Forestry Studies | Metsanduslikud Uurimused, Vol. 67, Pages 109–115

Population density of the Eurasian beaver (Castor fi ber L.) (Castoridae, Rodentia) in the Middle of

Alexey Andreychev

Andreychev, A. 2017. Population density of the Eurasian beaver (Castor fi ber L.) (Cas- toridae, Rodentia) in the Middle Volga of Russia. – Forestry Studies | Metsandusli- kud Uurimused 67, 109–115. ISSN 1406-9954. Journal homepage: http://mi.emu.ee/ forestry.studies

Abstract. The article presents research on the population density of the Eurasian beaver in the large, medium and small rivers of the Republic of . The population density of the beaver in the large rivers of the region varies from 0.45 to 0.62 colonies per km (average 0.52). The population density in medium rivers ranges from 0.36 to 0.48 colonies per km (average 0.4). In small rivers, population density ranges from 0.2 to 0.94 colonies per km (average 0.46). The total number of beavers in the region is about 17,000 individuals as at 2016.

Key words: Eurasian beaver, Castor fi ber, density population, colonies, European Russia, Mordovia.

Author’s address: Department of Zoology, Mordovian State University, Bolshevist- skaya str. 68, 430005, , Republic of Mordovia, Russia; e-mail: andreychev1@ rambler.ru

on re-acclimatisation. In total, 34 beavers Introduction were released. The Eurasian beaver was imported from the Voronezh Game Re- Currently, the populations of the Eurasian serve. The release into the wild was carried beaver (Castor fi ber L.) are being restored or out in small batches. The beavers were re- will be restored in many regions in Russia. leased into forest lakes, such as the Picher- However, scientists in different countries ki, the Taratinskoe, the Kocheulovo, and need to ascertain population density in dif- the Inorki. As a result, the beaver popu- ferent parts of the area (Halley & Rosell, lation has increased rapidly. The beavers 2003). Beavers undoubtedly affect many from the lakes spread throughout the riv- ecosystems and knowing the state of their ers – the Pushta, the Uzhovka, the Satis, populations is an important task (John- and the Yuzga. By 1950, the number of the ston & Naiman, 1990; Rosell et al., 2005). In growing population was estimated at 300 2009–2010, there were 572,500 individuals individuals. In 1956, 40 beaver individu- of the Eurasian beaver in the territory of als from the Mordovian reserve were re- Russia (Kolesnikov et al., 2011). leased in the Zubovo-Polyansky District to In Mordovia, river beavers were re- accelerate settlement in the Vad River. In leased in the Mordovia State Nature Re- 1959, there were 600 beavers and in 1964, serve by zoological expedition S.S. Turov. about 1,000 individuals (Borodina, 1966; This was carried out from 1936 until 1940 Borodina et al., 1970) in the river within the framework of the programme basin. Since 1961, beavers’ dwellings have

DOI: 10.1515/fsmu-2017-0016 © 2017 Estonian University of Life Sciences. All rights reserved 109

