Showing papers in "Behaviour in 2003"

Is the dog-human relationship an attachment bond? An observational study using Ainsworth's strange situation

Abstract: Ainsworth's 'strange situation' procedure was used to investigate the dog ( Canis familiaris ) - human relationship. 38 adult dog-owner pairs were observed in an unfamiliar room, introduced to a human stranger and subjected to four short episodes of separation. The procedure and behavioural analyses were as similar as possible to those used in studying human infants, except for the inclusion of an extra separation period in which the dogs were left alone in the room with articles of clothing belonging to the owner and stranger. A secure base effect was suggested by the fact that the dogs accepted to play with the stranger more in the presence of their owner than during his or her absence. They also explored more in the presence of their owner, but this appeared to be due to diminishing curiosity over time rather than a secure base effect. The dogs also exhibited a range of attachment behaviours, i.e. search and proximity seeking behaviours when separated from their owner, including following, scratching and jumping up on the door, remaining oriented to the door or the owner's empty chair and vocalising. They also greeted their owner more enthusiastically and for longer durations compared to the stranger. Finally, they contacted the owner's clothing more often and for longer durations compared to the stranger's clothing and spent more time next to the owner's chair when the owner's objects were present. Hence, the dogs' behaviour in the strange situation was very similar to that reported in human infants and chimpanzees. However, despite conducting detailed behavioural analyses, the order effects inherent in Ainsworth's procedure prevented the study from providing conclusive evidence that the dog-human bond constitutes an attachment.

Temporal dynamics and communication of winner-effects in the crayfish, orconectes rusticus

Abstract: A variety of factors influences the formation of hierarchical structures, and can include an altered aggressive state, an ability to physically dominate, and previous agonistic experience. Using male Orconectes rusticus, we tested the duration of the winner effect by varying the time between a winning encounter and a subsequent encounter by a 20, 40 or 60-minute interval. Varying the time between the two fights significantly altered the probabilities of initiating fight behaviour and of winning a fight. A crayfish with a 20-minute delay between its winning experience and its subsequent fight was significantly less likely to initiate fight behaviour and significantly more likely to win its next fight than was an animal whose next fight was delayed for 40 or 60 minutes. We then investigated whether the dynamics of this winner effect were influenced by perception of odour signals during agonistic interactions by blocking the chemo- and mechanoreceptors on the antennae and antennules to prevent reception of relevant cues communicating social status. Individuals fighting an opponent with this loss of sensory information were significantly more likely to initiate a fight, but then escalated at a slower rate to a higher fight intensity level. In addition, individuals had a decreased chance of winning an agonistic bout against an opponent deprived of sensory input from the antennae and antennules.

Migratory Timing of Humpback Whales ( Megaptera novaeangliae ) in the Central North Pacific Varies with Age, Sex and Reproductive Status

Abstract: Humpback whales migrate seasonally between high-latitude summer feeding grounds and low-latitude winter breeding grounds. Identification photographs of humpback whales were collected in the Hawaiian Islands between 1977 and 1995, and sighting histories were compiled for individuals. Analyses revealed that (a) mean dates of first identification were significantly earlier for juveniles and females with no calf than for males and females with a calf off the Big Island, and significantly earlier for juveniles than for females with no calf, males and females with a calf off Maui; and (b) mean dates of last identification were significantly earlier for juveniles and females with no calf than for males and females with a calf off the Big Island, and significantly earlier for females with no calf than for males and females with a calf off Maui. A within-subjects comparison showed that the date of first identification tended to be later for individual females in the years when they had a calf than in the years during which they had no calf. It was concluded that (a) migratory timing varies as a function of age, sex and reproductive status, (b) migratory timing is intimately connected with reproductive success and (c) migratory timing has important consequences for our understanding of humpback whale behaviour on the winter grounds.

