Содержание: Том 15 (1) 2016 (отпечатан 6 June 2016)
Saveljev A.P., Busher P., Hood G.
The Seventh International Beaver Symposium was held at the Voronezhsky State Nature Biosphere Reserve near Voronezh, Russia, from September 13–17, 2015. Approximately 100 beaver scientists and interested nonscientists from 18 countries presented new data and joined us for the five-day meeting.
In the Soviet Union experimental kill trapping (removal trapping) of Eurasian beaver began in 1960 in the Kirov region, and since 1963 the limited kill trapping was also permitted throughout Russia and Belarus. Regular trapping allowed obtaining large amounts of biomaterial, which significantly widened our knowledge on the general population ecology of beavers and on their behaviour during the under-ice period when observation is limited. The current decrease in demand for furs requires the realization of scientifically sound measures for beaver management based on ecological priorities.
This article provides a brief historical overview of research and management activities at the Voronezhsky Nature Reserve, Russia, and its role in the successful recovery of Eurasian beaver (Castor fiber) populations. I documented the various stages and actions for their protection, live-capture and release of Eurasian beavers from the 1930s to the 1980s. This review includes a list of several scientific studies conducted in the Voronezhsky Nature Reserve related to the biology and ecology of beavers, the development of a captive-breeding program, and research into specific diseases and parasites. Many of the materials for this study are key bibliographical references of the scientific publications found in the Proceedings of the Reserve.
Minnig S., Angst C., Jacob G.
Eurasian beaver (Castor fiber) has been reintroduced in Switzerland between 1956 and 1977. Individuals from the refugium population in France (C. f. galliae) were released in the Rhone catchment area and in tributaries of the Rhine catchment area in Western Switzerland. Individuals from the refugium populations from Norway (C. f. fiber) and Russia (C. f. orientoeuropaeus) were released in tributaries of the Rhine catchment in Eastern Switzerland. In the Rhine basin beavers of different origins came into contact. This study provides a first evaluation of the reintroduction program of beaver in Switzerland and gives implications for the post-release genetic management of the Swiss beaver population. We report on the genetic monitoring of the beaver population in Switzerland, based on the analysis of 251 dead found individuals collected from 1998 to 2014 and a combination of mitochondrial and nuclear genetic markers. We found no evidence of the presence of North American beaver (Castor canadensis) and we observed three mitochondrial DNA haplotypes, assigned to the refugium populations in France (C. f. galliae), Norway (C. f. fiber) and Germany (C. f. albicus). Based on the analysis of seven microsatellite loci, we inferred that the beaver population in Switzerland consists of two genetic clusters and we found evidence of a zone of secondary contact. We observed low levels of genetic diversity and we could show that individuals separated by distances up to 50 km were closely related.
Puzachenko A.Yu., Korablev N.P.
Allometry is a common phenomenon that is found in animals at different levels: between sexes, species, and higher taxonomic levels. For example, an ‘allometric mechanism’ of regulation shows variation at the population level and therefore it is the source of morphological diversity at the species level, and additionally, the allometric relationship is influenced by natural selection. To better understand the constraints of ontogenetic and static allometry, we investigated 493 skulls (15 measurements per skull) from three geographically isolated populations of Eurasian beaver (populations of Voronezh Reserve, Oka Reserve, and Central Forest Reserve), all belonging to the Eastern European subspecies Castor fiber orientoeuropaeus. The allometric growth in terms of the general length of the beaver skull depends on the specific growth of its rostral part (nasal bone, intermaxillae, and diastema) in all studded populations. The pattern of static allometry in adult animals was mostly similar to the pattern of ontogenetic allometry, but in adults, isometry was predominated. The PCA results showed clear differences in the ontogenetic allometric patterns of different populations. All these results confirm our preliminary hypothesis (Puzachenko & Korablev, 2014) about the influence of ontogenetic allometry on the skull parameters in these beaver’s populations.
Bashinskiy I.V., Osipov V.V.
