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Effect of affiliative and agonistic relationships on leadership behaviour in free-ranging dogs
Abstract
Consensus decisions about the nature and timing of group activities allow animals to maintain group cohesiveness, but also entail costs because individuals often differ with respect to their optimal activity budgets. Two mechanisms whereby animals reach a consensus include ‘consistent leadership’, in which a single dominant individual makes the decision, and ‘variable leadership’ in which several group members contribute to the decision outcome. Sharing of consensus decisions is expected to reduce consensus costs to most group members. Both patterns are thought to emerge from the complexity of social relationships of group members. We investigated the distribution of leadership during group departures in two packs of free-ranging dogs, Canis lupus familiaris, and tested how its distribution between individuals was affected by dominance rank-related affiliative and agonistic relationships. Although leadership was not entirely concentrated on a single group member, both packs had a limited number of habitual leaders. In the largest pack, the pattern of leadership changed from ‘variable’ to nearly ‘consistent’ after its size had shrunk. Habitual leaders were usually old and high-ranking individuals. However, high-ranking dogs that received affiliative submissions in greeting ceremonies were more likely to lead than dominant dogs receiving submissions only in agonistic contexts. During resting times, habitual followers associated more closely with habitual leaders than with other followers. These results suggest that in social species collective movements may arise from the effort of subordinates to maintain close proximity with specific valuable social partners.
... Domestic dogs are a good model to investigate the hormonal correlates of social behaviours and social bonds since they form affective and enduring bonds both with conspecifics [14,23,84] and humans [69,83]. An increasing body of data supports the role of the oxytocinergic system in the modulation of dog-human social interactions ( [47]; for a review see [17]). ...
... Behavioural synchrony is the ability of agents to efficiently coordinate their actions [30]. Various studies confirm that behavioural synchronization is linked to affiliation in both humans and animals (in humans: [22,44,54]; in bottlenose dolphins: [72]; in black railed godwit: [36]; in free-ranging dogs: [14]). Recent studies showed that dogs synchronize their location and behaviours (walking or staying still) with those of their owners both in an indoor room [28] and in an outdoor space [29]. ...
... The behaviours considered to be indicators of stress and discomfort ("self-directed signals") were: yawning [11], body/head shaking [11] and lips licking [11,12]. Gaze aversion (also referred to as "avoiding eye contact") i.e. looking away from the owner, in response to the owners look at them was also measured as it has been considered a submissive behaviour when observed between conspecifics [14,76]. ...
The relationship between dogs and their owners is characterized by an affective and enduring bond. It has been suggested that oxytocin might be the underlying mechanism driving this relationship, however evidence is mixed. In this study we tested whether intranasally administered oxytocin (compared to saline) would influence dogs’ behavioural synchrony and shared attention towards their owners. Each individuals’ pre and post administration oxytocin concentrations (measured in urine) were included in the analyses. Urinary oxytocin concentrations after administrations were positively associated with dogs’ duration of social proximity and looking behaviours towards their owners supporting the role of oxytocin in modulating dogs’ human-directed social behaviours.
... The relationship between dominance rank (position in a hierarchy) and related behaviours has been investigated in many species (for example; elephants (Loxodonta africana and Elephas maximus) [16], bottlenose dolphins (Tursiops truncatus) [17], chimpanzees (Pan troglodytes) [18][19][20][21], dogs (Canis familiaris) [15,[22][23][24][25][26][27], hyena (Crocuta crocuta) [28], gorilla (Gorilla gorilla) [29][30][31], female zebra finches (Taeniopygia guttata) [32], great tits (Parus major) [33], mountain chickadees (Poecile gambeli) [34], starlings (Sturnus vulgaris) [35], barnacle geese (Branta leucopsis) [36], male rainbowfish (Melanotaenia duboulayi) [37], and brown trout (Salmo trutta) [38]). However, far fewer studies have attempted to determine whether natural variation in personality can predict social status [27,37,39]. ...
... Several studies have already utilised owner questionnaires to determine the dominance status of dogs in multi-dog households [26,27,41,42]. When dominance is considered as an attribute of dyadic encounters, and not a property of individuals, the perception of each dogs' status can be based on consistent patterns in the outcome of interactions within dyads [23,43]. For example, in multi-dog households, dogs perceived as dominant by the owner have priority access to certain resources (for example, resting places and food rewards), undertake specific tasks (defend the group during perceived threats and lead other dog/s during walks), display dominance (win fights and over mark), have characteristic personality traits (measured using single item statements), and are usually older than subordinates [26]. ...
... The more knowledgeable individual can convey a true advantage to other group members. Dominance follows almost automatically from this asymmetrical arrangement [23,52]. The likelihood of formal dominance and/or leadership can be expected to increase with age for this reason, since aged animals have more experience if the environment is stable across generations. ...
Social dominance is an important and widely used concept, however, different interpretations have led to ambiguity in the scientific literature and in popular science. Even though in ethology dominance is an attribute of dyadic encounters, and not a characteristic of the individual, ‘dominance’ has often been referred to as a personality trait in animals. Since few studies have specifically examined the link between personality traits and dominance status, we investigated this in dogs living in multi-dog households using a questionnaire, which required owners to specify whether the dog had a dominant or submissive status, and comprised items of both the features of the individual (i.e. personality traits) and previous social experience (interactions with group members and strangers). Four distinct personality factors emerged from 23 behavioural items by principal component analysis, labelled as assertiveness, trainability, intraspecific aggression and independence. Binomial logistic regression was used to examine how the demographic information of the dogs and the personality factors predicted the owner’s estimate of the dog’ status as dominant or submissive. The personality factor assertiveness accounted for 34% of the variance in dominance status, trainability 5% and dog age contributed 4%. Dogs perceived as dominant scored more highly on the factors assertiveness and trainability, which can help explain why ‘dominance’ has often been suggested to be a personality trait, rather than a dyad-specific social status according to different traditions in behavioural research. Similar to the ‘social dominance’ trait in humans, owner ascribed dominance showed a quadratic trajectory in cross-sectional mean change across the lifespan, increasing during adulthood and then maintaining high levels until old age. Overall, our study proposes a multifactorial background of dominance relationships in pet dogs, suggesting that not only previous experience of social interactions between individuals but also age and personality traits influence owner perceived dominance status in multi-dog households.
... Age can also be expected to affect social behaviors in dogs ( Howse et al., 2018;Rosado et al., 2012). Social rank is likely to change with age ( Bonanni et al., 2010Bonanni et al., , 2017Cafazzo et al., 2010;Pal et al., 1998), which might affect at least some social behaviors like observational learning (Pongrácz, 2014;Pongrácz et al., 2008) and leadership ( Ákos et al., 2014). ...
... Previous work has reported that aging and in particular pathological aging could affect social responsiveness in dogs ( Howse et al., 2018;Rosado et al., 2012), although it is difficult to separate these observations from a general decline in activity. In addition, age also correlates with social rank in canines ( Bonanni et al., 2010Bonanni et al., , 2017Pal et al., 1998). Social rank by itself has been shown to affect some social behaviors, for example, social learning across several species (Nicol & Pope, 1999;Pongrácz, 2014), but also active versus passive approach to social interaction ( Schenkel, 1967), with dogs of higher rank being often the recipients rather than initiators of ritualized greetings ( Bonanni et al., 2010). ...
... In addition, age also correlates with social rank in canines ( Bonanni et al., 2010Bonanni et al., , 2017Pal et al., 1998). Social rank by itself has been shown to affect some social behaviors, for example, social learning across several species (Nicol & Pope, 1999;Pongrácz, 2014), but also active versus passive approach to social interaction ( Schenkel, 1967), with dogs of higher rank being often the recipients rather than initiators of ritualized greetings ( Bonanni et al., 2010). It was also observed that younger dogs initiate more muzzle contacts ( Howse et al., 2018) further strengthening the notion that higher age and/or rank are associated with being more passive in social interactions. ...
Introduction:
The aim of this study was to explore spontaneous social interactions between dyads of unfamiliar adult dogs. Although intraspecific encounters are frequent events in the life of pet dogs, the factors that might influence encounters, such as sex, dyad composition, reproductive status, age, and state of cohabitation (keeping the dogs singly or in groups), remained unexplored.
Methods:
In this study, we assigned unfamiliar, non-aggressive dogs to three types of dyads defined by sex and size. We observed their unrestrained, spontaneous behaviors in an unfamiliar dog park, where only the two dogs, the owners, and experimenter were present.
Results:
We found that the dogs, on average, spent only 17% of the time (less than 1 min) in proximity. Sex, dyad composition, reproductive status, and age influenced different aspects of the interactions in dyads. Female dogs were more likely to initiate the first contact in their dyad but later approached the partner less frequently, were less likely to move apart, and displayed less scent marking. Following and moving apart were more frequent in male-male interactions. Neutered dogs spent more time following the other dog and sniffed other dogs more frequently. The time companion dogs spent in proximity and number of approaches decreased with age.
Conclusion:
The study provides guidance for dog owners about the outcomes of intraspecific encounters based on the dog's age, sex, and reproductive status, as well as the sex of the interacting partner.
... Knowledge of the local environment is thought to be a potentially important leadership attribute that may encourage individuals to follow leaders (Bonanni, Cafazzo, Valsecchi, & Natoli, 2010;Lewis, Wartzok, & Heithaus, 2013;McComb et al., 2011;Seeley, 2010;Stroeymeyt, Franks, & Giurfa, 2011;Sueur & Petit, 2008b;Swaney, Kendal, Capon, Brown, & Laland, 2001). Theoretical models predict that variation in knowledge improves efficient decision making and overall group performance (Couzin, Krause, Franks, & Levin, 2005). ...
... Leaders are typically the more experienced (generally older) individuals in a group (Bonanni et al., 2010;Brent et al., 2015;Elgar, 2016;Maransky & Bildstein, 2001;Seeley, 2010) suggesting that 'reliable', established experience may be important for maintaining a leadership role. Thus, an individual's knowledge of the environment must be considered separately from its experience and/or 'reputation', which can be ascertained through field experiments that both track leadership experience and manipulate individual knowledge. ...
... When individuals of P. affinis were unfamiliar with their environment, they followed informed larvae irrespective of whether they were previously acquainted. This result is not consistent with patterns observed in many other group-living societies, where established leaders are recognized as older or more experienced and their leadership is likely to be maintained because it is reliable (Bonanni et al., 2010;Brent et al., 2015;Maransky & Bildstein, 2001). While leadership in P. affinis aggregations is similarly consensual and individuals within the group may be kin, knowledge that could benefit all individuals in the group has a greater influence on choice of leaders than social familiarity. ...
Leaders in democratic societies emerge by dint of followers, but the traits that determine who those leaders are, and the underlying mechanisms maintaining leadership, remain largely unknown. Models suggest a link between leadership and knowledge is important for group decisions, with more informed individuals guiding the uninformed majority. In larval aggregations of the Australian steel blue sawfly, Perga affinis, some individuals consistently lead the group on foraging trips more frequently than expected by chance. We manipulated both social group composition and the environment to determine in what circumstances leaders were retained within the aggregation. Leaders only resumed guiding group movement when they were familiar with (i.e. had knowledge of) the environment, a role they undertook even among unknown conspecifics. However, knowledgeable followers did not lead naïve aggregations. These results emphasize the importance of knowledge and prior experience in maintaining the leadership role within larval aggregations.
... Two other studies have observed synchronization when two dogs were running together: they influenced each other and the two synchronized their pace of running 24,25 . It has also been recently shown that dogs follow their conspecifics' direction of walking during group departures 26 . The dogs were more synchronized (both location and activity synchrony) with their favourite social partners 26 . ...
... It has also been recently shown that dogs follow their conspecifics' direction of walking during group departures 26 . The dogs were more synchronized (both location and activity synchrony) with their favourite social partners 26 . The authors proposed that it may reflect rules evolved for adaptation to the environment before domestication. ...
... The authors proposed that it may reflect rules evolved for adaptation to the environment before domestication. As dogs evolved from wolves 27 , which usually follow their more experienced parents, dogs may be predisposed to follow their favourite partners and/or the more experienced individuals in their group 26 . ...
Behavioural synchronization is widespread among living beings, including humans. Pairs of humans synchronize their behaviour in various situations, such as walking together. Affiliation between dyadic partners is known to promote behavioral synchronization. Surprisingly, however, interspecific synchronization has recived little scientific investigation. Dogs are sensitive to human cues, and share strong affiliative bonds with their owners. We thus investigated whether, when allowed to move freely in an enclosed unfamiliar space, dogs synchronize their behaviour with that of their owners'. We found that dogs visibly synchronized their location with their owner (staying in close proximity and moving to the same area), as well as their activity and temporal changes in activity (moving when their owner moved, standing still when their owner stood still, and gazing in the same direction as their owner). The present study demonstrates that owners act as attractors for their dogs in an indoor space, as mothers do for their children.