Food-associated Calls of Tufted Capuchin Monkeys (Cebus Apella Nigritus) Are Functionally Referential Signals

Abstract: In this paper I explore the possibility that tufted capuchin monkeys ( Cebus apella nigritus ) have food-associated calls, vocalizations that are functionally referential and may provide information about the presence of food to other individuals in the group. Functionally referential signals are those that meet two criteria: (1) they are context specific and (2) they elicit a response that is context independent. The study was conducted on a wild group of capuchins in a subtropical rain-forest in NE Argentina. To evaluate the degree of context specificity of the vocalizations I obtained focal animal sound recordings of the vocalizations emitted by individually recognized animals and indicated the socio-ecological context of call emission. I performed playback experiments to see if animals can respond to the food-associated calls in the absence of contextual information. Two vocalizations, grgrs and whistle series, were considered putative food-associated calls, because previous observations suggested an association of these vocalizations with the presence of food. Grgrs and whistle series were given at a higher rate when the focal animal was feeding on fruit at a highly productive source than in other socioecological contexts. Whistle series were also produced, although at a lower rate, in contexts other than feeding but whistle series given when feeding belong to an acoustically distinct type. Animals responded to the playback of food-associated calls with a rapid and direct movement to the speaker in almost 50% of the trials. Capuchins did not show this response to the playback of control stimuli. Food-associated calls in tufted capuchins can thus be considered functionally referential signals.

A Comparative Analysis of Social Play in Birds

Abstract: Summary Although social play is broadly distributed among mammals, it is infrequently encountered in other vertebrate taxa. It is, however, displayed in a fully realized and complex form in several groups of birds. Unambiguous accounts of social play have been recorded from thirteen species of parrots, seven species of corvids, and several hornbills and Eurasian babblers. We conducted an analysis of the avian play literature, testing for differences between avian taxa, as well as for correlations between play complexity, brain size, and age of first reproduction. Corvids were far more likely to show social object play than parrots. Corvids, parrots, and hornbills had larger relative brain sizes than would be predicted from a class-level allometric regression, but brain size was not associated with the complexity of social play among genera within taxa. Play complexity within parrots and corvids was, however, significantly associated with the age of first re production. The likelihood of complex social play appears to increase when delayed reproduction is accompanied by persisting relationships between adults and post-fledging juveniles. The adaptive significance of social play in birds thus offers intriguing parallels to similar analyses in mammals.

Social relationships in a group of horses without a mature stallion

Abstract: 1. The social relationships in a group of Icelandic horses without a mature stallion were studied. The horses were all familiar to each other. Mutual grooming and play relationships, spatial associations, dominance-subordinate relations and the effect of kinship on these relationships were analysed. 2. The social structure was clearly dominated by the behaviour of the adult mares. The horses preferred to form bonds within their social class (sex/age) and they kept close proximity with their friends. The group was effectively divided into two social subgroups, adult mares as one group and adult geldings and sub-adults as another group. The sub-adults and adult geldings formed associations, which were based on mutual grooming and play, while the adult mares did not play. Differences between the sexes were evident. Males played more than the females, had more playing partners and were more popular as playmates. 3. Aggression rates were low. The dominance hierarchy was linear. Adult mares ranked higher than adult geldings, sub-adults and the foals. Rank was significantly correlated with age. The closer the adult mares were in rank, the more they groomed with each other. Such relationships were not found amongst the other social group. 4. Kinship was calculated between all pairs of animals for up to 4 or 5 generations. Allogrooming and play frequencies and proximity were all positively correlated with kinship. Adult mares, which were close in the dominance hierarchy, were on average more related than those further apart. 5. The social relationships in the Icelandic herd were, to some extent, different from relationships reported from unmanaged and feral horse-herds with mature stallions and bachelors. Our results suggest that adult mares groom more in groups without a stallion. Furthermore, they have more preferred partners than in natural harems and their partners are other adult mares, not their weaned offspring as seems to be the case in feral herds. The sub-adults also seem to be more socially active in the absence of stallions. Interestingly, in the Icelandic group, the adult mares showed stallion like behaviours, like mounting and protecting foals. Only by studying the behaviour and the nature of the relationships of horses in groups of different compositions, can we expect to gain a comprehensive understanding about individual social strategies and cognitive capabilities of the species. Such knowledge is valuable for management and welfare of the horse.

