Distribution of the species
The Eurasian otter is a species that inhabits the largest part of Eurasia and Atlas Mountains. In Bulgaria until the 1930s it was present almost throughout the country, however, in the 1950s it declined significantly. In the 1970-1990 period its numbers increased again to 800 – 1 400 individuals. The higher population density is in Southeastern Bulgaria, as well as in the protected areas of Kresna-Ilindentsi and Pirin.
Description of the species (biological and ecological features)
It is found in the valleys, along the sea coast and in the mountains. The Eurasian otter inhabits natural river currents and closed water basins with a length of at least 15-20 km: with overgrown shores – dense tree and shrub vegetation, alder-groves and reed (low shores), various fish fauna and abundance of crayfish, frogs, vertebrates and mollusks.
The individual territory of the male may overlap that of 1 or more females. The dens are in the roots of shore trees. The cubs (2-4) are born in March – August and follow their mother for 1 year. In Southeastern Bulgaria fish is up to 93% of the prey (an average of 62% spring-summer and 74% autumn-winter). The otters catch their prey at a depth of up to 4 m.
Conservation status
Favorable.
Conservation state
The Eurasian otter is a protected species included in Annexes 2 and 3 of the Biodiversity Act (BDA) and Annex II of the Bern Convention. The species is also included in Annex I of the Convention in International Trade in Endangered Species of Wild Fauna and Flora (CITES) and in Annex II and Annex IV of Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora (Habitats Directive).
The Eurasian otter is part of the Red Data Book of Bulgaria (2015) with category “Vulnerable” (VU) and also included in the IUCN (International Union for Conservation of Nature) Red List of Threatened Species with category Near Threatened (NT).
*Note: For the description of vertebrates is used information from: Golemanski, V. & al. (eds). 2015. Red Data Book of the Republic of Bulgaria. Vol. 2. Animals. BAS & MoEW, Sofia [English ed.: ISBN 978-954-9746-22-8 (IBER – BAS), 978-954-8497-18-3 (MoEW)]; the website of the IUCN (International Union for Conservation of Nature).