The study of beaver’s (Castor fiber) impact on steppe rivers’ ecosystems was held within the Privolzhskaya Lesostep’ State Nature Reserve (Penza Province, Russia). We investigated how pond age and permanence of beaver ponds influenced the abundance and diversity of fishes and amphibians. The majority of beaver ponds in our study area were small and dams were easily destroyed by spring floods. The formation of stable long-term ponds was evident in rivers with low discharge. The most favorable parts of rivers for beavers were anthropogenic reservoirs, where swamping and high biomass of reeds were common. The rivers were inhabited by one species of lamprey (Eudontomyzon mariae), six fish species (Esox lucius, Leucaspius delineatus, Sabanejewia baltica, Misgurnus fossilis, Barbatula barbatula, Carassius carassius), and five amphibian species (Lissotriton vulgaris, Pelobates fuscus, Bufo viridis, Rana arvalis, Pelophylax lessonae). As a result of the damming, abundance, biomass of fishes, species diversity and abundance of amphibians increased. During long-term persistence of beaver ponds fish abundance declined (the oxygen level reduced), but the number of amphibians continued to appear (more shallow water bodies appeared). Also beaver dams led to isolation of fishes in different parts of valleys and served as barriers to spawning migrations (e.g. for pike and lamprey). When beavers abandoned ponds, amphibian abundance declined, and fish abundance increased — due to increased water flow. Thus, despite some positive effects, beaver ponds were not the key habitats for fishes and amphibians.
Danilov P.I., Fyodorov F.V.
In the European North of Russia the Eurasian beaver had been extirpated over two hundred years ago. Owing to active introduction and dispersals from the 1930s to the 1950s, beavers have re-colonized the natural ecosystems in the European North. Furthermore, Finland and Russia (Karelia, Leningrad and Arkhangelsk provinces) are now co-inhabited by two beaver species — the North American (Castor canadensis Kuhl) and the Eurasian (C. fiber L.) beaver. North American beavers, which have colonized a major part of Finland, Karelia and the Karelian Isthmus in the Leningrad Province, descended from the seven animals brought to Finland from the USA in the 1930s (Linnamies, 1956; Siivonen, 1956; Lahti, 1968). Subsequent intraregional translocations of these animals took place in both Finland and Russia (n=270). The main origins of Eurasian beavers introduced in provinces adjacent to Karelia (Arkhangelsk, Vologda and Leningrad provinces) (n=1349) were the Voronezh Province (26.5% of all releases in the study area), Republic of Belarus (20.8%), Mari El Republic (12.5%), Smolensk Province (6.2%), Bryansk Province (5.3%), Ryazan Province (3.6%), Komi Republic (1.5%), and other regions (5.6%). Intraregional translocations of the Eurasian beaver were also conducted (18%). In total, more than 1800 Eurasian beavers were introduced in the European North of Russia (Murmansk, Leningrad, Novgorod, Pskov, Arkhangelsk and Vologda provinces). The present-day North American beaver population is estimated at 12000 animals in Karelia and 1000 in the Karelian Isthmus, Leningrad Province (Danilov et al., 2007, 2012). Eurasian beaver numbers are estimated at 4000 animals in Karelia (Danilov & Fyodorov, unpublished data), with fewer than 40 beavers in the Murmansk Province (Kataev, 2015), 23000 in the Leningrad Province, 25000 in the Novgorod Province, 17600 in the Pskov Province, 21000 in the Arkhangelsk Province, and 32600 animals in the Vologda Province (Borisov, 2011). Presently, Eurasian beavers live in those areas in southern Karelia that were inhabited by North American beavers since they were released there at the end of the 1960s, i.e. one species has been replaced by the other (Danilov et al., 2007, 2011; Danilov & Fyodorov, 2015a). In southern Karelia, the closest distance between colonies of different beaver species is 10 km. Conversely, in north-eastern Karelia (Kemsky District), North American beavers penetrated into the Arkhangelsk Province and are colonizing areas inhabited by the Eurasian beaver. In 2015, they were spotted in the Arkhangelsk Province, 70 km east of the administrative border with Karelia.
