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Beaver (Castor fiber L, Castoridae) management in

VON G. SCHWAB & M. SCHMIDBAUER

Abstract Zusammenfassung Beavers were exterminated in Bavaria in Biber {Castor fiber L, Castoridae)- 1867. The reintroduction, conducted by the Management in Bayern „Bund Naturschutz in Bayern e.V." between 1966 and the late seventies, was very suc- Biber wurden 1867 in Bayern ausgerot- cessful: the present beaver population in tet. Die Wiederansiedlung unter der Füh- Bavaria is estimated at more than 6.000 in- rung des „Bund Naturschutz in Bayern e.V.", dividuals, and it is still growing and expand- die zwischen 1966 und Ende der 1970er Jah- ing into its former range. re stattfand, war sehr erfolgreich. Die derzei- tige Biberpopulation in Bayern wird auf über This success was paralleled by a growing 6000 Individuen geschätzt, nimmt weiter- number of conflicts between beavers and hin zu und breitet sich auf das ursprüngliche human land users in the densely settled and Gebiet aus. intensively used Bavarian landscape. Zeitgleich mit diesem Erfolg stieg auch Beavers fed on crops, beaver dams flooded die Zahl der Konflikte zwischen Bibern und forests, pastures and basements, beavers Landnutzern in der dicht besiedelten und digged their burrows under roads, fields and intensiv genutzten bayerischen Landschaft. high water dikes, and some of them felled Biber fressen Feldfrüchte, durch ihre apple trees in gardens. During the 1980s un- Dämme werden Wälder, Viehweiden und til the early 1990s, the beaver conflicts es- Keller überstaut, sie bauen ihre Röhren un- calated, less because of the real world prob- ter Straßen und Felder, in Hochwasserdäm- lems, but more because politicians and mass men und einige fällen Apfelbäume in Gär- media abused this conflict between nature ten. conservation and land owners for personal In den 1980er Jahren bis zu Beginn der gain. 1990er Jahre eskalierten die Konflikte, es Taking a closer look at beaver-human- waren keine weltbewegenden Probleme, conflicts, we found, that almost all conflicts aber Politiker und die überwiegende Mehr- root in the overuse of landscape by man: zahl der Medien missbrauchten diesen Streit beaver conflicts happen mainly in a narrow zwischen Naturschutz und Landnutzern zur strip along the river banks. Where man has persönlichen Profilierung. left some space to the rivers, there are only Betrachtet man diese Konflikte zwi- very few conflicts with beavers. Such unused schen Biber und Landnutzern näher, kommt areas are not only important for beavers and man zu der Erkenntnis, dass die Hauptursa- other plant and animal species, but more and che in der Übernutzung der Landschaft mainly for man himself (e.g. for protection of liegt: Der Großteil der Probleme liegt in ei- water and prevention of floods). nem schmalen Uferstreifen. Ließe man die- Key words: beaver, Castor fiber, man- sen Streifen ungenutzt, wären die Konflikte agement, Bavaria auf ein Minimum reduziert. Solche unge- nutzten Bereiche wären nicht nur für den Biber und andere Tier- und Pflanzenarten Denisia 9, zugleich Kataloge der OÖ. Landesmuseen wichtig, sondern vor allem auch für den Neue Serie 2 (2003), 99-106

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Menschen selbst, z. B. für den Wasserschutz In Bavaria, where a successful beaver und zur Verhinderung von Hochwässern. reintroduction between 1966 and the late 1970s yielded an still expanding population Introduction of more than 6000 animals, these conflicts remained unsolved for many years and Beginning in 1996, 30 years after caused increasing disputes between nature beaver's reintroduction, a beaver manage- conservation organisations and agencies and ment was developed with the goal to keep land users and their associations, the top de- and promote the beaver in Bavaria by cre- mand being the complete re-removal of ating and improving acceptance for beavers from cultivated landscape. beavers and their activities. The develop- ment of the beaver management was fund- In this paper we give a short overview of ed by the European Community, program the history of beavers in Bavaria and the LEADER II, and local authorities; the im- problems they are causing and present then plementation is funded by the "Bayerische the beaver management which was devel- Naturschutzfonds" (Bavarian State founda- oped in the last years to solve the problems tion for the protection of Nature), and the and - in the long run - to use the beaver as "Bund Naturschutz in Bayern e.V." (a a flagship species for the restoration of river- NGO). side forests.

