Increased reproduction success, enhanced foraging and reduced predation risk are usually regarded as major factors favouring the evolution of social behaviour. Here we formulate a series of hypotheses relating sexual, ecological and behavioural factors to evaluate their explanatory value for 13 extant otter species, estimating the extent to which each factor contributes to the sociality of each species. We also compare individual behaviours within some of the species. Four otter species are obligatory social; four are obligatory solitary; five present both types of social organization. Social organizations of otter species are not related to their phylogenetic relationships. However, many otter species exhibit intra-species patterns of flexible social lifestyles. Both solitary and social otters adjust their social patterns in response chiefly to food availability, but also to habitat features and competition.Group living is more common when intraspecific competition is reduced or trophic resources replenish rapidly. Under these circumstances, group members often forage individually. When otters forage individually, they often switch prey type when they compete with other conspecifics. Social structures of otters fall into seven types: (1) family groups; (2) extended family groups, often with an alpha dominant pair; (3) highly social groups with helpers; (4) collective hunting groups; (5) solitary lifestyle; (6) unstable mixed-sex groups; and (7) single-sex bachelor groups. When an individual of a species with variable sociality adopts one type of sociality, this may be only temporary. Variations in social life are actually based on a series of events that induce individuals to make decisions taking ecological factors into account.Although ontogenetic factors can influence delayed dispersal of otters, social factors rather than ecological factors could play an important role in the formation of groups, and cohesiveness and kinship appear to be secondary effects of reduced dispersal more than primary causes for living in a group. Appropriate adjustment of group behaviour reduces the cost of sociality because individuals avoid social interactions when benefits are low but gather together when group living provides real advantages. Although any one model is unlikely to explicate all facets of sociality, evolution towards a social group results mainly from interactions within a family.
Otter species are known to fluctuate intraspecifically from a solitary lifestyle to group-living arrangements. By examining what is known about habitat use and foraging style in otters of 13 different species, based on 93 studied sites, we assessed (1) the relationship between social habits and preferred habitats, (2) the relationship between species and prey preferences, and (3) the effect of predator avoidance on their social organization in order to assess the socio-ecological factors influencing otters. Females remain the core of their social stability. We show the major influence of habitats and feeding strategies (i.e. socio-ecology) of otters. The different species of solitary otters most often inhabit linear environments, such as freshwater ecosystems or wave-exposed marine coasts, and their habitat is often subject to disturbances that fragment their functional continuity. Social otters are more often found in extensive habitats with high plant cover, regular food resources and in areas with large predators compared to solitary species. The maintenance of regular resources and the fact that the main trophic resources are replenished rapidly might be determining factors driving sociality. Group-living and bachelor congregations among otters can also respond to pressure from large predators. This suggests that foraging, habitat use and the presence of large predators may be the drivers of sociality in otters. We conclude that most otters have a greater social potential than previously assumed, which is confirmed by their various vocalizations recently described.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.