Relative Importance of Social Status and Physiological Need in Determining Leadership in a Social Forager

Abstract

Group decisions on the timing of mutually exclusive activities pose a dilemma: monopolized decision-making by a single leader compromises the optimal timing of activities by the others, while independent decision-making by all group members undermines group coherence. Theory suggests that initiation of foraging should be determined by physiological demand in social foragers, thereby resolving the dilemma of group coordination. However, empirical support is scant, perhaps because intrinsic qualities predisposing individuals to leadership (social status, experience or personality), or their interactions with satiation level, have seldom been simultaneously considered. Here, we examine which females initiated foraging in eider (Somateria mollissima) brood-rearing coalitions, characterized by female dominance hierarchies and potentially large individual differences in energy requirements due to strenuous breeding effort. Several physiological and social factors, except for female breeding experience and boldness towards predators, explained foraging initiation. Initiators spent a larger proportion of time submerged during foraging bouts, had poorer body condition and smaller structural size, but they were also aggressive and occupied central positions. Initiation probability also declined with female group size as expected given random assignment of initiators. However, the relative importance of physiological predictors of leadership propensity (active foraging time, body condition, structural size) exceeded those of social predictors (aggressiveness, spatial position) by an order of magnitude. These results confirm recent theoretical work suggesting that ‘leading according to need’ is an evolutionary viable strategy regardless of group heterogeneity or underlying dominance structure.

Drivers of passive leadership in wild songbirds: species-level differences and spatio-temporally dependent intraspecific effects

“…Great tits are the largest and most dominant species in these flocks and regularly succeed over blue tits in competition for nest boxes (Dhondt and Eyckerman 1980;Minot and Perrins 1986;Kempenaers and Dhondt 1991). The fact that great tits are leading more often in this population is in line with existing theories of leading on the basis of dominance and energetic requirements (Rands et al 2006;Conradt et al 2009;Öst and Jaatinen 2013). Furthermore, more dominant individuals in this population are more vigilant during foraging, and there is a causal relationship between dominance and competence in choosing the safest foraging locations (Krams 1998), making great tits ideal leaders.…”

“…There are many possible ways to explain leading behavior, based on morphological, physiological, and behavioral characteristics ). One explanation is that leadership is driven by motivation, where individuals that are most in need of a particular resource are most likely to initiate behaviors to retrieve them (Furrer et al 2012;Öst and Jaatinen 2013;Hansen et al 2016). This is sometimes referred to as the "leading according to need" hypothesis (Conradt et al 2009;Sumpter 2009).…”

Group Coordination Processes and Determinants of Leadership in Red-fronted Lemurs (Eulemur rufifrons)

“…The balance can be tipped towards initiating by an increased interest in the reward. Hungry individuals or individuals with generally higher physiological needs, such as lactating females, have been observed to lead group movements more often (Fischhoff et al, 2007;Furrer, Kunc, & Manser, 2012;Krause, 1993;Nakayama, Johnstone, & Manica, 2012;Öst & Jaatinen, 2013). Furthermore, knowledge of an attractive resource can be a great incentive, as trained individuals lead naïve group mates to food resources in experimental studies in fish (Köhler, 1976;Reebs, 2000), sheep (Ovis aries) (Pillot et al, 2010) and meerkats .The scales can also be tipped by a reduction of the costs of initiating.…”

“…Furthermore, most of the studies on the effect of personality traits on leadership have been conducted in captivity, with personality tested while individuals were isolated from the group, although social context can strongly impact behaviour (Webster & Ward, 2011). The few studies conducted in the wild solely explored the connection between leadership and boldness and produced conflicting results (Berger, 1977;Öst & Jaatinen, 2013;Réale & Festa-Bianchet, 2003). Thus, studies in the wild that measure personality in a natural social context Red-fronted lemurs are medium-sized, cathemeral primates.…”

“…Apart from dominance rank, leadership can also be affected by age, sex, task-relevant knowledge or knowledge of the habitat, individual physiological needs, personality and social integration. Hungry individuals or individuals with generally higher physiological needs, such as lactating females, have been observed to lead group movements more often (Fischhoff et al, 2007;Furrer et al, 2012;Krause, 1993;Nakayama et al, 2012;Öst & Jaatinen, 2013). Adult individuals lead more often than subadults and in many species members of the philopatric sex lead group movements more often, presumably because they are more familiar with the habitat (Erhart & Overdorff, 1999;Leca et al, 2003;Pyritz, Kappeler, et al, 2011;Van Belle et al, 2013).…”