English summary
In connection with the release of beavers in 1999 in Klosterheden State Forest District (KLS), nature in and around the release localities was registered. The National Environmental Research Institute (NERI) coordinated technically and reported the monitoring of beavers during 1999-2003, and from 2004 Klosterheden State Forest District took over the practical monitoring. NERI assisted in the population estimate and reported the 2004 beaver monitoring on the basis of monitoring data from KLS. This report updates the status of population size, trend and growth at the end of 2004.
In April 2004 one two-day count was carried out instead of previously two two-day counts in April and October. Analyses of the data suggest that there is only a minor loss of information with this reduced effort. Furthermore, some water stretches were canoed during December 2004 in order to register beaver activity.
Observations made by the foresters and from the public are included in the population estimate and the mapping of spreading to new localities. On the basis of the actual number of observed individuals, the beaver population in the breeding season of 2004 was estimated at a minimum of 62 individuals, of which 11 were kits. Two dead beavers were registered in 2004 one of which was traffic killed. The number of beaver lodges increased in 2004 and at the turn of the year beavers could be registered at 18 confined localities. The beavers spread to new watercourses such as DamhusÅ and Tvis Å. The distribution pattern of territories in the Flynder stream system is dynamic. Quite new core areas come into existence whereas former areas have been deserted. Close to old lodges, new beaver lodges have been established, probably by young individuals from the family group establishing themselves within the existing territory.
Description of beaver habitats
In 2004 KLS supported eight territories and a total of 10 territories in the southern catchment area of KLS. During 2004 the beavers were present in most of the originally established lodges. In several places the core areas for beaver activity have changed within the territory. In areas inhabited by beavers during four to five years, beaver dams and lakes are built and the nature is substantially changed. Four lodges are registered close to existing lakes, three in KLS and two outside the district. The change of nature is less outspoken around lakes compared to dam building and damming along watercourses.
The impact on areas of production and the contact to riparian owners
During 1999 to 2003 all registered lodges were supervised and all landowners with beavers on their property were addressed. KLS continued this practice in 2004. The new lodges were inspected and registered as were all previous lodges. When experiencing problems, KLS in consultation with the owners undertook some preventative measures. The impact on areas of production was limited and no damage to commercial forest was experienced. In total, nine complaints were registered out of which three were from the same local-ity. On this basis, the overall estimate is that the number of incidences has been increasing in 2004 where the district has been forced to take preventative measures.
Information and communication to the public
The public interest in beavers continued to increase in 2004 comprising 83 guided beaver tours with 2,518 participants. During summer time, monthly publicly announced beaver tours are arranged and the local Nature School arranges tours for the affiliated schools. Arranged excursions comprised e.g. wildlife administrations from counties and municipalities, universities, colleges of education and state forest districts. Busses were often observed at mini exhibition by the lake Møllesøen with tourists independently walking downstream Flynder Å to inspect some of the most spectacular beaver localities. The foresters contributed to articles, news commentaries and television features.
Suggestions to future monitoring of beavers in Denmark
Having reintroduced a species, the IUCN recommends monitoring of the released individuals by tagging and tracking devices or by indirect methods such as identifying tracks, territory markings etc. The monitoring programme for 2005-2014 is proposed primarily to pro-vide knowledge on the growth and dispersal of the beaver population and the impact on the environment and thus ensure sufficient background knowledge for a suitable management of the species. Likewise it is important to collect experience in relation to the han-dling and establishing of preventative measures in the case of flooding and felling along watercourses and lakes.
Full report in pdf-format (1,670 kB).
