Eurasian Otter in the central part of the Slovak-Hungarian border area

 

The Eurasian otter (Lutra lutra) is a semiaquatic, territorial carnivore living in a large variety of aquatic habitats (Conroy and Chanin, 2002) and represents a flagship species for undisturbed rivers as well as for wetland recovery (Kruuk, 2006). The species has been protected in Slovakia since 1949 (Urban et al., 2011) and in Hungary since 1974, and this became strictly enforced from 1978 onwards (Kemenes, 1991). In the latest Red List of mammals of Slovakia, the otter is listed as “Vulnerable” (VU) (Žiak and Urban, 2001). In Hungary, it is classified as a “Near threatened” (NT) species (IUCN, 2001).

The otter occurs in most parts of Slovakia with the exception of the Western and South-Eastern lowlands (e.g. Urban, 2010a; Urban et al., 2010). The central part of the Slovak-Hungarian border area (in middle Ipeľ river catchment) is important from the “European Otter Habitat Network” (EUOHNE) point of view (Kadlečík, 1998). There is still a large otter population in Hungary, but according to recent observations, the population is decreasing, mostly due to unfavourable changes in wetland conditions (Gera, 2004, 2005). However, there is little available information on the distribution of otters from Nógrád and Heves counties (Lanszki, 2009), even though these territories are interesting from a distribution point of view (in this area are several protected wetlands). The current distribution of the otter in Hungary is depicted in the Atlas of Hungarian Mammals (Bihari et al., 2007).

Due to traditional and outstanding international cross-border cooperation between nature and landscape protection organisations (State Nature Conservation of the Slovak Republic, Banská Bystrica and Bükk National Park Administration, Eger), several studies have been carried out about otter distribution in this area. The first international Slovak-Hungarian otter mapping was undertaken in January and February 1996. This survey indicated that otters were present in most streams in this area in both countries (Urban and Kadlečík, 1996; Urban et al. 1996) (Fig. 1).

Results of the otter survey in the Novohrad/Nógrád region

Results of the otter survey in the Novohrad/Nógrád region

The second mapping was carried out in November 1997 (Urban and Kadlečík, 1998; Urban et al., 1997) and the third (summer) one was held in September 1998 (Urban et al., 2000). The results showed that the otter population in southern Slovakia and northern Hungary can be considered viable and has a great potential to spread westward and northward (e.g. Kadlečík, 1998). The information gathered from these mappings is being used to understand otter distribution in general.

Several mappings of otter activity were carried out in the Slovak part of this territory - Novohrad region (Hrivnák and Urban, 1995), middle part of the Ipeľ river catchment (e.g. Urban 1992), Cerová vrchovina Protected Landscape Area (PLA) (e.g. Hrivnák and Balázs, 1995a, b), Lučenská and Ipeľská kotlina basins (e.g. Tučeková and Urban, 2000; Urban, 2000; Urban et al., 2008). In the Cerová vrchovina PLA, otters are common on water flows with a sufficient trophic base. The greatest density of spraints was recorded around water reservoirs in the agricultural area (Balázs et al., 2010).

There are conflicts between the interests of fisheries and nature protection, both in fish farms (ponds) and fresh flowing waters (rivers, small streams). Reliable scientific information on ecology, and potential risks, which are all important for evaluating conservation status, are still insufficient. In winter of 2010-2011, we carried out further mapping of the otter distribution was done in the central part of the Slovak-Hungarian border. The aim of this paper is to summarize knowledge on the current distribution of otters in the study area based on this survey.