A. Andreychev been built (Borodin, 1970; Andreychev & 37 °C. The average annual precipitation in Kuznetsov, 2012) in the river basin. the territory of Mordovia is 480 mm. Over Until the end of the 20th century, bea- the course of observation lasting many vers in the region were hunted in all possi- years, periods of more and less humidifi ca- ble ways. As a result, they became extinct. tion were noted, ranging between the min- Beaver traps have been prohibited since imum and maximum values of 120–180 2005 when they were included in the Red mm. Distribution of precipitation across Book of the region. For a long time, sci- the territory is not very diverse. The aver- entifi c literature included no information age long-term value of evaporation is cal- on the number of beavers in the region. A culated to be in the range of 390–460 mm. small resurgence in beaver trapping has According to the research of botanists, occurred recently. The aim of this work is there are more than 1,230 species of vascu- to determine the density of the Eurasian lar plants from 495 genera and 109 families beaver population in different rivers in one in the modern fl ora of Mordovia. These of the central regions of Russia. include 4 species of plains, 8 horsetails, 18 ferns, 3 gymnosperms, and 1,197 species of fl owering plants. Herbaceous perennial Material and Methods and annual plants predominate. The num- ber of species of woody forms is relatively The Republic of Mordovia is located in the small: trees – 24, shrubs – 45, shrubs – 7, centre of the European part of Russia. Its semishrubs – 5. extreme points are defi ned by geographi- The territory of Mordovia includes cal coordinates 42º 11’ – 46º 45’ E and 53º coniferous broad-leaf, broad-leaf forests, 38’ – 55º 11’ N (Figure 1). The maximum shrub steppes and meadow steppes. The distance from west to east is 298 km and main forest forming species are the Scots the distance from north to south is 57 to pine (Pinus sylvestris L.), Norway spruce 140 km. The area of the republic is 26.2 (Picea abies (L.) Karst), European larch (Lar- thousand km2. Features of the geological ix decidua Mill.), English oak (Quercus ro- structure of Mordovia are determined by bur L.), common ash (Fraxinus excelsior L.), its location in the central part of the Rus- Norway maple (Acer platanoides L.), Scots sian Platform and the north-western slopes elm (Ulmus laevis Pall.), silver and pubes- of the . In the western part of cent birch (Betula pendula Roth., B. pubes- the Republic of Mordovia, the Volga Up- cens Ehrh.), black alder (Alnus glutinosa L.), land reaches the -Don Lowlands. small-leaved lime (Tilia cordata Mill.) and The climate of the region is moderate- black poplar (Populus nigra L.). ly continental with pronounced seasons Coniferous broad-leaf or mixed forests throughout the year. The infl ux of direct are located in the outwash plains and ad- solar radiation in Mordovia varies from 5.0 jacent terraced complexes. These include in December to 58.6 kJ/cm2 in June. Total both coniferous and broad-leaved trees. In radiation throughout the year is 363.8 kJ/ the sands of the outwash plains, the most cm2; the radiation balance is 92.1 kJ/cm2. common are pine forests, often with some The average annual air temperature varies characteristics of a taiga. Broad-leaved for- from 3.5 to 4.0 °C. The average tempera- ests are prevalent mainly in interfl uvial ture of the coldest month (January) is in spaces of secondary morainic and erosion- the range of –11.5...–12.3 °C. Temperature denudation plains with grey forest soils as drops down to –47 °C occur. The average well as in fl oodplain complexes. temperature of the warmest month, i.e. Mordovia is located in the south-west- July, is in the range of +18.9...+19.8 °C. Ex- ern part of the Volga River basin. 47% of treme temperatures in the summer reach the area is located in the basin of Sura and

110 Population density of the Eurasian beaver (Castor fi ber L.) (Castoridae, Rodentia) in the Middle Volga of Russia

Figure 1. Geographical position of the Republic of Mordovia in Eastern Europe.

111 A. Andreychev

53% in the basin of Moksha. Moksha is the all rivers. Small rivers make up 4% of the main river in western Mordovia that fl ows total and 22% of the length of all rivers. in the meridional direction to the confl u- The share of medium-sized rivers (the Issa, ence of the Urkat River, where its direction the Sivin, the , the Partsa, the Vad, the changes to the sublatitudinal. The Mok- Visha, and the ) in the total length is sha is the right tributary of the Oka River negligible (0.5%). Two rivers – the Moksha and empties into it. The channel is 60–90 and the Sura – are more than 500 km long m wide and 5–8 m deep. The absolute wa- (Water resources…, 1999). Small rivers and ter level is 89–126 m. The Moksha’s largest streams are distributed unevenly in the ba- tributaries in the territory of Mordovia are sins of large rivers. In the river Sura, there the Vad, the Satis, the Urkat, the Sivin, and are 24 small rivers and 286 very small riv- the Issa. ers and streams. 30 small rivers and 385 The Sura River fl ows along the south- very small rivers and streams fl ow into the eastern border of Mordovia. The width of Moksha River. the channel varies from 100 to 150 m and It is typical for small rivers to have a 5 its depth is 10 m. It fl ows 0.3–1.0 m/s and to 10 m wide channel, with extensions up its absolute water level is 90–115 m. The to 35 m; for average rivers, from 25 to 50 largest tributaries of the Sura include the m with extensions up to 70 m. Large rivers Bolshaya Ksha, the Bolshaya Sarka, the Pi- are 100 to 150 m wide and in the mouths, ana, the Menya, and the Alatyr. 300 m. Rivers are shallow and the prevail- The density of the river network in the ing depths for small rivers is 0.4 to 1.2 m, entire area is 0.23 km of river per km2. By for average ones 1.5 to 2.0, and for large the nature of intra-fl ow distribution, the ones 2.5 to 3.5 m. In rundowns, the depth republic’s rivers are of Eastern European throughout is less than 0.5 m. The fl ow type. The water regime of the rivers is rate varies from 0.2 m/s to 1.2 m/s in run- characterised by the presence of summer downs. and winter seasons, spring fl oods and au- The studies were conducted on the tumn fl oods. The most high-water month rivers of Mordovia during the period of is April. 3–15% of annual runoff occurs 2008–2016. The research was carried out in during the low-fl ow period. autumn, spring and summer due to a large The river’s length is used in the study amount of work. The rivers were surveyed as a criterion for classifying rivers. We val- by using the method described by Dyakov idate this method because most reference (Dyakov Yu, 1975). The number of settle- books on surface water resources are based ments in the rivers’ areas was recorded. on that classifi cation (Sokolov, 1964; Soko- The site of the river was selected and the lovsky, 1968; Yevstigneyev, 1990; Chalov, number of settlements in the channel was 1994). According to this classifi cation, determined. The density of individuals large rivers are rivers, the length of which in the settlement was estimated by feed- varies from 301 to 1,000 km. Medium riv- ing activity and other traces of life activ- ers are rivers with the length of 101 to ity (huts, dams, burrows). A great help in 300 km. Small rivers are rivers, the length the work was provided by hunters’ survey of which ranges from 26 to 100 km. The data. smallest rivers are usually the rivers with Initially, enumeration was launched in the length of up to 25 km. In the territory 2008 in the Chermeley River in the Sura of Mordovia, there are about 1,520 water- river basin (Andreychev et al., 2009). The courses with the total length of 9,250 km. counting station included 21 km from the The major share (96%) of the river network mouth on the riverbed. Each settlement of the republic falls on the smallest rivers. was indicated on the map by using GPS These constitute 65% of the total length of and the programme OziExplorer. This pro-

