Alternative Names (Synonyms)

• Otter
• Eurasian river otter
• European river otter
• Loutre commune (French)
• Loutre d'Europe (French)
• Eurasiatischer Fischotter (German)
• Fischotter (German)

Alternative species names (the second part of the binomial species names): [Genus] amurensis; [Genus] angustifrons; [Genus] aureventer; [Genus] aurobrunneus; [Genus] baicalensis; [Genus] barang; [Genus] ceylonica; [Genus] chinensis; [Genus] fluviatilis; [Genus] hanensis; [Genus] indica; [Genus] intermedia; [Genus] japonica; [Genus] kamtschatica; [Genus] kutab; [Genus] marinus; [Genus] meridonalis; [Genus] monticolus; [Genus] nair; [Genus] nepalensis; [Genus] nippon; [Genus] nudipes; [Genus] oxiana; [Genus] piscatoria; [Genus] roensis; [Genus] seistanica; [Genus] sinensis; [Genus] splendida; [Genus] stejnegeri; [Genus] vulgaris;  [Genus] whiteleyi (B141).

Names for new-borns / juveniles

General Appearance

Similar Species

• Larger size, flattened head and long, thick-based tapering tail distinguish from mink and aquatic rodents (B142).
• On land: larger than Mustela vison -American mink and lighter colour (mid-brown not dark brown/black), also by tail (B142).
• Head broader and flatter than in Martes martes - Pine marten, muzzle more rounded (B148).

References

Species Author

Major References

Husbandry references:
J23.12.w1

Legislation references:
W5.Oct01

• Wildlife and Countryside Directorate, Department of the Environment, Transport and the Regions (DETR)
• The Mammal Society
• Mammals Trust
• International Otter Survival Fund (IOSF)
• The Otter Trust

• British Mammal Factsheets

TAXA Group (where information has been collated for an entire group on a modular basis)

Parent Group

• Land carnivores: Mustelidae

Specific Needs Group referenced in Management Techniques

• Land carnivores: Mustelidae

Husbandry Information

Notes

• Accommodation of Casualty Lutra lutra - European Otter
• Hand-rearing Lutra lutra - Eurasian Otter
• Catching and Handling of Lutra lutra - Eurasian Otter
• Feeding of Casualty Lutra lutra - Eurasian Otter
• Release of Casualty Lutra lutra - European Otter

Measurement & Weight

Head

• Broad, flat and rounded.
• Skull: Narrow post-orbital constriction (B142).
• Nose: Nostrils high on head, can be closed under water. Long whiskers (vibrissae) on upper lip and mouth corners.
• Ears: small, round, nearly hidden in fur, can be closed under water.

(B52, B144, B147, B148)

Legs and Tracks

• Short powerful legs.
• Five toes.
• Webbed toes.
• Strong claws

(B52, B142, B144, B147, B148)

Tail

• Thick base, muscular, rounded, underside flattened, tapering.
• Used as rudder when swimming.

(B52, B144, B147, B148)

Length: 35-40cm (B52); 12-22in./30-55cm (B144), up to 50 cm B148.

Coat / Pelage

• Dorsal: glossy dark brown or chestnut brown
• Ventral: ventral slightly lighter brown.
• Throat: pale - buff to cream.
• Chin: may have white patch.
• Fur thick, dense: fine thick wool, upper hair, coarse shiny bristles.)
• Dense underfur - remains dry when in water.
• Coat appears shiny when wet and spiky after shaking.

(B52, B142, B144, B148)

• Coat may be paler brown (B52).

Neonate (New-born) Characteristics

Detailed Anatomy Notes
(Summary information provided for pertinent species-specific data cross-referenced in WILDPro)

• Reproductive: two or three pairs of nipples (B142, B144).
• Scent glands: anal gland either side of anus, proctodeal glands discharging into rectum (B142).

Natural Diet

• Fish, frogs, crayfish, crabs, other aquatic invertebrates.
• Also birds (waterfowl, waders, passerines), rarely mammals (rabbits, water voles).
• Sometimes aquatic insects.
• Mainly fish in most areas, some places more frogs or crayfish, and in coastal areas crabs may be up to 20% of diet.

(B142, B144, B147, B148)

Detailed Physiology Notes
(Summary information provided for pertinent species-specific data cross-referenced in WILDPro)

• (Spraints). Deposited often on prominent features e.g. logs and rocks, and same places used regularly.
• Dark, mucilaginous, musky smell when fresh. Reach 10cm long/1cm diameter.

(B142)

Feeding Behaviour

• Hunt for fish catching with mouth.
• Dive for crustaceans and clams.

