Use of space and movement patterns in monogamous adult Eurasian beavers (Castor fiber)

Abstract

Monogamy in mammals is characterized by reduced sexual dimorphism in morphology and behaviour. Ten pairs of Eurasian beaver Castor fiber were radio-tracked to test how far this concept can be applied to movement behaviour by focusing on sex-related effects on territory sizes and movement patterns. Within monogamous pairs, males and females occupied territories of almost equal size during the whole radio-tracking period and more specifically after parturition. The territories of pair members overlapped on average by 81.6 ± 14.0% SD while the territory overlap between residents and their neighbours was small to non-existent (on average between 0.5% and 2.2%). Males had larger 95% utility distributions than did females during the whole tracking period and after parturition. There was no significant difference between the 50% utility distributions for both sexes. Furthermore, males and females spent equal proportions of their time in territory border zones. There was a non-significant trend for males to move greater distances at night than females. Nightly distance moved correlated positively with territory size in females but not in males. Nightly distance moved correlated with neither body weight nor colony size. These results suggest that beavers show reduced sexual dimorphism in space use and movement patterns within adult monogamous pairs.

Resident beavers (Castor canadensis) do not discriminate between castoreum scent marks from simulated adult and subadult male intruders

“…We found no consistent sex differences in the observed responses. This is in line with the majority of other beaver studies (Hodgdon 1978;Svendsen and Huntsman 1988;Schulte 1998;Rosell and Bjørkøyli 2002;Thomsen 2002;Herr and Rosell 2004). Temeles (1994) pointed out that strangers generally pose a higher threat to a resident than neighbours do because, unlike neighbours, strangers do not yet own a territory or a mate and hence would be more likely to attempt to take over the resident's territory.…”

Territory and group sizes in Eurasian beavers (Castor fiber): echoes of settlement and reproduction?

“…Binoculars were used when needed. Given the range of behaviours displayed by the beavers in both study sites (see Nolet and Rosell 1994;Sharpe and Rosell 2003;Herr and Rosell 2004) it would appear that with due care, the effect of the spotlight, noise and the presence of the motorboat appeared to be minimal and we suggest that such disturbance is unlikely to have had an effect on the 8 beavers' behaviour. Indeed, on several occasions, animals approached the observers to within a distance of two metres and generally ignored the observers whilst doing so.…”

“…All group members also appear to participate in the provisioning of young before and just after their emergence from the natal den at c. two months of age (Wilsson 1971;Patenaude 1983;Müller-Schwarze and Sun 2003). Beaver populations vary markedly in both group size (Bradt 1938;Wilsson 1971;Rosell and Parker 1995) and territory size (Collins 1976;Heidecke 1986;Nolet and Rosell 1994;Herr and Rosell 2004), and are therefore an ideal species on which to examine the economics of defensibility within group territorial systems. Based on the rational outlined above, we might expect beavers to be maintaining some minimum economically defendable area that decreases in size with increasing habitat quality.…”

“…In that study, home range boundaries were determined by investigating changes in density of beaver signs along the river rather than more directly by radiotracking or mapping scent mounds. However, given that individual beavers are known to use and develop trails, ditches and feeding stations created by other colony members (Wilsson 1971; personal observation) and that individuals can spend a significant proportion of their activity near territory borders (Herr and Rosell 2004), we are tempted to conclude that variation in the density of beaver signs may be as much a product of heterogeneous use of preferred habitat within territories as any perceived spacing of colonies.…”

Short-term effects of tagging on activity and movement patterns of Eurasian beavers (Castor fiber)

“…Campbell et al 2013;Cross et al 2014;Tinnesand et al 2013). Since 1999, beavers have also been tagged with tracking devices such as VHF transmitters (Herr and Rosell 2004;Ranheim et al 2004), GPS systems (Steyaert et al 2015) and tri-axial accelerometers (Graf et al 2015). Consequently, information on age, sex, social status (dominant, subordinate; see Campbell et al 2012 for details), territory sizes, group sizes, reproduction and morphometric parameters (e.g.…”