Paşca C., Ungureanu L., Ionescu G., Popa M., Gridan A.
The reintroduction of Eurasian beaver (Castor fiber) in Romania started in 1998 and was a complete success in terms of population and natural range enlargement. The habitat modelling capacity of beaver was more and more obvious once with the increase of population densities, demonstrating the high potential of this species to create new trophic niches for other species and implicitly biodiversity enrichment. The study was conducted on a floodplain area near the Bвrsa River, where the habitat became a vegetation and fauna paradise, by the constant intervention of beavers that had colonized the area in 2009-2010. In the first stage of this study, the habitats were classified and existing stands, shrubs and herbaceous vegetation was demarcated according to their composition and age (for tree vegetation). Further, a habitat analysis has been performed grounded on the correlation of dendrochronological sampling and satellite images captured between 2005 and 2014. On the basis of the aforementioned method, the right moment for beaver installation within the studied area has been determined quite precisely. This study is a clear example that beavers succeed to use in their best interest the opportunities offered by nature. Moreover, through the changes they produce on the environment, beavers have a strong impact on the natural succession processes.
Beaver groups were examined from the dry steppe zone to the northern taiga zone from 1992 to 2014. The only region where beaver foraging activity limits the development of riparian trees and shrubs is the northern taiga, but here the effect of beaver on riparian plant communities is not critical in most settlements. However, even in the northern taiga tree forage availability is not a factor limiting the development of the beaver population. The beaver has its greatest impact on trees of preferred species and diameters. In 33.6% of settlements on the Pechora River and tributaries in the upper reaches, and in 17% of settlements in the Volosnitsa River I observed a shortage of preferred beaver foods. In the Samara lakes beavers remove two and half times the amount of woody vegetation on average compared to beavers living along the river. In 91.2% of settlements beavers removed up to 3% of the total woody plant resources per year. The trophic level base is not a factor limiting the development of the beaver population in all studied regions from the steppe zone to the northern taiga. Beaver foraging activity does not have a negative impact on plant communities, but the southern taiga woody vegetation is recovering faster than woody vegetation in the forest-steppe zone. In northern taiga beavers prefer birch with diameters up to 30 cm even when plentiful amounts of shrubby willows are present.
An overview of wolves as natural predator of the beaver in Eurasia and North America will be given. The impact of wolf on beaver populations is depending on local and seasonal conditions. Wolves are not able to reduce beaver populations. Our knowledge about the relations between beaver and wolf is still incomplete and should be further examined.
Saveljev A.P., Niamosor Batbayar, Shaariybuu Boldbaatar, Batseren Dashbiamba
For the purpose of preservation of a unique gene pool of autochthonous beavers Castor fiber birulai in 1985–2002 daughter population in adjoining regions of NW Mongolia and South Tuva (Tes River / Tesijn gol basin) has been introduced (Stubbe et al., 2005). Today this local population has reached 150 animals (Saveljev et al., 2015). The physical condition of the beavers that were caught by a sort of natural “ecological trap” late February, 2015 is described. As the result of extreme frosts animals have been blocked by frazil in the lodge and had no access to forage. Local people have released five animals from this ice captivity. All beavers had gnawed tails. Absence in this area of terrestrial large predators allows to assume with high degree of confidence that the reason of traumas at animals was self- (or allo-) gnawing. The facts of placentophagy and piscivory of beavers and infestation by opisthorchosis as well, as cases of predation and scavenging among mammals (the “obligate” phytophages) are discussed.
Mishin A.S., Trenkov I.P.
In this study we tried to research attractiveness of dry beaver ponds for large mammals. We used data of the frequency of visits of different species of mammals from beaver ponds and from dry marsh that was not inhabited by beavers but had similar conditions like a dry beaver pond. Camera traps (192 trap-nights) took pictures of 674 individuals of large mammals of eight species. It found the predominance of visits to the dry beaver ponds by the predatory mammals. Ungulates, except wild boar, visited the beaver ponds more often than the control marsh.