The key to the future of the beavers in Bavaria are the landowners, on whose The Beaver in Bavaria: properties the beavers are living. We consult a short history these landowners in case of conflicts with beavers and assist them in applying for fund- Historic distribution and extinction ing for protective measures; we also try to Beavers were a common species in convince them to give up agriculture or Bavaria up to the 16'h century. Their distri- forestry and to lease or sell the land to state bution over almost all of Bavaria, with ex- agencies or private nature conservation or- ception of the Alps and the higher areas in ganisations. We also do public relations work low mountain regions, is documented by on a broader scale to inform the general pub- about 300 names of villages, streams or lic about beavers, its benefits for wildlife, landscapes (ZAHNER 1997). The decline of conflicts and the solutions for the future of the beaver population began locally in the the beaver within the beaver management. 17th century, expanded through the 18 cen- Another important issue is the implementa- tury and ended with the killing of the last tion of beavers and its habitats in long-term Bavarian beaver in 1867 (WEINZIERL 1973). landscape planning, as this is one of the best The reason for the extinction of the ways to reserve areas for beavers and river- beaver in Bavaria was over-hunting. They side forests from an early stage. were hunted for meat, for their valuable pelt Beavers (Castor fiber L.) are very capa- and for castoreum, which was widely used as ble of modelling the land they live in (e.g. remedy. Habitat changes, esp. the regulation DJOSHKIN & SAFONOV 1972, NOVAK 1987): of the major rivers and large bog areas had beaver dams flood and wet large areas, their only an indirect influence by allowing an burrows and dens increase the structure of easier access for hunters into the last re- river banks, and the cutting of trees creates maining beaver territories (ZAHNER 1997). openings in the riverside forests. As positive as these activities are from a nature conser- Reintroduction vation point of view, as problem causing Reintroduction of beavers in Bavaria they are, when beaver express them in a cul- began in 1966, 99 years after the last beaver tivated landscape used by man: beaver dams was killed. Until the late 1970s, the "Bund flood corn fields, machinery and people may Naturschutz in Bayern e.V.", the major na- fall into beaver burrows, beaver burrows ture conservation NGO in Bavaria released threaten functionality of dikes, the last trees about 120 beavers in several different places disappear from the rivers. (WEINZIERL & FROBEL 1998). The beavers

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.j.....:....i....^.M....i~;^.. i.....:Vvi...Ji JL.IfA....: :....: ..A \.-JSl.... •... came from wild and captive source popula- j tions in Sweden, Finland, France, Poland .1.... I j... \ i . i and the Sovjet Union (WEINZIERL 1973). i H•s < r Reintroduction was permitted by the Bava- A A(A I v/ rian Ministery for Forestry and Agriculture, iAr* A as beavers were listed as game species at this A 5 time. h \ A A AH A AAIA, In the middle of the 1980s, some I \ x•\ A n k i A beavers were trapped in the central Danube V A AjA A A/A£ area in Bavaria and relocated to the Inn U r••# Am A AT • and river (SCHWAB et al. 1994). In \ A 4? A A*£A$AA northern Bavaria, beavers immigrated in the C A A AA Af A AA V i • early 1990s from a reintroduced population \A AA AA AA AA4 A of East German beavers in Hessia. (SCHWAB t } A AAA A A A A" AAA" i \ et al. 1994). i! J A A AAIL AA A A AAA A _i h. A \ A » AA A AAE A A. sA Present status of the Bavarian beaver 1AA A'A A A X A population i \ ( A-^ AA AA A A 1 X« A A A A A A A- During the first decades after reintro- t AAJ AJ A A A —i A duction, the Bavarian beaver population —• A A A A A A A A grew scientifically almost unattended. The /S£ A f A A 1 i >AA A AA A A A A / • V/ first state wide population estimate based > A A 4 A AA A on a poll and field work was conducted A / from 1988 to 1992. At this time, the popu- / M — — lation was estimated at about 800 to 1200 1 i ( A animals (SCHWAB et al. 1994). In 2002, we i A estimate the beaver population in Bavaria ij A to more than 6000 animals in 1500 h ^^ J "\ j> colonies. The beavers have reoccupied a r %, •— / —— large part of their former range (Fig. 1, £ { Regierung von Unterfranken 2001), al- i..... A though colony density is low at the borders If Fig 1. Beaver distribution in Bavaria. small drainage ditches in extensive farm of the present range. lands, they digged their burrows in the (Regierung von Unterfranken 2001) banks of sewage treatment ponds or under The Bavarian beavers have also changed roads, and they used drainage pipes under their legal status since reintroduction. They airport runways as lodges. In these areas, lost their status as game species and are now where beavers and man used the same land, a strictly protected species by European and an increasing number of conflicts between German laws (HIMMELSBACH 1994). beaver and man started in the 1980s.

