The otter, also known in Northwest Scotland by its Gaelic name Dobhran and Beaste Dubh (black beast), belongs to the same family as badgers, weasels, stoats, pine marten and mink.
Scotland is a European stronghold for the otter and it now occurs over the whole of the country. When pesticide pollution of waterways eliminated otters from most of England and Wales, they survived in Scotland’s cleanest water bodies in the north and west. Now the population has recovered, otters can easily be seen in many areas, but particularly on the west coast and the islands. In 2003, the total Scottish population was estimated at around 8,000.
Otters are largely solitary, semi-aquatic mammals that obtain most of their food from lochs, rivers or the sea. The Scottish population is unusual in that it comprises a particularly high proportion (perhaps 50% or more) of coastal-dwelling individuals that feed almost exclusively in the sea. Nowhere else in the British Isles are coastal habitats more important for this species than the coast and islands of western Scotland and Shetland; so much so that coastal otters are occasionally referred to as ‘sea otters’ despite the fact that they are exactly the same species as the animals which inhabit freshwaters further inland.
In freshwaters, otters feed mainly on fish such as trout, salmon and eels, but in the spring spawning frogs and toads become important prey. Mammals and birds are also taken occasionally. In these habitats, otters are largely (but not exclusively) nocturnal and occupy very large home ranges (around 32 km for males and 20 km for females). In contrast, their coastal counterparts are mainly active during the day and, because these productive inshore waters provide so much fish and crustacean prey, they need much smaller home ranges – as little as 4-5km of coastline. Coastal dwelling otters require a ready supply of fresh water to wash the salt out of their fur, which would otherwise rapidly lose its insulative properties.
The principal issues affecting Scotland’s internationally important otter population are: road kills and other unnatural mortality. Road casualties are considered to be the single biggest source of non-natural mortality. Commercial eel fishing and ‘creeling’ for crustaceans has also been identified as a threat in some areas. As a consequence, protective otter guards were developed for use with eel fyke nets, dramatically reducing otter drownings. Otter predation on stillwater fisheries (and occasionally also on domestic ducks and poultry) can sometimes be a serious problem for the owners and managers concerned. The solution usually lies with appropriate stock protection measures and guidance is available on protective fencing from the Specialist Anglers’ Alliance and in Otters and stillwater fisheries.
Despite these threats, the Scottish otter population is flourishing and in most parts of the country, there no evidence to suggest that they are having a detrimental effect on the overall population. Nevertheless, Scottish Natural Heritage continues to work closely with developers and road engineers to ensure that the appropriate mitigation measures are put in place on new road schemes to avoid casualties. Wherever possible such measures should also be retro-fitted at known black-spots on the existing network.
- 1 About otters
- 2 Otters and the law
- 3 Assessing the impacts of developments
- 4 Mitigation
- 5 Best practice
- 6 Contacts and further information
Scotland is the principal stronghold for the Eurasian otter (Lutra lutra) with the majority of the total British population resident here. The species has declined in many parts of Europe, including much of Britain during the 1960s and 1970s, but this was relatively minor in Scotland compared to England and Wales. As a result, our population is of international importance.
With a widespread population, otters are likely to be present on a wide range of potential sites in Scotland. These may be development projects, ranging from a new transport infrastructure to individual house plots. Even apparently benign proposals such as the development of an area for outdoor recreation can have an impact on otters if dogs are permitted on site.
Otters are a highly protected mammal species. If you are planning work in or around a river or wetland habitat, you should think about possible impacts on them as part of planning your project. Doing this early can identify potential conflicts promptly and resolve them, preventing costly delays later in the process.
When considering large scale industrial and/or housing developments in flood-plains, a holistic approach is needed in which consideration is given to the possible effects of the proposals on the river catchment as a whole. Loss of flood-plain area can result in changes to river flow characteristics, more extreme flood events, scouring of the riverbed and associated changes to the invertebrate and fish populations. All of these can have detrimental effects on otters, predominantly by impacts on their food supply. In order to maintain good body condition an otter needs to consume about 1 – 1.5kg of prey every day (predominately fish or frogs, but occasionally birds, mammals or crustaceans). At a local level the proposals may directly impact on the otter’s breeding or resting site. The otter in Britain has been recorded breeding in every month of the year and it is therefore difficult to avoid potential impacts through avoiding certain months in the year as with breeding birds.