... Specifically, gray wolves (Canis lupus) and domestic dogs (Canis lupus familiaris) were our model species since they diverged relatively recently; yet, their social organization and feeding ecologies are considerably different. Domestic dogs originally derive from ancestral gray wolves (Lindbladtoh et al. 2005;Frantz et al. 2016), and both species are highly social, forming stable social bonds with group members over multiple years (Harrington and Mech 1982;Bonanni et al. 2010). Wolves typically live in monogamous family units consisting of a breeding pair and the offspring from previous years (Mech and Boitani 2003). ...
... These findings are in line with long-term wild wolf research by Mech (1999), who found that regardless of rank, each wolf is able to defend their food source. Furthermore, in a free-ranging dog population, Cafazzo et al. (2010) found that around food, adult high-ranking dogs showed most aggression to middle-ranking dogs and relatively little to low-ranking individuals. Overall, this suggests that rank is a particularly relevant factor in mediating food tolerance in dogs, but potentially less so in wolves. ...
... Our primary prediction was that, because social relationships are important in both species (Harrington and Mech 1982;Bonanni et al. 2010), dyads with a stronger social bond should show more tolerance around food. In addition, we expected that in dogs at least, a higher difference in rank would promote more tolerance around the food than those dyads close in rank (Cafazzo et al. 2010). ...
Food sharing is relatively widespread across the animal kingdom, but research into the socio-ecological factors affecting this activity has predominantly focused on primates. These studies do suggest though that food tolerance is linked to the social relationship with potential partners. Therefore, the current study aimed to assess the social factors which influence food tolerance in two canids: wolves and dogs. We presented wolves and dogs with two paradigms: dyadic tolerance tests and group carcass feedings. In the dyadic setting, the affiliative relationship with a partner was the most important factor, with a strong bond promoting more sharing in both species. In the group setting, however, rank was the primary factor determining feeding behavior. Although the dominant individuals of both species defended the carcass more than subordinates, in the dogs, the subordinates mostly stayed away from the resource and the most dominant individual monopolized the food. In the wolves, the subordinates spent as much time as dominant individuals in proximity to, and feeding from, the carcass. Furthermore, subordinate wolves were more able to use persistence strategies than the dogs were. Feeding interactions in the wolves, but not dogs, were also modulated by whether the carcass was on the ground or hanging from a tree. Overall, the social relationship with a partner is important in food distribution in wolves and dogs, but the precise effects are dependent on species and feeding context. We consider how the different socio-ecologies of the two species may be linked to these findings.
Significance statement
Despite the fact that food sharing is relatively widespread in the animal kingdom, the specific factors underlying whether an animal will share with a specific individual are little understood. When it comes to decisions about food sharing in wolves and dogs, friendship is the deciding factor if it is just two of you, but in a bigger group rank position decides your access to the spoils. What is more, it seems that rank positioning is even more important in dogs than wolves as dominant dogs keep the food for themselves while each wolf pack member has a chance to eat. This is the first evidence that the importance of the social relationship in food sharing is dependent on the feeding context in canids.
Electronic supplementary material
The online version of this article (doi:10.1007/s00265-017-2339-8) contains supplementary material, which is available to authorized users.
... In a study of leadership behavior in 3 wild wolf packs in Yellowstone National Park, Peterson et al. (2002) found that breeding males and females led the majority of their pack's travels and activities. In another study of two groups of dog in the same Italian feral dog population studied by Cafazzo et al., (2010), Bonanni et al., (2010a) found that dogs who received affiliative submission were more likely to lead and be followed by others than were dogs that received more agonistic submission. As Charlie entered the group, other dogs would often crowd around her and lick her muzzle. ...
... They take the lead during hunts, travel, and territorial defense, but the cooperation of other pack members is crucial for successful group hunts and pup care (Mech, 1999;Packard, 2003;Peterson et al., 2002). Bonanni et al. (2010a;2010b) found that groups of feral dogs compete for territories and food resources and these groups tended to follow the lead of only a few high-ranking individuals in the group. Over the course of domestication, dogs came to rely primarily on humans for food, but it is likely that social relationships with other dogs remained (and still remains) important for survival and reproductive success for many feral and semi-feral dogs (Smuts, 2010 ...
... Many young and inexperienced animals would likely starve or get killed without the assistance and tolerance of older animals. This would explain the patterns that we find over and over in dogs and wolves of younger animals literally "kissing up" to older animals (Bonanni et al., 2010a;2010b;Cafazzo et al., 2010;Lockwood, 1979;Mech, 1970;Schenkel, 1967;van Hoof & Wensing, 1987;Zimen 1978). This general rule of affiliation and deference towards older dogs seems to explain the existence and the nature of dominance/submission in dogs. ...
This dissertation examines dominance, play, affiliation and social preferences in a group of 24 domestic dogs that socialize regularly at a dog daycare facility. In Chapter 1, we analyzed the frequencies and directions of aggression, submission, and dominance displays. The distribution of submission and aggression resulted in a significantly linear hierarchy in the group, and submission was the best indicator of dominance relationships. Age was significantly correlated with dominance rank with older dogs out-ranking younger dogs. Muzzle-licking met most of the criteria for a formal display of submission in dogs, but was displayed in only 18% of relationships. Only 29% of all possible pairs had discernable dominance relationships.
In Chapter 2, we examined the relationship between agonism, play and affiliation. Twenty-two percent of all possible pairs had known dominance relationships and also exchanged friendly behaviors (formal relationships), 21% of all pairs exchanged friendly behavior but had no discernable dominance relationship (egalitarian relationships), 50% of all pairs were never observed exchanging friendly or agonistic behaviors (non-interactive relationships), and 7% of pairs had known dominance relationships but did not exchange friendly behavior (agonistic relationships). Friendly behavior was much more frequent than agonistic behavior, and we found a complex association between the two. Egalitarian relationships as well as play and affiliation were more common between males and females than between same-sex pairs. Relationship affinity (an index combining play and affiliation) did not significantly differ in formal versus egalitarian relationships, but the latter were significantly more equitable and playful.
In Chapter 3, we investigated patterns of interventions during dyadic play. Interveners directed either (1) a playful behavior at one of the dogs (the target), (2) an affiliative behavior at the target, or rarely, (3) an aggressive behavior at the target. Individual rank did not influence individual interventions rates. Rank relationships between interveners, targets and non-targets did not influence playful interventions. Dogs tended to target higher-ranking dogs during affiliative interventions and target lower-ranking dogs during aggressive interventions, but the latter were too infrequent to apply statistical analyses. Dogs tended to target their preferred partners (“friends”) during play more than support them.
... Many group-living mammals defend group territories (e.g. meerkats, Suricata suricatta [1]; free-ranging dogs, Canis lupus familiarus [2]; lions, Panthera leo [3]; ringtailed lemurs, Lemur catta [4]; white-faced capuchins, Cebus capucinus [5]; vervet monkeys Chlorocebus pygerythrus [6]; red-tailed monkeys, Cercopithecus ascanius [7]; chimpanzees, Pan troglodytes [8,9]; other primates [10,11]). These territories provide benefits to group members, including resources such as food, water and shelter [12][13][14][15], and safety from intergroup attacks [16]. ...
... Third, the 'group size paradox' contends that collective action should break down more readily in larger groups due to increased opportunity for free-riders and decreased benefits for individuals [18]. Studies of individual species [2,5,23] and comparative analysis [11] indicate that cooperative investment decreases with increase in group size. Because chimpanzees are more likely to initiate boundary patrols when travelling in larger parties [47], in communities with fewer males, a larger proportion of males may be required to mount an effective patrol. ...
Group territory defence poses a collective action problem: individuals can free-ride, benefiting without paying the costs. Individual heterogeneity has been proposed to solve such problems, as individuals high in reproductive success, rank, fighting ability or motivation may benefit from defending territories even if others free-ride. To test this hypothesis, we analysed 30 years of data from chimpanzees ( Pan troglodytes ) in the Kasekela community, Gombe National Park, Tanzania (1978–2007). We examined the extent to which individual participation in patrols varied according to correlates of reproductive success (mating rate, rank, age), fighting ability (hunting), motivation (scores from personality ratings), costs of defecting (the number of adult males in the community) and gregariousness (sighting frequency). By contrast to expectations from collective action theory, males participated in patrols at consistently high rates (mean ± s.d. = 74.5 ± 11.1% of patrols, n = 23 males). The best predictors of patrol participation were sighting frequency, age and hunting participation. Current and former alpha males did not participate at a higher rate than males that never achieved alpha status. These findings suggest that the temptation to free-ride is low, and that a mutualistic mechanism such as group augmentation may better explain individual participation in group territorial behaviour.
This article is part of the theme issue ‘Intergroup conflict across taxa’.
... Regarding dominance, we predicted that in both dogs and wolves, subordinate individuals would be more stressed and actively look for social support more from the dominant partner than vice versa (Essler et al., 2017;Mazzini et al., 2013;McLeod, Moger, Ryon, Gadbois, & Fentress, 1996). Thus, subordinates should follow and seek proximity with their dominant partners ( Akos, Beck, Nagy, Vicsek, & Kubinyi, 2014;Bonanni, Cafazzo, et al., 2010;Peterson et al., 2002) and carry out more social referencing (i.e. by looking longer and alternating the gaze more often between novel stimuli and their partner) towards the dominant partner than vice versa (assuming that the more dominant partner is seen as better informed, Peterson et al., 2002;Bonanni, Cafazzo, et al., 2010). However, considering that dogs might form more despotic social groups than wolves (Range, Ritter, & Vir anyi, 2015), we also expected subordinate dogs to be generally more stressed than subordinate wolves. ...
... Regarding dominance, we predicted that in both dogs and wolves, subordinate individuals would be more stressed and actively look for social support more from the dominant partner than vice versa (Essler et al., 2017;Mazzini et al., 2013;McLeod, Moger, Ryon, Gadbois, & Fentress, 1996). Thus, subordinates should follow and seek proximity with their dominant partners ( Akos, Beck, Nagy, Vicsek, & Kubinyi, 2014;Bonanni, Cafazzo, et al., 2010;Peterson et al., 2002) and carry out more social referencing (i.e. by looking longer and alternating the gaze more often between novel stimuli and their partner) towards the dominant partner than vice versa (assuming that the more dominant partner is seen as better informed, Peterson et al., 2002;Bonanni, Cafazzo, et al., 2010). However, considering that dogs might form more despotic social groups than wolves (Range, Ritter, & Vir anyi, 2015), we also expected subordinate dogs to be generally more stressed than subordinate wolves. ...
Social relationships can be described by a series of components, all having putatively different functional roles in the lives of humans and other social species. For instance, certain relationship characteristics can strongly influence how individuals deal with stress, ultimately influencing their fitness. However, species vary highly in regard to which components of their relationships influence stress buffering and how. Variation in species’ social organization could explain such differences. Comparing closely related species subjected to different ecological constraints can be especially informative when investigating this hypothesis. Here, we compared whether relationship quality differently influences how grey wolves, Canis lupus, and domestic dogs, C. l. familiaris, react to a series of stressors. We tested the role of various relationship components (i.e. two affiliation indices and two aspects of dominance rank) in mediating stress reactivity, social support seeking and social referencing in dyads of pack-living animals. To do so, we conducted systematic long-term observations of the social interactions between animals and an experimental test battery exposing animal dyads to a series of stressors (e.g. novel environment exploration, separation from and consequent reunion with the partner, exposure to a novel object and a threatening human). We found that a large rank distance and high affiliation index based on the number of friendly behaviours exchanged during everyday life (but not dominance status or the affiliation index based on the time spent in body contact) were related to a dampened stress response in both species. These results suggest a functional role of these two relationship components in the stress buffering of both dogs and wolves.
... In several studies, the classification of an animal as follower or joiner was essential for the establishment of initiation success criteria, e.g. by formulated maximum values for the angle between the moving direction of the following animal and the trajectory of the initiator's movement (e.g. Bonanni et al., 2010). ...
... Initiation success criteria Bonanni et al. (2010) ≥2 animals walking in the same direction < 10 m distant to the initiator Erhart and Overdorff (1999) ≥50% of the group following within 10 min Jacobs et al. (2008) ≥1 animal following for at least 5 m within 15 min Entire group follows for at least 10 m leaving the sleeping site Leca et al. (2003) ≥3 animals following within 15 min and reaching the initiator's goal area Pyritz et al. (2011) Followers arriving within a 6 m radius of the initiator ≥10 min after termination of his movement Stueckle and Zinner (2008) ≥5 followers within 15 min Sueur et al. (2009) ≥1 joiner within 5 min Trillmich et al. (2004) ≥1 follower A.S. Cook, et al. The Leadership Quarterly xxx (xxxx) xxx-xxx of objective measures of individual movement behavior to compile a group level measure of coordination (King et al., 2015). ...
