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Water Vole

Water vole habitat, ecology, mitigation & the law


Ecology and Habitat
Current Status

What to do:
        Water voles on your land
        Habitat is threatened
        Water Volesand development

Once a common feature on most watercourses in the UK, water voles (Arvicola terrestris) have suffered a dramatic decline over the last 100 years but particularly during the last 30 years. Water voles favour slow-flowing, narrow water courses about 1 m in depth that do not fluctuate in water level through the year. Mud or clay banks and with plenty of bank side emergent vegetation is needed for burrowing, feeding and cover. The loss of such habitat and the introduction of the predatory American mink are considered to be the main factors of the decline.

Identification of water voles

Commonly known as the water rat, they are actually typically vole-like, with a rounded body, blunt nose and short round ears that are almost hidden by thick fur. They are much larger than other native voles, measuring about 22 cm head and body length and weighing between 200–350 grams. The fur is typically medium to dark brown but can vary from reddish brown to black.

Water voles are most frequently mistaken for brown rats (Rattus norvegicus), which often inhabit watercourses and are also excellent swimmers. However, brown rats are larger and heavier, have a pointed face, larger eyes and more obvious ears. Their tails also differ, the water vole having a short and furry tail unlike that of the brown rat which has a long, sparsely furred or naked looking scaly tail.

Ecology of water voles

Water voles only ever live very close to freshwater but do have a wide geographic distribution and can live in a diverse range of aquatic habitats. This is reflected in their diet – a nation-wide survey identified 227 species of plant eaten by the water vole in Britain. Primarily they feed on aerial stems and leaves of waterside plants but can also take freshwater molluscs and crayfish. In winter they rely heavily on eating the bark of willows, and the roots and bulbs of herbaceous plants. They will climb trees, up to about 2.5 m height, to strip bark or eat new leaves, especially of hawthorn, elder and willow.

Water voles live in colonies, usually stretched out along the watercourse as a series of territories. They live in a system of burrows in waterside banks and utilise only a narrow strip of land along the water’s edge. The burrows, dug by the voles biting the earth with its incisors and pushing the soil behind with its feet, comprise many entrances above and below the water, interconnecting tunnels, food storage and nesting chambers. Some boltholes are often incorporated in the territory – these are short tunnels ending in a single chamber used mainly to escape predators. Nest chambers occur at various levels in the steepest part of the bank, the nest consisting of shredded grass. Occasionally in marshy areas with few earth banks, they weave nests into the bases of sedges and reeds, which resemble a large ball of vegetation. Above ground, their activity is largely confined to runs in dense vegetation within two meters of the water’s edge. Discrete latrine sites along the runs and water’s edge mark territory boundaries. These consist of flattened piles of droppings topped with fresh ones.

Breeding takes place from March to October and females may have up to five litters annually, each litter with two to eight young.

Water voles do not hibernate but they do spend long periods within their nest chambers in winter and there may be little sign of above ground activity. Although predominately diurnal, males in particular, become more nocturnal in winter.

  Current status of water voles

Water voles were formerly widespread and common ranging from Cornwall to north east Scotland. They are absent from Ireland, the Isle of Man and the Scottish Islands, but do occur on Anglesey and the Isle of Wight. Thought once to number about 7,000,000 individuals in 1,000,000 colonies, recent estimates suggest a severe decline to just 200,000 voles in 3,000 colonies.

It is thought that damage to bankside vegetation and habitat loss and fragmentation due to river engineering works and farming practices, along with pollution, fluctuating water levels from drainage and climatic effects, competition and predation with brown rats and mink are all responsible for the decline of water voles.
Legislation covering the water vole

Water voles are a UK protected species covered by the following laws:

Wildlife & Countryside Act 1981 (as amended)
Countryside Rights of Way Act 2000

Water voles were added to Schedule 5 of the Wildlife and Countryside Act in a 1998 amendment. However, they receive limited protection because their inclusion on Schedule 5 is only in respect to Section 9(4). This means that, including protection by the CRoW Act, it is an offence to intentionally or recklessly damage, destroy, obstruct access to, any structure or place which water voles use for shelter or protection. It is also an offence to intentionally or recklessly disturb them while occupying a structure or place which it uses for that purpose.

The maximum fine on conviction of offences is currently £5,000. The CRoW Act amended the 1981 Act to allow for a custodial sentence of up to six months instead of, or in addition to, a fine. Fines may be imposed in relation to each offence committed, so operations involving repeated offences can potentially accrue large fines. In addition, items or equipment, which may constitute evidence of the commission of an offence, may be seized and detained. The CRoW Act also amends the Police and Criminal Evidence Act 1984 to render Section 9 offences ‘arrest-able’, giving the police significant additional powers.

If in doubt over any legal issue relating to water voles contact the relevant Statutory Nature Conservation Organisation (SNCO) for advice.

This is only a brief interpretation of the law concerning water voles – reference should always be made to the original texts of the legislation if more detailed interpretation is needed (UK & European Legislation)
What to do if you have water voles on your land
Advice for landowners – how you can help

If you are lucky enough to have water voles on your land you should firstly contact your local Biological Records Centre (Links). This will add valuable detail to the known distribution of water voles, helping to focus conservation efforts.
It is possible to help the general conservation of water voles by acting locally and enhancing the habitat conditions on your land to maximise their population, which will also increase overall biodiversity.

