La Loutre a une silhouette hydrodynamique avec une tête aplatie et un corps allongé. Ses pattes, munies de 5 doigts, sont courtes et palmées et sa queue massive se termine en pointe. Son pelage est brun uniforme, plus clair sur la face ventrale, surtout au niveau du cou. De petites taches blanchâtres sont présentes sur les lèvres et le cou permettant une identification des individus. Sa fourrure est très dense, lui assurant une totale imperméabilité. Ce mustélidé compte 36 dents : I3/3, C1/1, P4/3, M1/2. Les mâles sont généralement plus grands et corpulents que les femelles. Dans l’eau, la Loutre peut être confondue avec le Ragondin (Myocastor coypus) et le Castor d’Europe (Castor fiber).
En France, la Loutre est devenue crépusculaire et nocturne. Elle passe sa journée à se reposer dans son gîte tandis que la nuit est principalement consacrée aux déplacements et à la recherche de nourriture. Territoriale et solitaire, elle ne vit en couple que pendant la période du rut. La maturité sexuelle est atteinte vers 2-3 ans. L’accouplement peut avoir lieu toute l’année et se passe sur terre ou dans l’eau. La gestation dure une soixantaine de jour, sans diapause. La femelle met bas de 1 à 3 loutrons aveugles pesant une centaine de gramme. Ils s’émancipent entre 8 à 12 mois et peuvent vivre jusqu’à 3-5 ans dans la nature contre 15 ans en captivité. La Loutre d’Europe est essentiellement ichtyophage mais, opportuniste, elle consomme également d’autres types de proies : amphibiens, invertébrés aquatiques, mammifères, oiseaux,...
Ce mammifère d’eau douce occupe tous les habitats aquatiques. Elle se rencontre dans des milieux et zones climatiques très différents les uns des autres. La taille des domaines vitaux dépend des ressources disponibles, mais ils s’étendent sur environ 20 km le long d’un cours d’eau et peuvent atteindre 40 km. Au sein de son domaine vital, la Loutre possède plusieurs dizaines de gîtes, nommés « catiches », qu’ils soient de repos ou de mise bas. Les gîtes de repos peuvent être des terriers, se trouvant généralement dans la berge des cours d’eau, ou des couches à l’air libre situés dans des zones boisées impénétrables. Les gîtes de mise bas sont plus complexes et sont généralement bien cachés et peu accessibles. Les sites ou les femelles mettent bas et élèvent leurs jeunes sont fidèlement réutilisés d’année en années. La Loutre marque son domaine vital par le dépôt d’urine et d’épreintes (= fèces de la Loutre) qu’elle dépose le long des rives généralement au niveau de points marquants du paysage.
[Référence : KUHN R. & JACQUES H. 2011. La Loutre d’Europe Lutra lutra (Linnaeus, 1758). Société française pour l’Etude et la Protection des Mammifères. Encyclopédie des Carnivores de France 8 : 72p. ]
There are several open questions about its occurrence in the Southeast Asian region. It seems that the Eurasian Otter reached the island of Sumatra but, did not reach the island of Java. Conroy et al. (1998) are not sure if the evidence of otters on the island of Borneo really relates to the Eurasian Otter. Its occurrence has been confirmed from South Korea, southern China, Viet Nam, Cambodia, Lao PDR, Myanmar and Bangladesh (Lekagul and McNeely 1988, Hussain 1999). In India it occurs in northern, northeast and southern India. Formerly widely distributed in Japan, it is now believed to be extinct (Ando et al. 2007). Once widespread in the rivers of northern Mongolia (Mallon 1985), along the rivers of Mongol Altai Mountain Range, and along the Halh River in Ikh Hyangan Mountain Range (Bannikov 1954, Dulamtseren 1970, Sokolov and Orlov 1980). It has also been reported from downstream of the Tengis River in northern parts of Hvsgl Mountain Range (Tsagaan 1975, 1977) and around the Er River Basin in western Hentii Mountain Range (Tsendjav 2005). The Eurasian Otter can also be found occasionally along the Tes River in northern Hangai.
