Individual and social determinants of spontaneous group movements in cattle and sheep

Group-living animals travel together to collectively exploit the resources of their environment. This study investigates how social relationships and individual temperament traits affect movement orders in domestic cattle and sheep. We analysed spontaneous group movements occurring at pasture after a resting period in a group of 15 18-month-old Charolais heifers and a group of 19 1-year-old Romane ewe-lambs. For each species, animals had similar social experience and no kinship ties. Before that, animals were observed within the group to establish their social status (e.g. dominance and preferential relationships, and sociability), then in individual tests in order to assess their emotional traits. In both species, most individuals could initiate a group movement but some individuals were more successful than others in recruiting the rest of the group. Ewe-lambs, and to a lesser extent heifers, held preferential positions during travel. We did not find any significant correlations in either species between animal order and their position in the dominance hierarchy (heifers: P = 0.438; ewe-lambs: P = 0.574) while individuals linked by preferential bonds frequently followed each other during group movements (heifers: P < 0.001; ewe-lambs: P < 0.001). With regard to social traits, heifers with a low cohesion index, and with a lower number of partners with whom they develop frequent affinitive interactions, acted more frequently as 'first movers' (P = 0.040 and 0.023, respectively), as well as did ewe-lambs with a high spatial independency index (P = 0.002). Ewe-lambs with the highest cohesion indices were more frequently observed in front of the group while moving halfway between departure and arrival (P = 0.028). We did not find significant correlations between individual positions during group movements and emotional traits such as reactivity, boldness and fearfulness. We conclude that preferential bonds and individual traits related to social dependence were more influential in spontaneous group movements at pasture than were emotional traits and dominance status.     

How many for dinner? Recruitment and monitoring by glances in capuchins

Group members present physical and physiological differences according to their age, sex or social status, which could generate motivation differences among individuals during travel. In spite of these divergences of interest among individuals, the group succeeds more often than not in making a collective decision about departure time and which direction to take. To reach a consensus decision, animals should exchange information relating to characteristics of group movement through different communication channels. The main purpose of this study is to understand the function of behaviour patterns displayed during movements of white-faced capuchins (Cebus capucinus). We designed experiments in which we provoked collective movements involving a binary choice. During experiments, a video camera recorded the behaviour of each capuchin, which enabled us to determine which individuals displayed a behavioural pattern during travel and how this behaviour influenced the other group members. We found that looking backwards seemed to permit the recruitment of group mates during collective movement. This behaviour also seemed to allow the quantification of the number of followers, since the emitter modified its locomotion speed according to this number. In this preliminary study, we showed that visual behaviour was used to recruit and monitor group mates during collective movements and provided information on mechanisms involved in maintaining cohesion and coordination among group members during travel.     

Social Structure Affects Initiations of Group Movements but Not Recruitment Success in Japanese Macaques (<Emphasis Type="Italic">Macaca fuscata</Emphasis>)

Research on collective movements has often focused on the sociodemographic parameters explaining the success of some individuals as leaders or initiators of collective movements. Several of these studies have shown the influence of social structure, through kinship and affiliative relationships, on the organization of collective movements. However, these studies have been conducted on semi-free-ranging groups of macaques that were not faced with a natural environment and its constraints. In the socially intolerant rhesus macaque (Macaca mulatta) the success of an initiator correlates with its hierarchical rank, the most dominant individuals being the most successful. We investigated the collective movements of another socially intolerant macaque species, Japanese macaques, in the wild, to assess whether the social structure was still a determinant factor under natural conditions. In line with previous studies of macaques, we found that social structure drove the organization of collective movements. More dominant individuals initiated more collective movements. However, dominance did not affect the success of an initiation, i.e., the number of individuals joining. In addition, kinship strongly constrained the associations observed in females during collective movements. These results reflect the social structure of Japanese macaques, in which strong power asymmetry and kinship relationships constrain the majority of interactions between individuals within the group. Moreover, these results are similar to those observed in semi-free-ranging rhesus macaques and support the hypothesis of an effect of social determinants on collective movements of primates even under natural conditions.     