Beavers in a cultivated land- The "real world" problems scape: conflicts and solutions Beavers feed on crops During the beaver-free century in Beavers have easily accepted crops, esp. Bavaria, man had heavily altered the Bava- corn, sugar beets, wheat and rape as food. rian landscape: he had regulated rivers, he The direct loss of crops is mostly low and ac- had changed riverine forests into corn fields, cepted by farmers. More important than the and he had meliorated bogs into spruce damage to crops are damages to the creek plantations. Beavers, however, did not care banks by beaver slides, and thereby in- much about these changes in their habitats. creased erosion, beaver dams and channels They are a species with a very high adapt- build by beavers for easier access into a field, ability and low habitat requirements: some and beaver burrows under fields. water to swim and some plants for food. Beavers began to settle and build dams in

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Beavers cut trees a complete loss of the fish stock (SCHMID- By cutting trees for winter food or as BAUER 1996, unpubl.). building materials, beavers can cause a num- ber of conflicts. Beavers cut not only Solutions for "worthless" willow or aspen, but also eco- beaver-man-conflicts nomic valuable species (e.g. oak or acorn), they debark spruce and fir, feed on fruit- The activities of Bavarian beavers re- trees in villages and can clear cut expen- main almost exclusively within 20 m of the sively planted restoration areas. banks of rivers or ponds (SCHWAB et al. 1994). Problems only arise when humans The cutted trees can create further pro- use this small strip of land as well. There- blems, especially if they lie in the water and fore, the lasting solution of beaver-man- impair the drainage of high water, impede conflict lies in the removal of human land access to fields and meadows, block streets us in this range and the recreation of river- or railroad tracks, damage power lines, or side habitats. These unused areas are not damage small hydroelectric power plants. only important for the beaver and many other species, but mainly for man himself. Beavers build dams They buffer fertilizer and pesticide drainage Bavarian beavers build dams mainly in from the adjoining agriculture, and more small creeks and drainage ditches with in- important, they can be used as buffer areas sufficient water depth. The backwater of to protect villages and towns from floods. beaver dams can flood forests and kill eco- There are also a large number of techni- nomic valuable trees (e.g. spruce), or flood cal measures to prevent or minimize beaver agricultural fields, roads and basements of damages on local spots (e.g. HEIDECKE & houses. Mill creeks, fish ponds and water KLENNER-FRINGES 1992, SCHWAB et al. treatment plants can overflow due to beaver 1994). Gratings, sheet-pile walls or gravel build obstacles. The increased ground water layers prevent undermining of dams and level can clog up drainage pipes, increase roads (DVWK 1997), electrical fences keep erosion of soaked banks and destabilise rail- beavers out of areas, wire meshs and chemi- road tracks. cal repellents protect trees, culverts in beaver dam lower the impact of flooding, Beavers dig holes and a free running dog keeps beavers from The digging activity of the beavers re- eating roses in gardens. presents the biggest problem in the cultivat- ed landscape. The subterranean tunnels If protective measures are to expensive, reach several meters into the ground. If there or take a long time to be implemented, is any use of these areas (agriculture, roads, beavers are trapped and relocated to other gardens), there is a permanent danger for ve- areas (SCHWAB & SCHMIDBAUER 2001). hicles or people falling into the beaver tun- Compensation for damage caused by nels and being damaged. Beaver tunnels can beavers is not possible by state agencies, as also compromise the integrity of high water there is no damage compensation for any dikes and threaten the dams of mill creeks. free living wild animal in Bavaria (except Fishponds and water treatment pools can be some game species). There is, however, a drained as a result of beaver tunnels. In small privately based fund from the Bund drainage ditches and ponds, the increased Naturschutz in Bayern e.V, which allows sedimentation can be an additional problem. compensations as a first step to make a landowner more willing to accept long term Beavers disturb fishes solutions (WEINZIERL & FROBEL 1998). Beavers disturbing fishes is a special sea- sonal problem in fish hatcheries. In ponds, The problem behind the problems where fishes are kept in high densities for The solutions for conflicts between wintering, beaver activities keep the fishes beaver an man were known in Bavaria since moving. This results in weight loss and the early 1990s, but implementation of solu- higher oxygen consumption and may cause tions was between slow and not at all. This

