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

Abstract

Subadult intruding beavers (Castor spp.) could be expected to pose a higher threat than adults to territory holders because, unlike adults who usually own a territory, subadults need to acquire a territory and a mate to reproduce successfully. We tested the responses of territorial beavers (Castor canadensis Kuhl, 1820) to simulated intrusions by adult and subadult males. Territorial intrusion was simulated through scent playback experiments that exposed residents to castoreum from adult and subadult strangers simultaneously. We obtained responses from 13 resident beavers. Neither sniffing response nor physical or total responses differed between castoreum from adults and subadults. This was true for both sexes combined and separate. There was also no significant correlation between the mass of the scent donor and the response intensity. We found no evidence that territorial beavers responded differentially to castoreum scent marks from intruders of different ages. Either beavers consider all strange intruders as posing a high threat and hence do not treat them differentially or castoreum does not contain sufficient information to allow beavers to discriminate between age classes. We suggest that rather than directly assessing intruders by means of intrinsic information contained in the scent mark, beavers assess their competitors through scent matching.Résumé : L'intrusion des castors (Castor spp.) subadultes devrait poser une plus grande menace aux détenteurs de territoire que celle des adultes, parce que, contrairement aux adultes qui ont déjà un territoire, les subadultes doivent se trouver un territoire et s'accoupler afin d'assurer leur reproduction. Nous avons évalué les réactions de castors (Castor canadensis Kuhl, 1820) à des intrusions simulées de mâles adultes et subadultes. Nous avons simulé les intrusions territoriales par des expériences de récapitulation d'odeurs dans lesquelles les résidants sont exposés simultanément au castoréum d'étrangers adultes et subadultes. Nous avons enregistré les réactions de 13 résidants. Les réactions de reniflement, les réactions physiques et les réactions globales ne diffèrent pas en présence du castoréum des adultes et celui des subadultes. Cela vaut pour les deux sexes combinés ou considérés séparément. Il n'y a pas non plus de corrélation significative entre la masse du donneur d'odeur et l'intensité de la réaction. Il n'y a pas d'indication que les castors territoriaux réagissent différem-ment aux marques d'odeur de castoréum des intrus d'âges différents. Ou bien les castors considèrent tous les intrus comme posant une forte menace et ainsi ne les traitent pas de manière différentielle, ou bien le castoréum ne contient pas suffisamment d'information pour permettre aux castors de distinguer les classes d'âge. Nous croyons que les castors évaluent leurs compétiteurs par l'association des odeurs, plutôt que par une évaluation directe des intrus au moyen des informations intrinsèques contenues dans les marques d'odeur.[Traduit par la Rédaction]

Network analysis for species management in rivers networks: Application to the Loire River

“…It is also noteworthy that the observed and simulated ranges matched more closely for longdispersal distances (i.e., > 80 km for the beaver and > 3 km for the African clawed frog). For the Eurasian beaver, this dispersal distance is consistent with maximal empirical estimates of dispersal on the Loire River (Fustec et al, 2001), and is in the higher range of commonly measured dispersal distances in other waterways for this species (Saveljev et al, 2002) or for the Canadian beaver, Castor canadensis (Sun et al, 2000). For the African clawed frog, the colonization front has been estimated to shift at a speed of 1km/year (Fouquet and Measey, 2006).…”

Age Affects Over‐Marking of Opposite‐Sex Scent Marks in Meadow Voles, Microtus pennsylvanicus

“…The models for short‐lived animals did not explain the finding that 2–3, 5–7 and 10–12 mo old female voles did not differ in the amount of scent marks they depositing in an arena that was previously marked by an opposite‐sex conspecific. The frequency of scent marking in adult North American beavers was also not affected by their age (Herr et al. 2006).…”

“…Other studies demonstrated that scent marking was higher at or near puberty and then declined as individuals aged in gray mouse lemurs, honey badgers, and Mongolian gerbils (Arkin et al 2003;Begg et al 2003;Aujard & Né moz-Bertholet 2004;Cayetanot et al 2005). One study reported that the frequency of scent marking was not affected by age after North American beavers reached puberty (Herr et al 2006). Interestingly, many of the studies that examined the effects of age on scent marking focused on the behavior of individuals in areas that did not contain the marks of opposite-sex conspecifics.…”

“…2005). One study reported that the frequency of scent marking was not affected by age after North American beavers reached puberty (Herr et al. 2006).…”