Mar 06 2019

Eager Beavers Part 2 – Field Trip

Anyone visiting the Halls Cleave area of Fingle Woods over the last few months will no doubt have noticed the new “leaky dams” that have appeared along the bottom of the valley. These human-built structures are designed to hold back the water and release it gradually, creating additional wetland habitat and reducing the chance of downstream flooding during heavy rainfall

Leaky dams in Halls Cleave

Until their extinction in the UK around 500 years ago, the Eurasian Beaver (Castor fiber) would have carried out a very similar role within the British landscape. Recently, a group of Woodland Trust and National Trust staff and volunteers visited a small enclosure in Mid-Devon to learn more about these fascinating creatures and to see just what a landscape populated by beavers might look like

The group meets at the Fingle sawmill.

After meeting at the Sawmill Carpark in Fingle Woods, the group headed north into the Culm grassland country of Mid-Devon – its flat, open fields a marked contrast to the steep wooded hills of the Teign Valley. In a layby on a quiet country road we were met by Mark Elliott, leader of the Devon Wildlife Trust’s Beaver Project, and John Morgan, the local landowner who has hosted the beavers for the last few years.

Culm grassland surrounding the beaver enclosure

A short walk across the fields brought us to the gate into the beaver enclosure, where Mark gave us a brief history of the project. The 3-hectare enclosure was originally constructed in 2010, with funding from Viridor’s Landfill Tax Credit scheme. A 900m-long electrified fence was constructed around the site, with a mesh “skirt” sunk 6cm below ground level to reduce the risk of the beavers digging their way out. In 2011 a pair of beavers were introduced to the enclosure by local ecologist Derek Gow, and have spent the last 7 years gradually transforming the landscape.

Electric fence   Learning about the enclosure

As we entered the enclosure Mark explained that when the project began the area was mainly wet woodland, with very little light reaching the ground and no standing water. Now it is estimated the site can hold more than 1 million litres of standing water during periods of heavy rain.

The small stream which is the only water source entering the site

As we crossed a small stream, Mark pointed out a “V-notch weir’”, installed as part of an Exeter University project to compare the volume and quality of water entering and leaving the site. The project showed significant reductions in flood peaks, as well as lower levels of sediment, nitrogen and phosphates in the water flowing out of the enclosure. In addition, the water leaving the enclosure contains higher levels of dissolved organic carbon, a sign that the beaver habitat is capturing and storing carbon more effectively than the surrounding agricultural landscape.

Mark explaining the V-notch weir

Moving further into the enclosure, we began to see numerous signs of beaver activity. Trees had been felled, their stumps surrounded by characteristic piles of “beaver chips”, and fresh re-growth had been neatly snipped off. We had to tread carefully, as there were numerous deep channels dug between the tussocks, filled with clear flowing water. Mark told us that the beavers create these to expand their territory, allowing them to find food over a wider area whilst still having the refuge of deep water nearby. They also act as canals, allowing branches to be easily floated back to the beaver lodge

Beaver canal Felled tree and beaver chips

As we picked our way through the complex landscape, toads croaked in the vegetation, and the still surface of the pools was occasionally disrupted by a water beetle rising for air. We learned that the site hosts Willow Tit, a UK red-listed species which has suffered severe declines in recent years, as well as wetland-loving birds such as Woodcock, Snipe and Kingfisher. In ecology terms Mark described the beaver as a “keystone species”, saying “what it does to its environment is exactly what we should be doing with the landscape.” Vegetation surveys carried out annually over the life of the project have shown a gradual shift from dense willow scrub to a fen habitat dominated by Molinia grass, with big increases in wetland plants such as Water Mint and Potamogeton pondweeds.

Mark and NT Area Ranger Tom Wood discuss beaver tree felling techniques Willow buds breaking

Back on the more stable ground of the path that runs around the inside of the fence, Mark led us to the original pond that was dug as a starting point for the beavers when they were introduced in 2011. The pond is now dominated by an impressive “lodge” which has grown up over the years, along with a large pile of branches which the beavers have collected as a winter food source, allowing them to feed from beneath the ice if cold weather strikes

Beaver lodge Fingle Ranger Fred Hutt examines the beaver’s handiwork

Beside the pond was a large metal animal trap, and Mark explained that the beavers have produced several litters during the time they’ve been in the enclosure. As territorial animals the young will naturally disperse at around two years old, and so at this age they are trapped and relocated to other beaver projects around the country.

Live trap for beavers

Further along the path a mature tree ringed with metal mesh turned the talk to potential beaver – human conflicts in a landscape-scale reintroduction. Some concerns, such as predation of fish stock, are easily dealt with – beavers are herbivores, with a diet of plants, roots and bark. Conflict can arise, however, when beavers fell trees with either commercial or sentimental value. This can be mitigated by placing mesh around the trunk for protection, or coating the tree with a latex and sand mixture to discourage gnawing.

Anti-beaver mesh

As we finished our tour of the site Mark looked ahead to the future of beavers in Devon. Around 2013, a small population of beavers of unknown origin were found living wild on the River Otter in East Devon. In 2015, following tests to show they were free of harmful parasites, the Government granted Devon Wildlife Trust a 5-year licence to re-release these beavers into the wild for study. The population has now grown to around 40 animals, and with the trial licence due to expire in 2020 the hope is that the beavers will be allowed to remain in the river and continue to expand their population.

Beaver country

With data from projects around the country and across Europe showing the value of beavers in restoring wetlands, improving water quality and reducing flood risk there is a growing body of evidence to support the Government licencing further releases of beavers into the wild. Who knows – one day in the not-too-distant future some more dams might appear in Fingle Woods, created not by chainsaws and diggers but by the teeth and paws of wild beavers!

The Devon Wildlife Trust Enclosed Beaver Project is located on private land and is not open for public visits. The wild beavers on the River Otter can be seen (if you’re lucky!) from the public footpaths upstream of Otterton.

A big thank you to Mark Elliott and John Morgan for allowing us to visit and taking the time to show us around the site!

by Tom Williams

For more information on Fingle please visit www. finglewoods.org.uk/

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