Both Shared Leadership Theory and evolutionary theories of leadership emphasize the role of team-level patterns of influence on team or group success. Yet, most of the empirical work on the effects of shared leadership assesses the concept through patterns of subjective perceptions of leadership and behavior. Although these studies give us important insights, subjective perceptions of leadership are prone to biases. In this paper, we draw on evolutionary theories of the development of leadership in groups and argue that group-level patterns of observable behavior have a direct effect on team outcomes above and beyond patterns of leadership and behavior perceptions. On the basis of a brief review of ethological assessment methods of leadership in animal groups, we derive implications for team leadership research methods to test hypotheses on team-level influence patterns and performance. Emphasizing the role of influence in terms of interpersonal behavior we formulate implications for the assessment and analysis of verbal and nonverbal behavior in teams. Finally, we discuss how technological advances may be utilized to promote behavioral observations in team leadership research.
... www.nature.com/scientificreports/ and conspecifics 10,21,22 . As such, it is difficult to compare whether the types of relationships established by dogs with humans and conspecifics are in fact different. ...
... At the same time, research on dog-dog relationships has focused on other relationship components, such as affiliation and dominance, with results showing that dogs can form strong affiliative bonds with each other that can affect multiple aspects of their life, such as mating preferences 16 , food sharing 17 , cooperation 18 , and so on. These two lines of research focus on different components and different functions of relationships, and the only aspect they share is that both have demonstrated that dogs form differential relationships with both humans 19,20 and conspecifics 10,21,22 . As such, it is difficult to compare whether the types of relationships established by dogs with humans and conspecifics are in fact different. ...
Most dogs worldwide are free-ranging animals that form relationships mainly with conspecifics, yet research has focused mainly on the dog-human bond, leading to the hypothesis that dogs evolved specific abilities to form a unique relationship with humans. Although widespread, this hypothesis has not, as yet, been tested. Here we compared the relationships pet dogs form with their owner and with other dogs living in the same household. Using a bottom-up approach, we analyzed dogs’ behavior in a test battery with both dog and human partners. Results revealed that pet dogs’ relationships are characterized by three components (i.e. reference, affiliation and stress). A comparison between dogs’ intra- and inter-specific relationships found that overall dogs refer more to their owner, but also that some dogs form stronger affiliative bonds with conspecifics than with their owner. Moreover, we tested how different partners could help dogs cope with a stressful situation. We found that the type of relationship, rather than the partner species, predicts how dogs react to a social threat. Our results suggest that dogs can form relationships of comparable qualities with both humans and other dogs, and that these relationships vary along multiple components across different partners.
... group) behaviors of social organisms ranging from humans [9] to hyaena [29] to hymenoptera [25]. It potentiates complex patterns of cooperation and conflict (e.g., lions [15], hyaenas [4], meerkat [23], chimpanzees [10], humans [11]), organizes group movements (fish [7], humans [9], dogs [3]), and may prevent free-riding [17,24]. ...
... Let V be a [n×t−1]-sized matrix measuring individual velocity over time, on time series dataset D. For an individual 3 We use '•' to denote placeholders, e.g. for parameters. ...
Leadership is an important aspect of social organization that affects the processes of group formation, coordination, and decision-making in human societies, as well as in the social system of many other animal species. The ability to identify leaders based on their behavior and the subsequent reactions of others opens opportunities to explore how group decisions are made. Understanding who exerts influence provides key insights into the structure of social organizations. In this paper, we propose a simple yet powerful leadership inference framework extracting group coordination periods and determining leadership based on the activity of individuals within a group. We are able to not only identify a leader or leaders but also classify the type of leadership model that is consistent with observed patterns of group decision-making. The framework performs well in differentiating a variety of leadership models (e.g. dictatorship, linear hierarchy, or local influence). We propose five simple features that can be used to categorize characteristics of each leadership model, and thus make model classification possible. The proposed approach automatically (1) identifies periods of coordinated group activity, (2) determines the identities of leaders, and (3) classifies the likely mechanism by which the group coordination occurred. We demonstrate our framework on both simulated and real-world data: GPS tracks of a baboon troop and video-tracking of fish schools, as well as stock market closing price data of the NASDAQ index. The results of our leadership model are consistent with ground-truthed biological data and the framework finds many known events in financial data which are not otherwise reflected in the aggregate NASDAQ index. Our approach is easily generalizable to any coordinated activity data from interacting entities.
... However, this explanation is unlikely, as proximity networks were similar for W and AW1, but social interactions were still more common in admixed dyads. Moreover, as limited space may be a source of stress, a liative interactions might have been more frequent in wolves than in hybrids as an effective way of reducing stress levels in the group (see Aureli & Smucny, 2000; Bonanni et al., 2010). Furthermore, the lack of social interactions in AW2 could have depended on the fact that group members were not all siblings (in contrast to AW1) but came from different litters (although this was also the case for W), and were moved in the new enclosure only shortly before our observations. ...
Extensive introgression of genes from domesticated taxa may be a serious threat for the genomic integrity and adaptability of wild populations. Grey wolves ( Canis lupus ) are especially vulnerable to this phenomenon, but there are no studies yet assessing the potential behavioural effects of dog-introgression in wolves. In this study, we conducted a first systematic comparison of admixed (N = 11) and non-admixed wolves (N = 14) in captivity, focusing on their reaction to unfamiliar humans and novel objects, and the cohesiveness of their social groups. When exposed to unfamiliar humans in the experimental task, wolves were more vigilant, fearful and aggressive than admixed wolves, and less likely to approach humans, but also more likely to spend time in human proximity. When exposed to novel objects, wolves were more aggressive than admixed wolves, less likely to spend time in object proximity, and more likely to interact with objects, but also less vigilant and as fearful as admixed wolves. Finally, social networks were mostly more cohesive in wolves than admixed wolves. Overall, our study suggests that dog admixture may lead to important behavioural changes in wolves, with possible implications for conservation strategies.
... Groups across a broad range of taxa are structured by dominance rank despite large variations in cognitive skills. Dominance hierarchies are found in primates [9,10], social carnivores [11,12], ungulates [13,14], birds [15][16][17][18], fish [19], and even crustaceans [20,21]. These group-level social structures form and stabilize on the basis of perceptions and actions necessarily made at the individual level [22]. ...
Dominance hierarchies are group-level properties that emerge from the aggressions of individuals. Although individuals can gain critical benefits from their position in a hierarchy, we do not understand how real-world hierarchies form, or what signals and decision-rules individuals use to construct and maintain them in the absence of simple cues. A study of aggression in two groups of captive monk parakeets (Myiopsitta monachus) found a transition to large-scale ordered aggression occurred in newly-formed groups after one week, with individuals thereafter preferring to direct aggression against those nearby in rank. We describe two mechanisms by which individuals may determine rank order: inference based on overall levels of aggression, or on subsets of the aggression network. Both pathways were predictive of individual decisions to aggress. Based on these results, we present a new theory, of a feedback loop between knowledge of rank and consequent behavior, that explains the transition to strategic aggression, and the formation and persistence of dominance hierarchies in groups capable of both social memory and social inference.
... The protocol for the assessment of dogs undergoing TNR was developed using the SQP [3,4,19] as a model. The measures included in the protocol developed for this study included SQP measures, but also other approaches described in the existing scientific literature [11,[28][29][30][31]. In particular, affiliative behaviours (i.e., licking the other dog's muzzle, initiating physical contact, allo-grooming, play bow) and agonistic behaviours (i.e., raised hackles, submissive body posture, teeth baring, biting) were included in the protocol [32][33][34][35]. ...
A descriptive analysis, inter-observer and test–retest reliability of the animal-based measures (ABMs) included in the protocol were performed. This study aimed at the development of a welfare assessment protocol for dogs recruited in the trap-neuter-release (TNR) programmes and the description of the implantation of these programmes in Italy. Nine Italian regions carried out TNR programmes. A varied scenario, along with some critical issues, emerged. Fifty dogs were recruited and assessed simultaneously by two assessors to determine the reliability of ABMs included in the protocol. A subsample of ten dogs were assessed three times to assess test–retest reliability. All females were neutered against 36% of males. Most dogs were adults (58%) and of a large size (68%). Vaccine prophylaxis and parasitic prevention were regular in 13% and 76% of dogs, respectively. Few dogs showed lameness, evidence of pain, other clinical problems, or thermal discomfort. Overall, 82% of dogs did not show fear or aggression to unfamiliar people. The level of agreement between the two assessors was quite high, ranging from substantial (0.61–0.80) to perfect (1) for the majority of measures. This study highlighted some critical issues in TNR implementation and the suitability of the protocol as a tool for animal welfare assessment.
... For social animals, it is widely recognized that collective decision-making arises from social interactions between group members (Dyer et al. 2009) and, therefore, the priority is to maintain affiliated relationships with controllers of group movement. For example, in free-ranging dogs Canis lupus, habitual followers develop significantly closer spatial associations with habitual leaders during resting, and group movements benefit from the effort of followers to maintain close proximity with specific valuable social partners (Bonanni et al. 2010). Moreover, before and during group progressions, Verreaux's sifakas Propithecus verreauxi followers often emit vocalizations to leaders at high frequencies that can provide information about spatial distances between individuals and help to maintain group cohesion (Trillmich et al. 2004). ...
Coordination and consensus in collective behavior have attracted a lot of research interest. Although previous studies have investigated the role of compromisers in group consensus, they provide little insight into why compromisers would allow such social arrangements to persist. In this study, the potential relationship between group movements and conflict management in Tibetan macaques in Anhui province, China, was investigated using hierarchical cluster analyses. Some members with higher social centrality or social rank often formed a front-runner cluster during group movements. They had higher leadership success than individuals outside the front-runner cluster. Other members with lower social centrality or social rank often followed the group movements initiated by the front-runner cluster, and thus formed the compromiser cluster. Compromisers’ proximity relations with front-runners increased with their following scores to front-runners. Compromisers had fewer events of being attacked when they followed group movements initiated by the front-runners. The compromising process made compromisers lose the choice of direction preference, but it could increase their individual safeties. This trade-off suggests that compromisers play a role of decision-maker in coordination and consensus scenarios among social animals.
... Wolves rely on cooperation within their packs when raising offspring, hunting, and in territorial defense [17][18][19][20][21][22]. Free-ranging dogs can also live in packs and form long term social relationships [13,17,23], but they show much variation in their social organization. This probably depends on their genetics (i.e., genetic closeness to wolves; population origins: e.g., indigenous population, genetic mix of modern breeds; differences in relatedness to specific breeds; and relatedness among pack members), on local conditions (e.g., food availability, season), and on the extent of human influence [16,24,25]. ...
Domestication has affected the social life of dogs. They seem to be less dependent on their pack members than wolves, potentially causing dogs to be more alert towards their environment, especially when resting. Such a response has been found in dogs resting alone compared to wolves in the same situation. However, as this may be influenced by social context, we compared alertness (i.e., degree of activation along the sleep–wake continuum—measured via cardiac parameters) of pack-living and enclosure-kept dogs in two conditions: (1) alone, and (2) with pack members, and in two states of activation: (1) inactive wakefulness, and (2) resting. We found that when dogs were resting alone, alertness was higher than when resting in the pack; individual alertness was potentially influenced by social rank. However, alertness was similar in the two conditions during inactive wakefulness. Thus, depending on social context, familiar conspecifics may still provide support in dogs; i.e., domestication has probably only partly shifted the social orientation of dogs from conspecifics to humans. We suggest that cardiac responses of dogs may be more flexible than those of wolves because of their adaptation to the more variable presence of humans and conspecifics in their environment.
... In urban Panchkula, the evidence of temporally and spatially stable groups (p = 0.01 and p = 0.02, respectively) in the perimeter survey track in urban Panchkula is not unexpected as FRD are known to form temporary groups while transiting between their usual locations [14], such as between adjacent sectors in this study. However, the distribution of the different sized groups also did not follow a ZTPD in the industrial (p = 0.03 and p = 0.01 for Part I and Part II, respectively) and administrative sectors (p = 0.02), which suggests the presence of stable hierarchical social groups, similar to that reported in some international studies [43,44] and elsewhere in India [11]. Daniels and Bekoff [40], who similarly found that the group sizes of FRD in Mexico did not follow a ZTPD, believed that the dog-ownership practices of the resident community in the area influences the level of social organisation of FRD. ...