112 Population density of the Eurasian beaver (Castor fi ber L.) (Castoridae, Rodentia) in the Middle Volga of Russia gramme made it possible to calculate the that, on average, there are 3–4 individuals distance between settlements, dams, and per settlement, it is easy to determine the lodges, as well as calculate the area and total number of beavers as 17,000 individ- length of the coastline. uals only in rivers. Moreover, it is neces- The volume of counting work covered sary to take into account that beavers live 468 km of large rivers, 558 km of medium- practically in every lake in the basin of the sized rivers, and 1,269 km of small and Sura and the Moksha, as well as in artifi cial very small rivers. Statistical analysis was ponds (ponds). Therefore, the number of performed in MS Excel and PAST (Ham- beavers in all reservoirs in Mordovia will mer et al., 2001). be even higher.

Results 0.96 0.88 The population density of the Eurasian 0.8 beaver in large rivers in the region ranges 0.72 from 0.45 to 0.62 colonies per km (average 0.64 0.52) (Figure 2). The population density in 0.56 medium rivers varies from 0.36 to 0.48 col- 0.48 onies per km (average 0.4). In small rivers, 0.4 population density ranges from 0.2 to 0.94 0.32 colonies per km (average 0.46) (Sosnina et km) (beaver settlements/stream 0.24 Population density of beaver on rivers of density Population al., 2014). Thus, the average density of the A B C beaver in large and small rivers is higher Classes of rivers than in average rivers. However, the den- sity of the Eurasian beaver population in Figure 2. The variation range of Eurasian beaver population density on the region rivers. small rivers is ambiguous. They can be di- A – big river (n = 3), B – average river (n vided into three groups: those with a low = 5), C – small river (n = 33). Box plots population density (less than 0.3 colonies/ indicate median (solid line), 25–75% km), average density (from 0.3 to 0.5 colo- range (box) and the minimum and maxi- nies/km), and high density (more than 0.5 mum values (whiskers). colonies/km). The estimation of the number of bea- vers in different classes of rivers in the Discussion region showed that most settlements fall on small and smallest rivers. 250 beaver Literature includes a lot of guidance on settlements were registered in large riv- the restoration size and density of the Eur- ers and 220 settlements were registered in asian beaver and the American beaver (C. average rivers. By extrapolation, it can be canadensis). There are reports that beavers assumed that the number of settlements in were reduced in number at the site where medium rivers can be up to 300. Small riv- they were cut off by moving to neighbour- ers accounted for 570 settlements. In small ing areas (Bhat et al., 1993; DeStefano et al., and smallest rivers, with a total length of 2006). This is evidenced by the number of 8,032 km, the number of settlements can be beavers in different countries. A similar up to 3,700. Thus, the ratio of settlements pattern was observed in the western rivers in large, medium and small rivers is as fol- of Mordovia, in particular in the Vad, the lows: 6%, 7%, and 87%, respectively. The Partsa, and the Vyndrey. total number of settlements in the rivers Somewhat lower numbers of beaver of the region is 4,250. Taking into account population density compared to the rivers

