Otter head, notice that ears, eyes and nose are aligned © photo: Dick Klees
Otter (Luta lutra)
The otter is a member of the weasel family, with a specialized lifestyle that is closely related to the presence of water. He is lithe, playful with of the different otter species the largest distribution range which extends as a broad band through Asia and most of Europe. In Africa, he is confined to a strip under the Mediterranean Sea, the Maghreb countries. The species is missing in Egypt, for example, does not occupy the Nile River.
Features / Appearance
Swimming otters, © photo: Dick Klees
The otter is an elongated, streamlined animal with webbed toes at all its short legs. Its tail is long, round and powerful. Its body length is 50-95 cm, where the tail another 26 to 55 cm can add. Males with weights between 10-12 kg are important heavier than females, 5-7 kg. This sexual dimorphism (differences between men and women) accounts for many mustelids. The fur is dark brown above and light sable to gray on the belly side.
The coat is composed of two layers, dense hairs. The outer layer of guard hairs, beneath air tenacious woolly hairs. The air in the fur isolate the animal while swimming and diving, as subcutaneous fat is hardly present. The head is broad, flattened with small round ears. Ears, eyes and nose are aligned just above the waterline in swimming. Around the eyes and muzzle are strong whiskers, which can observe currents while diving. Important when fishing in troubled waters.
Distribution / Geographical variation
The otter will inhabit coastal waters as well as lakes and rivers, large and small, with adequate food presence. He is dependent on sufficient coverage on the banks. He inhabits the whole of Europe and large parts of Asia to the Far East. In Africa, his appearance is limited to the north, north of the Sahara, an area restricted to parts of the Maghreb countries bordering the Mediterranean. It concerns the northeast of Morocco, northern Algeria and Tunisia. In its vast distribution there are seven subspecies distinguished, in Europe and North Africa it concerns Lutra l.
Otters inhabit a wide variety of wetlands, lakes, rivers, streams and marshes. Several coastal regions, also in salt and brackish water. Most places are characterized by the occurance of cover vegetation on the banks, where they can hide. It is found from sea level up to middle and beginning of high mountains. Its habitat is often characterized as a narrow strip of banks and water which can be remarkably elongated. At coasts only, where freshwater is available as in places where rivers flow into the sea. Both for drinking water, as if to keep his coat in optimal condition, the otter depends on available fresh water.
Food and hunting strategy
Otters consume mainly fish, © photo: Dick Klees
As with most types of otter's diet consists mostly of fish. With a preference for smaller fish, up to about 25 cm. In total, some 80%, plus a whole range of other food items. Birds, small mammals, aquatic insects, reptiles, amphibians and shellfish, and freshwater mussels. Depending on season and availability shares may vary. Otters find their food while diving and swimming, whereby the whiskers are important for the detection under water. Unlike nose and ears, who are closed while diving, the eyes are kept open. Small prey are eaten in the water, larger prey is landed and eaten on the shore. Otters are on most places, active at night
Sexually mature are otters in the wild often rather than in captivity. Males with a half years and females around two years. In captivity it is usually 3-4 years. Pairings happen the whole year and the gestation period is 63-65 days. The gestation period can be extended by delaying the implantation of fertilized eggs. So that cups are born in a favorable time. The litter size ranges from 1-5 cups. Otters can reach an age of 17 years. (22 years in captivity)
Female with cups © photo: Dick Klees
The cups are born in a flood-free den, in a quiet spot in the female’s territory. The maternity nest is lined with plant material like grass and moss. The cubs are born blind and toothless. Otter cups measure about 15 cm long and are covered with fine, gray hair. After 35 days they open their eyes and they are weaned at an average of 16 weeks, after which they gradually begin to eat fish. At the age of two to three months they get the adult coat.
When they have their complete, waterproof coat, the mother encourages them to go swimming. Something which is not very appreciated in the beginning. Once used, they like to swim and play with each other in the water a lot of time. The family group of mother and children often remains for several months, rambling around together. Finally, they are expelled from the territory by the mother. Males play no role in the family, whatsoever.
Behavior and teritorium
Females have their own territory, a male territory overlaps the territories of one or two females, but live apart from other men. Otters live solitary, the exception is showing the family group of a female with her cubs. The territory boundaries are marked with droppings (spraints) and fragrances. Which prevent physical confrontations. Otters are nocturnal active in large parts of their range. Besides scents, vocal communication plays a role. Otters make a shrill whistling sound, which ends quivering by males in the mating season. Playing otters can make screeching noises in fights usually sounds like hoarse feline screams.
By the ability to move quickly in and under water otters have few natural enemies. On land, they are vulnerable to other, larger carnivores. And certainly otter cups are at risk by fox, jackal, eagle or wolf to be caught. Many cats are no water lovers, offering otters a save feeling in their environment.
Relation with humans
Otter drowned in fish trap, © photo: Dick Klees
The otter is seen as a competitor and prosecuted for fishing. Thereby he is equally vulnerable to inadvertently fall into traps and die by drowning. In the lake region of eastern Algeria, this happens frequently. Migrating he does not through, but especially along the water, while he crosses roads he can easily become a traffic victem.
Very sensitive to the otter are man-made alterations to waterways. Drainage, removal of riparian vegetation, construction of dams and weirs, drainage of wetlands, etc.
The otter is at the top of the aquatic food chain and is therefore susceptible to contamination by chemicals that accumulate in the food chain. The PCB's (polychlorinated biphenyls) have a constricting effect on the ovaries, which is very negative, influencing the reproductive capacity
And of new substantial resources the negative effects are hardly known. Vigilance is still required here.
Threats and Status
In Europe, the species is in a slow recovery process after dramatic lows in the 90s Especially through measures which limits the emissions of chemicals, in addition to measures to prevent calamities with traffic and fish traps.
The distribution and problems of the otter in North Africa are poorly known. As a start, there should be searched for the presence of animals in order to map populations, and collect droppings or fatalities to obtain material for analysis. It is possible that pollution-related problems play their role here too. We hope to produce answers on these questions after some time.
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