Adequate vaccination coverage of free roaming dogs (FRD) against canine rabies is not achieved primarily due to difficulties in administering parenteral vaccinations to this population. One factor associated with this difficulty is the tendency of FRD to form groups, which increases their aggressive behavior, resulting in a significant risk of dog-bites for the vaccinators. This study investigated factors that influenced FRD forming groups and their home-ranges, using data obtained from photographic capture-recapture/sight-resight surveys conducted in rural Shirsuphal (584 sightings) and urban Panchkula (3208 sightings), India. In the rural site, older dogs (OR 0.5, 95% CI 0.2–0.9, p = 0.03) and FRD sighted within 20 m of garbage sites (OR 0.6, 95% CI 0.4–0.9, p = 0.02) were less likely to be in groups. The number of dogs sighted with an FRD decreased with increased resight-probability of that dog (β= –1.0, p < 0.001). The rural FRD with smaller home-ranges were more likely to be sighted alone (OR 2.3, 95% CI 1.0–95, p = 0.04) than those with larger home-ranges. In the urban site, females (OR 1.3, 95% CI 1.1–1.5, p = 0.002) and older dogs (OR 1.5, 95% CI 1.1–2.1, p = 0.07) were more likely to be found in groups, and groups of dogs were more likely to be seen within 20 meters of garbage sites (OR 1.7, 95% CI 1.5–2.0, p < 0.001). The distribution of urban FRD sighted alone, in pairs, triads, and in packs of ≥4 dogs were not random in the administrative (p = 0.02), and the two industrial (p = 0.03 & 0.01) survey tracks of the urban site, implying stable groups. The resighting probability of a dog (β = 0.3, p < 0.0001) and presence of garbage within 20 m (β = 0.2, p < 0.0001) in the urban site increased the likelihood of sighting a FRD with other dogs. It is concluded that data on the resighting probability, presence of garbage points, and home-ranges can be utilised to guide the selection of parenteral or oral rabies vaccination to achieve a population vaccination coverage of 70% to break the transmission cycle of rabies virus in FRD in India.
... However, when a hierarchy was detected in a dog group, several parameters have been shown to covary with dominance status, such as age, sex, and personality. Older dogs were found to be more often dominant than young individuals (Mech, 1999;Peterson et al., 2002;Bonanni et al., 2010;Bonanni et al., 2017;Cafazzo et al., 2010;Trisko & Smuts, 2015). Therefore Bradshaw, Blackwell & Casey (2016) suggested that a simple rule of thumb could help to explain formal dominance in dogs: ''in order to be allowed to stay in the group, perform affiliative behaviour towards all the members of the group older than you are''. ...
Dominance is well defined in ethology, debated in psychology, and is often unclear among the dog owning public and in the press. However, to date, no study has examined how owners perceive dominance in dogs, and what different behaviours and personality types are used to describe dominant and subordinate individuals. A questionnaire study was launched to investigate the external validity of owner-derived estimates of dominance in dog dyads sharing the same household (N = 1,151). According to the owners, dogs rated as dominant (87%) have priority access to resources (resting place, food, and rewards), undertake certain tasks (defend and lead the group, bark more), display dominance (win fights, lick the other's mouth less, and mark over the other's urine), share certain personality traits (smarter, more aggressive and impulsive), and are older than their partner dog (all p < 0.0001). An age-related hypothesis has been suggested to explain dominance in dogs; but we found that dog age did not explain the occurrence of dominance related behaviours over the owners' estimate of dominance status. Results suggest that owner-derived reports of dominance ranks of dogs living in multi-dog households correspond to ethologically valid behavioural markers of dominance. Size and physical condition were unrelated to the perceived dominance. Surprisingly, in mixed-sex dyads, females were more frequently rated as dominant than males, which might correspond to a higher proportion of neutered females in this subgroup. For future studies that wish to allocate dominance status using owner report, we offer a novel survey.
... In several studies, the classification of an animal as follower or joiner was essential for the establishment of initiation success criteria, e.g. by formulated maximum values for the angle between the moving direction of the following animal and the trajectory of the initiator's movement (e.g. Bonanni, Cafazzo, Valsecchi, & Natoli, 2010). ...
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Both Shared Leadership Theory and evolutionary theories of leadership emphasize the role of team-level patterns of influence on team or group success. Yet, most of the empirical work on the effects of shared leadership assesses the concept through patterns of subjective perceptions of leadership and behavior. Although these studies give us important insights, subjective perceptions of leadership are prone to biases. In this paper, we draw on evolutionary theories of the development of leadership in groups and argue that group-level patterns of observable behavior have a direct effect on team outcomes above and beyond patterns of leadership and behavior perceptions. On the basis of a brief review of ethological assessment methods of leadership in animal groups, we derive implications for team leadership research methods to test hypotheses on team-level influence patterns and performance. Emphasizing the role of influence in terms of interpersonal behavior we formulate implications for the assessment and analysis of verbal and nonverbal behavior in teams. Finally, we discuss how technological advances may be utilized to promote behavioral observations in team leadership research.
... Why might these influential individuals emerge? Individuals may be persistent leaders, such as in elephants and dogs, as a result of being the oldest individual in the group and possessing the most experience, thereby influencing the social knowledge of their entire group due to their reliability (Bonanni, Cafazzo, Valsecchi, & Natoli, 2010;McComb et al., 2011;Payne, 2003). Furthermore, when group survival depends on a particularly influential individual, consequences may arise when these influential individuals are removed from their societies (Gilby et al., 2008;Lewis, Wartzok, & Heithaus, 2011;McComb et al., 2011;Pruitt & Pinter-Wollman, 2015). ...
The survival of an animal society depends on how individual interactions influence group coordination. Interactions within a group determine coordinated responses to environmental changes. Individuals that are especially influential affect the behavioural responses of other group members. This is exemplified by honey bee worker responses to increasing ambient temperatures by fanning their wings to circulate air through the hive. Groups of workers are more likely to fan than isolated workers, suggesting a coordinated group response. But are some individuals more influential than others in this response? This study tests the hypothesis that an individual influences other group members to perform thermoregulatory fanning behaviour in the western honey bee, Apis mellifera L. We show that groups of young nurse bees placed with fanners are more likely to initiate fanning compared to groups of nurses without fanners. Furthermore, we find that groups with young nurse bees have lower response thresholds than groups of just fanners. Our results suggest that individuals have the capability to influence other individuals to follow their fanning response as temperatures increase, and these social dynamics balance probability of fanning with thermal response thresholds. An influential individual may ultimately affect the ability for a society to efficiently respond to environmental fluctuations.
... Conversely, though free-ranging dogs have been observed to engage in joint territorial defence (e.g. [29][30][31]), alloparental care (e.g. [32][33][34]) and group hunting [35,36], they are mainly scavengers and exhibit a flexible and more promiscuous mating system [30,32,37,38] with pups being raised mostly by their mothers [32,38,39]. ...
Highly cooperative social species are expected to engage in frequent reconciliation following conflicts in order to maintain pack cohesiveness and preserve future cooperation. By contrast, in social species with low reliance on cooperation, reconciliation is expected to be less frequent. Here, we investigate the pattern of reconciliation in four captive wolf packs and four captive dog packs. We provide evidence for reconciliation in captive wolves, which are highly dependent on cooperation between pack members, while domestic dogs, which rely on conspecific cooperation less than wolves, avoided interacting with their partners after conflicts. Occurrence, intensity, latency, duration and initiation of wolf reconciliations appeared to vary as a consequence of a compromise between the costs (e.g. risk of further aggression) and the benefits (e.g. restoring relationship with opponents) of such interactions. Our results are in line with previous findings on various wolf packs living under different social and ecological conditions, suggesting that reconciliation is an important strategy for maintaining functional relationships and pack cohesiveness. However, current results on dogs are in contrast to the only other study showing that reconciliation can occur also in this species. Therefore, the occurrence of reconciliation in dogs may be influenced by social and environmental conditions more than in wolves. Which factors promote and modulate reconciliation in dogs needs to be further investigated.
... transient assemblage that forms only for the duration of a single emigration, but rather by a stable minority association whose members each reliably play a similar role in emigration after emigration, or in other words an 'oligarchy'. Although the exclusive control of a group's decision by one or a few older, more experienced or more dominant leaders has been documented in birds [30], wild dogs [31] and primates [32], the core 'oligarchy' of an emigrating ant colony is unique in that it is sub-divided into two subgroups, each specialized upon a different communication role, and further, communication within the oligarchy occurs primarily between these specialist groups rather than within them. Our investigations into the topology of the tandem recruitment networks revealed several properties in common with networks generated by the well-known 'preferential attachment' model of network growth. ...
Animals that live together in groups often face difficult choices, such as which food resource to exploit, or which direction to flee in response to a predator. When there are costs associated with deadlock or group fragmentation, it is essential that the group achieves a consensus decision. Here, we study consensus formation in emigrating ant colonies faced with a binary choice between two identical nest-sites. By individually tagging each ant with a unique radio-frequency identification microchip, and then recording all ant-to-ant 'tandem runs'-stereotyped physical interactions that communicate information about potential nest-sites-we assembled the networks that trace the spread of consensus throughout the colony. Through repeated emigrations, we show that both the order in which these networks are assembled and the position of each individual within them are consistent from emigration to emigration. We demonstrate that the formation of the consensus is delegated to an influential but exclusive minority of highly active individuals-an 'oligarchy'-which is further divided into two subgroups, each specialized upon a different tandem running role. Finally, we show that communication primarily occurs between subgroups not within them, and further, that such between-group communication is more efficient than within-group communication.
... We suggest that two other mechanisms are more likely to be at play. First, affiliation is known to be linked to leadership in dogs: dogs follow a leader individual better if they are affiliated to it (Bonanni et al. 2010). Leaders are often individuals possessing special skills about the environment, such as owners when walking outside. ...
Affiliation between interacting partners is associated with a high level of behavioural synchronization in many species. Pet dogs are known to share strong affiliative bonds with their owners and to synchronize their behaviour with them when moving freely indoors. Surprisingly, outdoor dog–human interspecific synchronization has seldom been investigated. We therefore explored whether, when allowed to move freely in a familiar outdoor space, dogs synchronize their behaviour with their owners’ movements. We found that dogs visibly synchronized both their location (staying in close proximity) and their activity (moving when their owner moved, and at the same pace, and standing still when their owner stood still) with those of their owners. By demonstrating that owners act as attractors for their dogs in an outdoor space, the present study contributes new data to the understanding of interspecific behavioural synchronization.
... Inúmeros estudos no decorrer dos últimos vinte anos têm se utilizado de cães domésticos como sujeitos experimentais. Dentre os temas estudados constam: A sensibilidade canina às dicas humanas (e.g., Bräuer, Kaminski, Riedel, Call, & Tomasello, 2006;Kupán, Miklósi, Gergely, & Topál, 2010), o desempenho adequado em testes de permanência de objetos (e.g., Gagnon & Doré, 1992), a possibilidade de existência de uma teoria da mente em cães (e.g., Bräuer, Call, & Tomasello, 2004), a habilidade no aprendizado de palavras (e.g., Kaminski, Call, & Fisher, 2004), o uso de lexigramas (Rossi & Ades, 2008), a capacidade de desviar uma rota após observar um modelo (Pongrácz et al., 2001), manipulação e busca de objetos (Kundey, Reyes, Taglang, Baruch, & German, 2010) e antecipação social (Bonanni, Cafazzo, Valsecchi, & Natoli, 2010;Kubinyi, Miklósi, Topál, & Csányi, 2003). ...
Communicative behavior with human interlocutor has been designated as essential to the adaptation of domestic dogs in their environments. The ability to follow human pointing in choice tasks is an example of social behavior that involves communication between dogs and humans, and is increasingly reported in the literature as a consistent phenomenon. Human beings are a relevant part of dog's social environment, a fact that is clearly explained by the evolutionary history of domestication. This study had the goal to bring together studies that analyzed dogs' ability to respond to cues given through explicit pointing by humans, stimulating a debate between Ethology and the Experimental Analysis of Behavior and presenting possibilities of explanatory synthesis. There are two tides in literature, one of which focuses on the processes of the dog's life history as determinants of communicative skills with humans (behavior-analytic approach) and an ethological approach emphasizing the process of canine domestication as independent variable. The ethological view is predominant in explaining the phenomenon mentioned above. Three articles were found that use a synthetic explanation of phylo and ontogenetic principles previously discussed in the present article, and they converge in arguing that evolution and epigenesis must have acted in order to prepare the domestic dog to respond to human communicative cues. It is concluded that social skills observed in dogs should not be solely attributed to an inherited factor, due to domestication, since learning is strong determinant of behavior; nor only to ontogeny, since conditioning process does not seem to be the only cause of communicative abilities seen in this species. It is also discussed the possible role of epigenesis in facilitating human-dog communication. The design of these experiments could strengthen with an increase of a debate between Ethology and the Experimental Analysis of Behavior.
