Leadership in mixed-sex groups of muskoxen during the snow-free season

Ihl, Claudia; Bowyer, R. Terry

doi:10.1644/10-mamm-a-109.1

Cited by 30 publications

(20 citation statements)

References 43 publications

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“…This delayed growth pattern corresponds with observations that the majority of harem bulls in unharvested populations are between 6 and 10 yrs old [17], [18] (hereafter: ‘prime-age’ bulls), resulting in a relatively small number of prime-aged individuals being responsible for most of the breeding [17]. The group-living social structure of muskoxen has been shown to be important for both predator defense [15] and other activities such as foraging [19]. Although females will charge predators [20], mature bulls frequently play a lead role in defending the group [21].…”

Section: Introductionsupporting

confidence: 78%

Possible Secondary Population-Level Effects of Selective Harvest of Adult Male Muskoxen

Schmidt

Gorn

2013

PLoS ONE

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Selective harvest regimes are often focused on males resulting in skewed sex-ratios, and for many ungulate species this strategy is sustainable. However, muskoxen (Ovibos moschatus) are very social and mature bulls (≥4 years old), particularly prime-age bulls (6–10 years old), play important roles in predator defense and recruitment. A year-round social structure incorporating large males into mixed-sex groups could make this species more susceptible to the effects of selective harvest if population composition and sex-ratios influence overall survival and reproductive success. Using detailed data collected on the muskox population occupying the Seward Peninsula, Alaska during 2002–2012, we formulated the hypothesis that the selective harvest of mature bulls may be related to documented changes in population composition and growth rates in this species. In addition, we reviewed existing published information from two other populations in Alaska, the Cape Thompson and Northeastern populations, to compare population growth rates among the three areas under differential harvest rates relative to our hypothesis. We found that on the Seward Peninsula, mature bull:adult cow ratios declined 4–12%/year and short-yearling:adult cow ratios (i.e., recruitment) declined 8–9%/year in the most heavily harvested areas. Growth rates in all 3 populations decreased disproportionately after increases in the number of bulls harvested, and calf:cow ratios declined in the Northeastern population as harvest increased. While lack of appropriate data prevented us from excluding other potential causes such as density dependent effects and changes in predator densities, our results did align with our hypothesis, suggesting that in the interest of conservation, harvest of mature males should be restricted until causal factors can be more definitively identified. If confirmed by additional research, our findings would have important implications for harvest management and conservation of muskoxen and other ungulate species with similar life-histories.

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Section: Introductionsupporting

confidence: 78%

Possible Secondary Population-Level Effects of Selective Harvest of Adult Male Muskoxen

Schmidt

Gorn

2013

PLoS ONE

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“…Motives for individual leadership have been hypothesized to be related to mating strategies [Fichtel et al, ]. For example, during the breeding season, male muskoxen ( Ovibos moschatus ) play more active roles in group movement and aggressively entice females to follow them and stay in their harems compared with non‐breeding times of the year [Ihl & Bowyer, ]. Similarly, male spider monkeys ( Ateles geoffroyi ) frequently lead their groups to the borders of their home ranges to make contact with females of neighboring communities [Chapman, ].…”

Section: Discussionmentioning

confidence: 99%

Social rank versus affiliation: Which is more closely related to leadership of group movements in Tibetan macaques (Macaca thibetana)?

Wang

Sun

Sheeran

et al. 2016

American J Primatol

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Research on leadership is a critical step for understanding collective decision making. However, only 4 of the 22 extant macaque species have been examined for the impact of social rank and affiliation on the initiation of collective movement. It is far from clear whether such impact exists and, if so, how it works among other macaques. To answer these questions, we investigated free-ranging, Tibetan macaques' (Macaca thibetana) group departures from a provisioning area and tested two alternative hypotheses: personal versus distributed leadership. Personal leadership predicts that a single, highest ranking individual initiates the most group movements, whereas distributed leadership predicts that different members lead the group on different occasions and affiliative individuals have more initiations. We recorded how often and how successfully adults initiated group movements from a provisioning area into the forest, and related these variables to the duration of interindividual proximity and grooming time in the forest. All adults initiated group movements, but did so variably. Social rank was related neither to the number of successful initiations nor to the success ratio of initiations. By contrast, eigenvector centrality based on proximity relations was positively correlated with the number and ratio of successful initiations. Moreover, successful initiations were positively correlated with social grooming. Overall, Tibetan macaques showed a pattern of distributed leadership. Our study demonstrated the relationship between social affiliation and individual leadership in a macaque society. Am. J. Primatol. 78:816-824, 2016. © 2016 Wiley Periodicals, Inc.

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“…This would allow leadership to emerge passively as a consequence of simple interaction rules (Vicsek et al 1995;Couzin et al 2002). In other species these responses have been described to change with experience (Reebs 2000), motivation (Nakayama et al 2012b), age (McComb et al 2011, or sex (Ihl & Bowyer 2011).…”

Section: Discussionmentioning

confidence: 99%

Robustness of flight leadership relations in pigeons

et al. 2013

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Collective animal movements produce spectacular natural phenomena that arise from simple local interactions among group members. Flocks of homing pigeons, Columba livia, provide a useful model for the study of collective motion and decision making. During homing flights, flock members are forced to resolve potentially divergent navigational preferences in order to stay together and benefit from flying in a group. Recent work has demonstrated that some individuals consistently contribute more to the movement decisions of the flock than others do, thereby generating stable hierarchical leader/follower networks. Yet, what attributes of a flying pigeon reliably predict leadership remains an open question. We examined the flexibility of an individual's hierarchical leadership rank (i.e. its ordinal position when flock members are ranked according to the average time differences with which they lead or follow others) as a function of changes in its navigational knowledge. We manipulated already established hierarchical networks in three different flocks, by providing certain individuals with additional homing experience. We found that such training did not consistently lead to an increase in birds' leadership ranks, and that, in general, the nature of leader/follower interactions between trained and untrained birds remained unaffected. Thus, leadership hierarchies in pigeon flocks appear resistant to changes in the navigational knowledge of a subset of their members, at least when these changes are relatively small. We discuss the implications of our results in light of the potential benefits of structural stability in decision-making networks

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Leadership in mixed-sex groups of muskoxen during the snow-free season

Cited by 30 publications

References 43 publications

Possible Secondary Population-Level Effects of Selective Harvest of Adult Male Muskoxen

Possible Secondary Population-Level Effects of Selective Harvest of Adult Male Muskoxen

Social rank versus affiliation: Which is more closely related to leadership of group movements in Tibetan macaques (Macaca thibetana)?

Robustness of flight leadership relations in pigeons

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