Coastal habitat is suitable over large portions of the European continent, including perimeters of the Celtic Sea, English Channel, Bay of Biscay, Irish Sea, Sea of the Hebrides, North Sea, Norwegian Sea, Baltic Sea, Gulf of Riga and Mediterranean Sea. Furthermore, some European countries offer suitable otter habitat hundreds of kilometres inland from the nearest sea. For example, in Romania, not only are European otter found within the Danube Delta, but far inland within the Carpathian Mountains. In Poland and Bulgaria, otters are found far inland in the rivers that have sufficiently high water quality and have a minimum of hydroelectric installations. The European otter, in fact, can be found in mountain valleys as high as 1400 metres in places such as Bulgaria, including numerous small watersheds in West Rhodopy Mountain, Bulgaria. In Turkey, however, overgrazing of riparian terrestrial cover, human hunting and water pollution have almost extirpated L. lutra from inland areas, except for parts of the Coruh River. In Soain L .lutra is found along parts of the coastline but also in interior riparian zones in such ecosystems as the Iberian sclerophyllus forests, where populations may be considered relicts of broader prehistoric distributions.
Lutra lutra inhabits most of Eurasia south of the tundra line and North Africa. (MacDonald, 1984)
Biogeographic Regions: palearctic (Native )
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 6750 g.
Average basal metabolic rate: 25.104 W.
Habitat and Ecology
In most parts of its range, its occurrence is correlated with bank side vegetation showing importance of vegetation to otters (Mason and Macdonald 1986). Otters in different regions may depend upon differing features of the habitat, but to breed, they need holes in the river bank, cavities among tree roots, piles of rock, wood or debris. The Eurasian Otters are closely connected to a linear living space. Most portion of their activity is concentrated to a narrow strip on either side of the interface between water and land (Kruuk 1995). Otter distribution in coastal areas especially the location of holts, is strongly correlated with the presence of freshwater (Kruuk et al. 1989, Beja 1992).
Within the group home range, shared by resident adult females, each had her own core area. Resident males had larger home ranges in more exposed parts of the coast which overlapped with other males and with at least two female group ranges. Male and female transients moved through group ranges, relegated to less favoured holts, habitat and food. In freshwater home ranges are longer for both sexes (Kruuk 1995). Erlinge (1969) suggested that males were hierarchical and territorial, influenced by sexual factors, while female ranges were influenced by food and shelter requirements of the family group. Green et al. (1984) and Kruuk (1995) found that adult males spent most of their time along the main rivers, whereas adult females occupied tributaries or lakes, as they did in Austria (Kranz 1995). Rosoux (1995) found no sexual differences in habitat utilization and considerable overlaps in range. Young animals usually occupied peripheral habitat, but Green and Green (1983) found differences between immature and mature young males, the later having access to all available habitat and the other restricted to marginal habitat, supplemented by visits to the main river when vacant, temporally or spatially. While males generally have larger ranges than females in the same habitat, sizes vary according to the type and productivity of the habitat, and methods of measuring ranges vary from study to study.
Like most Lutra species, fish is the major prey of Eurasian Otters sometimes exceeding more than 80% of their diet (Erlinge 1969, Webb 1975, Ruiz-Olmo and Palazon 1997). In addition to fish a whole range of other prey items have been recorded in their diet in variable proportions. These include aquatic insects, reptiles, amphibians, birds, small mammals, and crustaceans (Jenkins et al. 1980, Adrian and Delibes 1987, Skaren 1993). In a study conducted in Sri Lanka, Silva (1996) reported that the overall diet of the Eurasian otters consisted of 81.2% of crab, 37.5% fish and 8.7% frog. In addition to these the diet also included small quantities of water snakes, birds, small mammals and insects.
The percentage of crab in the diet of the Eurasian Otters in Sri Lanka varied from 72% to 85%, and fish from 25-31%. There was significant seasonal variation in the diet in different habitats. The relative importance of fish in the diet was significantly higher in the reservoirs and lakes than the rivers and streams. Crabs were more important to otters inhabiting streams than those inhabiting rivers and lakes. Crabs were eaten more than fish during the monsoon (de Silva 1997). However, in Huai Kha Kheng, Thailand 76% of the spraint had fish, 64% amphibians and 7% crab (Kruuk et al. 1994). The Eurasian Otter is capable of taking fish as large as 9 kg (Chanin 1985), however, many studies in Europe have revealed that the fish consumed by the Eurasian Otters are relatively small with a median length of 13 cm (Kruuk 1995).
