- © Craig Llewellyn
- © Arbeco Ltd.
- © Arbeco Ltd.
The European or Eurasion otter, Lurtra lutra, is a semi-aquatic mammal and is principally nocturnal. Otters occupy a range of wetland habitats including rivers, streams, ditches, lakes, marshes and coastal areas, feeding on a diet of fish.
An otter’s home range is around a 20-40km stretch of river for males and 10-20km for females and contains many resting places. Resting places are often located in holes amongst riverside tree roots, enlarged rabbit burrows or outlying badger setts. Otter’s rest above ground in patches of scrub and in undisturbed areas of tall grass or other similar tall vegetation.
Otters can breed at any time of year, with pregnancy lasting 63 days. Females give birth to 1 to 3 cubs, but occasionally up to 5.
Otter populations in the UK have declined over the 20th century, due to the introduction of certain types of pesticide in the mid-1950s.
An otter’s home range is large so it is important that the watercourses beyond the immediate development boundary are also surveyed.
Surveys involve a search for evidence of otters including presence of otter faeces, also known as spraints, characteristic footprints and water “slides” on the embankments. Otter spraints have a characteristic “sweet” smell and are deposited in prominent locations close to the watercourse on tree roots, stones, boulders, tussocks of vegetation or man-made structures such as bridge footings.
If evidence of otters is found on site then efforts must be made to protect them, or planning permission will be refused. This could involve altering the plans to avoid otter habitats or modifying construction site practice to minimise disturbance to otters and their habitat.
If it is not feasible to alter the development plans, then appropriate mitigation and compensation measures should be implemented. This must be done under a European Protected Species (EPS) licence. Mitigation and compensation measures may include artificial holts, wet culverts and dry tunnels.
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