... However, this was not consistent between all of the dogs and the relationships did not fall into a linear hierarchy involving multiple individuals. Consistent patterns of dominant and, more commonly, submissive behaviour were also seen between some individuals attending a day care centre (Trisko and Smuts, 2015) and free-ranging in Rome (Bonanni et al, 2010). However, as with Scott and Fuller (1965), such dominance relationships were not universal. ...
Aggression is the canine behaviour most likely to lead to relinquishment or euthanasia. Understanding how dogs socially interact and manage conflict is therefore of particular importance to veterinary professionals. Traditional approaches to the prevention and management of canine aggression advocated owners assert themselves as ‘pack leader’ through routine control of all resources and correction of any perceived challenge for them. At its most extreme this included physical punishment and steps to inhibit any initiative by the dog, including free movement and social interaction. The theory evolved from early to mid 20th century research into captive wolf behaviour, embellished by subsequent generations of dog trainers and behaviourists. However, more recent research into the behaviour of non-captive wolves and domesticated dogs, both in the home and living ferally, has brought the dominance theory into question. Perhaps more importantly, progress in the fields of animal welfare and training have highlig...
... Social relationships within the group, both agonistic and affiliative, affect the distribution of leadership (King et al. 2009). In species with a steep dominance hierarchy and intolerant social relationships, higher-ranking individuals often lead group movements (e.g., Squires and Daws 1975;Peterson et al. 2002;Sueur and Petit 2008;King et al. 2009;Bonnani et al. 2010;Flack et al. 2013). On the other hand, leadership is more likely to be distributed equally in species with a weakly linear or non-linear dominance hierarchy and tolerant social relationships (Squires and Daws 1975;Sueur and Petit 2008;Fernández et al. 2013). ...
Group-living animals need to coordinate their activity in order to maintain gregariousness. Although individuals have their own nutritional, social, and reproductive needs, they have to reach consensus to decide where and when to travel. Collective movements are the outcome of one individual’s departure, who is then followed by other group members. We investigated departure initiation in a group of bonobos at Wamba, DR Congo, to determine the distribution of leadership among group members. If three or more bonobos started moving more than 30 m, we assigned the individual who moved first as the one who initiated the movement. Two hundred and fifty-four departures were observed. First, we examined whether the frequency of initiation differed according to the following attributes of individuals: sex, age, stage in sexual swelling cycle, dominance, and affiliative relationship. We also examined whether one or more individual(s) initiate departure more or less frequently than expected by chance. A significant interaction between sex and age was found, indicating that the effect of age was greater among females than among males. Individuals who were more central to the grooming network initiated departures more frequently. The three oldest females initiated more often than expected. Old females may be followed because of coalitionary supports they often give to younger females, and of their greater knowledge about ranging area. Leadership in bonobos was not equally shared among group members, and old females were “key individuals” who helped to maintain cohesiveness in their fission-fusion society.
Significance statement
When group-living animals travel from one location to another, they must coordinate when and where to travel; otherwise, they might spread apart. Bonobos are one of our closest living relatives and have a fission-fusion social system. We investigated the initiation of group departure in wild bonobos to determine the distribution of leadership among group members. We found that the frequency of initiation was associated with the individual’s age, affiliative relationships, and male dominance rank. The three oldest females initiated departures more frequently than expected, suggesting that these individuals were habitual initiators and took an important role to preserve cohesiveness. We discuss how this “old female leadership” may emerge in a male-philopatric society.
... Wolves and dogs are interesting to study in this context because they diverged only between 15000 and 30000 years ago (Wang et al., 2013). Wolves and free-ranging dogs (i.e., 75-80% of the world dog population; Lord et al., 2013) show similar behavioral patterns in terms of living in pack-like groups and forming stable hierarchical structures (Mech and Boitani, 2003;Bonanni et al., 2010;Cafazzo et al., 2010). Crucially for the present study, however, they differ conspicuously in their foraging strategies. ...
Both human and non-humans species face decisions in their daily lives which may entail taking risks. At the individual level, a propensity for risk-taking has been shown to be positively correlated with explorative tendencies, whereas, at the species level a more variable and less stable feeding ecology has been associated with a greater preference for risky choices. In the current study we compared two closely related species; wolves and dogs, which differ significantly in their feeding ecology and their explorative tendencies. Wolves depend on hunting for survival with a success rate of between 15 and 50%, whereas free-ranging dogs (which make up 80% of the world dog population), are largely scavengers specialized on human produce (i.e., a more geographically and temporally stable resource). Here, we used a foraging paradigm, which allowed subjects to choose between a guaranteed less preferred food vs. a more preferred food, which was however, delivered only 50% of the time (a stone being delivered the rest of time). We compared identically raised adult wolves and dogs and found that in line with the differing feeding ecologies of the two species and their explorative tendencies, wolves were more risk prone than dogs.
... Taken into account that 76 -83% of the world's dog population represents free ranging dogs (Hughes & Macdonald, 2013;Lord, Feinstein, Smith, & Coppinger, 2013), we suggest that from an evolutionary perspective the similar performance of dogs and wolves in Study 2 is not surprising because relevant components of the social ecology of free-living dogs and wolves are rather comparable. Free-ranging dogs retained important aspects of the social organization of wolves in regard to dominance relationships, affiliative social interactions, leadership and coalition formation (Bonanni, Cafazzo, Valsecchi, & Natoli, 2010b;Bonanni, Valsecchi, & Natoli, 2010a;Cafazzo, Valsecchi, Bonanni, & Natoli, 2010;Mech, 1970). Because most of these social interactions shared by dogs and wolves likely require some form of visual coordination between pack-members (Range & Virányi, 2011), gaze following should be as important for dogs as it is for wolves when interacting with conspecifics. ...
Gaze following into distant space is defined as visual co-orientation with another individual's head direction allowing the gaze follower to gain information on its environment. Human and nonhuman animals share this basic gaze following behavior, suggested to rely on a simple reflexive mechanism and believed to be an important prerequisite for complex forms of social cognition. Pet dogs differ from other species in that they follow only communicative human gaze clearly addressed to them. However, in an earlier experiment we showed that wolves follow human gaze into distant space. Here we set out to investigate whether domestication has affected gaze following in dogs by comparing pack-living dogs and wolves raised and kept under the same conditions. In Study 1 we found that in contrast to the wolves, these dogs did not follow minimally communicative human gaze into distant space in the same test paradigm. In the observational Study 2 we found that pack-living dogs and wolves, similarly vigilant to environmental stimuli, follow the spontaneous gaze of their conspecifics similarly often. Our findings suggest that domestication did not affect the gaze following ability of dogs itself. The results raise hypotheses about which other dog skills might have been altered through domestication that may have influenced their performance in Study 1. Because following human gaze in dogs might be influenced by special evolutionary as well as developmental adaptations to interactions with humans, we suggest that comparing dogs to other animal species might be more informative when done in intraspecific social contexts. (PsycINFO Database Record
... We do not discuss in depth the mechanisms of formation of dominance relationships and the connection between dominance and leadership. The former has been modeled in the studies by Hemelrijk (2002), Beacham (2003), Forkman and Haskell (2004), and Dugatkin and Dugatkin (2007), and the latter is discussed in the studies by Peterson et al. (2002), Bonanni et al. (2010), and Akos et al. (2014). ...
A dominance hierarchy is an important feature of the social organisation of group living animals. Although formal and/or agonistic dominance has been found in captive wolves and free-ranging dogs, applicability of the dominance concept in domestic dogs is highly debated, and quantitative data are scarce. Therefore, we investigated 7 body postures and 24 behaviours in a group of domestic dogs for their suitability as formal status indicators. The results showed that high posture, displayed in most dyadic relationships, and muzzle bite, displayed exclusively by the highest ranking dogs, qualified best as formal dominance indicators. The best formal submission indicator was body tail wag, covering most relationships, and two low postures, covering two-thirds of the relationships. In addition, both mouth lick, as included in Schenkel's active submission, and pass under head qualified as formal submission indicators but were shown almost exclusively towards the highest ranking dogs. Furthermore, a status assessment based on changes in posture displays, i.e., lowering of posture (LoP) into half-low, low, low-on-back or on-back, was the best status indicator for most relationships as it showed good coverage (91% of the dyads), a nearly linear hierarchy (h' = 0.94, p
... Compared to previous literature, some innovation was introduced: a continuous recording, rather than a 5-s point sampling (used in most previous literature); the analysis of affiliative behaviours upon reunion with the owner; the stranger entered the room with the owner in the first episode, avoiding a possible order effect related to their appearance; passive behaviours were excluded, because their interpretation varies among Authors (calm: Prato-Previde et al., 2003, Palmer & Custance, 2008anxiety: Topál et al., 1998;emotional distress: Fallani et al., 2007); whining was analysed because it is a social signal of distress and may be related to fear and anxiety (Lund & Jørgensen, 1999;Partasarathy & Crowell-Davis, 2006;Palestrini et al., 2010), while other vocalizations were excluded, as possibly misleading in the assessment of emotional distress during separation; a recall test was carried out; new behaviours were analysed. Among the latter: proximity and attention seeking, according to studies on children's contact maintenance effect; and social wagging, as tail wagging in dogs conveys affiliative intentions (Schenkel, 1967;Bonanni et al., 2010). ...
Investigations of the dog-human bond using modified versions of the Ainsworth Strange Situation Test show some similarities in findings. However, methodological differences mean it cannot be concluded that this bond is comparable to that between children and their mothers. The aim of this study was to assess whether owners can represent an emotionally secure base for their dogs, using a modified version of the Ainsworth Strange Situation Test.
The videoed behaviour of 40 companion dogs was continuously sampled. Durations (seconds) of 22 behaviours were analyzed using Wilcoxon Tests (p<0.05) for differences between owner and stranger situations.
Significant differences in median values were found: contact with/proximity to door/chair/shoe was higher during the absence of owner vs stranger (143.0 vs 49.5, z=4.731, p=0.000); contact with/proximity to owner was higher than to stranger (127.0 vs 50.5, z=5.383, p=0.000); whining lasted longer during the absence of owner vs stranger (0.5 vs 0.0, z=3.099, p=0.002); exploration was higher in the presence of the owner vs stranger (20.5 vs 6.0, z=2.293, p=0.022); individual play was higher in the presence of owner vs stranger (2.5 vs 0.0; z=3.467, p=0.001).
The data suggest that dogs show behaviour similar to that of children in the Ainsworth Strange Situation Test. Owners, like mothers, can represent a secure base from which the dog can play and explore; be the preferred recipient of affiliative behaviour; and, in owner absence, dogs show behaviours indicative of distress. According to Bowlby’s definitions the dogs appear to be linked to their owners by a true attachment bond.
The absence of fear behaviours directed to the stranger in this study is different to that observed in children. This may reflect the different developmental stages at which children are tested versus dogs. In addition, reduced fear of strangers in dogs is known to relate to good interspecific socialization.
... This supports the distributed leadership hypothesis, which predicts that social affiliation plays a role in leadership. The importance of social affiliation is consistent with several other studies (e.g., dogs, Canis lupus: Bonanni et al. [2010]; Tonkean macaques: Sueur et al. [2009]; Sueur & Petit [2008a,b]). King et al. [2011] suggested that chacma baboons with higher eigenvector centrality coefficients in their spatial network were more likely to induce group mates to follow their initiations. ...
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. © 2016 Wiley Periodicals, Inc.
... Studies of free-ranging dogs suggest possible benefits of strong conspecific bonds. Bonanni et al. (2010a) showed that younger dogs tended to follow older dogs with whom they had affiliative relationships. Followers could benefit from letting more knowledgeable elders guide them, and leaders could benefit by having followers close by to support them in intergroup encounters (Bonanni et al., 2010b). ...
