Otter and Water Vole Surveys

Otter are protected under the Conservation of Habitats and Species Regulations (2010), with additional protection under the Wildlife and Countryside Act (1981), as amended

If a project is likely to cause disturbance to otter or their shelter then a licence must be obtained from Natural England prior to works commencing.

Otter inhabit mainly freshwater systems, however they have been found on nearly every type of water body within the UK. Otters are territorial and loyal to their home ranges which include a number of above and below ground shelters (Known as couches and holts respectively). The size of an otter’s territory is dependent on food and shelter availability but male territories have been known to reach up to 40km.

Otters breed at any time of year and litters are usually made up of two or three cubs. The female rears the cubs alone while males occupy separate holts. The cubs remain in their holts for around three months and stay with their mothers for up to a year.

Water voles receive legal protection through section 9 of the Wildlife and Countryside Act (1981), as amended. If a project is likely to cause disturbance or damage to a water vole shelter then a licence must be obtained from Natural England before works can commence.

Water voles are found throughout Britain, on many types of waterways but mainly along well vegetated banks of slow flowing rivers, ditches, dykes and lakes. They inhabit nest chambers underground at varying levels which are all connected with an extensive burrowing system that usually incorporates some underwater entrances.

Water voles feed on grasses and waterside vegetation and create lawns outside their burrow holes where this vegetation has been eaten. They occupy ranges along the bank of the waterway, for males this can be up to 130 metres long which can incorporate multiple female territories which are up to 70 metres long. During the breeding season latrines are used to mark their territories.

Breeding season occurs from March to September, during which time the females

Otters are elusive animals that are rarely seen so a survey entails looking for signs of their presence. Both sides of the river bank (depending on access) will be systematically surveyed to look for otter signs, including;

• Tracks
• Spraints (droppings) in each of the three categories: Dried fragmented, dried intact, not fully dry.
• Feeding remains
• Otter couches (above ground shelters)
• Otter holts (below ground shelters)

All otter signs will be recorded on a location map and a grid reference taken at each location. This information can then be used to create a detailed map of otters at the site. These surveys can only inform of the presence of otters, not the population number and are best undertaken in dry weather as rain can wash away otter signs.

Water voles are rarely seen so a survey is based on the presence of signs of water vole presence. River banks will be surveyed from the water’s edge up to two meters up the bank to look for signs indicating water vole presence. The signs to look for are:

• Droppings
• Latrines – the majority of droppings are deposited n latrine sites either at range boundaries or near to burrows
• Feeding stations – remains of vegetation are often left in neat piles by the water’s edge
• Burrows – distinguishable from burrows of other species in that they are wider than they are high and will often have a well grazed lawn around the entrance.
• Footprints

An OS field map of the site and a GPS handset will be taken on the survey to record the location and grid reference of each water vole sign encountered on the survey. This information can then be put into a detailed map of the site. Surveys should ideally be carried out in dry weather as rain can wash away water vole signs.

If otters are found inhabiting an area where development is to take place then appropriate mitigation guidelines must be followed. Where possible a 30m buffer around the otter holt should be fenced off to minimise disturbance to the otters and works should only occur during the day when the otters aren’t active.

As otters do not have a specific breeding season works can occur all year round, however, if any otters are found to be breeding or nursing young then works should cease until cubs are at least 8-10 weeks old. If this is not possible the protection zone should be extended to 100-200m around the holt.

If works are likely to cause damage to an otter holt, or occur within 30m of an otter shelter then a Natural England Licence will be required.

Where possible, development works should aim to avoid water vole burrows by not developing within 3-6m of the bank edge. Where this is not possible and the development is likely to cause damage or disturbance to water voles or their burrows a Natural England licence will need to be applied for and mitigation guidelines put in place.

Water vole mitigation includes placing exclusion fencing around the burrow to prevent the water voles from accessing the site. Where development is likely to destroy or damage a water vole burrow then a trapping and translocation programme may be required where there is no suitable alternative.

Any development works should be avoided during the breeding season, May to August and any development affecting burrows should be avoided between November and February when water voles spend most of their time on their burrow. The optimal time for works and for trapping or exclusion mitigation is September-October and March-April.