Intra- and inter-sexual aggression by bonobos in the context of mating

Abstract: Previous work on bonobos (Pan paniscus) has focused on the role of aggression in the context of conflict resolution in captive groups. This study investigates events of aggressive behaviour of wild bonobos to evaluate its significance in the context of mating. Temporal association (15 minutes) between aggression and mating was used to assume functional relationship. The proportion of events that were found to be related to mating activity was highest for female-female aggression followed by male-male, male-female, and female-male aggression. The results suggest that intrasexual aggression is used to manipulate the mating success of competitors: Males competed for access to oestrus females, aggression between males was high on mating days, and aggressors had higher mating rates than targets. Harassment by females disturbed mating attempts of targets, the rate of aggression increased with the number of oestrous females per party and following harassment, aggressors tended to mate more often with the male partner of the target female. Unlike intrasexual aggression, support for the predicted functions of inter-sexual aggression in the context of mating was weak. Aggression by males against females was rare and was almost never followed by mating between aggressor and target. Female aggression against males occurred frequently but appeared to be independent of mating behaviour. The results did not support the female-defence alliance hypothesis (Parish, 1996). However, when males and females engaged in close association, the rate of aggression tended to be lower and rates of mating were higher than during control periods. We suggest that male intersexual aggression is incompatible with intersexual bonding and propose that the potential benefits that males derive from affiliative long-term association with females prevent males from being aggressive against females.

The Choice of Post-conflict Interactions in Wild Chimpanzees (Pan troglodytes)

Abstract: Summary Some costs of cone icts remain after an aggressive interaction has been terminated. Postcone ict management in social living animals can reduce those costs by means of a variety of interactions implemented after aggression ( e.g.reconciliation, consolation, redirected aggression). Each post-cone ict interaction (PCI) provides different advantages and disadvantages, although the functions may sometimes overlap. Individuals can therefore choose a PCI to achieve the most favourable outcome within a given cone ict situation. We examined 876 dyadic aggressive interactions among 18 wild chimpanzees ( Pan troglodytes verus ) of both sexes in the Tai National Park, Co te d’ Ivoire. We investigated which cone ict-condition led to which type of PCI and related the choice of PCI to its advantages and disadvantages. Tai chimpanzees used reconciliation to resolve cone icts among high value partners and when approaching the former opponent was unlikely to entail further aggression. Consolation seemed to substitute for reconciliation, when were opponents low value partners or approaching the former opponent was too risky, such as when further aggression was likely. Tai chimpanzees renewed aggression after undecided cone icts and when losers were unexpected. They used

Are Vigilance, Risk From Avian Predators and Group Size Consequences of Habitat Structure? A Comparison of Three Species of Squirrel Monkey (Saimiri oerstedii, S. boliviensis, and S. sciureus)

Abstract: We compared the interactions between vigilance, risk from avian predators, and typical group size for three species of squirrel monkey (Saimiri oerstedii, S. boliviensis, and S. sciureus). Field studies of each species in relatively undisturbed habitats provided data including behavioral interactions between avian predators and squirrel monkeys and the latter's vigilance response, habitat use, group size, population density and within-group food competition. Three hypotheses were examined. The first two identified aspects of the habitat structure exploited by squirrel monkeys and their avian predators as key parameters. (1) The overall success of avian attacks is a function of the density of understory vegetation present to hinder these birds from closely approaching individual troop members. (2) The extent of continuous canopy forest cover within habitats underlies which of two vigilance strategies are exhibited. Preemptive vigilance occurs when monkeys allocate time to visual scrutiny in a manner consistent with the intent of obtaining advance warning on the approach of an avian predator. During reactive vigilance, in contrast, monkeys are not overtly vigilant against an aerial attack until an attack or other stimulus strongly indicative of immediate risk occurs. Preemptive vigilance occurs in open habitats with little canopy, while reactive vigilance predominates when birds can make effective ambush attacks from forest canopy cover. Both hypotheses were supported. Group sizes vary significantly across the three squirrel monkey species with S. boliviensis having the largest and S. sciureus the smallest mean group size. Our third hypothesis examined the premise that group size in social animals reflects a tradeoff between predation risk (whether based on long-term observations or extrapolated from habitat structure) and within-group food competition. The power of this tradeoff mechanism to explain group-size variation was contrasted with a simpler, one parameter model, within-group food competition under an ideal free distribution. The ideal free distribution approach was consistent with the observed ranking of group sizes, whereas the tradeoff model provided mixed results. In retrospect, the weakness of the tradeoff model is not surprising. Changes in the risk incurred by individual members of a squirrel monkey troop as a consequence of variation in group size are likely of much smaller magnitude than the risk exposure resulting from local habitat structure.

