EFFECTS OF DEVELOPMENTS ON OTTERS
Are Otters Likely to be Affected?
As well as being vulnerable to the loss of their shelters, otters may also suffer from habitat loss, leaving them more open to disturbance, and from pollution which may not only affect their food supply but the animals themselves. The effects of development on otters can vary considerably and may not always be obvious. Therefore, each development proposal should be given careful consideration with otters in mind in case the proposal is damaging to their interests. If otters are present on site, then it is best to know this at an early stage rather than have a late discovery cause delays during construction. There is no substitute for professional advice both in ascertaining their presence and advising on appropriate mitigation measures.
Simply because a site is not next to water does not mean that otters may not be present as they can use holts 500m and more away. Furthermore 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 may be helpful to find out if there are otters in the vicinity, while local information from reliable sources such as conservation groups can also be useful.
Development can impact on otters in various ways, for example:
- habitat destruction: the availability of suitable cover is essential for otter shelters and if the animals are to tolerate incidental disturbance in the longer term
- 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 recreation areas
Fortunately, many developments, such as the installation of pipelines, are sufficiently flexible to avoid otters and their shelters if the animals are found on the site in good time; the avoidance of damage to these features should be the primary aim of both planners and developers.
The need for a survey applies to almost any proposal that is considered likely to lead to disturbance of otters or damage to an otter’s place of shelter. Even relatively small-scale proposals such as bridge repairs or bank works have the potential to impact on otters and therefore a limited survey is recommended to identify any sensitivities. At the other extreme, large developments spread over extensive areas, such as wind farms, require a rather different approach.
The function of the survey is to identify any sensitive features and to establish the presence or absence of otter activity. In particular, the survey should identify evidence of otter shelters, as it is usually these which ultimately constrain a development in terms of licensing. There is no ‘one size fits all’ methodology - the scope of the survey must be appropriate to the circumstances and the scale of the proposed development. Find out more guidance on otter surveillance and monitoring.
As a guide, for ‘small’ schemes such as individual bridges, pipeline crossings, local bank works and individual houses, a survey of 200-250m both upstream and downstream of the site should suffice, but with particular attention being paid to important riverine features such as in stream islands and reed beds. Beyond about 250m, disturbance from the proposed activity is unlikely to be an issue.
For major road schemes and other similar linear developments, the survey should encompass at least 250m on each side of all alternative routes and the same distance beyond the end of the scheme. The survey should record all evidence of otter activity within this area. In some cases a broader survey corridor encompassing 500m 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 is likely to require both an element of essentially linear watercourse survey and ‘two dimensional’ (spatial) survey 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 is unlikely to be practical, so for large wind farms, a radius of 250m around each proposed 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 100m 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.
It should be remembered that weather conditions can play a major part in determining the value of an otter survey and that sprainting frequency varies seasonally. 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 and these could therefore be easily missed.
Avoiding Disturbance to Otters
Apart from protecting otters themselves, the legislation safeguards their places of shelter and this has particular welfare considerations as, with the exception of Shetland, there is no specific season when otters give birth. It is therefore impossible to schedule works in order to prevent disturbance to an otter with cubs.
Works that can be expected to cause disturbance to otters or may damage or destroy their places of shelter, should only proceed after the appropriate licence has been issued by the Scottish Government. The licence may include specific conditions designed to minimise the impact of the development and provide appropriate mitigation. It is recommended that these conditions are integrated within an agreed working method statement which takes account of the species’ requirements. This should be formulated by the developer and/or their otter specialist in consultation with SNH.
In some cases, a licence may not be necessary, provided adequate safeguards are in place. This is the ideal objective of any proposal and is most likely to be achieved where there is ample flexibility in the design. Safeguards may be introduced by the planning authority as a series of specific conditions on the planning consent, or specified in the form of an agreed working method statement. Examples of such measures are given below and these should be regarded as forming the basis for good working practice in any situation where otters are involved. It is emphasised, however, that SNH should be consulted to determine whether the proposed measures are sufficient to avoid the need for a licence.
disturbance during the works should be minimised by declaring an area within at least 30m of 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 in this context. 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 such areas (such as field drains) during the construction phase should be minimised.
- any temporarily exposed open pipe system should be capped in such a way as to prevent otters gaining access, as may happen when contractors are off-site. recreational sites should be planned to minimise the direct impact of humans and dogs on the most important areas of otter habitat, including the most significant areas of cover. Footpaths and cycleways along riverbanks should, where possible, be designed to avoid known otter shelters. Paths should preferably be re-routed away from the river bank by at least 30m from the site of the shelter. However, a balance must be sought in each case between the ideal and what is likely to be achievable (in terms of visitor management) in practice.
- disturbance after the completion of the works can be minimised by maintaining as much tree and scrub cover around the otter shelter as possible and enhancing this by planting additional thicket type vegetation and, if necessary, fencing-off the entire area from livestock. If such measures are proposed, consideration should be given to other riparian species, such as water voles, whose habitat requirements are different.
There are circumstances in which the Scottish Government may issue a licence to allow the destruction of an otter shelter. This must be undertaken with great care using handwork wherever 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 in fact occurring at the 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 200m 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 risk disturbance, provision exists within the licensing system to facilitate this.
The use of fencing in this way has been undertaken proactively, particularly in England and Wales, to create so-called ‘otter havens’. These seem to be most successful when located on spurs of riparian land, such as in meanders, or in other parts of the riparian zone where otters are more likely to take overland ‘short cuts’ between sections of the river system.