Otters and the law
Otters are legally protected in Scotland by the Conservation (Natural Habitats, &c.;) Regulations 1994 (as amended) – “the Habitats Regulations”. Under these Regulations, otters are classed as European Protected Species and are given the highest level of species protection. In summary it is illegal to:
- deliberately or recklessly kill, injure or take (capture) an otter;
- deliberately or recklessly disturb or harass an otter;
- damage, destroy or obstruct access to a breeding site or resting place of an otter (i.e. an otter shelter).
There are several specific offences of deliberate or reckless disturbance, see Protected mammals – Otters for details. Otter shelters are legally protected whether or not an otter is present.
As well as the specific protection for otters and their resting places, the Government has designated a suite of Special Areas of Conservation (SACs), 44 of which have been selected in Scotland for their otter interest. Information on the status of otters at these sites are available in Scottish Natural Heritage Commissioned Report No. 211.
In planning your project, you need to consider whether your work may have a significant effect on such a site (either alone or in combination with other plans and projects). If this is likely, and you need either a licence or planning permission, the competent authority is obliged to carry out an Appropriate Assessment of the implications of the project against the conservation objectives for that site. This is part of the process in determining whether a project can be given consent. Scottish Natural Heritage must be consulted in such cases. Where it cannot be determined that there would not be an adverse effect on the integrity of the site, a development may only be permitted where:
- there is no alternative solution; or
- there are imperative reasons of over-riding public interest including those of a socio-economic nature.
It is not the intention of the law to prevent all development in areas used by otters. However, legal protection does require due care to be taken to the presence of the species and appropriate action taken to safeguard the places they use for shelter or protection. If a potential problem is identified, then often a modification to the development is sufficient to ensure that otters will not be adversely affected and no offence committed.
There is also provision in the legislation to allow certain otherwise illegal activities to take place under licence. Further information on how licensing applies to work in areas supporting otters can be obtained here.
Assessing the impacts of developments
Otters and the planning system
Planning authorities are required to take account of protected species and habitat conservation when they consider planning applications, see Scottish Planning Policy. As otters are European Protected Species, planning authorities have to be satisfied that your proposal will not have an adverse effect on them. If you need planning permission for your work, you should provide sufficient information to help the local authority make this assessment. If you do not provide enough information, your permission could be delayed or, at worst, refused. Where there may be a conflict, you need to consider what measures you could take to avoid, reduce or offset the impact on otters.
Are otters likely to be affected?
The effects of work on otters can vary considerably and may not always be obvious. As well as being vulnerable to the loss of their shelters, there may be habitat loss which leaves them more open to disturbance, or pollution which may affect the animals as well as their food supply. Negative impacts on otters are most likely to arise as a result of the following:
- habitat destruction – the availability of suitable cover is essential for otter shelters and for the animals to tolerate disturbance
- damage to shelters – these are essential for breeding and resting
- destruction of food sources – damming rivers and streams, draining ponds and otherwise altering watercourses may all contribute to a reduction in the amount of food which is available
- disturbance – otters are intolerant of dogs or, where suitable cover is absent, intense human disturbance such as recreational areas
Otters can use holts 500m from water so, because a site is not next to water it does not mean that otters may not be present. Also, the size of the watercourse is no indicator as small streams are often used as feeding sites and connecting routes.
Reference to national survey data, such as the NBN gateway and reliable local sources, may be helpful to find out if there are otters in the vicinity. However, none of these sources are a substitute for professional advice both in determining the presence of otters and advising on the actions needed to avoid damage or disturbance.
A survey will be needed for any proposal that is likely to lead to disturbance or damage to an otter’s place of shelter. The aim of this is to identify any sensitive features, notably otter shelters, and to establish the presence or absence of otter activity; it is usually the presence of otter shelters that ultimately constrains licensing of a development. The scope of each survey must be tailored to suit the circumstances and the scale of the proposed work.
As a general guide, a survey of 200-250 m both upstream and downstream of the site should suffice for small schemes such as individual bridges, pipeline crossings, local bank work and individual houses. Particular attention should be paid to important riverine habitat features such as in-stream islands and reed beds.
