Biodiversity action in Exmoor

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Otter numbers surveyed

Exmoor’s wild otters are secretive creatures and are seldom seen, even by those who study them and take a keen interest in them. However, thanks to the Somerset Otter Group, a survey has been carried out across the whole of Exmoor National Park.

How the otter survey was carried out

The secret behind calculating otter numbers lies in looking for otter spraint, the technical term for otter droppings.

Otters are normally solitary animals, except for breeding. They are constantly travelling along the rivers, employing a system of scent marking to leave messages for each other. So otter spraints are deposited in prominent positions that would be difficult for another otter to miss: A large rock in the middle of the river or on the inside of a bend, or a ledge under a bridge. When fresh, spraints are dark and oily with the crunchy texture of fish bones and scales. Older spraints tend to dry out and fade and become more brittle.

What the otter survey revealed

One of the most exciting discoveries made during the otter survey was that otters are using territories high up on the moor near the headwaters of the main rivers, not just restricting themselves to the larger main rivers.

The survey calculated that there are now at least 23 otters living on Exmoor. Numbers were previously thought to be much lower than this, although statistics are hard to come by.

Winning the war against Japanese knotweed

The problem with knotweed

Five years ago, if you took a walk in the Heddon Valley or along the River Barle, you would probably have encountered large stands of the hugely invasive plant Japanese knotweed and its Himalayan cousin.

First introduced to Britain in Victorian times as an exotic garden plant, the rampant growth of Japanese knotweed in the wild now costs 150 million pounds each year to remove and control.

The plant can grow up to one metre a month. Its tough roots and stems can break through tarmac and concrete causing havoc when it appears near roads and buildings.

But the plant also stifles biodiversity - it takes over and destroys native habitats and the plants and animal in the areas where it grows.

The reason that the plant has caused such a devastating impact on the UK environment is that it has no natural enemies here so it has been able to rampage through natural habitats.

In Japan the plant does not cause a problem because it is kept in check by over 200 plant-eating insects, and disease-causing fungi.

The knotweed situation on Exmoor now

Today, thanks to the hard work of the Exmoor Knotweed Project, knotweed is becoming a thing of the past. In many areas the plant has been completely eradicated including at:

  • Watersmeet ravine woodland
  • the deep valley of the Heddon
  • the unspoilt Barle river

The National Park Authority, Natural England, the Environment Agency and The National Trust joined forces with a weed control contractor and local landowners to treat the weed by spraying it in late summer and early autumn. The scale of the project covered:

  • more than 800 sites
  • an area the size of five football pitches

Exmoor mire restoration work

What are mires?

Mires are peat-accumulating habitats such as blanket bogs, valley bogs and fens.

Blanket bog is the commonest mire type on Exmoor - there are more than 30sq km in the Park.

Why do mires matter?

On Exmoor blanket bog and peat covers the central moorland but it has been dried out by centuries of moorland reclamation, agricultural drainage and domestic peat-cutting. As a result much biodiversity has been lost - many interesting plants, animals and birds have disappeared and the land has become dominated by moorland grasses.

What work has been done to improve Exmoor's mires?

From 2006-2010 work was carried out to re-wet and restore these interesting and valuable wildlife areas with ditch-blocking and water management techniques.

Restoration work took place at 12 moorland locations:

  • Exmoor National Park Authority-owned moorland at Blackpitts, Exe Head and Long Holcombe
  • National Trust-owned Moorland at Aldermans Barrow Allotment
  • Privately-owned moorland at Verney's Allotment, Roostitchen, Broadmead, Squallacombe, Great Vintcombe, Codsend moor, Hangley Cleave and North Twitchen

What is the result of mire restoration work?

In total 50km of ditch was blocked with more than 4,300 ditch blocks made from bales, wood and peat.

This has resulted in the re-wetting of more than 300 hectares of moorland.

In November 2010 the new Exmoor Mires On The Moors scheme received £3.8m of mire restoration funding for work over the next 4 years.

www.exmoor-nationalpark.gov.uk/moorlands

Exmoor and Dartmoor work to save threatened butterfly

The Two moors Threatened Butterfly Project has seen marsh fritillary butterfly numbers increase from just 99 to more than 1,000 in three years.

This is a joint project to reverse the declines of the marsh fritillary, high brown fritillary and heath fritillary on Dartmoor and Exmoor.

How they went about halting butterfly's decline

  1. Advice and support given to farmers and landowners on more than 140 sites covering over 1,500 hectares of key habitats for the butterflies
  2. Working with local community groups, running training sessions and recruiting volunteers to survey numbers of caterpillar webs in the autumn months
  3. These groups to carrying out practical habitat management of fritillary sites on more than 71ha of habitat

Evidence that shows butterflies are on the increase

The number of marsh fritillary has begun to increase on Dartmoor - the species was previously in decline:

  1. Previously abandoned sites have been re-colonised and some new ones have also been colonised
  2. Just 99 caterpillar webs were recorded on sites in 2007. By 2009 this had increased to 689 and by 2010 it was 1,179
  3. The previous rapid decline of the High Brown Fritillary has been halted on Dartmoor
  4. 29 farms have agreed to maintain suitable habitats for the butterflies (Higher Level Stewardship agreements)
  5. Spin-off benefits include improved conditions for nationally-threatened species such as bog hoverfly, pearl-bordered fritillary, small pearl-bordered fritillary, narrow-bordered bee hawk-moth, dormouse and barn owl

www.butterfly-conservation.org

Ospreys return to England

A Lake District National Park project, working with the RSPB and Forestry Commission has brought back breeding Ospreys to England - not seen since the 1830s