The Eurasian Otter is largely solitary and the adult otters tend not to associate with other adults except for reproduction. The family group of mother and offspring is the most important unit of otter society. In Shetland, where several adult animals used the same stretch of coast, encounters between adults were rare (Kruuk 1995) and the species was strikingly non-social. Kranz (1995) found evidence of social group formation beyond the occasional associations of two or more family groups, which suggests that under some circumstances otters of all ages and sexes may form temporary mutually tolerant gatherings.
In most of its range the Eurasian Otter is predominantly nocturnal (Green et al. 1984). The exception is Shetland, where otters were entirely diurnal (Kruuk 1995). Green et al. (1984) found that activity was largely circumscribed by the solar rhythm so that the duration of activity varied through the year with night length. The reverse situation was found in Shetland with activity restricted by the day length (Kruuk 1995). Some workers have found a break in activity in the middle of longer nights or days and single peak around midnight or midday in shorter nights or days, although up to four activity periods per night has been recorded. Kruuk (1995) links otter activity to that of prey species, with the favoured marine species more vulnerable in daylight and those in freshwater easier to catch at night. In coastal habitats, tidal patterns influence otter activity, with significant preference shown for feeding at low tide, both in Shetland and on the Scottish west coast (Kruuk 1995).
The Eurasian Otter attains sexual maturity at around 18 months in males and 24 months in the case of females, but in captivity it is usually three to four years (Reuther 1991). They are non-seasonally polyoestrous (Trowbridge 1983), mating in captivity has been observed at all times of the year (Reuther 1999). The gestation period is approximately 63-65 days, the litter size varies from 1 to 5, and the life expectancy is around 17 years (Acharjyo and Mishra 1983).
- UNESCO-IOC Register of Marine Organisms
Lutra lutra forage in water and nest on land. They inhabit rivers, lakes, streams, freshwater and peat swamp forests, ricefields, ocean shores, fjords, caves, and terrestrial habitats adjacent to waterways. Covered dens and dry resting sites are found in earth tunnnels, tree roots, boulder piles, shrubs, and banks. In its territory of 1 to 4 miles, each river otter has fixed locations for getting into and out of the water, rolling, sunbathing, and sliding on "otter stairways". (Grzimek 1990, Sivasothi 1994)
Aquatic Biomes: lakes and ponds; rivers and streams; coastal
Lutra lutra individuals eat fish, crustaceans, clams, small mammals and amphibians, birds, eggs, insects, worms, and a small amount of vegetation. They use their vibrissae (whiskers) as sensing organs underwater to monitor the movements of fishes and other prey. River otters hunt and feed several times a day, consuming about 1kg of food daily. (Grzimek 1990, MacDonald 1984, Heggberget 1994)
Threatened Vertebrate Associates in the Hindu Kush Alpine Meadow Ecoregion
The Hindu Kush alpine meadow has an expanse of some 10,900 square miles, situated in northeastern Afghanistan and northern Pakistan. Most of the lands lie within the Hindu Kush Mountain Range in the altitude bracket between 3000 to 4000 meters, and correspondingly most of the precipitation is in the form of snow. This ecoregion is classified within the Montane Grasslands and Shrublands biome.
This ecoregion manifests a low rate of vertebrate endemism; however there are ten special status mammals found here, ranging from the status of Endangered to Near Threatened. The Hindu Kush alpine meadow ecoregion consists of higher elevation terrain of moderate to severe slopes. Vegetation is often sparse or almost lacking, with resulting pastoral usage of low intensity grazing of goats and sheep in some areas. Soils are largely leptosols, but many areas are covered by large expanses of rock outcrop or rocky scree. In the limited areas of arable soils, wheat is sometimes farmed, although growing of opium poppies is the only cash crop. Most of the water available for plant and animal life is supplied by snowmelt. The Helmand River, Afghanistan's largest watercourse, represents the chief catchment within the ecoregion, with headwaters rising in the Hindu Kush Range, and eventual discharge to the endorheic Sistan Basin.
Special status mammals found in the Hindu Kush alpine meadow are: the Near Threatened argali (Ovis ammon), the Vulnerable Asiatic black bear (Ursus thibetanus), the Near Threatened European otter (Lutra lutra), the Near Threatened leopard (Panthera pardus), the Endangered markhor (Capra falconeri), the Near Threatened mountain weasel (Mustela altaica), the Near Threatened Schreiber's long-fingered bat (Miniopteris schreibersi), the Endangered snow leopard (Uncia uncia), the Near Threatened striped hyena (Hyaena hyaena) and the Endangered Moschus leucogaster. Special status birds in the Hindu Kush alpine meadow are represented by the Endangered Egyptian vulture (Neophron percnopteris).
