Otters: surveys and mitigation for development projects

Standing advice for local planning authorities to assess the impacts of development on otters.

Applies to England

Survey reports and mitigation plans are required for development projects that could affect protected species, as part of getting planning permission or a mitigation licence. Surveys need to show whether protected species are present in the area or nearby, and how they use the site. Mitigation plans show how you’ll avoid, reduce or manage any negative effects to protected species.

This is Natural England’s species standing advice for local planning authorities who need to assess planning applications that affect otters.

Local planning authorities should use this advice to decide what is needed for surveys and planning mitigation measures to protect otters.

If a local planning authority consults Natural England and the Environment Agency on the same planning application, Natural England will use this standing advice and the Environment Agency will lead on providing additional advice.

Ecologists need to decide which survey and mitigation methods are right for the project being worked on. If this guidance can’t be followed, they’ll have to include a statement with the planning or licence application explaining why.

Where this guide says ‘you’ it means the ecologist.

Get more detail on:

How otters are protected

The Eurasian otter is the only native UK otter species. It’s fully protected as a European protected species (EPS) and is also protected under sections 9 and 11 of the Wildlife and Countryside Act 1981.

You’re breaking the law if you:

  • capture, kill, disturb or injure otters (on purpose or by not taking enough care)
  • damage or destroy a breeding or resting place (deliberately or by not taking enough care)
  • obstruct access to their resting or sheltering places (deliberately or by not taking enough care)
  • possess, sell, control or transport live or dead otters, or parts of otters

If you’re found guilty of an offence you could get an unlimited fine and up to 6 months in prison.

Decide if you need to survey

Survey for otters if:

  • distribution and historical records suggest otters may be present
  • the development will affect a water body (eg river, stream, lake, sea or marshland)
  • development will affect habitats near a water body directly or through environmental impacts, eg noise, light

Survey methods

Surveys should be done by a suitably experienced surveyor. They might also have to be a licensed surveyor.

Look for evidence of otters, including:

  • dung (spraints)
  • tracks (footprints)
  • feeding remains
  • otter slides (into water)
  • holts (underground dens)
  • couches (above ground sites where otters rest during the day)

You can survey at any time of year but the best time is spring. This is because evidence is often easier to find during spring, as water levels recede and wet mud is exposed where paw prints can be seen more easily.

You might not need to do detailed survey work if avoidance and mitigation measures are built into development proposals, but you must provide enough information in the survey to understand:

  • what kinds of impacts there might be on otters
  • how impacts might affect otters

Otter activity varies according to the season. You might need to do several surveys throughout the year to establish how big the impacts are and what mitigation measures might be necessary. How many surveys you’ll need to do depends on:

  • how likely it is that otters will be affected by any development work
  • the size of the development, eg if it’s a large development close to where otters are it might affect them more

Assess the impacts

Otters are highly territorial animals with large home ranges. Depending on the quality of the habitat and availability of food males can range along rivers for 35km. Otters will continue to try and use routes if alternatives are not included in a mitigation strategy.

Assess the impacts this development would have on otters if no mitigation measures were planned and submit the assessment with your planning or licence application. Impacts to consider include:

  • habitat loss or degradation in or near water bodies
  • habitats being cut off and becoming fragmented
  • holts and resting places being removed
  • disturbance to resting and feeding places
  • disturbing their usual routes, eg road bridge or culvert works forcing otters to use roads or bridges that might mean it’s more likely that otters will be killed or injured on the road
  • changes to water quality which could also affect food sources

Mitigation, compensation methods and avoiding impacts

Use avoidance, mitigation and compensation to deal with potential impacts you’ve identified that might affect otters.


Aim to avoid negative effects, which may include avoiding:

  • work on or near the water body and known otter habitat
  • disturbance effects, eg by leaving a buffer zone along a river
  • night works


Use mitigation measures to reduce the impacts if you can’t avoid negative effects. You’ll have to identify and suggest these if you’re the applicant.

The local planning authority will have to assess what difference the mitigation measures would make to the anticipated effects of the project.

Mitigation measures may include designing the development so that it:

  • retains otter habitats in the water body and bank
  • avoids road crossings and culverts
  • uses otter-proof fences to stop otters getting into development sites


Use compensation measures to offset any remaining negative impacts for otters.

Compensation measures should:

  • result in no net loss of breeding or resting sites
  • provide enhanced habitat, eg quality or area compared with that lost if a significant impact is predicted
  • remedy any loss of otter access and habitat connectivity

Compensation measures can include:

  • constructing artificial holts to replace those that will be damaged or removed
  • building viaducts or underpasses to allow otters to cross barriers like roads
  • installing mammal ledges on bridges and culverts to allow for continued passage alongside water bodies
  • restoring or improving habitats to compensate for those that will be lost

Additional licensing Information

This guidance is provided for ecologists and developers considering applying for a mitigation licence for otters where disturbance or harm to otters and their habitat is likely to happen.

Your mitigation licence application needs to follow the above standing advice and this additional licensing information or it may be refused.

Get an EPS mitigation licence

Usually you should be able to avoid harming the otters or damaging or blocking access to their habitats. Apply for a mitigation licence if you can’t avoid this.

Get planning permission if you need it before you apply for a licence.

You’ll need expert help to apply, eg from a qualified ecologist.


You might need to survey the area again and adjust your mitigation plans if necessary, depending on when you did the surveys, if you’re applying for a mitigation licence.

You won’t need a licence if you’re using most methods of surveying unless there’s going to be any disturbance of the otter or its resting place, eg using an endoscope camera to explore a hole that might be a holt.

Other licences

Find out more about survey, research and possession and apply for otter licences.

Published 6 October 2014
Last updated 5 April 2019 + show all updates
  1. Changed which sections of the Wildlife and Countryside Act give protection to otters.

  2. The link for more detail on surveys and mitigation is now higher up in the guide.

  3. First published.