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.
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. Ireland has the highest density of Eurasian otters in Europe. In Italy, they can be found in the Calore river area.
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. 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
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, and so those of males and females may overlap .Mating takes place in water. Eurasian otters are non-seasonal breeders (Males and females will breed at any time of the year) and are found that their mating season was most likely determined by simlpy 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 wieght when being compared to the female body mass ia about 10%. The period of offspring/mother dependency is bout 13 months.. After a gestation period one to four pups are born, which remain dependent on the mother for a year. 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. 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 under water.
The European Otter declined across its range in the second half of the 20th century  primarily due to pollution from pesticides such as organochlorine pesticides (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 for example in Britain 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 , 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. They are listed as Near Threatened by the 2001 IUCN Red List.
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