Acta Theriologica

, Volume 51, Issue 1, pp 107–112 | Cite as

Use of dawn and dusk sight observations to determine colony size and family composition in Eurasian beaverCastor fiber

  • Frank Rosell
  • Howard Parker
  • Øyvind Steifetten


The methods used to determine family composition and colony size in Eurasian beaverCastor fiber Linnaeus, 1758 are often poorly described in published reports. Here we show how repeated counts of colony size in a random sample of colonies (n = 19) varied between dusk and dawn, between the months of August and September, and following successive counts. Mean counts at dusk and the following dawn did not vary significantly, though mean colony size was significantly greater in August than September. However, because all colony members are rarely seen during a single dusk or dawn count, successive counts often provided new information about the maximum number in each age class. This allowed us to adjust colony size following each count using the largest values thus far obtained, with the result that the mean adjusted colony size increased during six successive counts over seven weeks from 2.4 to 3.8. Family composition based on information from all six counts was 54% adults, 26% yearlings and 19% kits. Evidence suggests that kits in particular are undercounted by this method. Figures for colony size and composition in beaver should be viewed with caution if not obtained by methods tested for both precision and accuracy.

Key words

population estimation colony size monogamy management Norway 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Brady C. A. and Svendsen G. E. 1981. Social behaviour in a family of beaver,Castor canadensis. Biological Behavior 6: 99–114.Google Scholar
  2. Brozdnyakov V. V., Skobelev A. A. and Shestun K. V. 1997. Population dynamics of the beaver in Samarskaya Oblast. Russian Journal of ecology 28: 245–249.Google Scholar
  3. Buech R. R. 1985. Methodologies for observing beavers (Castor canadensis) during the activity period. [In: Nocturnal mammals. R. P. Brookes, ed]. Pennsylvania State University, Pennsylvania: 29–34.Google Scholar
  4. Buech R. R. 1995. Sex differences in behaviour of beavers living in near-boreal lake habitat. Canadian Journal of Zoology 73: 2133–2143.CrossRefGoogle Scholar
  5. Busher P. E. 1983. Interactions between beaver in a montane population in California. Acta Zoologica Fennica 174: 109–110.Google Scholar
  6. Busher P. E., Warner R. J. and Jenkins S. H. 1983. Population density, colony composition, and local movements in two Sierra Nevadan beaver populations. Journal of Mammalogy 64: 314–318.CrossRefGoogle Scholar
  7. Djoshkin W. W. and Safonow W. G. 1972. Die biber der alten und neuen welt. Neue Brehm-Bücherei, Ziemsen Verlag, Wittenberg: 1–168. [In Ger man]Google Scholar
  8. Dunbar R. 1984. The ecology of monogamy. New Scientist 103: 12–15.Google Scholar
  9. Easter-Pilcher A. 1990. Cache size as an index to beaver colony size in Northwestern Montana. Wildlife Society Bulletin 18: 110–113.Google Scholar
  10. Gunson J. R. 1970. Dynamics of the beaver of Saskatchewan’s northern forest. MSc thesis, University Alberta, Edmonton: 1–122.Google Scholar
  11. Hartman G. 1997. Notes on age at dispersal of beaver (Castor fiber) in an expanding population. Canadian Journal of Zoology 75: 959–962.CrossRefGoogle Scholar
  12. Hay K. G. 1958. Beaver census methods in the Rocky mountain region. The Journal of Wildlife Management 22: 395–402.CrossRefGoogle Scholar
  13. Heidecke D. 1984. Investigations of ecology and population dynamics of the European beaver,Castor fiber albicus, Matschie, 1907. Part 1. Biological and population-ecological results. Zoological Jahrbücher Systematics 111: 1–41.Google Scholar
  14. Hodgdon H. E. and Larson J. S. 1973. Some sexual differences in behaviour within a colony of marked beavers (Castor canadensis). Animal Behaviour 21: 147–152.CrossRefGoogle Scholar
  15. Jackson M. D. 1991. Beaver dispersal in western Montana. MSc thesis, University of Montana, Missoula: 1–77.Google Scholar
  16. Johnsen J. and Kaasa H. K. 1991. [Population study of beaver in Bø Township 1990–1991]. BSc thesis, Telemark Distriktshøgskole, Bø: 1–155. [In Norwegian]Google Scholar
  17. Kile N. B. and Nakken P. J. 1995. [Colony and brood size of beaver (Castor fiber) in the Gautestad region of Evje-Hornes Township, Aust Agder County]. BSc thesis, Høgskolen i Telemark, Bø: 1–28. [In Norwegian]Google Scholar
  18. Kleiman D. G. 1977. Monogamy in mammals. Quarterly Review of Biology 52: 39–69.CrossRefPubMedGoogle Scholar
  19. McTaggart S. T. and Nelson T. A. 2003. Composition and demographics of beaver (Castor canadensis) colonies in central Illinois. American Midland Naturalist 150: 139–150.CrossRefGoogle Scholar
  20. Müller-Schwarze D. and Houlihan P. W. 1991. Pheromonal activity of single castoreum constituents in beaver,Castor canadensis. Journal of Chemical Ecology 17: 715–734.CrossRefGoogle Scholar
  21. Novak M. 1987. Beaver. [In: Wild furbearer management and conservation in North America. M. Novak, J. A. Baker, M. E. Obbard and B. Malloch, eds]. Ontario Ministry of Natural Resources, Toronto, Ontario: 283–312.Google Scholar
