European Otter

European River Otter
Conservation status

Near Threatened (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Mustelidae
Subfamily: Lutrinae
Genus: Lutra
Species: L. lutra
Binomial name
Lutra lutra
(Linnaeus, 1758)
Range map

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.

It differs from the North American river otter by its shorter neck, broader visage, the greater space between the ears and its longer tail.[2]

Contents

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. It is believed to be currently extinct in Liechtenstein, and Switzerland, It is proven to be extinct in the Netherlands. They are now very common in Latvia, along the coast of Norway and in Northern Britain, especially Shetland where 12% of the UK breeding population exist[3]. Ireland has the highest density of Eurasian otters in Europe. In Italy, they can be found in the Calore river area. These creatures live in the South Korean area, and are endangered.

Diet

The European Otter's diet mainly consists of fish. However, during the winter and in colder environments fish consumption is significantly lower and the otters use other sources for their food supply. This diet can include birds, insects, frogs, crustaceans and sometimes small mammals, including young beavers[4]. In general this opportunism means they may inhabit any unpolluted body of freshwater, including lakes, streams, rivers, and ponds, as long as there is good supply of food. European Otters may also live along the coast, in salt water, but require regular access to freshwater 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.

Behavior and reproduction

An otter on a bed of flowers

European Otters are strongly territorial, living alone for the most part. An individual's territory may vary between about one and forty kilometres long (about 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 [5].Mating takes place in water. Eurasian otters are non-seasonal 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 month old and the average age of first breeding is found to be 2.5 years old. Gestation for the 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.[6]. The male plays no direct role in parental care, although the territory of a female with her cubs is usually entirely within that of the male[5]. 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. It has long been thought that they hunt using sight and touch only; but evidence is emerging that they may also be able to smell underwater - possibly in a similar manner to the Star-nosed mole.[7][8]

Conservation

A European Otter skeleton

The European Otter declined across its range in the second half of the 20th century[9] 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.[10] 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. Recovery is partly due to a ban on the most harmful pesticides that has been in place across Europe since 1979,[11] partly to improvements in water quality leading to increases in prey populations, and partly to direct legal protection under the European Union Habitats Directive[12] and national legislation in several European countries.[13][14][15] In Hong Kong, it is a protected species under Wild Animals Protection Ordinance Cap 170. It is listed as Near Threatened by the 2001 IUCN Red List[16].

References

  1. ↑ 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. Downloaded on 21 March 2009. Database entry includes justification for why this species is near threatened
  2. ↑ American Natural History, by John Davidson Godman, published by Hogan & Thompson, 1836
  3. ↑ ""Shetland Otters"". "Shetland Otters". http://www.shetlandotters.com/shetlands-otters.php. Retrieved 2010-03-15. 
  4. ↑ Kitchener, Andrew (2001). Beavers. p. 144. ISBN 187358055X. 
  5. ↑ 5.0 5.1 "Territoriality of the otter Lutra lutra L." Erlinge, S. (1968), Oikos, No. 19, 81-98.
  6. ↑ Hauer S., et al. "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 (2002): 329-340.
  7. ↑ Alleyne, Richard (2010-06-05). "Can otters smell underwater?". Daily Telegraph (London). Archived from the original on 2010-06-06. http://www.webcitation.org/5qIDV2lGC. 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.”" 
  8. ↑ "Late Summer". Director: Richard Taylor Jones; Camera Operators: Richard Taylor Jones, Charlie Hamilton James; Producer: Philippa Forrester. Halcyon River Diaries. BBC. BBC One, London. 2010-06-06. No. 4.
  9. ↑ ""The Eurasian Otter (Lutra lutra)"". English Nature. http://www.english-nature.org.uk/lifeinukrivers/species/otter.html. Retrieved 2010-03-15. 
  10. ↑ "Otter: Background to selection". Jncc.gov.uk. http://www.jncc.gov.uk/ProtectedSites/SACSelection/species.asp?FeatureIntCode=S1355. Retrieved 2010-03-15. 
  11. ↑ "Council Directive 79/117/EEC of 21 December 1978". Eur-lex.europa.eu. http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31979L0117:EN:HTML. Retrieved 2010-03-15. 
  12. ↑ "Council Directive 92/43/EEC of 21 May 1992". Eur-lex.europa.eu. http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31992L0043:EN:HTML. Retrieved 2010-03-15. 
  13. ↑ "Species other than birds specially protected under The Wildlife and Countryside Act, 1981: Schedule 5 (Animals)". Jncc.gov.uk. 2005-08-30. http://www.jncc.gov.uk/page-1815. Retrieved 2010-03-15. 
  14. ↑ "Wildlife Act 1976 (Ireland)". Internationalwildlifelaw.org. 1976-12-22. http://www.internationalwildlifelaw.org/WILDLIFEACT1976_1.html. Retrieved 2010-03-15. 
  15. ↑ Otters of the world
  16. ↑ ""Lutra lutra– Near Threatened"". Iucnredlist.org. http://www.iucnredlist.org/search/details.php/12419/summ. Retrieved 2010-03-15. 

External links