Male consortship behaviour in chacma baboons: The role of demographic factors and female conceptive probabilities

Abstract: There is evidence for a general relationship between male dominance rank and mating success in primates, although the strength of this relationship differs among species In chacma baboons (Papio hamadryas ursinus) male rank is found to be of more importance than in the other savannah baboon subspecies However, even though the priority-of-access model explains the proportion of time spent in consortship for males of different rank in chacmas, highest-ranking males usually consort less often than expected In this study, conducted in the Drakensberg Mountains of Natal and at De Hoop in the Western Cape, we investigated why dominant males in four study troops consorted only between 50% and 75% of days that they were expected to consort according to the priority-of-access model Consortship success of highest-ranking males was primarily dependant on the number of available oestrous females in a troop This was likely due to costs involved in consorting which limit the amount of days that a male could spend in consortship Females pass through several cycles before conceiving and highest-ranking males were observed to consort more often on the conceptive cycle compared to the nearest nonconceptive cycle, but this was only true for males that were already resident for several months Recently immigrated males that became highest-ranking often consorted during nonconceptive female cycles, while older, lower-ranking males consorted during the conceptive cycles We propose that males with longer residency have more information about reproductive state of females and thus higher reproductive success than recently immigrated males

Appraising Behaviour During Male-male Interaction in the Japanese Horned Beetle Trypoxylus Dichotomus Septentrionalis (Kono)

Abstract: Detailed contest behaviour of the Japanese horned beetle, Trypoxylus dichotomus septentrionalis, was examined in the field. Male-male interactions have three sequences, and in these sequences four behavioural stages were recognized. After two males encountered (Stage 1), they always faced and shoved each other with their horns (Stage 2: 'Shoving'). Then, if the horn length or body size difference between the contestants was large, one male began to retreat and was chased by the other male, and the interactions terminated (Stage 4A: 'Chasing'). If the difference was small, the interactions proceeded to the escalated fighting stage (Stage 3: 'Pry'), in which two males put their horns under their opponents and push and try to flip them up each other. The interactions, which proceeded to Stage 3, have two ways of termination. If the body size difference was large, one male was flipped up by the other male, and the interactions was terminated quickly (Stage 4B). If the difference was small, the interactions was not terminated so quickly and continued until one male began to retreat, proceeding to Stage 4A. It is suggested that males with shorter horns relative to the opponents avoid the escalated fighting stage, 'Pry', after perceiving the horn length difference during 'Shoving', which would be an appraising behaviour. Thus, 'Shoving' is the most important stage among all the interaction processes in that the highest proportion of judgement is made here. The great allometric variation of horn length would presently function more greatly for enhancing the efficiency of mutual appraisal than that in actual fighting.

Sexual segregation in desert bighorn sheep (ovis canadensis mexicana)

Abstract: One or several factors could explain sexual segregation, in which males and females of polygynous, sexually dimorphic species form separate herds during most of the year. Bighorn sheep (Ovis canadensis) are polygynous ungulates that exhibit extreme sexual dimorphism and segregate into ram and ewe herds outside of the rutting season. Four major hypotheses for sexual segregation were tested in a population of desert bighorn (O. c. mexicana) at the Red Rock Wildlife Area, New Mexico, from 1999-2001. We collected data on the size, composition, and location of ram and ewe groups during the summer period of segregation. Activity budgets were recorded for males in ram herds and females in ewe herds, and foraging selectivity was measured for males and females in mixed groups during early rut. Habitat was evaluated by measuring forage availability, ruggedness, and visibility at sites utilized by ram and ewe groups. Ram herds utilized areas with more available forage compared with ewe sites, while ewe groups preferred more rugged terrain than that used by ram groups. Ewe groups occurred much closer to free water sources than did ram groups. Bighorns in ram and ewe groups did not differ in foraging time or selectivity, nor did time spent moving, reclining, or ruminating differ between the sexes as predicted by the 'activity budget hypothesis'. The results support the predictions of the 'reproductive strategy-predation risk hypothesis', which proposes that males seek more abundant forage in order to build up body condition needed to maximize mating success (even if exposing themselves to greater predation risk), while females choose rugged terrain that minimizes predation risk to themselves and their offspring (even if sacrificing forage abundance). Female bighorns chose sites that provided access to water, also predicted by the 'reproductive strategy-predation risk hypothesis', indicating that lactation-related water requirements may constrain the movements of ewe groups and contribute to patterns of sexual segregation in desert bighorn.