Known prey organisms
Based on studies in:
UK: Yorkshire, Aire, Nidd & Wharfe Rivers (River)
This list may not be complete but is based on published studies.
- E. Percival and H. Whitehead, 1929. A quantitative study of the fauna of some types of stream-bed. J. Ecol. 17:282-314, from p. 311 & overleaf.
- Hall SJ, Raffaelli D (1991) Food-web patterns: lessons from a species-rich web. J Anim Ecol 60:823842
- Huxham M, Beany S, Raffaelli D (1996) Do parasites reduce the chances of triangulation in a real food web? Oikos 76:284300
Life History and Behavior
Perception Channels: tactile ; chemical
Status: captivity: 22.0 years.
Lifespan, longevity, and ageing
Lutra lutra has a continuous breeding cycle and female otters have a continuous estrus cycle. Mating can take place either in water or on land. The main mating season is from February to March and July. Gestation lasts 60 to 70 days and weaning occurs at 3 months. Each female river otter usually gives birth to 2 or 3 cubs which are 99 to 122gm at birth. The cubs' eyes open after one month and they begin to leave the nest after two months. The young stay with their mothers for up to 14 months and reach sexual maturity after 2 or 3 years. (Heggberget 1994, Grzimek 1990)
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average birth mass: 110.5 g.
Average gestation period: 61 days.
Average number of offspring: 2.
Average age at sexual or reproductive maturity (male)
Sex: male: 548 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 548 days.
Molecular Biology and Genetics
Barcode data: Lutra lutra
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
-- end --
Download FASTA File
Statistics of barcoding coverage: Lutra lutra
Public Records: 3
Specimens with Barcodes: 5
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
The species was listed on The IUCN Red List as Near Threatened in 2004 and 2008 based on declines in parts of the range, the lack of information from many parts of its range, and the sensitivity of the species to sudden changes in threats. The listings also took into account the status of subpopulations in the far east - China and Indo-China, where it was thought they might be declining because of possible over-exploitation.
This Near Threatened assessment is more of a precautionary listing, as it indicates that while the recovery in western Europe is genuine that the conservation actions for this species need to be sustained. Besides, there is still concern about what is happening in parts of its range in Asia due increasing habitat loss and poaching.
- Near Threatened (NT)
- 2004Near Threatened (NT)
- 2000Vulnerable (VU)
- 1996Lower Risk/least concern (LR/lc)
IUCN Red List of Threatened Species: near threatened
Pollution is major threat to the otters in western and central Europe, the main pollutants posing a danger to otters are the organochlorines dieldrin (HEOD) and DDT/DDE, polychlorinated biphenyls (PCBs) and the heavy metal mercury. Coastal populations are particularly vulnerable to oil spills. Acidification of rivers and lakes results in the decline of fish biomass and reduces the food resources of the otters. The same effects are known to result from organic pollution by nitrate fertilizers, untreated sewage, or farm slurry.
In addition, major causes of mortality from range countries are drowning and road kills. Fyke nets set for eels or for fish as well as creels set for marine crustaceans have a great attraction to otters and a high risk to those that successfully try to enter these traps.
A further potential threat is strangulation by transparent, monofilament drift net. A potential risk comes from traps designed to kill other species, especially underwater cages constructed to drown muskrats. Illegal hunting is still a problem in many parts of their distribution range. In several European countries political pressure especially by fishermen has resulted in granting of licenses for killing otters (Reuther and Hilton-Taylor 2004).
There is an ongoing discussion about the problem of reintroduction of otters. In recent years it is feared that it may contaminate the genetic structure of the native population (Mason 1992, Reuther 1998).
A European Breeding Programme (EEP) for self-sustaining captive populations was started in 1985. Monitoring programmes have been established in many range states in Europe. Several reintroduction programmes has been initiated in Europe such as in UK, Sweden and Netherlands which have been successful in restoring otters back into their former habitats.
Relevance to Humans and Ecosystems
In the past river otters were considered to be the main competition of fishermen and a bounty was paid by the Swiss goverment for each otter killed. (Sivasothi 1994)
The pelts of river otters are considered to be valuable to humans. (Grzimek 1990)
The European otter (Lutra lutra), also known as the Eurasian otter, Eurasian river otter, common otter and Old World otter, is a European and Asian member of the Lutrinae or otter subfamily, and is typical of freshwater otters.