Sex differences in leadership during group movement in mantled howler monkeys (Alouatta palliata)

Benefits of group life depend in large part on whether animals remain cohesive, which often requires collective decisions about where and when to move. During a group movement, the leader may be considered as the individual occupying the vanguard position of the group progression, when its movement evokes following by other group members. In nondespotic societies, individuals with greater incentives to move frequently are leaders. During 15 months of observations (1,712 contact hours), we investigated two mantled howler monkey (Alouatta palliata) groups at La Flor de Catemaco (Los Tuxtlas, Mexico) to examine whether sex and female reproductive state influenced leadership likelihood in two contexts: movements toward feeding trees; movements associated with loud calls, a group-defense behavior used by males of this genus. Females led and occupied forward positions during group movements toward feeding trees more often than adult males. Adult females led these movements more frequently when they were gestating than when they were lactating or cycling. There were no differences between sexes in the leadership of group movements associated with loud calls. Leadership by gestating females is perhaps the result of their higher nutritional/energetic needs when compared with cycling females, and of their greater mobility when compared with lactating females carrying dependent offspring. Female leadership during movements toward feeding trees may be a mechanism to optimize access to food resources in mantled howler monkeys.     

Hazing and movements of Canada geese near Elmendorf Air Force Base in Anchorage, Alaska

Bird strikes to aircraft are a serious economic and safety problem in the United States, annually causing millions of dollars in damage to civilian and military aircraft and the occasional loss of human life. We observed movements of 1236 neckbanded lesser Canada geese (Branta canadensis parvipes) to determine efficacy of hazing as a means to reduce goose presence at Elmendorf Air Force Base (EAFB), Anchorage, Alaska from August to October 1997. Emphasis was on movements of geese onto EAFB with additional data collected at the other two major airports in the area, Anchorage International Airport (AIA) and Merrill Field Airport (MFA). Daily observations indicated the presence of 208 individual neckbanded geese on EAFB, and 20% returned more than once after being hazed from EAFB. We identified three staging areas, geese utilized prior to entering EAFB, and three post-hazing dispersal sites. Collared geese began moving onto EAFB 30–40 days post-molt with the largest proportions moving onto EAFB 70–90 days post-molt. We observed 75 neckbanded geese on AIA from seven molting sites, and 23% returned more than once after being hazed from AIA. We observed 141 neckbanded geese on MFA from 14 molting sites, and 21% returned more than once after being hazed from MFA. Our data indicated that as long as local goose populations increase, large numbers of Anchorage area geese are likely to enter one of the airports creating a variety of management problems. Hazed geese returning to airports multiple times present a special hazard to aircraft safety because they appear to have become habituated to non-lethal scare tactics. We recommend an integrated management approach to limit the Anchorage area goose population utilizing various control techniques which are acceptable to Anchorage residents while continuing the hazing program at area airports.     

Scanning pattern of greater rheas,<Emphasis Type="Italic"> Rhea americana</Emphasis>: collective vigilance would increase the probability of detecting a predator

Many models using vigilance to predict the probability of detecting an approaching predator assumes that prey scanning events should be produced at random. Consequently, the length of intervals among successive scans must follow a negative exponential distribution. We analyzed the scanning behavior of the greater rhea, Rhea americana, which is a gregarious, flightless bird, in eastern Argentina. We investigated whether individual and/or collective scanning departed from random and whether this departure varied with group size. We used two simulation models based on observed scanning sequences to assess the effectiveness of vigilance on the individual and collective level when faced with an opportunistic or stalking predator. The analysis of 59 behavioral sequences of wild greater rheas foraging solitary or in groups of two to six or more individuals revealed that the inter-scan length of individual sequences significantly departed from random. In contrast, inter-scan intervals for collective vigilance were shorter than individual ones, but only fit the random expectation for groups of two and five individuals. Models showed that collective vigilance could increase the probability of detecting a predator, thereby reducing their vulnerability, independent of whether the predator uses a stalking or opportunistic approaching strategy.     

