Eurasian beaver: reintroduction
The Eurasian beaver went extinct in the Netherlands, but has been reintroduced and its numbers are rising steadily.
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Extinction
The last Eurasian beaver in the Netherlands died in 1826. The species had already gone extinct in Great Britain and Italy and in the 19th century it went extinct in many other European countries. A few small populations remained, along the Elbe and Rhône, for example.
Reintroduction in the Biesbosch reserve
In spring 1988 some Eurasian beavers from the Elbe were released in the Biesbosch reserve. In total 42 Eurasian beavers had been released there by 1991. Since then, numbers have risen steadily: in 2002 there were about 80 animals.
Appearance elsewhere
Since 1994, 54 Eurasian beavers in total have been released in the Gelderse Poort, a complex of nature development areas east of Nijmegen. Initially, mortality was high, but since 1998 the population has been growing - though it remains below the number of animals originally released.
Small numbers of Eurasian beavers have been sighted in various other localities, particularly in the river region and along the Roerdal. These animals have come from the Biesbosch, Gelderse Poort and Eifel areas. Since 1990 a population has developed in Flevoland from individuals that have escaped from Lelystad Wildlife Park. The population has spread through east and south Flevoland and in 2002 comprised about 20 animals.
In total there are currently over 130 Eurasian beavers living in the Netherlands. Now that beaver numbers are increasing, it is becoming increasingly likely that there will be intermixing between the groups in the river region.
Reproduction
Reproduction rates in the river region are below the rates in most of the populations of Eurasian beaver outside the Netherlands. Possible reasons for this are the high cadmium contents found in the animals' kidneys, the poor quality of the food available, and disturbance from human activity. Reproduction rates are higher in the Flevoland polders; here the river and lake beds are less contaminated with heavy metals and there is a more varied food supply.
The Eurasian beaver is on the Red List of mammals.