For major road schemes and other similar linear developments, the survey should encompass at least 250 m on each side of all alternative routes and the same distance beyond the end of the scheme. All evidence of otter activity should be recorded within this area. In some cases, a broader survey area of 500 m on each side of the various alternative routes may be more appropriate. These recommended distances should be extended if any small watercourses provide routes to lochs or short watershed crossings, to locate important routes for otters. Such routes may be shortcuts across the landscape which do not follow linear features, but cut across them or shorten a route along them. Road developments which do not take account of these otter paths pose an increased risk of roadkill to otters.
For large extensive developments such as wind farms, the survey will need to include both watercourses and a wider spatial element, to ensure that the positioning of the turbines and associated infrastructure will not interfere with any key features for otters. For these large sites, complete coverage of the whole site may not be practical so, for large wind farms, a radius of 250 m around each turbine location and associated infrastructure should be surveyed in detail with the intention that, should an otter shelter be discovered in close proximity to any part of the development, the proposals can be amended to avoid damage to the shelter. Similarly, a detailed survey of at least 100 m either side of any indicative proposed routes for access tracks is required to ensure that the final route for the track does not impact on otter shelters.
Weather conditions can influence the results of an otter survey. Furthermore, sprainting frequency varies seasonally and sprainting behaviour may vary with reproductive condition. However, there is unlikely to be any time when spraints are not found, except during or after heavy rain and flood conditions. Thus surveys undertaken during periods of high water or peak leaf fall are unlikely to be productive. Irrespective of water conditions, spraints are unlikely to be found near to natal holts, particularly while the cubs are young, and these could therefore be easily missed. Remote cameras can be invaluable in determining whether breeding is taking place at a holt, but note that placing these devices close to an otter shelter requires a licence.
If it is not possible to avoid having an effect on otters during the course of your work, you will need to consider what measures to take to mitigate any damage or disturbance.
New roads (and some existing ones) can be a particular problem for otters and may lead to significant mortality amongst the local population. Road mortalities tend to occur at times when rivers are in spate and otters are obliged to leave the watercourses and cross roads, when normally they would safely follow the river channel beneath the bridges.
Under these circumstances, the ideal is to design river crossings that retain a wide strip of accessible riparian habitat on either side to accommodate spates. This provides a safe route under the bridge at all times. Clearly the local topography is often such that this ideal is not always achievable, in which case mitigation can take a number of forms, some of which may also be appropriate in other situations.
Key methods available are:
- Tunnels and culverts
Further guidance on the above will be available in July.
Where the destruction of a holt has to take place, suitable restitution would be to provide one or more artificial holts made from logs, boulders or pipes to tried and tested design. If they are to be successful, you should seek advice on the type, location and construction, taking into account the general needs of the species.
There are several different specifications for these. In riverine and other freshwater habitats, both log pile holts and pipe and chamber holts are commonly constructed. In coastal situations, a slightly different design based on the latter is usually more appropriate. In such circumstances, it may be possible to incorporate an artificial holt within the rock armour fabric of, for example, newly constructed coastal defences, provided that the necessary measures are in place to prevent otter access to nearby roads. (If prevention of access cannot be assured, it is wise to discourage the use of rock cavities for this purpose, and infilling the large ones may, therefore, become necessary).
Fortunately many developments, such as the installation of pipelines, are sufficiently flexible to avoid otters and their shelters if the animals are found on site in good time. This should be the main aim when planning any work in an area with otters present. Where this is not possible, other measures may help to avoid, reduce or offset any impacts.
With the exception of Shetland, there is no set season in which otters in Scotland give birth. It is, therefore, impossible to schedule work to prevent disturbance to an otter with cubs. However, examples of good practice in situations where otters are involved are set out below.
Disturbance during the works should be minimised by declaring an area of at least 30 m radius from an otter shelter out-of-bounds to everyone at all times. Before any work starts on site, this protection zone should be fenced off to keep people out, whilst not affecting otter movements. It should also be clearly demarcated using coloured tape or some other form of obvious visible marking. Chestnut pale fencing, or Heras link fencing, are effective for this. This will protect the shelter during the construction phase and, if necessary, form the basis for the provision of enhanced cover thereafter. Vegetation should not be cleared from this area. The creation of a protection zone, particularly in urban areas where there may be a risk of vandalism, should always be undertaken carefully and without attracting undue attention.