102 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at had several reasons. Personnel at the local as conflict between beaver biology and ex- nature conservation agencies was not isting habitat structures, and less as a prob- trained on dealing with a strictly protected lems of the human dimensions associated "problem" species and did not have the time with and behind it. to act quickly in case of a conflict; and if Therefore another way of dealing with they found the time to act, there was almost beaver conflicts was established by building no funding for damage compensation or for a beaver management in Aldo LEOPOLD'S supporting preventive measures. (1933) sense: manage the people not the For farmers, under heavy economical beavers. Manage the people, from farmers pressure from politics and the international who have the problems, to politicians who markets, the beaver was often used as scape- make the laws, to get the land to set aside goat: if you can not do anything against the for nature. The beavers, and all the other European Community, then hit at least the species, will then do the rest - as they did for beaver. They felt, that everybody else was million of years without being managed by having the benefits of the beavers (from humans. creating habitats to the pure pleasure that he his back in Bavaria), and that they them- „Evolution" of the beaver selves were the only ones who had to pay management the bills. This exaggeration, on the other The first steps towards this beaver ma- side, made nature conservation people un- nagement in Bavaria started in 1996. A bio- derestimate the real problems and not tak- logist from the Wildlife Society ing the land users serious. So, even in severe (Wildbiologische Gesellschaft München cases, with damages of thousands of EUROs, e.V), commissioned by the Government of no trapping permits for beavers were issued. Upper Bavaria (Oberbayern) consulted farmers and landowners in the county of Last not least, mass media and politi- Neuburg- in Central cians used pushed this „classic" conflict be- Bavaria to solve their beaver problems and tween nature conservation and farmers for helped them to find funding for compensa- their own advantages, turning every beaver tion and protective measures. Although not burrow in a corn field into a deadly thread all cases could be solved (SCHWAB 1996, un- for farmers, just to make the headlines. publ.), landowners showed that they were So, 30 years after the first reintroduction, willing to accept the beaver, if they got ad- Bavarian beavers had grown into a schizo- vice, help and financial support in case of phrenic species: they were a holy cow for problems. On the other hand, nature con- some nature conservationists, and the equi- servation organisations learned, that there valent of the medieval rat plague for the are some cases, where beavers cause intoler- farmers. Some farmers organisations even able damages and had to be removed by wanted the beaver completely removed from trapping. the cultivated landscapes in Bavaria, which means (as Bavaria is almost 100% cultivated In northern Bavaria a similar approach landscape) nothing else as the re-eradication. was undertaken to solve the conflicts with beavers in fish hatcheries (SCHMIDBAUER 1996, unpubl.) in the district of Oberpfalz. In Beaver management: the same year, the Bavarian State Ministery the Bavarian way for Environment Protection (Bayerisches Staatsministerium für Landesentwicklung The disparity between real beaver con- und Umweltfragen) issued guidelines for na- flicts and their presentation in the media, ture conservation agencies on problem solu- and the disparity between possible solutions tions and financial support programs (BSTM- and the amount of implementations LU 1996, unpubl. (updated 1999)). showed, that existing administrative and or- ganisational structures were not suitable of The results of the first two projects in solving the beaver conflicts. This was partly 1996 encouraged the agencies involved to due to lack in manpower and money, but al- establish a beaver management for all of so because beaver conflicts were mainly seen Bavaria. This was done in two projects with

