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1

Scent marking in Eurasian beaver Castor fiber during winter

100%
Rosell F., Bergan F.
Acta Theriologica
|
2000
|
tom 45
|
nr 2
The Eurasian beaver Castor fiber Linnaeus, 1758 deposit castor fluid (castoreum) and/or anal gland secretion at scent mounds in their territory year round. We investi­gated the hypothesis that during winter Eurasian beavers may intensify use of scent, in year round ice-free water systems, during the breeding season. This study showed that the median number of scent marks in 7 territories increased significant ly in the breeding (January-March 1996}, compared to the nonbreeding portion of winter (October- -Decemher 1995), which is consistent with our prediction. The median number of scent marks was significantly higher during February, compared to January and March. This may be due to females approaching or being in oestrous in our study area during February. Further studies are, however, needed to clarify how information in scent marks are coded and transmitted during the breeding season.
2

Abnormal incisor growth in Eurasian beaver

100%
Rosell F., Kile N. B.
Acta Theriologica
|
1998
|
tom 43
|
nr 3
An abnormally long incisor of an adult Eurasian beaver Castor fiber Linnaeus, 1758 is reported. The animal weighed about 20 kg and was in good condition when shot at 3 years of age. The tooth had grown at an angle in towards the beaver's left eye. Assuming the animal to be 35 months old and total tooth length to be 13.5 cm, then growth rate would have been 0.39 cm per month. This report indicates that beaver can survive despite abnormal growth of one incisor.
3

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

81%
Rosell F., Parker H., Steifetten O.
Acta Theriologica
|
2006
|
tom 51
|
nr 1
107-112
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.
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