Interspecific Mate Choice Following Cross-fostering in a Mixed Colony of Greylag Geese (Anser anser) and Canada Geese (Branta canadensis). A Study on Development and Persistence of Species Preferences1

The role of early experience in mate choice and species preference of geese was studied in an experiment where young greylag geese (Anser anser) were cross-fostered by Canada geese (Branta canadensis). In two successive years, all eggs from 9 nests of wild Canada geese were removed and replaced by greylag goose eggs. The young greylag geese then followed their Canada goose foster parents on their southward migration in autumn, to return with them in spring. Of 35 returning birds, all 16 females paired with greylag goose males (100%) whereas of 19 males 5 paired with Canada goose females (14%) and the remaining 14 with greylag goose females (74%). The pair bonds generally persisted as long as both birds were present, but after loss of a partner, the remaining bird usually re-mated. Even when this happened several times during the lifetime of a male, the new mate was always a Canada goose female, showing that the males were sexually imprinted to this species. The Canada goose females which had mated with the greylag ganders also remated when widowed, but their new mate could be either a Canada goose or a greylag goose.     

Do greylag geese ( Anser anser) use traditional roosts? Site fidelity of colour-marked Nordic greylag geese during spring migration

In 1995 to 2000, site-fidelity of colour-marked Nordic greylag geese (Anser anser) was examined during spring migration in the Rheiderland, an important stopover site in NW Germany. The results demonstrated that site fidelity in greylag geese depends very much on the mating status of the geese. Paired birds showed a significantly higher site fidelity than unpaired adults. There was no difference in the length of the roosting period between the two social groups. The year-to-year return rate of individuals showed significant differences in relation to the individual breeding success. Birds with high numbers of young showed a significantly higher return rate than birds with low numbers of young.Communicated by F. Bairlein     

Inter- and intra-season stability of vocal individual signatures in a social seabird, the crested auklet

Vocal plasticity due to changes of social context is well documented in passerine birds. In other bird species, the impact of social environment changes on the whole vocal structure and on individual specific signatures remains largely unexplored. Here, we assessed inter- and intra-season stability of specific features of individual signatures in advertising calls of crested auklet (Aethia cristatella) males and tested the effects of pair mate and territory changes on the stability of the calls. The crested auklet is a highly social seabird of the North Pacific that breeds in dense colonies, and its individuals switch pair mates and territories with probability of 25–54%. During summer 2008–2010, we recorded 464 trumpet calls from 21 individually marked males and determined their pair mates and positions of their displaying places on a breeding colony of Talan Island, Sea of Okhotsk. We found that strong individual specific features of crested auklet trumpet calls stay stable not only during one season but also from year to year. However, we failed to find any effects of pair mate or territory changes on individual signatures of crested auklet trumpet calls. Our results suggest that crested auklets can potentially use their individually specific trumpet calls to form long-term social bonds both between pair mates and between neighbors; however, future experimental studies should test whether this is indeed the case.     

The Organization of Collective Group Movements in Wild Barbary Macaques (Macaca sylvanus): Social Structure Drives Processes of Group Coordination in Macaques

Social animals have to coordinate activities and collective movements to benefit from the advantages of group living. Animals in large groups maintain cohesion by self-organization processes whereas in smaller groups consensus decisions can be reached. Where consensus decisions are relevant leadership may emerge. Variation in the organization of collective movements has been linked to variation in female social tolerance among macaque species ranging from despotic to egalitarian. Here we investigated the processes underlying group movements in a wild macaque species characterized by a degree of social tolerance intermediate to previously studied congeneric species. We focused on processes before, during and after the departure of the first individual. To this end, we observed one group of wild Barbary macaques (Macaca sylvanus) in the Middle Atlas, Morocco using all-occurrence behaviour sampling of 199 collective movements. We found that initiators of a collective movement usually chose the direction in which more individuals displayed pre-departure behavior. Dominant individuals contributed to group movements more than subordinates, especially juveniles, measured as frequencies of successful initiations and pre-departure behaviour. Joining was determined by affiliative relationships and the number of individuals that already joined the movement (mimetism). Thus, in our study group partially shared consensus decisions mediated by selective mimetism seemed to be prevalent, overall supporting the suggestion that a species’ social style affects the organization of group movements. As only the most tolerant species show equally shared consensus decisions whereas in others the decision is partially shared with a bias to dominant individuals the type of consensus decisions seems to follow a stepwise relation. Joining order may also follow a stepwise, however opposite, relationship, because dominance only determined joining in highly despotic, but not in intermediate and tolerant species.     