Female dominance and social structure in alaotran gentle lemurs

Abstract: Summary Lemur social systems have the striking social feature, that adult females consistently evoke submissive behaviour of adult males. In the Alaotran gentle lemur, Hapalemur griseus alaotrensis , however, female dominance has not been studied yet. Here we cone rm female dominance over males on the basis of a 5-month e eld study of the social behaviour of four groups, in the Lake Alaotra marshland of eastern Madagascar. Further, we found that dominant individuals initiated aggressive interactions signie cantly more often than lowerranking ones, they initiatedgroup movements more often and higher-ranking individuals were groomed more often. The spatial cone guration was remarkable, since individuals were closer in space to those more distant in rank.

Wolf Pack Territory Marking in the Bialowieza Primeval Forest (Poland)

Abstract: Summary We analysed data on territory marking with urine, scats, and ground scratching by wolves (Canis lupus) belonging to four packs in the BiaA owie C Primeval Forest, Poland. The aims were to determine: (1) seasonal variation in the marking rates, (2) signie cance of various kinds of marking in territory demarcation, and (3) relationship between spatial distribution of wolves’ marking and their use of territory. Continuous radio-tracking and subsequent snow tracking of the collared wolves were the main methods. Deposition rates of scats showed little variation in time and space, whereas rates of urine marking and ground scratching showed large seasonal and spatial variation. Wolf marking rates with urine and ground scratching were highest during the cold season (October-March) and peaked during the mating season, in January and February. Marking intensity did not grow with the number of wolves in a pack, and per capita rates of marking were highest in wolves travelling singly or in pairs. Mean marking rates per km of wolf trail were low in the core areas of territories, and increased

Competition and the Exchange of Grooming Among Female Samango Monkeys (Cercopithecus Mitis Erythrarchus)

Abstract: Current socioecological models argue that multi-female primate groups engaging in co-operative, between-group resource competition (BGC), should have egalitarian social relations that promote cohesion among group members, while those that experience strong within-group competition (WGC) should exhibit nepotistic and despotic social behaviour (van Schaik, 1989; Sterck et al. , 1997). Here we investigate the idea that very slight WGC can have strong effects on social relationships, even in 'egalitarian' populations, and that individual responses to ecological conditions may vary among group members. We estimated the intensity of both BGC and WGC and used the Biological Markets model to examine their effects on female dominance and grooming distributions for a group of samango monkeys ( Cercopithecus mitis erythrarchus ) in a high-density, territorial population. We found high levels of territorial activity consistent with female resource defence, low levels of within-group aggression and only slight effects of contest competition on diet. Individual grooming bouts were reciprocal, with no effects of rank, demonstrating that grooming was not exchanged for feeding tolerance. However, in contrast to other C. mitis populations, female samangos maintained a consistent, linear dominance hierarchy that was reflected in the overall patterns of association and grooming, with high-ranking females receiving more grooming, and lower-ranking females were less likely to take part in territorial activity. Our results support the prediction of the current socioecological model that WGC effects on female relationships will always be greater than the cohesive effects of BGC (Wrangham, 1980; Cheney, 1992), and show that a simple 'egalitarian' description of C. mitis female relationships is insufficient.

Social and spatial aspects of male subgrouping in a community of wild chimpanzees

Abstract: Strong social bonds typically develop between dyadic pairs of male chimpanzees. These bonds are manifest in several contexts, including association, grooming, and proximity. Here we demonstrate that social bonds exist at a higher level of organization among males living in an extremely large community at Ngogo, Kibale National Park, Uganda. An analysis of over 2,500 hours of observation of 35 individuals revealed two distinct subgroups of male chimpanzees. Males that composed each subgroup can be identified on the basis of their tendency to associate in temporary parties. Matrix permutation tests indicated that subgroup members tended to maintain spatial proximity to each other and participate together in territorial boundary patrols. Subgroups formed along the lines of age and rank; members of a small subgroup were younger and lower ranking than individuals in a larger subgroup. Despite this social clustering of males, community integrity remained intact with low levels of aggression between individuals of different subgroups. After controlling for the effect of association, significantly more aggression occurred within compared to between subgroups. In addition, males of the different subgroups displayed significant overlap in their use of the community territory and thus showed no tendency to divide spatially. We compare our findings with those from other animal species and chimpanzee populations and discuss them in the context of the unusual demography of the Ngogo community.