Dog social behaviour has been well studied, but little is known about affiliative relationships between dogs. We report a yearlong study of dominance and affiliation in 24 dogs at a dog daycare facility and provide additional details on dog relationships through long-term observations of pairs of dogs who lived together in the same household or met frequently for years. Companion dogs formed highly differentiated relationships with one another. At daycare, some dyads affiliated and displayed one-way submission (formal dominance), others affiliated without a dominance relationship (egalitarian), and the majority of dyads did not affiliate at all (agonistic or non-interactive). The dogs in household environments showed formal and egalitarian relationships, and two dyads exchanged two-way agonism without submission (unresolved). Sex influenced the types of relationships dogs formed, with mixed sex dyads more likely to affiliate and less likely to exhibit dominance than same-sex pairs. Dominance influenced the nature of affiliation in relationships; egalitarian dyads were more likely to play and showed more equitable gentle affiliation. Gentle affiliation was reciprocal in the group as a whole, but it was highly skewed in many dyads, especially those with dominance relationships. Gentle affiliation was usually, but not always, directed up the hierarchy. Certain dyads affiliated at much higher rates than others, indicating that the dogs formed friendships. Most friends were mixed sex and/or egalitarian pairs, but friendships occurred in all of the sex class/dominance combinations. Long-term observations demonstrated how dyadic relationships can change over time. Such highly differentiated relationships suggest significant social complexity in dogs.
In the current chapter we focus on the social relationships dogs and wolves establish with their pack mates. Dominance and affiliation are relevant features to describe the social relationships of both wolves and dogs. In both species, submissive behaviours and greeting are the best indicators of formal dominance relationships, and in general a linear hierarchy can be detected in most packs. While wolf packs may show a more consistent pattern of clear hierarchical relationships than dogs, subdominant wolves are still more willing to stand their ground to get access to resources, which is accepted by the higher-ranking wolves to some degree. In dogs, this pattern cannot be observed but instead high-ranking animals dominate resources and may escalate into aggression if lower-ranking animals do not keep their distance. In regard to affiliation, measures of proximity and affiliative rates correlate in wolves and dogs, suggesting that both can be used as indexes of bondedness, although, arguably, exchange of affiliative interactions provides a more accurate measure. Behaviours shown in the play contexts in terms of competitive vs. more gentle play reflect the social relationships the animals exhibit outside of play. In accordance, winning positions during dyadic play are exhibited more by the dominant individual in the dyad, and in general there seems little evidence of ‘fair play’ in terms of adherence to the "50:50” rule.
In collective movements, specific individuals may emerge as leaders. In this study on the domestic horse (Equus ferus caballus), we conducted experiments to establish if an individual is successfully followed due to its social status (including hierarchical rank and centrality). We first informed one horse about a hidden food location and recorded by how many it was followed when going back to this location. In this context, all horses lead their groupmates successfully. In a second step, we tested whether group members would trust some leaders more than others by removing the food before the informed individual led the group back to the food location. In addition, two control initiators with intermediate social status for which the food was not removed were tested. The results, confirmed by simulations, demonstrated that the proportions of followers for the unreliable initiator with highest social status are greater than the ones of the unreliable initiator with lowest social status. Our results suggest an existing relationship between having a high social status and a leadership role. Indeed, the status of a leader sometimes prevail at the detriment of the accuracy of the information, because an elevated social status apparently confers a high level of trust.
In case of social animals often we can observe dominance hierarchies among the group members around limited resources. Once stabilized, hierarchy can help the access to these resources – in favour of the dominant individuals – without serious conflict or harm. While we can easily identify the limited resources in nature, in case of companion dogs, all essential resources are provided by the owner thus shortcutting competition. While it seems that its original function is not present in companion dogs, dominance hierarchies were still described in dog groups. As everyday competition for essential resources is seldom part of the lives of most companion dogs, our aim was to find what traits might be related to the formation of these hierarchies and the rank of the individuals. We designed an online survey for owners of multiple dogs to assess i) the dominance relationship between the co-habiting dogs via their everyday interactions and ii) their personalities using the Canine Big Five questionnaire. We received responses for 1082 dogs. Four of the five personality traits had a significant association with dominance: while more extroverted (p = 0.0003), conscientious (p = 0.0006), and open (p = 0.0088) dogs scored higher on dominance, more agreeable dogs scored lower (p < 0.0001). In accordance with previous studies, we also found that older dogs tend to be more dominant (p = 0.001). We also found a small but not negligible number of dog-pairs that had no difference in their dominance scores. Although our study is not suitable for detecting causality, the results show that there is a complex association between owner-perceived dominance and personality in group-living companion dogs.
Dogs’ remarkable success in living in a human-dominated world rests on a set of adaptations to cohabitation with humans. In this paper, I review the nature of these adaptations. They include changes in reproductive and foraging behavior from their ancestor species, wolves, which can be understood as adaptations to the change from hunting live prey to feeding on human food residues. Dogs also show several changes in social behavior which are more controversial and even somewhat paradoxical. Contrary to theories of canine domestication which view dogs as less aggressive and more cooperative than wolves, several studies show that dogs’ social interactions with conspecifics are more hierarchical and competitive than are wolves’. As scavengers rather than hunters, dogs do not need to cooperate with conspecifics the way that wolves do. But how then can we understand dogs’ willingness to cooperate with humans? I propose an integrated account of dogs’ social behavior that does not assume that dogs need to recognize the species-identity of the individuals with whom they interact. Because of the overlap in formal signals of dominance and submission between dog and human and people’s complete control over the resources dogs need, I propose that people occupy a status of “super-dominance” over dogs. This conception suggests several new lines of research which could shed light on the human-dog relationship to the benefit of both partners.
This chapter contextualizes the dog-human relationship in the dog's origin as a scavenger on the fringes of human settlements over 15,000 years ago. It then reviews the evidence for unique evolved cognitive structures in dogs that could explain their success in a human-dominated world. Failing to find evidence of unique human-like social-cognitive capacities I then review uncontroversial facts of dogs' basic behavioral biology, including reproductive and foraging behavior and, particularly, affiliative and attachment-related behaviors. This leads to consideration of dogs' social behavior, both conspecific and toward other species, especially humans. I draw attention to a seldom-noted apparent contradiction between dogs' stronger affectional bonds toward humans than toward members of their own species. Dogs' social groups also show steeper social hierarchies accompanied by more behaviors indicating formal dominance than do other canid species including wolves. I resolve this contradiction by proposing that dogs' intense sensitivity to social hierarchy contributes to their willingness to accept human leadership. People commonly control resources that dogs need and also unknowingly express behaviors which dogs perceive as formal signs of dominance. This may be what Darwin was referring to when he endorsed the idea that a dog looks on his master as on a god. Whatever the merits of this idea, if it serves to redirect behavioral research on dogs in human society more toward the social interactions of these species in their diverse forms of symbiosis it will have served a useful function.
Affiliation between individuals is socially adaptive as it helps to build and maintain bonds between group members and is central to social cohesion. One of the main factors in creating and maintaining affiliation is behavioral synchronization, particularly local synchrony which is defined as being at the same place as other individuals, whatever the activity. In dogs, a very social species, it is known that individuals who are more closely affiliated will exhibit more local synchrony that less affiliated individuals. In ethology, significance of the phenomenon is still undervalued, even in studies specifically aiming to describe the social organization within groups. We suggest that local synchrony could be very informative for scientists to consider when observing groups of dogs interacting. The present study thus investigated whether local synchrony could be a tool to measure the degree of affiliation existing between dogs. To do so, a target dog surrounded by three different dogs (one affiliated with the target dog, and two unfamiliar) was observed during a walk. An observer, who was deliberately unaware of the identity of the three dogs relative to the target dog, analyzed the target dog's behavior toward the other dogs. Results revealed that the target dog spent significantly more time associating with the affiliated dog. The target dog was observed in the same area, as well as in close proximity to the affiliated dog, and the target dog also initiated more closeness with its affiliated conspecific compared to the two unfamiliar dogs. It is concluded that local synchrony is therefore an effective tool to evaluate affiliation between dogs. Theoretical as well as practical implications are discussed.
It is believed that domestic dogs rarely form packs with age-graded hierarchical structures similar to those found in wolves. Dog-wolf comparisons in captivity suggest that human control has reduced dog dependency on cooperation with conspecifics, resulting in a more despotic dominance order. However, free-ranging dogs are under stronger natural selection than purebred dogs. They are dependent on companions’ social support but usually exhibit lower reproductive skew than wolves, possibly because access to easily available human-derived food may have relaxed within-group competition. We investigated social dominance in 5 packs of mongrel dogs living in a free-ranging or semifree-ranging state. We aimed at replicating the findings of the few studies that detected a dominance hierarchy in dogs using a larger sample of packs. Additionally, we provided behavioral measures of social tolerance. We found that a linear hierarchy existed in all packs studied and that the rank order was positively related to age in all packs but one. In 2 packs in which testing was possible, age was a better predictor of dominance than body size. Potentially injurious aggression was very rare. Hierarchy steepness in dogs was similar to that found in wolves and in tolerant primates. Submissive reversals were more common in dogs than in wolves. These results suggest that age-graded hierarchies in dogs are more common than previously thought, that rank is not usually acquired through fighting because subordinates rely on the guidance of elders, and contradict the view that domestication has increased despotism in dogs.
Dogs are known to be skilled at using human social signals such as pointing at a target, gaze, visual direction of attention, and facial emotional cues. Two non-mutually exclusive hypotheses have been proposed to explain these abilities: the domestication hypothesis and the “Two Stage” hypothesis. One way to test the Two Stage hypothesis is to compare subpopulations of dogs with different histories with humans. For example, the abilities of pet dogs, who live in human homes and have developed strong affiliative bonds with humans, can be compared with those of shelter dogs, who live in social isolation and are deprived of extended contact with humans. Here we review the extant literature on studies comparing these two subpopulations using identical protocols. Pet dogs perform better than shelter dogs at following human pointing and at estimating humans’ attentional state or direction of visual attention. Shelter dogs seem to be more socially driven to gaze and interact with humans compared to pet dogs. Shelter dogs’ impoverished contact with humans is the best candidate explanation for these results. We survey results highlighting the importance of life experience and learning in determining dogs’ abilities to use human social cues, and argue that shelter dogs may have learned not to respond to human cues that are not useful to them, or have lost some previously acquired skills due to a lack of exposure to humans. Finally, we encourage further research that adds to both our theoretical and practical understanding of the impaired abilities of shelter dogs to use human social cues, and its link with the effect of life experiences.
We investigated the initiation of group movements in white-faced capuchin monkeys, Cebus capucinus, with the aim of determining whether a single individual with high dominance status consistently leads movements or whether leadership is distributed between group members. The group studied was reared in semifree-ranging conditions. A multivariate analysis followed by univariate analyses demonstrated that leadership was not concentrated on a single individual in this species. All individuals could initiate a collective movement. Nearly half of group members regularly succeeded in recruiting at least three followers. Although both sexes had similar rates of start attempts, females succeeded more frequently than males. We found no significant effect of the dominance status on the percentage of successful attempts. The use of a slow speed, looking back towards the other group members, or trills by the initiator heightened the likelihood of success in group movement initiation. An initiator starting from a core position in a clumped group was more successful than one starting from an edge position in a clumped group or from a dispersed group. Furthermore, the probability of successful start attempts was higher when the group remained stationary for a long period. Leadership in white-faced capuchins appears to be distributed between group members rather than exclusively concentrated on high-ranking individuals. © 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
For coordinated movement, group-living individuals have to reach consensus decisions through recruitment processes. Success in recruitment can depend on the spatial distribution and behaviour of animals before and/or after departure, and on their affinitive relationships. We tested the effect of such factors on recruitment processes in a group of 19 ewe lambs, Ovis aries, at pasture. Two observers continuously videotaped the behaviours of animals from a platform located in the centre of the field. Results showed that group orientation, group vigilance and activities such as head movements, stillness and number of steps increased before departure. Using general linear modelling we found that changes in most of these variables predicted the number of participants in movements. Similarly, activity of the first mover was modified in the last 2 min preceding departure, and at departure time the location and number of close neighbours of the first mover were especially influential in recruiting conspecifics. Animals first recruited were those that were close to the first mover and also its preferential partners. The behaviours of the second and third moving individuals could further influence the recruitment process. Moreover, there were clues that individuals were able to recruit others intentionally. Our findings emphasize that decision making in a group of domestic sheep was a continuous and distributed process. Recruitment depended both on group state and on the behaviour of individuals and their social relationships.
Group-living animals have to make trade-offs to reach consensus and travel together. We investigated the recruitment processes underpinning decision-making at departure in a group of 20 female domestic geese (Anser domesticus) kept in semi-free-range conditions. Two observers continuously videotaped the behaviours of the birds. Data were analyzed using multiple regression analyses. We found that decision-making was a continuous and distributed process. Departure was preceded by an increase in the arousal state of group members and their initial orientation influenced recruitment. Patterns of group movement could be predicted from the behaviours of individuals before departure. Individuals' locations, moves and signals could act as passive or communicative cues. A higher number of vocalisations and arousal behaviours led to a larger number of individuals recruited. Some individuals were more efficient than others in recruiting followers but any geese could initiate a movement. First movers recruited a higher number of mates when they had a greater number of neighbours. Not only the first mover but also the behaviours of the second and third movers prompted further individuals to follow. There was no evidence that geese were able to intentionally recruit others, rather they synchronized and adjusted each other's motives until reaching a consensus.