Effects of Passive Social Support in Juvenile Greylag Geese (Anser anser): A Study from Fledging to Adulthood

In general, support by social allies may reduce stress, increase an individual's status and facilitate access to resources. In Greylag geese (Anser anser), offspring stay with their parents for an entire year or even longer and thereby enjoy social support in encounters with other flock members. We investigated the influence of spatial distance to one's allies on the outcome of agonistic encounters in a natural flock situation for a total of 12 sibling groups after fledging. In addition, we tested two groups of hand‐raised juvenile geese over a time span of 11/2 yr. Passive (i.e. not interfering) human supporters of different familiarity were placed at a standard distance during food provisionings, which produced a tight flock situation. Success in agonistic interactions increased with decreasing distance to members of their social unit. The hand‐raised juveniles were more successful in agonistic interactions and showed increased feeding rates when accompanied by a familiar human than when alone or with a non‐familiar human. The effect of the presence of familiar humans on success in agonistic encounters significantly decreased with increasing age, while feeding rates remained elevated. The positive effects of social support were particularly evident in females. We conclude that social support has similar effects and functions in the highly social greylag geese as reported for social mammals.     

The effect of boldness on decision-making in barnacle geese is group-size-dependent

In group-living species, decisions made by individuals may result in collective behaviours. A central question in understanding collective behaviours is how individual variation in phenotype affects collective behaviours. However, how the personality of individuals affects collective decisions in groups remains poorly understood. Here, we investigated the role of boldness on the decision-making process in different-sized groups of barnacle geese. Naive barnacle geese, differing in boldness score, were introduced in a labyrinth in groups with either one or three informed demonstrators. The demonstrators possessed information about the route through the labyrinth. In pairs, the probability of choosing a route prior to the informed demonstrator increased with increasing boldness score: bolder individuals decided more often for themselves where to go compared with shyer individuals, whereas shyer individuals waited more often for the demonstrators to decide and followed this information. In groups of four individuals, however, there was no effect of boldness on decision-making, suggesting that individual differences were less important with increasing group size. Our experimental results show that personality is important in collective decisions in pairs of barnacle geese, and suggest that bolder individuals have a greater influence over the outcome of decisions in groups.     

Female Coordination of Group Travel in Wild Propithecus and Eulemur

Coordination of primate group movements by individual group members is generally categorized as leadership behavior, which entails several steps: deciding where to move next, initiating travel, and leading a group between food, water sources, and rest sites. Presumably, leaders are able to influence their daily foraging efficiency and nutritional intake, which could influence an individual's feeding ecology and long-term reproductive success. Within anthropoid species, females lead group movements in most female-bonded groups, while males lead groups in most nonfemale-bonded groups. Group leadership has not been described for social prosimians, which are typically not female-bonded. We describe group movements in two nonfemale-bonded, lemurid species living in southeastern Madagascar, Propithecus diadema edwardsi and Eulemur fulvus rufus. Although several social lemurids exhibit female dominance Eulemur fulvus rufus does not, and evidence for female dominance is equivocal in Propithecus diadema edwardsi. Given the ecological stresses that females face during reproduction, we predict that females in these two species will implement alternative behavioral strategies such as group leadership in conjunction with, or in the absence of, dominance interactions to improve access to food. We found that females in both species initiated and led group movements significantly more often than males did. In groups with multiple females, one female was primarily responsible for initiating and leading group movements. We conclude that female nutritional needs may determine ranging behavior to a large extent in these prosimian species, at least during months of gestation and lactation.     

Modeling the flocking propensity of passerine birds in two Neotropical habitats

We examined the importance of mixed-species flock abundance, individual bird home range size, foraging height, and foraging patch characteristics in predicting the propensity for five Neotropical passerine bird species (Slaty Antwren, Myrmotherula schisticolor; Golden-crowned Warbler, Basileuterus culicivorus; Slate-throated Redstart, Myioborus miniatus; Wilson’s Warbler, Wilsonia pusilla; and Black-and-white Warbler, Mniotilta varia) to forage within flocks, rather than solitarily. We used study plots in primary mid-elevation forest and in shade coffee fields in western Panama. We expected that all species would spend as much time as possible flocking, but that the social and environmental factors listed above would limit compatibility between flock movements and individual bird movements, explaining variability in flocking propensity both within and among species. Flocking propensity was well predicted by home range size and flock abundance together, for four of the five species. While flock abundance was uniform across plots, home range sizes varied among species and plots, so that home range size appeared to be the principle factor limiting flocking propensity. Estimates of flock abundance were still required, however, for calculating flocking propensity values. Foraging height and patch characteristics slightly improved predictive ability for the remaining species, M. miniatus. In general, individual birds tended to join flocks whenever one was available inside their home range, regardless of a flock’s specific location within the home range. Flocking propensities of individual species were lower in shade coffee fields than in forests, and probably vary across landscapes with variations in habitat. This variability affects the stability and species composition of flocks, and may affect survival rates of individual species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The effects of individual interactions and habitat preferences on spatial structure in a grassland bird community

