EXPLORING BEAVER HABITAT WITH GOOGLE EARTH:
Reintroduction and Distribution of Beavers in Europe
The distribution and reintroduction of beavers in Europe has been the topic of many of the articles by D.J. Halley of the Norwegian Institute for Nature Research (Department of Terrestrial Ecology) and F. Rossell, Telemark University College,( Department of Environmental and Health Studies), Norway. Their poster map: "Reintroduction, range expansion, and population development on a continental scale: the beaver's reconquest of Eurasia" gives a good overview of the state of beaver in Europe and Asia. The two maps below (Figures 1, 2) are described in the poster map.
These maps can be used as guide to explore beaver habitat with Google Earth and the success of reintroduction initiatives. Of course the Eurasian Beaver (Castor fiber) does not build the large dams and lodges easily visible on high resolution Google Earth images in North America. But signs of beaver can be found in some areas especially when more detailed country maps are used as guide.
Only Finland introduced the North American Beaver (Castor canadensis) see olive green shading on the map below.
Figure 1: Distribution of beavers in Europe, excluding Russia. Locations of relict populations are marked in black: 1 Castor fiber fiber ; 2 C. f. albicus ; 3 C. f. galliae ; 4 C. f. belarusicus. Red shading represents the present range of C. fiber; green shading represents the range of C. canadensis in Finland. Red squares are reintroduction sites where range has not yet spread significantly; red crosses represent planned reintroductions, with date where known. Countries marked 'F' have feasibility studies in progress.
Figure 2. Distribution of beavers in European Russia and Asia. Locations of relict populations are marked in black: 4 Castor fiber belarusicus; 5 C. f. osteuropaeus ; 6 C. f. pohlei ; 7 C. f.tuvinicus ; 8 C.f. biruli . Red shading represents the present range of C. fiber; green shading represents the range of C. canadensis.
The Following abstract gives a good thumbnail sketch of Beaver history in Eurasia. The beaver's reconquest of Eurasia: status, population development and management of a conservation success Auteur(s) / Author(s) HALLEY D. J. ; ROSELL F. ;
Résumé / Abstract
Overhunting reduced Eurasian Beaver (Castor fiber) populations to c. 1200 animals, in eight isolated populations, around the end of the 19th century. Protection, natural spread and reintroductions led to a powerful recovery in both range and populations during the 20th century, which continues at a rapid pace. The minimum population estimate is 593 000. There are also c. 12 500 North American Beaver (C. canadensis) established in Finland and Russian Karelia; however, other populations of C. canadensis introduced in Austria, Poland and France appear to be extinct. Castor fiber is now established throughout Europe with the exception of the British Isles, Iberia, Italy and the southern Balkans; reintroductions are continuing. Considerable further expansion in range and population, especially in western Europe and the lower Danube basin, can be expected. If current trends continue, C fiber will, within a few decades, be a fairly common mammal in much of Europe. Following initial recolonization, populations typically show a pattern of rapid range extension within a watershed, followed only later by rapid population growth, and a barrier effect of watershed divides, which can be strongly isolating where physical or habitat barriers (such as mountains or intensive farmland) intrude between watersheds. Management of beaver distribution should therefore operate at the watershed scale, except where large human-made dams form significant barriers to spread. The period of rapid population increase, if unchecked, leads to a phase of population decline as marginal habitats are occupied and exhausted. This coincides with a peak in conflicts with human land-use interests. A regulated hunting take of healthy beaver populations is recommended as the optimal management regime in managed landscapes. Early provision of interpretation and public viewing opportunities has been a feature of several recent reintroductions. This provides a benefit to the local economy through wildlife tourism, and helps foster positive attitudes to beavers.
Mammal review ISSN 0305-1838 2002, vol. 32, no3, pp. 153-178 [26 page(s) (article) Blackwell Science, Oxford, ROYAUME-UNI (1970) (Revue) INIST-CNRS, Cote INIST : 15938, 35400010495944.0010