(B144, B147)

Parental Behaviour

Social Behaviour / Territoriality

• Mainly solitary (B142).
• Territory shoreline strips 320ft/100m wide, 1- more than 30 miles long /2-50km long (B144). 1 animal per 2-3km lakeshore or 5km of stream - 0.7-1.0 animal per square km of water (B147). Straight line home range 15km males, 7km females (B147).
• Home ranges may be small (few hundred metres) in very productive areas (B142).
• Examples include: Shetland 2-13km of coast, Perthshire male 39km river, females 16 and 22 km of river. Sweden females 4-8km across on lakes and interconnecting streams, with 11-21km for males (B142).
• Male territories exclusive of other males, female territories exclusive of other females (B147).
• Variable overlap female territories with one another (overlap in Perthshire, but exclusive in Sweden) (B142).
• Variable overlap male territories (Partial overlap Sweden, in Perthshire less overlap than for females) (B142).
• Male range territories may overlap with several females (B147).
• Territories marked with scent (B147). Mark home ranges with spraints, particularly males (B142).
• Occasional fights (B147). Fights not recorded in wild (B142).
• Dominance hierarchy among males, with favoured territory to highest ranking animal (B142, B147).
• Males mainly solitary (B147) but may join female when cubs about 6 weeks old (B147).

Sexual Behaviour

• Vigorous chasing and play involved in courtship, with pair staying together for about one week.
• Mate on land or in water.

(B142)

Predation in Wild

• Skuas may take very small juveniles in Shetland.
• On continental Europe, sea eagles, wolves, lynx.

(B142)

Activity Patterns

• Use fixed runs within territory.
• Walk, run and bound on land.
• Expert swimmer and diver, closing nostrils and ears when under water and surfacing every few minutes to breath.
• Swim using all four legs at surface, and by lumbar dorso-ventral flexion under water.
• Usually rest in holt or dense cover above ground.
• Rest in open usually for short times, including sunning.
• Playful.

(B142, B144, B147, B148)

• Active dusk and night, but also in daytime if not disturbed (B144).
• Hunt at night (B148).
• Mainly nocturnal on rivers but active in day on coasts, particularly early morning/late evening in summer (B142).

General Habitat Type

• Lakes, rivers, streams, marshes, also coasts.
• Travel overground between watersheds.

(B142, B144)

Nests / Burrows / Shelters

• Holt may be dug, or natural hole used, in bank of river/stream/lake.
• Entrances below water level.
• Dens may have several passages.
• Living chamber/nest above water level, with dry leaves and grass lining.
• With ventilation shaft.

(B147, B148)

Distribution and Movement (Migration etc.)

• Not found: Mediterranean islands (except Corfu, Lesbos, Chios, Euboea). Probably extinct in Lichtenstein, Netherlands, Switzerland. (B143).
• Europe: Good populations remaining: Portugal, Ireland, Greece, Scotland, northern taiga of Russia Natural recovery: Finland, Great Britain (B143).
• Britain: Remain through Ireland and most of Scotland. Reasonable populations south-west England and counties bordering mid-Wales, with low populations in north, south and eastern England, while absent from south Wales, Anglesey, central England (B142).

(B51, B52, B143, B147, B148)

Reintroduction/restocking projects Switzerland, Sweden, Great Britain, Spain (B142, B143).

Intraspecific variation

• Ten subspecies recognised. Small differences between subspecies and not well investigated (B143).
• No subspecies recognised (B142).

Conservation Status

• Formerly widespread in Europe, but declined central and northern Europe, to extinction in some areas. (B143, B144, B148).

• Crashes in populations 1960s-1970s, (B143); severe declines from 1957 thought due to organochloride pesticides, also PCBs, heavy metals (B142).

• In Britain: native, population localised but generally increasing. Pre-breeding population estimate for mid-1980's of about 7350, with 350 in England, 6600 in Scotland, 400 in Wales. Significantly higher population by mid 1990s. Population estimate of this widely-distributed species was based on a limited amount of data and considered likely to be inaccurate by up to 50% in either direction (B221).

• Bern Convention Appendix II (B143).
• EU Habitats & Species Directive, Annex II & Annex IV (B143).
• EC 338/97 Annex A (B143).
• Protected under Wildlife and Countryside Act 1981 in Britain, also protected in Northern Island (B142).
• This species is listed on Schedule 6 (Animals which may not be killed or taken by certain methods) of the LUK2 - Wildlife and Countryside Act 1981 of the United Kingdom. (W5.Oct01)

• Appendix I (Reservation by Russian Federation) (B143).
• Appendix I (B147).

• Formerly chemical pollution, hunting (for fur and sport), habitat loss. Now widely protected against hunting (B142, B143).
• Also road traffic accidents, incidental capture in fish/crustacean traps (B142, B143, B221).
• Possible role of decreased river/lake productivity due to acidification (B143, B221).
• PCB contamination may influence population recovery (B143, B221).
• Potential threat to coastal populations from oil spills (B221).

• EEP (European Breeding Programme) started 1985 for self-sustaining captive population, with total captive population about 200 animals.
• As of 1993, 55 of 60 holders of otters had agreed to co-operate in EEP and their animals were included in the studbook.

(B143)