Why Might Conflicts Over Group Movement Arise in Animal Societies - and How Could These Conflicts Be Resolved?

Introduction

Living in groups offers an evolutionary advantage to many animal species (Rannala and Brown, 1994). It allows for complex social interactions and coordinated behaviours that enhance survival across a diverse range of ecosystems (Aureli and Schino, 2019). This collectiveness is noticeable when studying the fluid and synchronised movements of groups, like starling murmuration (Goodenough et al., 2017) or the wave-like front of the wildebeest migration (figure 1) (Gueron and Levin, 1993). 

phenomenon across the animal kingdom; it reflects many characteristics we see in highly complex and charismatic human societies (West et al., 2007). It is a fundamental aspect of survival and evolutionary success. Group living provides numerous benefits, including enhanced foraging efficiency, protection from predators, and improved mating opportunities (Rubenstein, 1978); these advantages have prompted research across many scientific disciplines. Moreover, the study of collective movement (where groups synchronise their movement) looks at a combination of concepts from physics and biology to give insight into how simple rules dictating individual behaviour can give rise to complex formations like bird flocks (Dyer et al., 2008). Conflicts over group movement involve disagreements and competitive interactions arising from within animal groups; this occurs when members have differing interests, information, or objectives regarding how, when, or why they are going to move (Conradt and Roper, 2010). This discussion will investigate the causes of conflicts over group movement in animal societies, also analysing the range of strategies used to resolve these conflicts. It will highlight the interplay between individual preferences and collective decision-making. Firstly, the roots of within-group conflict will be addressed; this includes conflicting interests based on individual needs, conflicting information, and resource scarcity. Then, how animal societies resolve these issues will be investigated. This will look at mechanisms like despotic decisions, consensus (or democratic) decisions, and fission-fusion dynamics. Previous research in this field has documented the dynamics of group movement; it shows social hierarchies, environmental pressures, and individual behaviours all impact conflict and consensus in animal groups (Strandburg-Peshkin et al., 2015, Conradt and Roper, 2005, Wong et al., 2007, Kao et al., 2014). 

Causes Of Conflict In Group Movement

Conflicts over group movement in animal societies arise from multiple factors of individual needs, varying information, and resource availability (Petit and Bon, 2010). Individual needs in animal groups reflect the unique characteristics of each member, such as food preferences, safety, reproductive opportunities, and environmental conditions (West et al., 2007). Individuals can have different interests based on their existing affiliations, relatedness, size, sex, and age. The diverse needs among group members can lead to conflicting interests when the group must decide on a single course of action; this may include which territory to occupy or the direction of migration (Couzin et al., 2005). In a pride of lions, for example, adult lions may wish to pursue risky territories that are rich in prey; this, however, would conflict with the needs of mothers with cubs who would prefer a safer, more secluded area to avoid encounters with rival prides or lone males (Sunquist and Sunquist, 2002). Another example is, alpha wolves may prioritise routes similar to those of lions with prey abundance, whereas older individuals would find these routes challenging and want to conserve energy to avoid predators (Messier, 1985). In addition to conflicting personal needs, differences in the information received or perceived by group members may further complicate conflicts. Conflicting information looks at situations where group members receive or interpret environmental cues differently. This gives room for varying opinions on the best course of action (Sueur et al., 2011, Kerth et al., 2006). Sensory capabilities, experiences, or positions within the group can all affect how Individuals see threats or opportunities. One example is that, during migration, younger birds may rely on the social cues from more experienced and older birds for navigation (Woodrey, 2000). Alongside this, Kerth et al. in 2006 manipulated the information individual bats had about the suitability of new roosts (Figure 2). 

When essential supplies needed for the survival and well-being of the group, such as food, water, nesting sites, or mates, are limited, competition among group members is heightened. Often, individuals may act selfishly for their own benefit, at the expense of others in the group (Couzin et al., 2005, King et al., 2009, Bourke, 1999). During the dry season, elephants are known to gather around the few watering holes. This can lead to aggressive interactions, not just between group members within a herd, but also between different species that rely on the same water sources (Kinyanjui, 2020). These conflicts associated with individual needs, information differences, and limited resources, display the need for strategies within animal groups to manage and resolve conflicts; this is to ensure the survival and cohesiveness of the group. 