Spatial structure and the distribution of individuals within a community might be influenced by several factors such as habitat heterogeneity and local interactions among individuals of the same and different species. We investigated the spatial distributions of eight bird species in a grassland community during the breeding season and examined whether the spatial distributions of individuals were influenced by interactions among neighboring individuals or different habitat preferences of different bird species.
In order to identify the effects of the interactions among neighboring individuals and habitat preference, we developed a randomization test in which species identifications were randomly allocated to the observed individual positions within areas with the same vegetation structure. The randomization test indicated that individuals tend to have territories near the territories of individuals of the same species or of a particular species more frequently (or less frequently) than those expected from random distributions of individuals.
Among these associations, only one case was explained by individual interactions, and 19 cases were explained by habitat preference.
The results suggest that both individual interactions and habitat preference affected the spatial distributions of individuals and possibly influence the species compositions and diversity in grassland bird communities.     

Grunt to go—Vocal coordination of group movements in redfronted lemurs

To remain cohesive as a group, individuals must coordinate their movements between resources. In many species, vocalisations are used in this context. While some species have specific movement calls, others use calls which are also employed in different contexts. The use of such multicontextual calls has rarely been studied quantitatively, especially during both the pre‐departure and departure period associated with collective decisions. We thus investigated the use of close calls (“grunts”) for the coordination of collective movements in four groups of wild redfronted lemurs (Eulemur rufifrons) in Kirindy Forest, Western Madagascar. Group movements are started by an initiator, who moves away from the group and is joined by followers setting out in the same direction. We observed collective movements and recorded vocalisations from 18 focal individuals (54 movements recorded for followers, 21 for initiators). The grunt rate of both initiators and followers was higher in the pre‐departure period than in a control context (i.e., during foraging). Initiators of collective movements grunted more often than followers in the pre‐departure period as well as at individual departure. The latter difference was due to the initiators’ grunt rates increasing earlier than the followers’ and remaining at an elevated level for longer. These observations suggest that grunts serve to coordinate the departure by indicating the individual's readiness to move. The pre‐departure period, in which both initiators and followers showed an elevated grunt rate, may provide the basis for a shared decision on departure time. The difference in initiator and follower call rates suggests that grunts may have a recruitment function, but playback experiments are required to test this potential function. Overall, our study describes how multicontextual close calls can function as movement calls, with changes in call rate providing a potential feedback mechanism for the timing of group movements. This study thus contributes to a more detailed understanding of the mechanisms of group coordination and collective decision‐making.     

Organization of Group Members at Departure Is Driven by Social Structure in Macaca

Researchers have often explained order of progression of group members during joint movement in terms of the influence of ecological pressures but rarely that of social constraints. We studied the order of joining by group members to a movement in semifree-ranging macaques with contrasting social systems: 1 group of Tonkean macaques (Macaca tonkeana) and 1 group of rhesus macaques (M. mulatta). We used network metrics to understand roles and associations among individuals. The way the macaques joined a movement reflected the social differences between the species in terms of dominance and kinship. Old and dominant male rhesus macaques were more often at the front of the movement, contrary to the Tonkean macaques, which exhibited no specific order. Moreover, rhesus macaques preferred to join high-ranking or related individuals, whereas Tonkean macaques based associations during joining mostly on sexual relationships with a subgroup of peripheral males.     