Mixed-species associations of Diana and Campbell's monkeys : the costs and benefits of a forest phenomenon

Abstract: One of the most striking behavioural patterns of many forest primates concerns their tendency to live in semi-permanent mixed-species groups. Functional investigations have ascertained that individuals obtain some antipredator benefits without paying the costs of intra-species resource competition. Despite these advances, very little is known about the subtle mechanisms that keep mixed species groups together on a daily basis. Our results showed that in the Diana-Campbell's monkey association both species benefited from each other in diverse and idiosyncratic ways. In the presence of Campbell's monkeys the conspicuous Diana monkeys were more likely to descend into the lower forest strata, increased their foraging behaviour, and individuals became less vigilant. The cryptic Campbell's monkeys, in turn, were able to use the higher forest strata and exposed areas more often, spread out over larger areas, were more likely to travel, and engaged in more conspicuous vocal behaviour when associated with Diana monkeys. These data suggested that both species benefited from each other in ways that went beyond passive group-size related antipredator benefits, such as a dilution effect and increased chances of predator detection. Instead, the increased safety of the mixed species group allowed individuals to exploit their ecological niche more broadly, to forage more efficiently, and to engage in more social behaviour, suggesting that the benefits of mixed species groups are much more varied and diverse than currently thought.

A behavioral comparison of captive-born, reintroduced golden lion tamarins and their wild-born offspring

Abstract: [The behavioral development of reintroduced, captive-born animals and their wild-born offspring is understudied, limiting the scientific understanding and, therefore, utility of reintroduction as a conservation tool. Several reintroduction programs have shown that survival rates of captive-born animals are lower than those of their wild-born offspring. However, whether these differences are because of increased behavioral competency of wild-born animals or age-related factors is unknown. This study compared behavior of captive-born golden lion tamarins to that of their age-matched first- and second-generation descendents. Subjects included 134 golden lion tamarins living in and around the Poco das Antas Biological Reserve in Brazil. Overall, captive-born animals were deficient in locomotor and foraging skills as compared with their wild-born offspring, and some of these deficiencies persisted after two years in the wild. Locomotor and foraging differences were also observed between generations of wild-born animals, suggesting that behavioral change continued past the first generation. Recommendations for future reintroductions with this and other species include: (1) increased exposure to complex environments prior to release; (2) intensive post-release support; (3) introduction of naive animals with experienced conspecifics when possible; (4) comparisons of reintroduced and wild populations when possible; and (5) short-term management plans aimed at the survival of captive-born individuals combined with long-term plans focused on maximizing natural adaptive processes., The behavioral development of reintroduced, captive-born animals and their wild-born offspring is understudied, limiting the scientific understanding and, therefore, utility of reintroduction as a conservation tool. Several reintroduction programs have shown that survival rates of captive-born animals are lower than those of their wild-born offspring. However, whether these differences are because of increased behavioral competency of wild-born animals or age-related factors is unknown. This study compared behavior of captive-born golden lion tamarins to that of their age-matched first- and second-generation descendents. Subjects included 134 golden lion tamarins living in and around the Poco das Antas Biological Reserve in Brazil. Overall, captive-born animals were deficient in locomotor and foraging skills as compared with their wild-born offspring, and some of these deficiencies persisted after two years in the wild. Locomotor and foraging differences were also observed between generations of wild-born animals, suggesting that behavioral change continued past the first generation. Recommendations for future reintroductions with this and other species include: (1) increased exposure to complex environments prior to release; (2) intensive post-release support; (3) introduction of naive animals with experienced conspecifics when possible; (4) comparisons of reintroduced and wild populations when possible; and (5) short-term management plans aimed at the survival of captive-born individuals combined with long-term plans focused on maximizing natural adaptive processes.]

