Beavers on the Oka river

The autumn estimation of beavers in the Prioksko-Terrasny biosphere reserve is complete. It’s results and restoring populations of these rodents on the Oka comments Senior Researcher, PhD Sergey Albov.

“Acclimatization of beaver in the Soviet Union is a grand experiment, carried out across the vast and varied natural conditions of the country. Modern range and number of beaver in Russia and CIS countries shows that in terms of settlement the experiment was successful. The former habitat of beaver is not yet restored, but in the 70-ies of the last century, an artificial resettlement was discontinued. The stage of beaver unaided resettlement began. At the same time it is time to sum the results of this experiment.

On the one hand, beaver was a mandatory component of coastal and water-related ecosystems throughout the Holocene, i.e. over 10 thousand years. In other words, for the enormous length of time beavers and forests were existing together. At the same time, especially intensive deforestation began in the last 2 – 3 centuries, when the number of beaver start to decline dramatically. Thus the present-day slogan “Kill a beaver – save a tree” is untenable.

On the other hand, for a hundred years, this rodent was absent from the great part of its area. Therefore, despite the fact that the beaver is a native species, it’s reacclimatization likely to be considered as the introduction of a new invasive species into the formed biocenosis. Moreover, over the years with the lack of beaver the number of population has increased significantly. Beaver, returning to the borders of its former range, turns to face the environment heavily modified by man, with the resulting conflicts.

As you can see, the result of an experiment carried out is multifaceted and contradictory, but an exhaustive analysis of the results is far from complete. To this must be added that the resettlement of beaver was conducted not only in our country, but in Western Europe, North and South America. The evaluation of the results of resettlement is conducted by scientists of these countries. In September this year in the Voronezh Reserve the 7th International Beaver Symposium was held. It was attended by scientists from 20 countries.

Among the various reports posts of particular interest were made by reserve staff. In protected areas there are conditions when population growth is limited only by natural factors. The number of beavers reach a level at which the density of the population corresponds to the maximum capacity of the medium and the formation of new settlements is not happening, but isn’t reduced. In other words, there is an opportunity to see what it is – an ideal beaver population.

In our reserve the situation with beavers is similar to that. They were introduced in the reserve in 1948 and to date have inhabited almost all its waterways. Their number in the last 20 – 25 years varies highly. But the development of the beaver population occurred against the background of almost complete absence of large predators. Only in the last 10 years, the reserve has become inhabited by lynx. How would this affect the population of beavers, time will tell.

Estimation of beavers in the reserve conducted this fall showed that there were no significant changes compared with the previous year. Their number remained at last year’s level of about 50 animals. In the reserve there is still 13 beaver settlement, though their strength and accommodations have changed.

This year Oka river became shallow. The resulting shoals created a good opportunity to explore the coastal thickets of willow from the river side. As a result, for the first time in the reserve, beaver settlements were mapped and estimation of beavers on the Oka left bank within the buffer zone of the reserve was conducted. In this area we found three settlements of beavers, a total of about 20 animals.

Thus, the resettlement of beavers from the reserve is over. At the moment the beaver population in the reserve is a part of a large population of the Oka river. “