Leapfrog migration and residents: New migratory habits in Swedish Greylag geese

Knowledge about intraspecific and individual variation in bird migration behavior is important to predict spatiotemporal distribution, patterns of phenology, breeding success, and interactions with the surrounding environment (e.g., human livelihoods). Such variation is key to adaptive, evolutionary responses, i.e., how individuals respond spatiotemporally to the environment to maximize fitness. In this study we used GPS location data from one to three full annual cycles from 76 Greylag geese (Anser anser) to test the hypothesis that geese originating at five latitudinally separated capture sites in Sweden have different migration strategies. We also assessed individual consistency in movement strategy over consecutive annual cycles. We used the scale‐independent net squared displacement modeling framework to quantify variables of autumn and spring migration for geese from each capture site: distance, timing, and duration. Our results demonstrate a positive correlation between migration distance and latitudinal origin. Geese from the northernmost site on average migrated farther south and about 15 times as far as the short‐moving or resident geese from the two southernmost sites. Movement strategies of individual geese varied considerably both within and among capture sites. Individual consistency in movement strategy from one annual cycle to the consecutive was high in geese from the northern sites moving the farthest, whereas the resident or short‐moving geese from the southernmost sites generally showed lower or no individual consistency. These changes have come about during a time span so short (i.e., ca. 35 years or 8–10 generations) that it can unlikely be explained by classical Darwinian between‐generation adaptation. Consequently, and given that young geese follow their parents during their first migration, we presume an important role of within‐family, inter‐generation change as a driver behind the large‐scale changed migration habits in Swedish Greylag geese.     

Collective Factors Reinforce Individual Contributions to Human-Wildlife Coexistence

Conserving large carnivores while keeping people safe depends on finding means for peaceful coexistence. Although large carnivore populations are generally declining globally, some populations are increasing, causing greater overlap with humans and increasing potential for conflict. One method of reducing conflict with large carnivores is to secure attractants like garbage and livestock. This method is effective when implemented; however, implementation requires a change in human behavior. Human-wildlife interaction is a public good collective action problem where solutions require contributions from many and individual actions have effects on others. We used the collective interest model to investigate how individual and collective factors work in concert to influence landowner attractant securing behavior in Montana, USA, in black (Ursus americanus) and grizzly bear (U. arctos) range. We used data from a mail-back survey to develop logistic regression models testing the relative effects of collective and individual factors on landowners' attractant securing behaviors. The most important factor was whether individuals had spoken to a wildlife professional, a reflection of social coordination and pressure. Other collective factors (e.g., social norms [i.e., expectations and behaviors of peers] and the existence of discussion networks [i.e., how much social influence an individual has]) were equally important as individual factors (e.g., beliefs, age, gender) for influencing attractant securing behavior among Montana landowners. This research suggests pathways for wildlife managers and outreach coordinators to increase attractant securing behavior by emphasizing collective factors, such as social norms, rather than appealing exclusively to individual factors, such as risk perception of large carnivores. Furthermore, wildlife agencies would be justified in increasing their efforts to connect with landowners in person and to connect with members of the public who play an important role in discussion networks. This research demonstrates that, even on private lands, collective interests may be a missing and important piece of the puzzle for encouraging voluntary attractant securing behavior and improving wildlife-human coexistence. © 2021 The Wildlife Society.     

Benefits of family reunions: social support in secondary greylag goose families

Social interactions are among the most potent stressors. However, social allies may diminish stress, increase success in agonistic encounters and ease access to resources. We studied the role of social support as a major mechanism for individual stress management in families of free-ranging greylag geese (Anser anser). Greylag geese are long-term monogamous, live in a female-bonded social system, and fledged offspring stay with their parents until the next breeding season (‘primary families’). Should parents then fail to fledge young, subadults might rejoin them in summer after molt is completed (‘secondary families’). We have previously shown that primary greylag goose families reap benefits from active social support in agonistic encounters, and also excrete lower levels of immuno-reactive corticosterone metabolites (CORT, ‘passive social support’). Here we investigated how far active and passive social support continues in secondary goose families. Although we found that active support in agonistic encounters was almost absent in secondary families, subadult male geese won an increased number of agonistic encounters due to the mere presence of their secondary family. Particularly adult and subadult females benefited from passive social support through decreased CORT, whereas males did not. Decrease in the hormonal stress response during challenging situations, induced by social allies, may help the females' long-term energy management, thereby improving the odds for successful future reproduction. We discuss whether joining a secondary family may be an alternative tactic for young geese towards optimizing their start into a complex social life.