Two's Company, Three's a Crowd: Differences in Dominance Relationships in Isolated Versus Socially Embedded Pairs of Fish

Abstract: Summary We performed experiments with cichlid e sh to test whether several basic aspects of dominance were the same in isolated pairs as in pairs within a social group of three or four. We found that the social context, whether a pair was isolated or within a group, strongly affected the basic properties of dominance relationships. In particular, the stability of relationships over time, the replication of relationships in successive meetings, and the extent of the loser effect were all signie cantly less in socially embedded pairs than in isolated pairs. We found no signie cant winner effect in either isolated or socially embedded pairs. These e ndings call into question many current approaches to dominance that do not consider social context as an important factor in dominance behavior. These e ndings also cast serious doubt on the validity of empirical and theoretical approaches based on dyadic interactions. Among these approaches are game theoretic models for the evolution of aggressive behavior, experimental designs evaluating how asymmetries in attributes ine uence the outcome of dominance

Models of Dominance Hierarchy Formation: Effects of Prior Experience and Intrinsic Traits

Abstract: Results of experimental research are used to develop theoretical models of dominance hierarchy formation that incorporate effects of prior aggressive experience and body size. A combination of analytical models and computer simulations confirm previous theoretical treatments showing that intrinsic attributes such as body size fail to account for the degree of hierarchy linearity observed in nature for typical within-group variance of such attributes. Moreover, these models explain the mathematical dynamics of the operation of winner/loser effects during hierarchy formation. Additionally, I present an analysis of these models which shows that the degree to which relationships of component triads (all combinations of three individuals in a group) within a hierarchy develop sequentially can have a significant effect on linearity and is an emergent feature of prior experience effects that previously has not been examined. I explain how this feature can operate through physical and behavioral features of social groups that increase physical proximity of subgroups within a larger group, thus increasing the probability of sequential relationship development in component triads, which in turn provides the conditions for winner/loser effects to significantly increase the probability of component triad transitivity and hierarchy linearity.

The Social Function of Allo-marking in the European Badger (Meles meles)

Abstract: The adaptive significance of sociality in European badgers (Meles meles) is often explained on the basis of ecological factors, but little is known about their social interactions. Here, we investigate how allo-marking of conspecifics with subcaudal gland secretions might serve as a behavioural mechanism to create a shared group-odour, thus functioning simultaneously to maintain group cohesion, and as an individual advertisement signal. The odour of subcaudal secretions, which encodes group-membership and individual-specific information, is partly generated by the bacterial flora in the subcaudal pouch. Studying the interactions of 40 different adults from two social groups, we analysed 3021 instances of allo-marking, which may be either mutual, i.e. two badgers pressing their subcaudal pouches against each other simultaneously (155 events) or sequential, i.e. one badger marking the body of another individual (2866 events). Sequential marking is significantly more frequent than mutual marking, although both occur significantly more often during the mating season and the cub-rearing season than at other times. Whereas mutual marking appears to be independent of individual-specific parameters, sequential allo-marking is strongly influenced by sex, age, and reproductive status. We propose that mutual marking generates a common group-smell by facilitating the exchange of pouch bacteria, thus aiding in group-cohesion, while sequential marking serves two purposes, to distribute the common group-smell, and to advertise individual-specific, fitness-related information. Strong correlation of the frequencies of sequential and mutual allo-marking as well as the allo-grooming behaviour between particular clusters of group members suggests the existence of sub-groups within badger groups.

Energy expenditures during reproduction by sockeye salmon (Oncorhynchus nerka)