Resolution Of Conflicts

The resolution of conflicts over group movement is important for maintaining animal groups’ strength and ensuring there are still collective benefits within the society. When groups display a single dominant individual or a social hierarchy, there are usually despotic decisions that occur. These are decisions that the rest of the group must follow, regardless of individual needs or interests (King and Cowlishaw, 2009, Couzin et al., 2005, Biro et al., 2006). In these types of societies, the dominant individuals enforce their preferences on group movements. This can quickly resolve conflicts. Although it may suppress the needs of lower-ranking group members. Elephants have the matriarch make critical decisions on migration routes and watering holes (McComb et al., 2011, Lee and Moss, 2012). Similarly, in gorillas, the silverback makes the primary decisions about movements, feeding spots and resting of the group (Margulis et al., 2003). Whilst despotic decision-making is efficient and effective at resolving conflicts, consensus (or democratic) decision-making can lead to more balanced outcomes. Consensus decision-making in animal groups involves multiple members participating in the decision-making process. This leads to a choice that reflects an action preferred by the majority of the group (Conradt and Roper, 2005). This method is often used by groups that do not have a dominant individual. African wild dogs display consensus decisions whilst hunting. Group members engage in sneezing; the more sneezes, the more likely the group are to hunt (Walker et al., 2017). Additionally, when ants relocate their nests, workers investigate potential sites and lay pheromone trails. The higher the intensity of the pheromones, the higher the likelihood of the colony moving to that particular site (Cronin, 2013). Consensus decisions eliminate the negative effects of conflict by taking into account most individuals’ preferences and needs. Both despotic and consensus decision-making reduce conflict; however, fission-fusion societies offer an additional method for resolving conflict by allowing flexibility and individual decision-making within groups. Fission-fusion societies are characterised by a complex social structure, where the size and composition of the group change frequently. Individuals or sub-groups can split off (fission) and merge (fusion) in response to environmental and social factors (Aureli et al., 2008). Compositions of sub-groups are likely to depend on the same factors influencing individual interests: existing affiliations, relatedness, sex, size, and age. This dynamic way of living in groups allows individuals to take advantage of all appropriate opportunities selfishly, whilst still reaping the benefits of a group. Chimpanzees are well documented on their fission-fusion dynamics; sub-groups form based on factors like food availability and social preferences. During times where resources are not limited, larger groups come together to enhance protection and utilise cooperative foraging (Shibata et al., 2022, Lehmann and Boesch, 2004). Spider monkeys are also another example of an animal group displaying fission-fusion dynamics. They often split into smaller foraging groups during the day to reduce competition at food patches (Asensio et al., 2008). Fission-fusion is a highly adaptable strategy to alleviate conflict. It reflects an evolutionary flexibility in response to changing environmental conditions. These conflict resolution strategies are all social solutions, inferring great intelligence of animal societies; they provide them with evolutionary advantages, and could inspire innovative ways researchers could address environmental issues these animals face in the future.

Conclusion

This discussion has explored why conflicts over group movement arise in animal societies and has investigated strategies to resolve these conflicts. It has looked at the interaction between individual behaviours and group cohesion. Conflicts emerge from a variety of factors, of which some include differing individual needs, conflicting information, and competition over resources. Methods to resolve this are not discrete, as within documented evidence, there have been displayed varying levels of despotic and consensus decision making, as well as fission-fusion dynamics. Understanding these strategies can improve our knowledge of the evolutionary advantages that have led to social cohesion and resilience in group living. Many of these points discussed can be applied in a wider context. Starting with us, there are many cooperative strategies humans could learn and utilise within our societies. Also, studying the migration patterns of species like elephants and wildebeest can help mitigate human-wildlife conflict; it would allow for a better understanding of more effective conservation strategies like improved wildlife corridors (Riggio and Caro, 2017). Another example is looking at white-nose syndrome in bats (Hoyt et al., 2021). If there is a better understanding of group dynamics and movement patterns, strategies can be formed to reduce the spread of this disease. An especially important reason why it is important to understand collective movement and conflict is for captive breeding programs. Creating enclosures that allow for the natural group dynamics of species could reduce stress levels and promote better success in breeding attempts (Eisenberg and Kleiman, 1977). Future research may need to focus on how climate change affects these aforementioned group dynamics and movement patterns. Species are adjusting their migration patterns, including a worrying shift of most species towards the poles (Thuiller, 2004). Investigating conflicts over group movement and how these conflicts are resolved could provide us with the knowledge for effective conservation. As group movement is explored, further understanding of animals’ survival, adaptability, and resilience is being uncovered. This not only furthers the field of animal behaviour but may help in the face of future challenges.

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