The impact of motorway construction and general roadworks on TB incidence in cattle herds is a continuing issue of contention.

Farmers have long held that the disruption of badger setts in an area due to road or motorway construction has been a major contributor to subsequent TB outbreaks.

This belief remains an article of faith for many farmers, despite an absence of scientific evidence linking construction works with disease outbreaks.

The debate was brought back into focus following the publication in September of a scientific study which was carried out during the M11 motorway’s construction in Wicklow.

The debate around road construction works and TB outbreaks in cattle herds continues.

The study found no evidence to support the contention that motorway construction seriously disturbed the ranging patterns of local badgers. It could not be argued, therefore, that badger disruption was to blame for TB outbreaks around road building projects.

“Given the modest disruption in ranging behaviour seen in this badger population, both during and after road construction, we believe it is unlikely that fully mitigated major road upgrades would result in a perturbation effect sufficient to increase TB in the local cattle,” a research article based on the study concluded.

Study

The study was carried out by scientists and researchers from the Department of Zoology in Trinity College, the National Parks and Wildlife Service, the Department of Agriculture and the Agri-Food and Biosciences Institute in Belfast.

It involved the fitting of GPS collars to 80 badgers trapped in the target area along the route of the M11. Data was then collected on the roaming habits of these badgers between April 2010 and October 2016. This spanned the period before construction started to after all the roadworks had been completed.

The badgers’ ranging behaviour was assessed using a variety of movement metrics, including home range size, nightly distance moved, the distance of extra-territorial excursions and the frequency of these movements.

The distances badgers move each night vary considerably, from an average of 7km per night at low population densities to an average of less than 1km (849m) per night at higher population densities.

The sizes of home ranges vary seasonally and with population density. They can be up to 22km2 in low-density populations, back to 0.26km2 in very high-density populations.

On average, the Wicklow badgers travelled a median distance of 657m per night. The majority of journeys were below 2km, with 11.25km being the maximum distance recorded. This median nightly travel increased from 651m before construction to 848m after the roadworks. However, the increase was not viewed as hugely significant.

Similarly, the median home range size increased, but not massively, from 0.87km2 to 1.07km2. More movement was recorded outside of badgers’ home ranges, but the study found that the frequency and distance of these forays was not greatly accentuated by the motorway construction.

“Taken together, our results suggest that any effect of road construction on ranging behaviour in badgers was very small, and that territoriality was not disrupted in our population,” the research article maintained.

“Given the small degree of disruption to ranging behaviour evidenced, we believe it is unlikely that any increase in TB breakdowns in cattle would have occurred as a result,” it added.

Former IFA president’s experience tallies with that of other farmers

The findings of this research study are unlikely to shift farmers’ opinions, however.

Former IFA president Joe Healy is convinced that a TB outbreak on his Athenry farm in 2015 was linked to works on the M6 motorway from Dublin to Galway.

“We never had TB on our farm until 2015. We were hit reasonably hard in just one round. And the only thing different around the place at that time was that the motorway was being built,” Healy explained.

“It was the same for four or five other farmers around here who never had TB until 2015 either,” he said.

Healy said he never purchased in stock, so there was no opportunity to buy in the disease. He claimed the one common denominator was the motorway, as it touched all the affected holdings.

The former IFA leader does not agree that badgers are not unduly disrupted by roadworks. Badgers were far more evident around the area during the motorway construction phase, he maintained.

“Nearly constantly you’d see a badger at the side of the road. And before that, or since, you wouldn’t notice them at all. They were a lot more visible then – dead or alive,” Healy said.

The Athenry dairy farmer – who stressed that he is not anti-motorway – is “totally convinced” that roadworks disturb badgers, and that disturbed badgers spread TB.

“No matter what anyone says to me, I would always say that it was the motorway being built that caused the sudden outbreak of TB in this area. Thankfully, it all cleared up once things settled down, and that was within a few months. And none of us have had TB in the last six years.”

Given that Joe Healy’s experience tallies with that of many other farmers, the debate around road construction works and TB is likely to continue.

Badger app launched

A badger on the move.

A new Badger Activity app to allow farmers to immediately report signs of badger activity on their lands has been launched by the Department of Agriculture.

The phone app is viewed as an enhancement of the wildlife control leg of the Department’s TB eradication programme. Farmers’ reports will help the Department to build a more comprehensive picture of badger activity and facilitate the extension of its badger vaccination programme.

The app can be downloaded from www.bovinetb.ie and includes a manual with sample photos of badger setts, latrines, pathways, snuffle holes and paw prints.

The Department has a database recording the location of some 45,000 badger setts but wildlife specialists maintain that there are many more unknown setts across the country.