep farmers lost no lambs to foxes, according to a survey. And while lamb mortality was 6 percent, only one percent was to foxes.
The British Ministry of Agriculture, Fisheries and Food has cited a figure of 0.5 for fox predation and described it as insignificant. (Not quite relevant, but a banner was seen outside Leinster house the other day calling for an end to foxhunting.) Y