Proc. VIIth International Otter Colloquium DISTRIBUTION OF THE EURASIAN OTTER (Lutra lutra) IN AUSTRIA 1990-1998 Jutta JAHRL WWF Austria, Ottakringerstr. 114-116, A-1160 Vienna, Austria. e-mail: [email protected] Abstract: In the absence of a national survey, the status of the otter in Austria for the period 1990-1998 is outlined based on as many sources as possible. The majority of otters occur in the northern and southeastern border areas. As far as is known very few, and probably transient individuals, occur in the rest of the country. For large parts of Austria, however, no information is available. INTRODUCTION The Eurasian otter (Lutra lutra) was once widespread throughout Austria. After heavy direct persecution in the 19th century, continued destruction of habitat brought the species to the verge of extinction. Regulation of rivers, drainage of the extensive marshlands along the rivers, intensification of agriculture and human settlement, and especially the exploitation of running waters for hydroelectric purposes has degraded the formerly prime habitats. Only in a few parts of Austria has the otter survived. MATERIAL AND METHODS Data on the occurrence of otters in Austria during the period 1990-1998, originating from various sources, were analyzed and collected, and distribution points mapped. Data accrued from, e.g., systematic investigations, random catches, direct sightings and the occurrence of indirect signs or dead otters. In some cases and for some localities, use of particular symbols are approximations only. RESULTS AND DISCUSSION The present status of the otter varies greatly within Austria. The vast majority of country's otters are found in the northern and southeastern border areas, where a lower level of industrial development allows more natural habitat to exist, while the interaction with healthy populations in neighbouring countries enables a constant exchange of animals. In addition, the presence of fishponds seems to have been important for the survival of the species in Austria. It is to be expected that their occurrence in these regions will expand. The rest of the country contains, as far as is known, only a few, and probably migrating otters. Large parts of Austria have, however, not yet been investigated. Vorarlberg: On account of otter footprints found there in 1985, and of its nearly natural river habitat, the Bregenzerwald in the northern part of Vorarlberg was the focus of an otter survey in 1995. Despite a questionnaire being distributed, with some positive indications forthcoming, the survey found - 153 - Proc. VIIth International Otter Colloquium no evidence of otters. Otters could, therefore, have lived there at very low densities on account of a shortage of fish as well as disturbance by a hydroelectric scheme, until the flushing of a reservoir caused them to abandon the region (KRAUS, 1997). Northern Tyrol: In the Tyrol otters are considered to have been extinct for several decades. However, an otter found dead in southern Bavaria close to the Austrian border, and the discovery of otter footprints in the vicinity indicate that individual otters could migrate into this region. The most promising area to search for otters in Northern Tyrol was considered to be the Lech valley. Although a survey was carried out here in 1997, no sign of otters was found (KNOLLSEISEN, 1997). Eastern Tyrol: Otters seem to have disappeared from Eastern Tyrol after the flood disasters of 1965/66, and the subsequent management of rivers. Field surveys in 1994 revealed no evidence of their presence (JAHRL, 1995). This absence has been confirmed by other surveys (BODNER, pers. comm.; KNOLLSEISEN, pers. comm.; MICHOR, pers. comm.). Salzburg: Of this federal state mainly the southern part has been surveyed. Despite repeated and credible reports, field surveys in 1994 failed to reveal any definite signs. Accounts on a questionnaire have concentrated on the area around the capital city (JAHRL, 1995). Focussed research has now revealed that otters are actually present in many parts of the town (JAHRL, 1998a). Upper Austria: The northern part of Upper Austria is one of the strongholds of Austria’s otters. KRANZ (1995) postulated an expansion of otters in this area, which forms part of a large common population that inhabits parts of Bavaria, the Czech Republic, and Upper and Lower Austria. Local surveys (FISCHER, 1993; HAUNSCHMID, pers. comm.; JAHRL, 1996; KRANZ, 1995; SCHMALZER, pers. comm.) show a clear picture of the situation in this area. Few records are available for the area south of the Danube; here only a few signs were found (MICHOR, pers. comm., KRANZ, 1995). Lower Austria: The highest otter densities within Austria occur in the northwestern part of Lower Austria. Here a large number of fishponds enhances the carrying capacity of the region for otters, but the damage these fish-eaters are said to cause leads to increasing problems (BODNER, 1995). An expansion of the population is presumed (KRANZ, 1995). KNOLLSEISEN (pers. comm.) surveyed the eastern part of Lower Austria in 1998. He found several spraints at the boundary of the River March, while its tributaries and the Danube east of Vienna yielded negative results. In addition, an otter was found dead (GUTLEB, loose-leaf collection) while sparse otter signs (KRAUS, pers. comm.; SIEBER, pers. comm.) indicate rare visits of otters to this region. In the southwestern part of the country KRANZ (1995) and KRAUS (pers. comm.) proved the scattered but extensive presence of otters, which stretches eastwards to Vienna along the Danube. The southeast neighbouring Burgenland was surveyed in 1997, but only a few sites yielded otter sign (JAHRL, 1998b). - 154 - Proc. VIIth International Otter Colloquium Vienna: Up to the early nineties, single otter signs were found only in the southeast of Vienna (SIEBER, pers. comm.; SIEBER and BRATTER, 1987). The discovery of an otter track in the western outskirts in 1997 illustrates, however, how close single otters have already come to the town. Burgenland: Surveys in 1996 and 1997 indicate a population that increases markedly from north to south. The resident otters of southeastern Styria and Burgenland seem to benefit from being part of a larger common otter population of Hungary, Slovenia and southeastern Austria (JAHRL and KRAUS, 1998; KRAUS and JAHRL, in prep.). KRAUS (pers. comm.) on account of his research in the eighties assumes an increase in the population in southern Burgenland. Styria: The first otter survey was in 1986 (KRAUS, 1986). A second in 1993/94 provides more recent data on otter distribution. The results reveal a widespread occurrence only in lowland rivers and streams in southeastern Styria, bordering on Burgenland and Slovenia (SACKL et al., 1996). Isolated signs in the alpine regions of northern and western Styria (GUTLEB, pers. comm.; KRANZ, 1995 and pers. comm.; SACKL et al., 1996) presumably originate from migrating individuals, which could be relics of a population which formerly covered the entire country, decimated initially by persecution and subsequently by destruction of habitat. Although SACKL et al. (1996) do not assume an increase in the Styrian otter population, KRAUS (pers. comm) believes that a slight increase has been taking place in the southeast. Carinthia: As a result of the returns of questionnaires, a survey of the most promising rivers was carried out in 1991/92. Only a single otter sign could be found (WIESER, 1993). Surveys and the results of other authors (AUER, pers. comm., EISNER and SIEBER, 1993; FORSTNER, 1990; HUBER, pers. comm., JAHRL, 1995; KNOLLSEISEN, pers. comm.; MICHOR, pers. comm.; SENITZA, pers. comm.) support the notion of a few otters migrating through Carinthia, possibly coming from Slovenia. Destruction of habitat, especially by hydroelectric power plants, is thought to be the main reason for this situation (WIESER, 1993). Acknowledgements - This paper was made in cooperation with Erhard Kraus, Michaela Bodner, Michael Knollseisen and Alois Schmalzer, and with contributions by Arno Gutleb, Wolfgang Honsig-Erlenburg, Thomas Huber, Andreas Kranz, Klaus Michor, Helmut Pechlaner, Hannes Seehofer and Johanna Sieber. 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