Water voles are principally herbivores and known to eat 227 plant species so the provision of the right kinds of plants is not a primary concern – where there is water there is likely to be some of the right plants present. What is key to their success is the management of the water and bankside vegetation. Advice must be sought from the Environment Agency before any work is carried out in or near a watercourse.Some examples of sympathetic management for water voles is described below.

Water voles require clean water and lush growth of native species of emergent vegetation but not too much shade from shrubs or trees. Most waterside banks need managing to prevent the prolific growth of trees and shrubs that will eventually turn the bank into scrubland. This is commonly achieved either by grazing livestock or by mowing. However, over grazing and trampling (termed poaching) of stream banks by livestock is very detrimental. Excessive grazing reduces the amount of food available for water voles and poaching destroys their burrows and compacts the soil making it difficult for burrowing. Restricting access of livestock to streams and fencing the banks a few meters from the stream is ideal.

If this is not possible then some useful compromises are:

fencing only parts of the bank to provide some refuge areas for water voles
fencing off meanders as this uses little fencing materials relative to the amount of ideal water vole habitat that is protected
using electric fencing as a temporary exclusion method to allow periodic rotation of refuge areas which also prevents dominant coarse, rank and scrubby vegetation from taking over the bank
low stocking densities reduces excessive grazing and poaching.

Cutting and strimming bankside vegetation can have much the same effect as over grazing by livestock because it removes cover and food resources for water voles. If mowing of the bank is deemed necessary then as many of the following pointsshould be followed as possible in order to provide suitable habitat for water voles.

Use hand-held strimmers rather than flail mowers because the weight of this machinery on the banks damages burrows.
Cut in late autumn, preferably winter when water voles are least active above ground
Avoid cutting areas known to be inhabited by water voles. Remember it is againstthe law to intentionally or recklessly damage, destroy, obstruct access to, any structure or place which water voles use for shelter or protection.
Leave large sections uncut on each bank, alternating the cutting regime annually to ensure that scrub growth is prevented but sufficient food and cover is left for water voles. As a minimum, strips of 5 m should be left uncut in every 20–50 m sections.If this is not possible one whole bank could be left uncut and the opposite bank cut the following year.
Leave a small strip of vegetation at the toe of the bank near the waters edge
Put the cut vegetation into discrete ‘habitat’ piles at the top of the bank. This formsideal habitat for invertebrates, amphibians and reptiles.Competition and predation by brown rats and the non-native mink is a big threat. Discouraging brown rats and the control of mink is beneficial not only for water voles but also for many species of birds that they predate such as dipper and grey wagtail. However, cases of unintentional poisoning and trapping of water voles have occurred and even known to cause local extinctions

Remember that water voles are harmless to humans and unlike rats are not known to transmit leptospirosis.

  What to do if a water vole site is threatened by a development

Ideally, it is best if water vole habitats are protected before planning permission has been given for development of a site. If a known or suspected water vole site is threatened by a development, the local planning authority and the local office of the SNCO should be informed as far in advance as possible. These organisations will ensure that appropriate surveys are licensed to establish the status of water voles on the site and that alternatives to the proposed development are considered as part of the planning process.

For activities that do not require planning permission it is best to contact the landowner before any work is due to start. The local SNCO or Wildlife Trust might be able to assist and provide advice to the landowner regarding conservation of their population of water voles.

If there is evidence that the law has been broken or is about to be, the police should be informed, the best contact being a Police Wildlife Liaison Officer. For offences or potential offences such as pond draining/infilling or fish stocking it is worth also contacting the local office of the Environment Agency.
  What to do if water voles are discovered during a development

If water voles have only been discovered after development of a site has commenced you can contact us for advice. All works should be halted until an appropriate survey has been undertaken and appropriate measures taken to protect the water voles on site. Remember it would be an offence to proceed with work which will damage water vole burrows without an appropriate license.

For the development to proceed, special protection and compensation must be provided for the water voles’ environment. This is usually termed mitigation, and specialist licensed ecological consultants such as JPR Environmental provide its strategies. Mitigation normally takes the form of improving adjacent habitat by creating or restoring appropriate habitat features, see below for more details.
  Mitigation for water voles

Experienced ecological consultants must provide mitigation strategies, as specific requirements need to be met if Local Planning Authorities are to grant permission for a development. Mitigation projects for water voles may require licences from DEFRA or EN and permission from the Environment Agency which are normally arranged by ecological consultants. JPR Environmental offer a complete service of survey, design, implementation and management of water vole mitigation projects. Please contact us for more information.

Detailed surveys of sites are essential to help identify what specific mitigation strategies are suitable for each site. Mitigation recommendations are variable as they are normally site specific but tend to favour enhancement of existing habitat rather than translocations and the possibilities of new habitat creation.

Appropriate management of ponds and other waterways is crucial for the success of water voles. In most cases populations of water voles benefit from the creation of isolated pools with appropriate banks for burrowing. The pools do not need to be particularly large or deep, so several can often be incorporated or created close to a development site. It is important to provide long lengths of banks for burrows so ponds usually take a highly convoluted shape with an average of 1 m depth.

In cases where planning permission has been granted to sites that contain water voles, they may have to be excluded from certain areas. This has been done by fencing around a pond or larger terrestrial area that is known to contain the water voles. Ring-fencing contains the water voles during the development and can help to protect them from machinery and other operations. This method is only appropriate if the site will remain suitable for the water voles once development is complete. If the site is not to be suitable then the water voles will need to be translocated to another suitable site. This can also employ ring-fencing but should only be considered as a last resort as translocations are not always successful and the methods are costly in both time and money.
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