Lifting the lid on the badger's secret life

ONCE, a few thousand years back in evolutionary history, the badger was probably a loner, like most of the mustelid family. Stoats, minks, otters and pine martens are all mustelids, and none of these live sociably, in clan groups, as Meles meles does. What happened to make the badgers of north west Europe so gregarious?

When men began farming, they reorganised the landscape. They cleared the forest, which reduced the badger's cover, and created cattle pastures full of earthworms, the badger's main prey. As wilderness became countryside, badgers, like people, learned the virtues of togetherness. In Ireland today, an average main badger sett and its feeding territory is shared by half a dozen adults, male and female.

Multiply that by 34,000 badger groups and you get something over 200,000 as the species population for the State - among the highest in Europe and similar to the general density in Britain's badger areas. We have nothing like the high numbers - 20 badgers per square kilometre - reported from the Cotswold hills of Gloucestershire: three to four badgers in that space is quite a lot for Ireland. And in the uplands of our west and north west there are big areas with very few badgers, if any at all.

Until the new Badger and Habitat Survey of Ireland, just published by the Stationery Office, very little was known about the size, distribution and ecology of the badger population. The survey took four years of fieldwork and involved some 50 wildlife rangers. Their co ordinator, Dr Chris Smal of the National Parks and Wildlife Service, is author of the final and bulky report.

Its immediate raison d'etre is, of course, concern about the badger's role in outbreaks of TB in cattle - whatever, precisely, this turns out to be. The detailed work of matching badger densities to particular kinds of habitat could save a lot of time and money when, as may well happen, it comes to sprinkling "high risk" areas with badger vaccination baits.

It's unfortunate but scarcely surprising to find that badger, densities are highest in areas of prime agricultural grassland used for cattle grazing. Wheat and barley counties such as Wexford and Carlow have the same sort of low badger numbers as Donegal and Kerry, where moorland, hills and sheep predominate.

"Land that is suitable to cattle grazing rather than arable," writes Dr Smal, "is often undulating and broken, and unsuitable for machinery: this land pattern may create a greater habitat diversity and more patches of scrub and woodland ... It is, in other words, the varied and leafy kind of landscape that we value most as countryside.

AND within it, the abundant hedgerows, dry ditches and tree lines offer badgers their best habitats for setts. Dr Smal does his best to distract the cattle farmers from sending at once for the bulldozer: "It seems improbable," he writes, "that a means of managing the habitat composition of the environment (with regard to reducing badger density) can be suggested, that would not also have profound consequences for the largest part of the Irish agricultural sector and the overall Irish environment."

The exact relationship between habitat, badgers and cattle is one that he keeps circling around and worrying at, as if it might yield some unexpected insight. He asks questions aloud: "Is TB incidence Fin cattle correlated with cattle density, (or perhaps herd density?), is TB in cattle correlated with badger density?; is TB in cattle correlated with hedgerow density?, is boundary length/field size per unit of cattle grazing (with implications of herd contact) a causal factor, or, if badger densities are correlated with hedgerow density, are the badgers implicated instead?"

His questions take on particular point when he looks at one of the big puzzles in the Irish badger situation: how is it that Northern Ireland, with much the same high densities of badgers living in the same habitats, has had a significantly lower level of bovine TB?

The results of a parallel survey in the North have still to be published. But one big difference is that Northern Ireland gives more of its grassland to sheep. Could it be that when cattle herds are more dispersed, with flocks of sheep as a cordon sanitaire, the badger's infective role is diminished? Too much of anything, too close together, is so often bad news ecologically.

Looking at the apparent differences in TB levels between the Republic, Northern Ireland and south west Britain, all with much the same densities of badgers, Dr Smal thinks that the badgers contribution to the disease, however it comes about, cannot be very high".

On the other hand, he says, if he is proved wrong, and transmission is linked to badger density, "then the difficulties of managing badgers are intense. The majority of Irish badgers co exist with cattle, so their removal cannot be contemplated on practical, let alone on conservation grounds".

Even where licences are granted to farmers to snare and kill badgers in a two kilometre radius around farms with a TB outbreak less than half the animals are actually removed. It takes about 27 man days to survey such an area properly, and 400-500 "snare nights" to capture more than three quarters of the adult badgers in one social group.

The vaccination approach, whether for badgers or - preferably - for cattle, seems," says Dr Smal, one of the best practical options." If not the only one around.