Habitat management for adders

The purpose of this page is to provide a summary overview of best-practice guidance for land management where the adder Vipera berus is present. The guidance focusses on the North Pennines National Landscape, and the northern uplands of England more widely. This guidance note was produced by the North Pennines National Landscape, with funding from the National Lottery Heritage Fund and Northumbria Water’s Branch Out Fund.

The adder is a champion species for the North Pennines National Landscape. The species was selected due to its value as a proxy indicator of overall ecosystem health – being both a predator and prey item of a range of other species, and preferring diverse mosaics of open vegetation communities.

Adders are listed as vulnerable to extinction and it is the responsibility of local authorities, funding bodies and land managers to give due consideration to their conservation in any decision-making process.

To find out about adder identification, ecology and conservation status please visit the Adders Up page .

Key principles of land management for adders

Complexity

Adders prefer a complex mosaic of different habitat types, offering the greatest range of opportunities throughout their life cycle. Aim to create a range of sward heights, including short-cropped areas and/or bare ground (which provide basking opportunities) and areas of taller vegetation (providing cover and feeding opportunities) in the form of rough or tussocky grassland, heathland, scrub and low-density woodland.

Connectivity

Aim to maintain corridors of cover through open landscapes. Adders are easily predated by raptors, corvids, pheasants Phasianus colchicus, foxes Vulpes vulpes and stoats Mustela erminea. Field buffer strips, hedgerows, and dry-stone walls are all excellent ways of improving connectivity in the landscape.

Lack of disturbance

People and their pets can be a major source of disturbance, reducing adders’ ability to reproduce and survive. If the site is accessible to the public, encourage visitors to keep dogs on leads and consider using signage and/or interpretation to promote responsible access.

Positive messaging may also help to dispel fears and misconceptions, which have historically led to persecution.

Exclusion fencing around known hibernacula or basking areas can be an effective way of mitigating disturbance and can prevent accidental trampling / disturbance by livestock.

Methods of habitat management

Grazing

Perhaps the most sensitive way of managing vegetation during the growing season (when adders are active) is to use native breeds of grazing animal, at a sensitive stocking intensity and duration. Mechanical tools such as flails, mowers, and even brushcutters/strimmers can cause injury if used outside of the main hibernation period (November to January) without first checking the vegetation for any reptiles and amphibians that may be present. Grazing animals however, when used carefully, cause gradual changes in the vegetation structure and generally move more slowly – allowing herptiles to disperse.

The appropriate stocking density and seasonal duration of grazing required to maintain structural diversity will vary depending on the stock used and the habitats present on site. The grazing regime should be flexible, responding to the climate (un-foreseen drought, periods of heavy rainfall) as necessary to achieve the key principles.

In some situations, it may be possible to use a site for winter grazing of stock that are kept elsewhere during the summer months – thus minimising the potential for conflict between adders, livestock and the need for productivity in the farmed landscape; by grazing the land outside of the most sensitive period for reptiles.

Exclusion fencing, or no-fence collars, can be used to great effect where trampling and/or disturbance of key hibernation and basking areas is an issue. Baseline surveys, ongoing monitoring and an understanding of key habitat features are required to prevent damage to these areas.

Bracken control

Sensitive methods for the management of bracken without heavy machinery or herbicidal sprays should be encouraged. In the growing season, methods may include the use of a horse-pulled roller to bend and damage the stems of the bracken – thus weakening the rhizomes over time. They may also include the use of livestock – for example, by encouraging cattle to trample and damage rhizomes during the winter, outside of the main growing season. This may be achieved via bale-grazing, or by placing mineral-licks in problem areas. No-fence collars can also be used to achieve these aims, but require a greater infrastructure investment.

Care should be taken not to focus livestock onto hibernacula areas – having robust baseline data on reptile distribution will allow an informed management plan to be developed.

Scrub management

Scrub encroachment into open habitats can be a significant issue on some sites.

Scrub can be managed via grazing (or rather, browsing), though depending on the livestock chosen, it may not be possible to stock animals at a sufficiently high density without also causing ground damage and disturbance of reptiles.

Goats and sheep browse scrub more preferentially than cattle, and therefore fewer animals could achieve the same objective without causing significant ground-damage.