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originally somewhat different main focuses. Training and organising "local One project, running from 1998 to 2001 was beaver consultants" funded by the European Community, Bavaria is just too big to be adequately LEADER II Program, and 5 counties in cen- covered by the two beaver managers work- tral Bavaria; it's main focus was to develop ing for the Bund Naturschutz in Bayern e.V. the organisation and structures for the A network of individuals from the local beaver management (SCHWAB 2002, un- public shall support the nature conservation publ.). The other project, running from agencies and the beaver managers in con- 1998 to present is funded by the "Bayerische sulting, implementing solutions and moni- Naturschutzfonds", a state guided grant, and toring the beaver population. the "Bund Naturschutz in Bayern e.V.", the major nature conservation NGO in Bavaria; Monitoring the beaver population it's focus is on the Bavarian wide implemen- Data quality on beaver's area of distribu- tation of the beaver management (SCHWAB tion and population size is highly variable & SCHMIDBAUER 2002, unpubl.). within Bavaria. A monitoring system would The job description for beaver help to recognise potential conflicts earlier management and to act better in advance. The monitor- ing system will be set up in the next years The first activities in 1996 had mainly a based on the local beaver consultants. fire fighter function: solve the problems which had been present for years. This is still Mediating between authorities, a major part of the work, but for the future, NGO's and individuals the activities will shift more towards preven- One of the most important jobs is to be tion of conflicts. All beaver management ac- a mediator between the parties involved, as tivities are conducted in close co-operation many "beaver" conflicts have their roots in with nature conservation agencies, especial- ly on the county level. Beaver management completely different and much older quar- is not a replacement, but a consulting help rels between a farmer and a nature conser- for these agencies. The main activities of the vation agency. beaver management are: Public relations work Consulting in case of problems and Many beaver conflicts arose from a lack helping in implementing solutions of knowledge (e.g. fishermen believing that The beavers are still expanding their beavers eat fish, or farmers fear that beavers range in Bavaria, and in spite of all preven- have the same reproductive rates as rats). tive measures, there will always be individual Information on beaver biology, conflicts, so- conflicts. Here it is necessary, to consult the lutions and management is therefore a vital people involved as quick as possible to mini- part of beaver management. mise and prevent negative attitudes against beavers. It is also necessary not only to con- Develop a use for "surplus beavers" sult, but also the help people in implement- So far, most of the beavers trapped in ing solutions (e.g. protecting trees or crops). Bavaria could be used for reintroduction pro- grams, mainly in the Danube countries in Introducing beavers in all habitat Eastern Europe (SCHWAB & LUTSCHINGER related planning systems 2001). These programs will be finished with- Preventing conflicts is better than sol- in the next couple of years; so it necessary to ving conflicts. The best and least expensive develop a further use for these beavers, con- way to prevent beaver conflicts is to take sistent with existing laws and within the ac- beavers and preventive measures against ceptance of nature conservation organisa- beaver damages into account in all planning tions. systems working in potential beaver habitat. This will be done by training the personnel Get money in agencies and companies responsible for Beaver management, anda esespeciallp y this plannings. buyining land costs money. One majomajorr task is

104 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at therefore to find the financing for the ma- areas, and new peoples will be involved. nagement and the restoration of riverside Therefore, beaver management as described forests. above will also be extended in the foresee- able future. Summed up, the task of the beaver ma- nagement is to bring the beaver back in the It will take it's time, before beavers will heads and hearts of the people, who simply be accepted by most people as what they are. forgot how to live with this fascinating crea- Not a holy cow and not the reincarnation of ture and to bring fonvard what the beaver medieval rats, but a fascinating species that stands for: the recreation of riverside forests, creates and shapes landscapes for the bene- not (only) for beavers and other species, but fits of many species, including man himself. also for man himself. The urgent need for what's behind the Organisation of the beaver beaver management was demonstrated in management August 2002 (and earlier in May 1999). Floodings in Bavaria caused damages of Beaver management in Bavaria is a joint hundreds of millions of EUROs. If only part project between NGO-operated beaver of this money would have been available managers and state agencies. Presently, during the preceeding years to buy "beaver" there are two beaver managers in Bavaria, land along the rivers, a lot of water could working for the "Bund Naturschutz in Bay- have flooded these lands, and a lot of houses ern e.V." Funding is provided by the "Bay- along the Danube would have stayed dry. erische Naturschutzfonds". In an increasing Not only in August 2002, but also in the fu- number of counties, the beaver managers ture floodings to come. are supported by the so called "local beaver consultants". These are people form the lo- cal public (hunters, farmers, fishermen, na- References ture conservationists, etc.) which are inter- BStMLU (Bayerisches Staatsministerium für Lan- ested in supporting the beaver management. desentwicklung und Umweltfragen) (1996): Vollzugshinweise über Maßnahmen zur Ver- Local beaver consultants are mainly hinderung von Schäden durch Biber. — Un- working as volunteers, guided by and ex- published, 1-12. penses paid by county authorities. Their DJOSHKIN W.W. & W.G. SAFONOV (1972): Die Biber training is organised by the Bayerische der Alten und Neuen Welt. — Wittenberg- Akademie für Naturschutz und Landschafts- Lutherstadt, 1-168. pflege. Training includes all aspects of DVWK (Deutscher Verband für Wasserwirtschaft beaver management, from beaver biology to und Kulturbau e.V.) (Eds.) (1997): Gestaltung communication skills. Their main task is to und Sicherung der von Bisam, Biber und Nu- tria besiedelten Ufer, Deiche und Dämme. — be the first, because neighbourhood, address Wirtschafts- und Verlagsgesellschaft Gas und in case of a conflict. They consult in "stan- Wasser mbH, Bonn, 1-83. dard" problems (e.g. protecting apple trees), HEIDECKE D. & B. KLENNER-FRINGES (1992): Studie über help in implementing solutions, are in- die Habitatnutzung des Bibers in der Kultur- formed about the beaver territories in their landschaft. — 2. Int. Symp. Semiaquatisch area and get into contact with the beaver Säugetiere. Wiss. Beiträge der Martin-Luther- manager in case of more complicated pro- Universität Wittenberg-Halle, 215-266. blems. HIMMELSBACH V. (1994): Der Biber im Arten- schutzrecht. — In: Bayerisches Landesamt für Umweltschutz (Ed.): Biber. Schriftenreihe des The future? Bayerischen Landesamtes für Umweltschutz 128 (Beiträge zum Artenschutz 18), Beaver management in Bavaria is still München, 67. young, but the first years show, that we are LEOPOLD A. (1933) Game Management. — Charles heading in the right direction: many con- Scribener's Sons, New York, 1-481. flicts could be solved, many avoided. NOVAK M. (1987): Beaver. — In: NOVAK M., BAKER J., But there is still a long way to go. Beaver OBBARD M. & B. MALLOCK (Eds.), Wild furbearer management and conservation in North population is still expanding it's range and America, Ashton-Potter Ltd., Ontario, sizes. There will be new problems in new 283-312.