113 A. Andreychev of other countries were found particu- sections. The obtained data should be tak- larly in the European rivers of Mordovia. en into account in the future with subse- It should lead to comparisons of the situ- quent releases of beavers in different land- ation in some other regions. The density scapes of Mordovia. They are important of beaver population in Newfoundland is for environmental organisations in the re- 0.24 beaver colony sites/km (Bergerud & gion (Andreychev, 2012), as the restoration Miller, 1977). of water dwellers depends on the success Our data on the density of beaver settle- of their activities. It is known that by re- ments are consistent with the results of sci- storing beaver populations, conditions for entists from Norway, Sweden, and Fin- biodiversity are created and improved. land (from 2.4 to 3.8 individuals in the settlement) (Parker et al., 2002; Rosell et al., Acknowledgements. We are grateful to 2006). The density of the American beaver Alexandr Lapshin and Vyacheslav Kuznet- population in Tierra del Fuego (TDF) (Ar- sov for support in carrying out fi eld stud- gentina) is 0.2–5.8 beaver colony sites/km ies, and Natalia Letkina for English proof- (Lizarralde, 1993). Between 1999 and 2001, reading. the mean density of the beaver population in the Chilean part of TDF and the adjacent southern island Navarino (NAV) was 1.03 References (range: 0.15–1.91) and 1.1 per km (Skewes et al., 2006). Andreychev, A.V. 2012. Organization theriological Comparable results of counting can be Protected Areas in the Republic of Mordovia, the face. – Proceedings of the Dagestan State Peda- led by counting areas of the American bea- gogical University, 4, 17–22. (In Russian). vers in Allegany State Park and their vicin- Andreychev, A.V., Kuznetsov, V.A. 2012. Mammals ity in New York from 1984 to 1996, thus the of Mordovia. (Mlekopitayushchie Mordovii). density of the breeders was 45 to 64 pairs × Mordovia State University, Saransk. 100 pp. (In Russian). 2 / 250 (study area) = 0.36 to 0.51 beavers/ Andreychev, A.V., Kuznetsov, V.A., Lapshin, A.S., km2 (Sun et al., 2000) Grishutkin, G.F. 2009. Status of the population In southwestern Sweden, according to eurasian beaver (Castor fi ber L.) in Bolsheber- an estimate calculated as the sum of all eznikovskii district in the Republic of Mordovia (on registration papers). Rare animals of the Re- found colonies divided by the sum of all public of Mordovia: Material of maintenance of surveyed areas, the beaver population den- the Red Data Book of the Republic of Mordovia sity of the whole province increased from in 2009. Izdatelstvo Mordovskogo Universiteta, 0.10 colonies/km2 in 1976 to 0.19 colonies/ Saransk, p. 7–11. (In Russian). Bergerud, A.T., Miller, D.R. 1977. Population dynam- 2 km in 1987, and then levelled at 0.21 colo- ics of Newfoundland beaver. – Canadian Journal nies/km2 in 1999 (Hartman, 2003). of Zoology, 55(9), 1480–1492. Our research has shown that in small Bhat, M.G., Huffaker, R.G., Lenhart, S.M. 1993. Con- rivers of the region, the conditions for bea- trolling forest damage by dispersive beaver pop- ulations: Centralized optimal management strat- ver habitation are better in comparison egy. – Ecological Applications, 3(3), 518–530. with medium and large rivers. In the con- Borodin, L.P. 1970. Russian desman in the fl ood ditions of the continuing protection of the plains of rivers Moksha and Sura. – Proceedings beaver population in Mordovia, it is pos- of the Mordovia State Nature Reserve, 5, 61–90. (In Russian). sible to restore their abundance in the riv- Borodina, M.N. 1966. Materials for the study of dy- ers where they were exterminated due to namics of beaver populations Moksha. – Proceed- movements from neighbouring small riv- ings of the Mordovia State Nature Reserve, 3, ers. The species from the Red Book cannot 5–37. (In Russian). Borodina, M.N., Borodin, L.P., Tereshkin, I.S., be excluded. In the future, it is necessary Shtarev, Y.F. 1970. Mammals Mordovia reserve. to conduct constant research on changes – Proceedings of the Mordovia State Nature Re- in the number of beavers in different river serve, 5С, 5–60. (In Russian).

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Received February 24, 2017, revised February 19, 2018, accepted March 2, 2018

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