In this paper we compare some socio-ecological traits of feral dogs and wolves in order to assess the social ecology of feral dogs in terms of its adaptive value in the natural environment, and to evaluate to what extent the domestication process altered the wolf's socio-ecological patterns. Referring to feral dogs as those dogs living in a wild state with no food and shelter intentionally provided by humans, and showing a continuous and strong avoidance of direct human contacts, we review the currently available information on feral dog ecology, and particular reference is made to a 3-year term project on feral dog ecology in Abruzzo, Italy. Through comparison of relevant behavioural and ecological features of both wolves and feral dogs, we hypothesize that some aspects of the feral dogs' ecology, having escaped natural selection pressures, represent primarily expression of “evolutionary inertia” or an epiphenomena of artificial selection. Fitness-related measures of sociality, demography, reproduction, space-use, activity patterns, and feeding ecology in feral dogs tend to support our original hypothesis: feral dogs are not reproductively self-sustaining, suffer from high rates of juvenile mortality, depend indirectly upon humans for food, co-optable individuals, and space, and their demography appears dominated by unpredictable mechanisms. However, further research is needed, especially concerning different ecological conditions and multi-generational time-scales, as well as the role that dominant breed-types and cross-breeding history within feral dog groups might play in the expression of the analyzed socio-ecological features.
Different aspects of the etho-ecology of the stray dog population in Valencia (Spain) were investigated. Densities of between 127 and 1304 stray dogs km−2 overlap with density estimates reported for other populations. A male:female ratio of 2:1 is also in agreement with earlier studies. Behavioral observations revealed that these dogs will occasionally form groups with dominance hierarchies and communal defense of a territory. From the stability of these groups, long-term affiliative bonds apparently exist among group members. This finding conflicts with the accepted notion that urban stray dogs are asocial and do not form stable social groups. Methodological problems may invalidate earlier claims that urban stray dogs are asocial animals. This is due to improper use of a Poisson model for assessing social organization. It is suggested that stray dogs possess, like most canids for which an adequate data base exists, remarkable behavioral plasticity allowing them to adjust their social system to prevailing ecological constraints.
In animal groups, collective movements emerge from individual interactions. Biologists seek to identify how characteristics of actors in these groups, and their relationships, influence the decision-making process. We distinguished two basic factors determining leadership in group choices: identity and state. We hypothesized that identity is more important to leadership in groups with stable relationships, which permit the development of habitual roles. In groups with fluid membership, particular individuals or subgroups are less likely to emerge as consistent leaders. Instead, we predicted that movement initiation in unstable groups depends on individual state at the time of the decision. We characterized how identity and reproductive state influenced leadership patterns in the movements of plains zebra. As in many other mammals, lactation in this species significantly alters water and energy needs. We investigated leadership in tightly knit harems and loosely bonded herds of multiple harems. Harem females tended to have habitual roles in the initiation of harem movement. In herds, however, we found no consistent leaders among harems. At both levels of social organization, lactation was a key determinant of leadership. In harems, lactating females were more likely to initiate movement than nonlactating females. In turn, harems containing lactating females were more likely to lead herd movements. Thus, we conclude that social relationships and reproductive state together shape the interactions that produce group behaviours. One benefit to lactating females of leading herd movements is preferential access to scarce water. Thus, leadership roles in group decisions may have fitness consequences.
We investigated the initiation of group movements in white-faced capuchin monkeys, Cebus capucinus, with the aim of determining whether a single individual with high dominance status consistently leads movements or whether leadership is distributed between group members. The group studied was reared in semifree-ranging conditions. A multivariate analysis followed by univariate analyses demonstrated that leadership was not concentrated on a single individual in this species. All individuals could initiate a collective movement. Nearly half of group members regularly succeeded in recruiting at least three followers. Although both sexes had similar rates of start attempts, females succeeded more frequently than males. We found no significant effect of the dominance status on the percentage of successful attempts. The use of a slow speed, looking back towards the other group members, or trills by the initiator heightened the likelihood of success in group movement initiation. An initiator starting from a core position in a clumped group was more successful than one starting from an edge position in a clumped group or from a dispersed group. Furthermore, the probability of successful start attempts was higher when the group remained stationary for a long period. Leadership in white-faced capuchins appears to be distributed between group members rather than exclusively concentrated on high-ranking individuals. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
Current knowledge about social behavior of free-ranging domestic dogs is scarce, and the possibility that they could form stable social groups has been highly debated. We investigated the existence of a social-dominance hierarchy in a free-ranging group of domestic dogs. We quantified the pattern of dyadic exchange of a number of behaviors to examine to what extent each behavior fits a linear rank-order model. We distinguished among agonistic dominance, formal dominance, and competitive ability. The agonistic-dominance hierarchy in the study group shows significant and substantial linearity. As in random assortments of captive wolves, there is a prominent but nonexclusive male agonistic dominance in each age class. The agonistic rank-order correlates positively and significantly with age. Submissive--affiliative behavior fulfills the criteria of formal submission signals; nevertheless, it was not observed among all dogs, and thus, it is not useful to order the dogs in a consistent linear rank. Agonistic-dominance relationships in the dog group remain stable across different competitive contexts and to the behaviors considered. Some individuals gain access to food prevailing over other dogs during competitions. Access to food resources is predicted reasonably well by agonistic rank order: High-ranking individuals have the priority of access. The findings of this research contradict the notion that free-ranging dogs are "asocial" animals and agree with other studies suggesting that long-term social bonds exist within free-ranging dog groups. Copyright 2010, Oxford University Press.
Dominance rank in female chimpanzees correlates positively with reproductive success. Although a high rank obviously has an advantage for females, clear (linear) hierarchies in female chimpanzees have not been detected. Following the predictions of the socio-ecological model, the type of food competition should affect the dominance relationships among females. We investigated food competition and relationships among 11 adult female chimpanzees in the Taï National Park, Côte d'Ivoire (West Africa). We detected a formal linear dominance hierarchy among the females based on greeting behaviour directed from the subordinate to the dominant female. Females faced contest competition over food, and it increased when either the food was monopolizable or the number of competitors increased. Winning contests over food, but not age, was related to the dominance rank. Affiliative relationships among the females did not help to explain the absence of greetings in some dyads. However comparison post hoc among chimpanzee study sites made differences in the dominance relationships apparent. We discuss them based on social relationships among females, contest competition and predation. The cross-site comparison indicates that the differences in female dominance hierarchies among the chimpanzee study sites are affected by food competition, predation risk and observation time.
Unshared consensus decision-making processes, in which one or a small number of individuals make the decision for the rest of a group, are rarely documented. However, this mechanism can be beneficial for all group members when one individual has greater knowledge about the benefits of the decision than other group members. Such decisions are reached during certain activity shifts within the population of bottlenose dolphins residing in Doubtful Sound, New Zealand. Behavioral signals are performed by one individual and seem to precipitate shifts in the behavior of the entire group: side flops are performed by males and initiate traveling bouts while upside-down lobtails are performed by females and terminate traveling bouts. However, these signals are not observed at all activity shifts. We find that while side flops were performed by males that have greater knowledge than other male group members, this was not the case for females performing upside-down lobtails. The reason for this could have been that a generally high knowledge about the optimal timing of travel terminations rendered it less important which individual female made the decision.
This paper reviews the literature on leadership in vertebrate groups, including recent work on human groups, before presenting the results of three new experiments looking at leadership and decision making in small and large human groups. In experiment 1, we find that both group size and the presence of uninformed individuals can affect the speed with which small human groups (eight people) decide between two opposing directional preferences and the likelihood of the group splitting. In experiment 2, we show that the spatial positioning of informed individuals within small human groups (10 people) can affect the speed and accuracy of group motion. We find that having a mixture of leaders positioned in the centre and on the edge of a group increases the speed and accuracy with which the group reaches their target. In experiment 3, we use large human crowds (100 and 200 people) to demonstrate that the trends observed from earlier work using small human groups can be applied to larger crowds. We find that only a small minority of informed individuals is needed to guide a large uninformed group. These studies build upon important theoretical and empirical work on leadership and decision making in animal groups.
The aims of the study were to characterize the cortisol response to immobilization stress in African wild dogs (Lycaon pictus) and to investigate the relationship between stress and sociality in these pack-living canids. Ad lib. observations were made on a captive pack of 19 wild dogs. Individuals were classified as either dominant or subordinate. Cardinal and ordinal dominance indices were also calculated for pack members, as were three other behavioral indices. Active and passive dominance styles were distinguished. Serial blood samples were drawn from animals after chemical immobilization and again after ACTH challenge. The relationship among rank, plasma cortisol concentration, and behavioral style was investigated. When data were combined over the entire study period, there was no obvious relationship between rank and cortisol concentrations or cortisol responsiveness to immobilization stress. Instead, younger animals had higher cortisol concentrations than older ones. Age cohorts were also clearly separated on the basis of behavioral profiles. For males, these distinctions among age classes were especially apparent during the second part of the study period, when subadults occupied dominant positions in the hierarchy. Adult males maintained relatively low cortisol concentrations, despite being involved in and losing a high proportion of dominance interactions. Age-related differences in cortisol profiles of dominant individuals may be explained by differences in the style of dominance employed, with younger males using proportionately more active dominance (threats used to elicit submission). The separation of age classes according to rank, behavioral styles, and cortisol concentrations may reflect improved social skillfulness with age.
Mitochondrial DNA control region sequences were analyzed from 162 wolves at 27 localities worldwide and from 140 domestic
dogs representing 67 breeds. Sequences from both dogs and wolves showed considerable diversity and supported the hypothesis
that wolves were the ancestors of dogs. Most dog sequences belonged to a divergent monophyletic clade sharing no sequences
with wolves. The sequence divergence within this clade suggested that dogs originated more than 100,000 years before the present.
Associations of dog haplotypes with other wolf lineages indicated episodes of admixture between wolves and dogs. Repeated
genetic exchange between dog and wolf populations may have been an important source of variation for artificial selection.
THE FIRST REAL BEGINNING to our understanding of wolf social ecology came from wolf 2204 on 23 May 1972. State depredation control trapper Lawrence Waino, of Duluth, Minnesota, had caught this female wolf 112 km ( 67 mi) south of where L. D. Mech had radio-collared her in the Superior National Forest 2 years earlier. A young lone wolf, nomadic over 100 km2 (40 mi2) during the 9 months Mech had been able to keep track of her, she had then disappeared until Waino caught her. From her nipples it was apparent that she had just been nursing pups. "This was the puzzle piece I needed," stated Mech. "I had already radio-tracked lone wolves long distances, and I had observed pack members splitting off and dispersing. My hunch was that the next step was for loners to find a new area and a mate, settle down, produce pups, and start their own pack. Wolf 2204 had done just that."
Population size and density, age structure, survivorship patterns, sex ratios, and social organization of urban, rural, and feral dog (Canis familiaris) populations were examined in Cd. Juarez, Mexico (urban site) and on the Navajo reservation (rural and wild sites) between June 1983 and December 1984. Urban and rural dogs were less social than expected whereas feral dogs characteristically lived in packs. Seasonal variation in the structure of feral dog packs was influenced by reproduction, both directly (pups born into the pack) and indirectly (pregnant females may temporarily emigrate form the pack to give birth).