The European otter is a typical species of the otter subfamily. Brown above and cream below, these long, slender creatures are well-equipped for their aquatic habits. Its bones show osteosclerosis, increasing their density to reduce buoyancy. This otter differs from the North American river otter by its shorter neck, broader visage, the greater space between the ears and its longer tail. However, the European otter is the only otter in its range, so it cannot be confused for any other animal. Normally, this species is 57 to 95 cm (23–37 in) long, not counting a tail of 35–45 cm (14–18 in). The female is shorter than the male. The otter's average body weight is 7 to 12 kg (15.4–26.4 lbs), although occasionally a large old male may reach up to 17 kg (37 lbs). The record-sized specimen, reported by a reliable source but not verified, weighed over 24 kg (53 lbs).
Range and habitat
The European otter is the most widely distributed otter species, its range including parts of Asia and Africa, as well as being spread across Europe. Though currently believed to be extinct in Liechtenstein, and Switzerland, they are now very common in Latvia, along the coast of Norway and across Great Britain, especially Shetland, where 12% of the UK breeding population exist. Ireland has the highest density of Eurasian otters in Europe. In Italy, they can be found in southern parts of the peninsula. The South Korean population is endangered.
In general, their varied and adaptable diets mean they may inhabit any unpolluted body of fresh water, including lakes, streams, rivers, and ponds, as long as the food supply is adequate. European otters may also live along the coast, in salt water, but require regular access to fresh water to clean their fur. When living in the sea, individuals of this species are sometimes referred to as "sea otters", but they should not be confused with the true sea otter, a North American species much more strongly adapted to a marine existence.
The European otter's diet mainly consists of fish. During the winter and in colder environments, though, fish consumption is signiﬁcantly lower, and the otters use other sources of food, including amphibians, crustaceans, insects, birds and sometimes small mammals, including young beavers.
Behaviour and reproduction
European otters are strongly territorial, living alone for the most part. An individual's territory may vary between about one and 40 kilometres long (about one-half to 25 miles), with about 18 km (about 11 miles) being usual. The length of the territory depends on the density of food available and the width of the water suitable for hunting (it is shorter on coasts, where the available width is much wider, and longer on narrower rivers). The territories are only held against members of the same sex, so those of males and females may overlap.Mating takes place in water. Eurasian otters are nonseasonal breeders (males and females will breed at any time of the year) and it has been found that their mating season is most likely determined simply by the otters' reproductive maturity and physiological state. Female otters are sexually mature between 18 and 24 months old and the average age of first breeding is found to be 2.5 years old. Gestation for L. lutra is 60–64 days, litter weight when being compared to the female body mass is about 10%. After the gestation period one to four pups are born, which remain dependent on the mother for about 13 months. The male plays no direct role in parental care, although the territory of a female with her pups is usually entirely within that of the male. Hunting mainly takes place at night, while the day is usually spent in the European otter's holt (den) – usually a burrow or hollow tree on the riverbank which can sometimes only be entered from underwater. Though long thought to hunt using sight and touch only, evidence is emerging that they may also be able to smell underwater – possibly in a similar manner to the star-nosed mole.
The European otter declined across its range in the second half of the 20th century primarily due to pollution from pesticides such as organochlorine (OCs) and polychlorinated biphenyls (PCBs). Other threats included habitat loss and hunting, both legal and illegal. European otter populations are now recovering in many parts of Europe. In the United Kingdom the number of sites with an otter presence increased by 55% between 1994 and 2002. In August, 2011, the Environment Agency announced that otters had returned to every county in England since vanishing from every county except the West Country and parts of Northern England. Recovery is partly due to a ban on the most harmful pesticides that has been in place across Europe since 1979, partly to improvements in water quality leading to increases in prey populations, and partly to direct legal protection under the European Union Habitats Directive and national legislation in several European countries. In Hong Kong, it is a protected species under Wild Animals Protection Ordinance Cap 170. It is listed as Near Threatened by the IUCN Red List.
