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Please use this identifier to cite or link to this item:
http://hdl.handle.net/2282/762
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| Title: | Use of dawn and dusk sight observations to determine colony size and family composition in Eurasian beaver Castor fiber |
| Authors: | Rosell, Frank
Parker, Howard
Steifetten, Øyvind |
| Issue Date: | 2006 |
| Publishers version: | http://acta.zbs.bialowieza.pl/contents/?art=2006-051-1-0107 |
| Abstract: | The methods used to determine family composition and colony size in
Eurasian beaver Castor 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. |
| Keywords: | Beavers
Population estimation
Colony size
Management
Monogamy |
| Publisher: | Polish academy of sciences, Mammal research institute |
| Document type: | Journal article |
| URI: | http://hdl.handle.net/2282/762 |
| Appears in Collections: | Institutt for natur-, helse- og miljøvernfag
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