Description and analysis of a complex system is most likely to begin with the most conspicuous features, gradually progressing to consider the more subtle ones. In group-living primates sex and aggression are often the most conspicuous behaviours, and these were the focus of much of the early research on primates in social groups (e.g. ZUCKERMAN, 1932). In many species adult males are more conspicuous than females, because of their greater body size, and other sexually dimorphic features, and they are also frequently dominant to them. Perhaps because of this, adult males were seen as the central figures in the group, fulfilling a "control role" (BERNSTEIN, 1970), maintaining cohesion and settling disputes. As field research progressed, it became clear that males are relatively transitory members of the group in many species, and that it is the females that form the stable core. Dominance relations among females were reported to be more stable than those among males, and kinship was revealed as a major factor governing both dominance and affiliative behaviour among females (KAWAMURA, 1958; SADE, 1967; MISSAKIAN, 1972, 1974; NETTO & VAN HOOFF, 1986; DATTA, 1988). Later studies found evidence in several species of lasting affiliative relationships between adult males and females (TAKAHATA, 1982; CHAPAIS, 1983;
We analyzed the leadership behavior of breeding and nonbreeding gray wolves (Canis lupus) in three packs during winter in 1997-1999. Scent-marking, frontal leadership (time and frequency in the lead while traveling), initiation of activity, and nonfrontal leadership were recorded during 499 h of ground-based observations in Yellowstone National Park. All observed scent-marking (N=158) was done by breeding wolves, primarily dominant individuals. Dominant breeding pairs provided most leadership, consistent with a trend in social mammals for leadership to correlate with dominance. Dominant breeding wolves led traveling packs during 64% of recorded behavior bouts (N=591) and 71% of observed travel time (N=64 h). During travel, breeding males and females led packs approximately equally, which probably reflects high parental investment by both breeding male and female wolves. Newly initiated behaviors (N=104) were prompted almost 3 times more often by dominant breeders (70%) than by nonbreeders (25%). Dominant breeding females initiated pack activities almost 4 times more often than subordinate breeding females (30 vs. 8 times). Although one subordinate breeding female led more often than individual nonbreeders in one pack in one season, more commonly this was not the case. In 12 cases breeding wolves exhibited nonfrontal leadership. Among subordinate wolves, leadership behavior was observed in subordinate breeding females and other individuals just prior to their dispersal from natal packs. Subordinate wolves were more often found leading packs that were large and contained many subordinate adults.
White-nosed coatis maintain a social structure of female-bonded group (called bands) and solitary males. I examined the foraging success of social and solitary individuals and the possible importance of interspecific foraging competition in maintaining the social system, particularly in the associated context of sexual dimorphism. The study population was almost entirely frugivorous-insectivorous. Invertebrate foraging success did not filter between solitary band members, although solitary adult females more successful than those in bands. Fruit foraging success of solitary adult male was generally greater than that of band member, although this result varied with patch size and dependent on the age less of examined band members. Small food patches showed the greatest differential between the foraging success of solitary male and band members. Agonistic interactions between males and bands often occurred at fruiting trees, and foraging group size was important in determining the outcome of the event. Larger males were able to displace solitary females and small foraging groups from fruit patches. In turn, larger of smaller females displaced solitary males. Male-male agonism at fruit patches was also common, with larger, older males usually winning agonistic interactions. These findings suggest that coati social structure directly influence foraging, and I therefore hypothized that the coati social system is monitored (in part) by body size sexual dimorphism interacting with reliance on patchy defendable foods. Female group living allows increased access to patchy resources that are otherwise unavailable due to small body size relative to competing male. In contrast, larger male are able to access food patches without living in groups that might increase foraging competition.
To benefit from group living, group members need to keep the group cohesive by coordinating time and direction of travelling. Self-organization and leadership are two means of coordination and two types of decision can be made on the group level: combined and consensus. We studied the initiation process of group movements during the morning departure of a group of chacma baboons, Papio hamadryas ursinus, from its sleeping site in De Hoop Nature Reserve, South Africa. Findings from other female-bonded primate groups led us to hypothesize that females should play a major role in the decision-making process. Approximately 75% of the adults made a start attempt, with 62 of 92 attempts being by males. There was no sex difference in the probability of being successful when initiating an attempt. Lactating females initiated fewer than pregnant or cycling females. Thus, at least for this group of chacma baboons, leadership appeared to be distributed and the decision about the timing of departure and travel direction seemed to be a partially shared consensus decision with adult males contributing more to the decision outcome, with a slightly more prominent role of the dominant male. Our results do not support the ‘leading females’ hypothesis. No behavioural patterns that might serve as specialized signals leading to a more successful recruitment of other group members were observed. The departure process appeared to be coordinated merely through individuals setting an example by moving off.
Teeth-baring in a large captive rhesus monkey group (Macaca mulatta) was observed over a 30-month period. Its directional consistency among adults was significantly higher than that of aggression. The unidirectionality was so extreme that the facial display must be seen as a formal status indicator; ie, a signal of which the direction is independent of short-term contextual variation. As such, it seems adapted for communication about the state of the relationship. Formal dominance relationships among adults could be arranged in a hierarchy which approached perfect linearity. Focal observations demonstrated that teeth-baring was associated with withdrawal. It was uncommon among foraging monkeys, perhaps because dominant animals paid less attention to their subordinates in this context. The speed of rank acquisition by young females, in terms of received teeth-baring, was highest among peers and lowest against the group's old matriarchs. The age at which dominance over unrelated adult females was achieved correlated negatively with the amount of affiliative contact with these females. This translates into a positive correlation between bonding and rank establishment, indicating that dominance processes may be indistinguishable from social integration.
Behaviour patterns related to the coordination of group members and the spatial integration of the reproductive units of gelada baboons (Theropithecus gelada) were examined in order to determine how group cohesion is maintained. The dominant female tended to maintain a spatial position nearest to the male during non-social periods, where she fulfilled a pivotal role maintaining coordination between the male and the rest of his females. Females tended to strike a balance between maintaining visual contact with the male and keeping near their preferred social partners. Progressions were usually initiated by lactating females, but decisions about whether initiated leads are followed up by the unit as a whole were shared between the male and the dominant female. The male and the dominant female were also found to play an important role in maintaining the unit's spatial integrity by threatening away members of other units and by giving support to members of their own unit who were threatened by other units.
The chapter examines two phylogenetically fixed traits in the behavioral repertoire of the dwarf mongoose; indicate the constraints they place on the species from behavioral, sociological, or ecological standpoints, and show how these constraints have been circumvented through the evolution of behavior patterns or social systems, which compensate for their presence. Two behavior patterns in the repertoire of the dwarf mongoose are considered in this chapter to illustrate their intrinsic involvement with the ecology and sociology of the species from the point of view of adaptation and imposed constraints, and their proximate and ultimate effects on survival. Their association with territoriality and their relationship with predation avoidance are considered in the discussion, as are the advantages and disadvantages of group territoriality in the light of the constraints these behavior patterns impose. Group life of dwarf mongoose appears to have evolved as a means of protection against predators, not only of the young, as in many animals that form groups during the breeding season, but of the adult members as well. Behavioral mechanisms have evolved to counter both avian and ground predation, these being more or less effective depending on the predator concerned.
We have looked at different taxonomic groups to reveal where self-organization theory can make an important contribution to explaining collective behavioral patterns. Because this is a newer area of research, and because vertebrate groups may be difficult to study, developing theories of self-organization for these groups (which can then be tested empirically) is particularly challenging. Consequently we focused on how modeling approaches (particularly those that are individual based) have been, and are being, used to help reveal the organizational principles in human crowds (Sections II.B.1 and II.C), ungulate herds (Section II.A), fish schools, bird flocks (Section II.D), and primate groups (Section III.C). The collective behavior of such systems is largely characterized by the interactions among individual components, and thus is well suited to an approach that seeks to elucidate generative behavioral rules. We also discussed the evolution of collective behaviors (Section II.D.3). Here, theory has been important in demonstrating that different collective behaviors can exist for identical individual behaviors, suggesting that the evolution of collective (extended) phenotypes may be more complex than it may, at first, appear. Behavioral differences among individuals within a group may have an important internal structuring influence, and by using simulation models we showed how individuals can modify their positions relative to other group members (e.g., to move relative to the front or center of a group) without necessitating information about their current position within the group (Section III.B). This is important because it is unlikely that individuals within large groups (e.g., pelagic fish schools) can determine their absolute position relative to all other group members; thus we argue that natural selection is likely to act on the kind of local rules we discussed. In Section IV we discussed how local self-organized interactions result in the distribution of animals at a larger spatial and temporal scale, showing how mathematical studies of group size distributions are being used to make testable predictions about how individual behavior translates to that at the level of a population (Sections IV.A and IV.B) and how differences among individuals within a population may lead to phenotypically assorted groups within a population (Section IV.C). We also addressed the "optimal group size" concept (Section IV.D). As an alternative to the view in which individuals explicitly assess the size of groups and then make a decision to leave or join, we showed how local rules of thumb could be used by individuals to modify their probability of being within a group of a given size. We demonstrated that in real organisms (schooling fish) group size distributions (and hence the probability of an individual being within a group of certain size) is context dependent, and that this behavior is entirely consistent with a self-organized mechanism whereby individuals change local interactions as conditions change. In considering self-organization within vertebrate groups it is evident that the organization at one level (e.g., that of the group) relates to that at higher levels (e.g., that of the population). For example, self-sorting processes that lead to internal structuring within groups also result in population-level patterns when such groups fragment (e.g., phenotypic assortment), thus affecting the probability that an individual will be in a group of a given size and composition at any moment in time. These population properties then feed back to the individual interactions by changing the probability of encounters among different members of a population. Thus, to understand collective behaviors fully these properties cannot necessarily be considered in isolation.
I examine leadership in Wolf (Canis lupus) packs based on published observations and data gathered during summers from 1986 to 1998 studying a free-ranging pack of Wolves on Ellesmere Island that were habituated to my presence. The breed- ing male tended to initiate activities associated with foraging and travel, and the breeding female to initiate, and predomi- nate in, pup care and protection. However, there was considerable overlap and interaction during these activities such that leadership could be considered a joint function. In packs with multiple breeders, quantitative information about leadership is needed.
Submission in the wolf and dog is defined on the basis ot its motivation: submission is the effort of the inferior to attain friendly or harmonic social integration.
Submission functions as an appeal or a contribution to social integration, but only if it meets a corresponding attitude in the superior. The form of submissive behavior in wolf and dog is ritualized and symbolized cub-behavior. Two main forms of submissive behavior occur in wolf and dog: active submission, derived from begging for milk or food, and passive submission, derived from the posture which the cub adopts when cleaned by its mother.
The definition of submission is generally applicable to vertebrates living in groups based on intimacy and a social hierarchical order. The concept of submission as the role of the defeated in the terminal phase of fight with the function to inhibit automatically aggression in the superior should be dismissed. In vertebrates at least three types of conflict with different terminal phases occur: (1). Severe fight based on intolerance; ends with flight by the inferior or with his death. (2). Ritualized fight over a privilege; ends with the “giving-up-the-claim ritual” of the inferior, which automatically blocks the aggression of the superior. (3). Minor conflict in closed groups; settled by submissive behavior of the inferior.
In closed vertebrate groups, intermediate forms between (1) and (3) occur, depending on the proportion between activated intimacy and intolerance.
Seven major types of sampling for observational studies of social behavior have been found in the literature. These methods differ considerably in their suitability for providing unbiased data of various kinds. Below is a summary of the major recommended uses of each technique: In this paper, I have tried to point out the major strengths and weaknesses of each sampling method. Some methods are intrinsically biased with respect to many variables, others to fewer. In choosing a sampling method the main question is whether the procedure results in a biased sample of the variables under study. A method can produce a biased sample directly, as a result of intrinsic bias with respect to a study variable, or secondarily due to some degree of dependence (correlation) between the study variable and a directly-biased variable. In order to choose a sampling technique, the observer needs to consider carefully the characteristics of behavior and social interactions that are relevant to the study population and the research questions at hand. In most studies one will not have adequate empirical knowledge of the dependencies between relevant variables. Under the circumstances, the observer should avoid intrinsic biases to whatever extent possible, in particular those that direcly affect the variables under study. Finally, it will often be possible to use more than one sampling method in a study. Such samples can be taken successively or, under favorable conditions, even concurrently. For example, we have found it possible to take Instantaneous Samples of the identities and distances of nearest neighbors of a focal individual at five or ten minute intervals during Focal-Animal (behavior) Samples on that individual. Often during Focal-Animal Sampling one can also record All Occurrences of Some Behaviors, for the whole social group, for categories of conspicuous behavior, such as predation, intergroup contact, drinking, and so on. The extent to which concurrent multiple sampling is feasible will depend very much on the behavior categories and rate of occurrence, the observational conditions, etc. Where feasible, such multiple sampling can greatly aid in the efficient use of research time.
This paper reports quantitative leadership differences in semi-captive bar-headed geese (Anser indicus) at different times of the year, and in different types of groups. Leading is defined here as causing the departure or determining the direction of movement of the whole group. No permanent and exclusive leader of a pair or family group was found, rather relative leading frequencies of male, female and young showed a definite shifting pattern. Females led more often than their mates prior to breeding, and on nest pauses during the incubation period, but less often in summer, autumn and early winter. In families there was no difference between the frequencies of male and female leading. Family females led relatively more often than those of pairs without offspring. This difference was related to the presence, not the number, of young. Goslings led the family about as often as the parents during the rearing period in early summer, less often in autumn, winter and next spring. Such differences and changes are to be expected where competence in particular tasks and dependence on partners vary between group members, and where different situations require different abilities. For the geese, the results can be related to the different options of group members and to the different benefits they derive from leaving (or 'staying put') or following (or waiting for the others) in different situations.