Social Networks and the Formation and Maintenance of River Otter Groups

Abstract

Many studies have evaluated why male mammals form social groups; few however have investigated how these groups are formed and maintained. We observed behavioral interactions of 15 male river otters (Lontra canadensis) captured in Prince William Sound (PWS), Alaska, and held in captivity for 10 mo. Because the otters were captured in various areas and differed in age and relatedness, we were able to test how kinship and age influenced social interactions. We also explored how kinship, age and social interactions in captivity related to geographic spacing after the otters were released back in PWS. In 284 h of observations, the otters exhibited more positive than negative interactions. Social network models indicated that in the early stage of captivity, there were more links among individuals than in the late stage. In the late‐stage period, older animals that had higher testosterone levels exhibited increased social distance and lower information centrality (a network connectivity metric). Social distance was not related to genetic distance, nor did it relate directly to age, although both social distance and age were correlated with post‐release geographic distance. Thus, the formation of male groups in coastal river otters is largely influenced by familiarity and past experience, rather than kinship. The maintenance of groups, especially during the mating season, is a function of reproductive status and age, with older animals withdrawing from the social network during that time. What other phenotypic characters may contribute to the formation and maintenance of river otter groups merit future exploration.

A system for automatic recording of social behavior in a free-living wild house mouse population

“…Social networks have proved to reveal valuable information on the mechanisms and functions of group living in animal species [40][41][42][43], on the spread of diseases or behavioral innovations [44][45][46][47], as well as on dispersal [48]. For our study population, social network visualization revealed structuring in eleven or twelve social groups ( Fig.…”

Communication stations: cameras reveal river otter (Lontra canadensis) behavior and activity patterns at latrines

“…Although the animals were held in a captive facility rather than in a natural habit, there was some similarity in the behaviors observed in these studies. Rostain et al (2004) observed sniffing, grooming, wrestling, and scent marking, and Hansen et al (2009) observed grooming, wrestling, and mounting. The description of defecation provided by Rostain et al (2004) suggests defecation often is associated with a ''raise and flicking of the tail''.…”

“…It is important to note that solitary animals do not wrestle, and if we limit the observations to social behaviors (i.e., allogroom, wrestle, mount), wrestling comprised 44.4 % of social observations. Wrestling has been observed among captive, wild-caught otters (Hansen et al 2009); this behavior was specifically described as play by Rostain et al (2004), given the lack of aggression. Allogrooming, social behavior also observed in latrines, was observed for the same otters (Rostain et al 2004;Hansen et al 2009).…”

“…Previous studies have used ethograms to experimentally assess behavior of river otters captured in the wild and held in captivity (Rostain et al 2004;Hansen et al 2009). Although the animals were held in a captive facility rather than in a natural habit, there was some similarity in the behaviors observed in these studies.…”

“…Rostain et al (2004) and Hansen et al (2009) described the behaviors of captive river otters, but the extent to which these observations represent the behaviors of river otters in their native home range is unclear. Study of latrine behavior will contribute to better understanding of the function of latrine sites and strengthen the basis of research methods that depend on latrine sites to reach conclusions about river otter populations.…”