  22. Olstad O. 1937. [Range of beaver (Castor fiber) in Norway]. Nytt magasin for naturvidenskapene 77: 217–273. [In Norwegian]Google Scholar
  23. Osmundson C. L. and Buskirk S. W. 1993. Size of food caches as a predictor of beaver colony size. Wildlife Society Bulletin 21: 64–69.Google Scholar
  24. Parker H. and Rosell F. 2001. Parturition dates for Eurasian beaversCastor fiber: when should spring hunting cease? Wildlife Biology 7: 145–149.Google Scholar
  25. Parker H., Rosell F., Hermansen T.A., Sørløkk G. and Staerk M. 2001. Can beaverCastor fiber be selectively harvested by sex and age during spring hunting? Pages 164–169. [In: The European beaver in a new millennium. A. Czech and G. Schwab, eds]. Proceedings of the Second European Beaver Symposium, 27–30 September, 2000, Białowieża, Poland.Google Scholar
  26. Parker H., Rosell F., Hermansen T.A., Sørløkk G. and Staerk M. 2002a. Sex and age composition of spring-hunted Eurasian beaver in Norway. The Journal of Wild life Management 66: 1164–1170.CrossRefGoogle Scholar
  27. Parker H., Rosell F. and Gustavsen Ø. 2002b. Errors associated with moose-hunter counts of occupied beaverCastor fiber lodges in Norway. Fauna norvegica Serie A. 22: 23–31.Google Scholar
  28. Patric E. F. and Webb W. L. 1960. An evaluation of three age determination criteria in live beavers. The Journal of Wildlife Management 24: 37–44.CrossRefGoogle Scholar
  29. Payne N. F. 1982. Colony size, age, and sex struc ture of Newfoundland beaver. Journal of Wildlife Management 46: 655–661.CrossRefGoogle Scholar
  30. Rosell F. 1994. Factors affecting territory size and scent marking behaviour in the European beaver (Castor fiber). MSc thesis, University of Trondheim, Norway: 1–33.Google Scholar
  31. Rosell F., Bergan F. and Parker H. 1998. Scent-marking in the Eurasian beaver (Castor fiber) as a means of territory defense. Journal of Chemical Ecology 24: 207–219.CrossRefGoogle Scholar
  32. Rosell F. and Bjørkøyli T. 2002. A test of the dear enemy phenomenon in the Eurasian beaver (Castor fiber). Animal Behaviour 6: 1073–1078.CrossRefGoogle Scholar
  33. Rosell F. and Parker H. 1995. Beaver management: present practice and Norway’s future needs. Telemark Colege, Bø, Norway: 1–137. [In Norwegian with an English summary]Google Scholar
  34. Rosell F. and Steifetten Ø. 2004. Subspecies discrimination in the Scandinavian beaver (Castor fiber): combining behavioral and chemical evidence. Canadian Journal of Zoology 82: 902–909.CrossRefGoogle Scholar
  35. Schulte B. A. 1993. Chemical communication and ecology of the North American beaver (Castor canadensis). PhD thesis, State University of New York, Syracuse: 1–194.Google Scholar
  36. Schulte B. A. 1998. Scent marking and responses to male castor fluid by beavers. Journal of Mammalogy 79: 191–203.CrossRefGoogle Scholar
  37. Semyonoff B. T. 1957. Beaver biology in winter in Archangel Province. Russian Game Reports 1: 71–92.Google Scholar
  38. Siegel S. and Castellan N. J. Jr 1988. Nonparametric statistics for the behavioral sciences. 2nd ed. McGraw-Hill, New York: 1–316.Google Scholar
  39. Sokal R. R. and Rohlf F. J. 1995. Biometry. The principles and practice of statistics in biological research. 3rd ed. W. H. Freeman and Company, New York: 1–887.Google Scholar
  40. Sun L. 1996. Chemical kin recognition in the beaver (Castor canadensis): behavior, relatedness and information coding. PhD thesis, State University of New York, Syracuse: 1–184.Google Scholar
  41. Sun L. and Müller-Schwarze D. 1997. Sibling recognition in the beaver: a field test for phenotype matching. Animal Behavior 54: 493–502.CrossRefGoogle Scholar
  42. Svendsen G. E. 1980. Population parameters and colony composition of beaver (Castor canadensis) in southeast Ohio. American Midland Naturalist 104: 47–56.CrossRefGoogle Scholar
  43. Townsend J. E. 1953. Beaver ecology in western Montana with special reference to movements. Journal of Mammalogy 34: 459–479.CrossRefGoogle Scholar
  44. Tyurnin B. N. 1984. Factors determining numbers of the river beaver (Castor fiber) in the European North. Soviet Journal of Ecology 14: 337–344.Google Scholar
  45. Wilson E. O. 1975. Sociobiology: the new synthesis. Belknap Press of Harvard University, Cambridge: 1–665.Google Scholar
  46. Wilsson L. 1971. Observations and experiments on the ethology of the European beaver (Castor fiber L.). Viltrevy 8: 115–266.Google Scholar

Copyright information

© Mammal Research Institute, Bialowieza, Poland 2006

Authors and Affiliations

  • Frank Rosell
    • 1
  • Howard Parker
    • 2
  • Øyvind Steifetten
    • 3
  1. 1.Faculty of Arts and Sciences, Department of Environmental and Health StudiesTelemark University CollegeNorway
  2. 2.Faculty of Arts and Sciences, Department of Environmental and Health StudiesTelemark University CollegeBø i TelemarkNorway
  3. 3.Department of Ecology and Natural Resource ManagementNorwegian Uniwersity of Life SciencesÅsNorway

Personalised recommendations