Abstract: From 1994 to 1996, behaviour and energy use by sockeye salmon spawning in Gluskie Creek, British Columbia, was investigated by a combination of behavioural observation and electromyogram (EMG) telemetry. The spawning life was 7.6 days for males and 10.6 days for females. Both sexes held in pools for a few days, with an average cost of 7.9 kcal/day, before starting to spawn. During spawning, dominant males performed 6 behavioural acts per 10 min, charging being the most frequent followed by quivering, chasing, digging, lateral and posture displays. Spawning females performed 4.4 behavioural acts per 10 min, digging being the most frequent followed by charges and chases. Following egg deposition, females entered a nest guarding phase and, in the latter stages of spawning, males adopted subordinate behaviour. Guarding females and subordinate males performed 1.1 and 1.6 behaviours per 10 min respectively. Lateral and posture displays by males lasted 6.3 s and 11 s respectively but all other behaviours lasted less than 2 seconds. Holding behaviour and posture displays required the most energy in males and holding and digging in females. Dominant males and spawning females expended 23.9 kcal/day whereas guarding females and subordinate males expended 11.0 kcal/day. Frequency of behaviours during active spawning was similar to other populations. Length of spawning life was shorter, however, and total energy expended was less than estimates for other populations based on body constituent analysis. Although EMG telemetry may underestimate total energy expenditure, other recent measures of gross energy expenditure by Stuart River sockeye also indicate that energy available for reproduction was low in this population due to declining average size and low energy reserves in fish arriving at the spawning grounds.

Grooming Interactions Among the Chimpanzees of the Budongo Forest, Uganda: Tests of Five Explanatory Models

Abstract: Patterns of allogrooming among the Sonso community of chimpanzees of the Budongo Forest, Uganda, were examined and found to closely resemble those at other study sites. Strong affiliative bonds among males were reflected in high levels of grooming compared with other sex combinations. Adult males groomed, and received grooming most often from, other adult males and also adolescent females which were the only females with regular oestrous cycles during the study. Males had a wider diversity of grooming partners than females and groomed more equitably. However, males concentrated the majority of their effort on a very small number of partners compared with other sites. Grooming reciprocity was found among all age/sex combinations with the exception of adult male-female dyads once immediate reciprocation in the form of synchronous mutual grooming was removed from the analysis. Since grooming among males is thought to play a major role in servicing relationships and agonistic coalitions that can improve dominance status, competition for high-ranking grooming partners was predicted to influence the distribution of grooming among males. Grooming was indeed directed up the male hierarchy and closely ranked males groomed each other more often than those that were distantly ranked. However, when only adult males were considered, rank had little effect on grooming distributions. High rank appeared to influence access to females, but did not attract more female grooming partners. Grooming distributions in this average-sized community did not fit a number of alternative priority of access models which assume competition for high-ranking grooming partners that Watts (2000b) found to have some explanatory value in one very large community of chimpanzees, but not in a smaller, more representative one. Although rank is highly likely to influence coalition partner choice, whether such relationships depend upon strategic grooming partner choices in wild chimpanzees is presently unclear.

The Opportunistic Serpent: Male Garter Snakes Adjust Courtship Tactics to Mating Opportunities

Abstract: Reproductive males encounter potential mates under a range of circumstances that influence the costs, benefits or feasibility of alternative courtship tactics. Thus, males may be under strong selection to flexibly modify their behaviour. Red-sided garter snakes (Thamnophis sirtalis parietalis) in Manitoba overwinter in communal dens, and court and mate in large aggregations in early spring. The number of males within a courting group varies considerably, as do the body sizes of both males and females. We manipulated these factors to set up replicated courtship groups in outdoor arenas, and analysed videotapes of 82 courtship trials to quantify courting behaviours of male snakes. Larger and more heavy-bodied males courted more vigorously than did their smaller, thinner-bodied rivals, and large females attracted more intense courtship. The major effect, however, involved the number of rival males competing for copulation. Males in large groups not only reduced their overall vigour of courtship, but also modified their tactics in such a way as to benefit from the courtship activities of rival males. That is, they devoted less energy to inducing female receptivity (which requires energy-expensive caudocephalic waving) and more effort to behaviour (tail-searching) that enhanced their own probability of mating if the female gaped her cloaca. This social parasitism reveals an unsuspected plasticity and complexity in the behavioural tactics of reproducing male snakes.

Free female choice in house mice: Leaving best for last

Abstract: We investigated female multiple mating in the house mouse (Mus musculus), a promiscuous mammal that exhibits male-male competition. Our experimental design, which allowed females free movement between confined dominant and subordinate males, enabled the study of females' preferences and their mating strategies unconstrained by direct male-male competition. We found that: (1) Females were actively promiscuous, always switching male after the first mating session. (2) They accepted more intromissions and ejaculations from the dominant than from the subordinate male. