The country’s first ever ‘beaver pass’ has recently been built by Network Rail under the Highland mainline.
The tunnel was created to help the protected species pass under the railway, and to prevent potential flooding issues caused by the dams built across the drainage culverts - a structure which allows water to flow under a road, railroad, trail - under the line.
There is a growing population at the Tay River catchment around Perth and not long ago, a culvert near Gleneagles was blocked by part of a beaver lodge, causing flooding on an area part of a Site of Special Scientific Interest (SSSI) intended for wet woodland, scrub and fen meadow habitats.
This called for a solution to ensure the beaver's safety and that of their habitat, whilst minimising their impact on the rail network.
Because beavers are a protected species, this means it is illegal to capture, injure, disturb, harass or kill a beaver, or to damage, disturb or obstruct a beaver’s resting or breeding place without the right authorisation.
The Network Rail team worked closely with species specialists at NatureScot, and secured the appropriate licenses to work in the SSSI, enabling them to pump the water out of the area.
NatureScot advised Network Rail throughout the process, and three pumps were deployed and fitted with screens and floats to prevent trapping wildlife. This took place over a number of days before the 2m high 5m wide beaver dam was removed by hand.
James Morrison, ecologist, with Network Rail Scotland, commented “to a beaver, a culvert probably looks like a hole in a dam - the barriers they build to restrict the flow of water - so they are very popular damming spots."
“The action we took near Gleneagles is the first beaver pass installed in the country that we are aware of. It is a repeatable solution which works to protect Scotland’s Railway as well as safeguarding the beaver populations and other wildlife.”
He continued, "the beavers will naturally expand across Scotland and as they do, it is possible they could occasionally impact Network Rail's infrastructure through felling trees on to the line, flooding caused by their dams or burrowing into railway embankments. However, they are an important keystone species and we need a proactive approach and sensitive solutions that allow us to co-exist.”
Once the culvert was cleared, the beaver pass was installed and wild mesh was fitted on both sides of the tunnel, in line with the SEPA best practice guidelines for altering culverts, allowing wildlife - such as beavers and otters - to thrive.
As part of the initiative, an additional 45mm pipe has been inserted through an existing larger culvert drain, with wild mesh fitted on both sides, protecting the railway whilst still allowing the movement of wildlife.
Dr. Roo Campbell, a member of NatureScot’s Beaver Mitigation Team, said “beavers are an important component of a healthy ecosystem whose presence usually brings a host of benefits, including creating ponds and wetlands where other species thrive, alleviating downstream flooding, and improving water quality."
He added, “But occasionally they can cause issues. Our team advise on and provide mitigation against beaver issues across Tayside, but this situation is definitely one of the most challenging we’ve faced."
“We are pleased that Network Rail have been so proactive in working to live with the beavers at the site. NatureScot will continue to monitor the effect the beavers have on the SSSI.”
More work is to be undertaken in the near future to widen the pass to a 600mm pipe to make sure even the biggest adults can get through easily.