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Regierung von Unterfranken. (Ed.). (2001): Biber in Unterfanken - Flussmeister der Natur. — Regierung von Unterfanken, Würzburg, 1-6.

SCHMIDBAUER M. (1996): Bestandsermittlung, Pro- blemanalyse sowie Erarbeitung eines Maß- nahmenkonzeptes und dessen Umsetzung zu Bibervorkommen in ausgewählten Oberpfäl- zer Teichgebieten. — Unpubl. report, 1-82.

SCHWAB G. (1996): Biberprobleme und -lösungen im Landkreis Neuburg-Schrobenhausen. — Unpubl. report, 1-47.

SCHWAB G. (2002): Modellhaftes Bibermanagement in der Region mit Landkreis Kel- heim. Schlussbericht 2001. — Unpubl. report, III + 46pp. + appenices.

SCHWAB G. S G. LUTSCHINGER (2001): The return of the Beaver to the Danube watershed. — In: CZECH A. & G. SCHWAB (Eds.), The European Beaver in a New Millenium. Proceedings of 2nd European Beaver Symposium, 27-30 Septem- ber 2000, Bialowieza, Poland, Carpathian Heritage Society, Poland, 47-50.

SCHWAB G. & M. SCHMIDBAUER (2001): The Bavarian Beaver-Reextroductions. — In: CZECH A. & G. SCHWAB (Eds.): The European Beaver in a New Millenium. Proceedings of 2nd European Beaver Symposium, 27-30 September 2000, Bialowieza, Poland, Carpathian Heritage Soci- ety, Poland, 51-53.

SCHWAB G. & M. SCHMIDBAUER (2002): Jahresbericht 2001. Tätigkeit als Biberberater. — Unpub- lished annual report, 19 pp. + Appendix.

SCHWAB G., DIETZEN W. & G. v. Lossow (1994): Biber in Bayern. Entwicklung eines Gesamtkonzep- tes zum Schutz des Bibers — In: Bayerisches Landesamt für Umweltschutz (Ed.), Biber. Schriftenreihe des Bayerischen Landesamtes für Umweltschutz 128 (Beiträge zum Arten- schutz 18), München, 9-44.

WEINZIERL H. (1973): Projekt Biber. — Stuttgart, 1-63.

WEINZIERL H. & K. FROBEL (1998): Auf zu neuen Ufern! Die Wiedereinbürgerung des Bibers in Bayern. — Nationalpark 100: 46-50.

ZAHNER V. (1997): Der Biber in Bayern. Eine Studie aus forstlicher Sicht. — Bayerische Lan- Authors' adresses desanstalt für Wald und Forstwirtschaft, M. Sc. Gerhard SCHWAB , 1-63. Wildbiologe Hundldorf Deggendorfer Straße 27 D-94553 Mariaposching [email protected]

Dipl.-Biol. Markus SCHMIDBAUER Jahnstraße 16 D-93093 Donaustauf Germany [email protected]

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