- Ruiz-Olmo, J., Loy, A., Cianfrani, C., Yoxon, P., Yoxon, G., de Silva, P.K., Roos, A., Bisther, M., Hajkova, P. & Zemanova, B. (2008). Lutra lutra. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 21 March 2009. Database entry includes justification for why this species is near threatened
- Hayashi, S.; Houssaye, A.; Nakajima, Y.; Chiba, K.; Ando, T.; Sawamura, H.; Inuzuka, N.; Kaneko, N.; Osaki, T. (2013). "Bone Inner Structure Suggests Increasing Aquatic Adaptations in Desmostylia (Mammalia, Afrotheria)". PLoS ONE 8 (4): e59146. Bibcode:2013PLoSO...859146H. doi:10.1371/journal.pone.0059146. PMC 3615000. PMID 23565143.
- Godman, John Davidson (1836) American Natural History, Hogan & Thompson.
- Hans, Kruuk (2007). Otters ecology, behavior and conservation. Oxford University Press. ISBN 978-0-19-856587-1.
- European Otter. theanimalfiles.com
- European Otter. purpleopurple.com
- Wood, Gerald L. (1983) The Guinness Book of Animal Facts and Feats. Sterling Pub Co Inc , ISBN 978-0-85112-235-9
- "Shetland Otters". Shetland Otters. Retrieved 2010-03-15.
- Jędrzejewska, B.; Sidorovich, V. E.; Pikulik, M. M.; Jędrzejewski, W. (2001). "Feeding habits of the otter and the American mink in Białowieża Primeval Forest (Poland) compared to other Eurasian populations". Ecography 24 (2): 165–180. doi:10.1034/j.1600-0587.2001.240207.x.
- Pagacz, Stanisław; Witczuk, Julia. "Intensive exploitation of amphibians by Eurasian otter (Lutra lutra) in the Wolosaty stream, southeastern Poland". Annales Zoologici Fennici 47: 403–410. doi:10.5735/086.047.0604.
- Weber, J.-M. (1990). "Seasonal exploitation of amphibians by otters (Lutra lutra) in north-east Scotland". Journal of Zoology 220: 641 651. doi:10.1111/j.1469-7998.1990.tb04740.x.
- Kitchener, Andrew (2001). Beavers. Whittet Books. p. 144. ISBN 1-873580-55-X.
- Erlinge, S. (1968). "Territoriality of the otter Lutra lutra L.". Oikos 19: 81–98. doi:10.2307/3564733. JSTOR 3564733.
- Hauer, Silek; Ansorge, Hermann; Zinke, Olaf (2002). "Reproductive performance of otters Lutra lutra (Linnaeus, 1758) in Eastern Germany: Low reproduction in a long-term strategy". Biological Journal of the Linnean Society 77 (3): 329. doi:10.1046/j.1095-8312.2002.00097.x.
- Alleyne, Richard (2010-06-05). "Can otters smell underwater?". Daily Telegraph (London). Archived from the original on 2010-06-06. Retrieved 2010-06-06.
Hamilton James said: “I always had an inkling that otters could smell underwater and I wanted to prove it. As it was dark and the fish was fully submerged it proved that the otters had to be using a sense other than sight or touch to locate it. After reviewing the footage I noticed a tiny bubble which hit the fish and was sniffed back in by the otter.”
- Director: Richard Taylor Jones; Camera Operators: Richard Taylor Jones, Charlie Hamilton James; Producer: Philippa Forrester (2010-06-06). "Late Summer". Halcyon River Diaries. Episode 4. BBC. BBC One. http://www.bbc.co.uk/programmes/b00sqkbv.
- "The Eurasian Otter (Lutra lutra)". English Nature. Retrieved 2010-03-15.
- "Otter: Background to selection". Jncc.gov.uk. Retrieved 2010-03-15.
- Michael McCarthy (2011-08-18). "Otters return to every county in England". The Independent. Retrieved 2011-08-19.
- "Council Directive 79/117/EEC of 21 December 1978". Eur-lex.europa.eu. Retrieved 2010-03-15.
- "Council Directive 92/43/EEC of 21 May 1992". Eur-lex.europa.eu. Retrieved 2010-03-15.
- "Species other than birds specially protected under The Wildlife and Countryside Act, 1981: Schedule 5 (Animals)". Jncc.gov.uk. 2005-08-30. Retrieved 2010-03-15.
- "Wildlife Act 1976 (Ireland)". Internationalwildlifelaw.org. 1976-12-22. Retrieved 2010-03-15.
- Otters of the world. otter.org
- Laidler, Liz. Otters in Britain. David & Charles, 1982. ISBN 0715380699