Alternatively, the use of machinery / hand tools can be employed in the winter (outside of the bird nesting season). Care should be taken to prevent over-exposure of known hibernacula areas by removing too much vegetation.

Burning/cutting of heathland vegetation

Within the North Pennines National Landscape, large areas of heathland and bog are managed for the shooting of Red Grouse Lagopus lagopus. This form of land management typically involves burning, or cutting, of heathland vegetation to create a mosaic of sward heights for the benefit of grouse foraging and re-production.

Any controlled burning or cutting of heathland vegetation should ideally be carried out during the main hibernation season (November to January), to reduce the direct impacts of these practices on reptiles.

The more indirect impacts of intensive burning / cutting may also include a reduction in the structural and botanical diversity of heathlands, and the over-exposure of hibernacula features.

Stock exclusion

In an intensive, rather than extensive, grazing system, it may not be possible to reduce stocking rates sufficiently to allow diverse habitat mosaics to develop. In these cases, setting aside areas can be of great benefit. Excluding livestock for an extended period can allow for the development of habitat mosaics which are of great benefit to herptiles and a range of other faunal groups. Exclosures, when sited in cloughs, can also benefit catchment water quality as they prevent poaching / dunging of the watercourse. Exclosures may require limited grazing or mechanical management every 5-10 years to maintain areas of open space.

Public access

The Herpetological Conservation Trust, in 2005, suggested that across all sites surveyed as part of the ‘Make the Adder Count’ survey; the most frequently reported negative factor was disturbance by public pressure (46% of sites) (Herpetological Conservation Trust, 2005). This related to disturbance of the adders themselves, rather than disturbance of their habitat.

National Landscapes are areas of significant natural beauty, and tourism is an important source of income for many local businesses. Disturbance by people and their dogs is a complex factor in land management but can be approached in two ways:

1) Exclusion – “hard” solutions such as fencing, or “soft” solutions such as the installation of boardwalks or gravel pathways – resulting in reduced disturbance and trampling of vegetation, and fewer informal tracks. Soft boundary features such as scrub planting or dead hedging may also encourage visitors to remain on designated footpaths.

2) Engagement – increased signage and interpretation, and public education efforts, can also be extremely effective. They can help to dispel misconceptions, reduce persecution, and encourage responsible access principles. They can also lead to increased engagement with conservation action and citizen science projects. Careful use of language in these endeavours is vital to their success.

Habitat creation

Sensitive ongoing management is generally the most desirable outcome for herptile conservation. In some instances, where there is no scope for a total change in management on a site, or as a means of increasing the available over-wintering habitat resource, it can also be useful to build hibernacula.

A hibernaculum is a feature in which animals (including reptiles, amphibians, invertebrates and mammals) seek refuge through the colder winter months. Natural examples include disused vole and rabbit burrows, and piles of rocks or logs. Dry stone walls can also provide excellent hibernacula.

An artificial hibernaculum can be created by digging a shallow pit (the depth of which will be dictated by the soil type – if soils are not free-draining then deeper hibernacula may be liable to flooding and would be more successful if built above ground level), and in-filling with large, coarse material such as stone, rubble, and logs. The aim is to create a series of cavities, some of which are beneath the surface of the ground, where temperatures will remain more stable through the winter.

These features should be sited in a sunny location, and adjacent to good cover (e.g. bracken, rough grassland, scrub, woodland edge). Consider erecting exclusion fencing around these features to prevent disturbance or trampling by livestock. Above-ground log and brash piles are also of value for sheltering herptiles, though they may not provide stable temperatures through the winter.

Low density native scrub planting, or natural colonisation of areas fenced off from livestock, can also be beneficial – creating islands of cover in areas where a total change in stocking density or land management is not possible. These areas of cover provide important refuge from predation, and when combined with hibernacula features, can provide a valuable resource for adders in the farmed landscape. These may be scattered across a land holding to increase connectivity and reduce the total area of open ground which might otherwise need to be traversed.

Further information, opportunities, solutions will be included in a forthcoming guidance document ‘Habitat management for adders in the North Pennines National Landscape.’

For more information, please contact Henry Barrett, Conservation Officer at the North Pennines National Landscape.