Ecological survey calendar › Otters
When to survey for otters in Wales and England
Updated November 2026. Based on Natural England's current standing advice.
Otter surveys can be done at any time of year. The main constraint is the river, not the season: high flows wash away spraint and other signs, so surveys are best avoided straight after a spate. Otters can breed in any month, so riverside works need checks whenever they are planned.
Survey windows, sensitive periods and works timing
| Activity | Type | When | Notes |
|---|---|---|---|
| Otter surveys | Survey | All year | Possible all year. Avoid surveys straight after high flows. |
Optimal survey Possible, not ideal Sensitive period Works window
Timing depends on the site, the weather in a given year and what the planning authority and licensing body need. Upland and northern sites can run later. See every species group side by side on the ecological survey calendar.
About otters
Otters range widely along rivers, coasts and wetlands, using holts and resting sites in banks, tree roots and dense cover. They can breed at any time of year, so there is no safe season for works near a holt.
Legal protection
Otter is a European protected species under the Conservation of Habitats and Species Regulations 2017.
Licensing
Wales: Works affecting otter breeding or resting sites need a European protected species licence from Natural Resources Wales.
England: Works affecting otter breeding or resting sites need a licence from Natural England.
Practical tips
- Check for holts and resting sites whenever riverside works are planned, as otters can breed in any month.
- Note river levels on each visit. High flows wash away spraint and latrines and can make an absence result unreliable.
Common questions
When is otter survey season?
Any time of year (Natural England standing advice; Chanin, 2003). Avoid surveys straight after high flows, which wash away spraint and tracks.
Is there a season when works near otters are safe?
No. Otters can breed in any month, so holts and resting sites need checking before works at any time of year.
Do I need a licence for works near an otter holt?
If the works would damage or disturb a breeding or resting site, yes: from Natural Resources Wales in Wales or Natural England in England.
Need a survey or advice on timing? Ecoleg's licensed ecologists programme surveys across Wales and England so the right work happens in the right season. Call 07356 123706.
Request a quoteSee the full calendarSources
- Chanin, P. (2003) Monitoring the Otter. Conserving Natura 2000 Rivers Monitoring Series No. 10.
- Natural England (2025) Protected species and development: advice for local planning authorities, survey timings table (accessed November 2026).
Updated November 2026. General guidance only: confirm timing for your site with a suitably qualified ecologist.