Access to open water habitats, including freshwater sites near the coast, must be safeguarded at all times. Impacts to established otter paths and traditional routes between areas should be minimised.
Any temporarily exposed pipe system should be capped to prevent otters gaining access when contractors are off site. Recreational sites should be planned to minimise the direct impacts of humans and dogs on the most important areas of otter habitat, including the most significant areas of cover. This includes designing footpaths and cycleways along riverbanks to avoid known otter shelters, routing them away from the river bank by at least 30 m from the shelter location. This will involve a balance between the ideal and what is likely to be achievable in practice.
Disturbance after completion of work can be minimised by maintaining as much tree and scrub cover around the otter shelter as possible. This can be enhanced by planting additional thicket-type vegetation and, if necessary, fencing off the entire area from livestock. Consideration may also be given to other riparian species, such as water voles.
Removal of otter shelter
There are circumstances in which the destruction of an otter shelter may be done under licence. This must be carried out with great care using handwork where possible in order to avoid harm to an otter which may be using the structure at the time. The work should be supervised by an appropriate specialist and measures should be taken to ensure that the shelter is unoccupied at the time.
If breeding is suspected where construction work is already underway, on-site activity should be suspended until it can be demonstrated that either (a) breeding is not occurring on site or (b) the cubs are sufficiently old (and therefore mobile) for alternative sites to be used elsewhere. If breeding is confirmed but the cubs are still very young, it is advisable to suspend work for up to 8-10 weeks in the area until they are mobile. If this is not possible, a much larger protection zone will be required of between 100 and 200 m from the otter shelter. The exact size of this protection zone will be influenced by local circumstances and may need to be larger than this in some cases. Both of these measures are designed to avoid disturbance to otters and thereby avoid the need for a licence. However, where there are imperative over-riding reasons for continuing with the work and risking disturbance, provision exists within the licensing system to facilitate this.
Contacts and further information
Chanin P. (2003) Ecology of the European Otter. Conserving Natura 2000 Rivers Ecology Series No.10 English Nature, Peterborough.
Chanin P. (2003) Monitoring the Otter Lutra lutra. Conserving Natura 2000 Rivers Monitoring Series No.10 English Nature, Peterborough.
Environment Agency (1999) Otters and River Habitat Management (2nd edition). Bristol.
Forestry Commission Scotland & Scottish Natural Heritage (2009) Guidance Note 35c: Forest operations and otters in Scotland
Green R. & Green J. (1997) Otter Survey of Scotland: 1991-94. Vincent Wildlife Trust, London.
Grogan A., Philcox C. & Macdonald D. (2001) Nature Conservation and Roads: advice in relation to otters. Wildlife Conservation Research Unit/Highways Agency.
Highways Agency (1998) Design Manual for Roads and Bridges. Volume 10. Nature Conservation Advice in Relation to Otters (Under revision)
Iuell, B., Bekker, G.J., Cuperus, R., Dufek, J., Fry, G., Hicks, C., Hlavac, V., Keller, V., B., Rosell, C., Sangwine, T., Torslov, N., Wandall, B. le Maire, (Eds.) 2003. COST 341 – Wildlife and Traffic: A European Handbook for Identifying Conflicts and Designing Solutions.
Kruuk H. (1995) Wild Otters: Predation and Populations. Oxford University Press, Oxford.
Kruuk H. (2006) Otters: Ecology, Behaviour and Conservation. Oxford University Press, Oxford.
Liles G. (2003) Otter Breeding Sites. Conservation and Management . Conserving Natura 2000 Rivers Conservation Technical Series No.5 English Nature, Peterborough.
Newton, J., Nicholson, B. & Saunders, R. (2011) Working with wildlife: guidance for the construction industry (C691). CIRIA.
Scottish Environment Protection Agency (2000) Ponds, pools and lochans. Guidance on good practice in the management and creation of small waterbodies in Scotland.
Scottish Environment Protection Agency (2010) Guidance for applicants on supporting information requirements for hydropower applications. The Water Environment (Controlled Activities) (Scotland) Regulations 2005 (CAR)
Scottish Planning Policy
Strachan, R. (2007) National survey of otter Lutra lutra distribution in Scotland 2003-2004. Scottish Natural Heritage Commissioned Report No.211 (ROAME No. F03AC309).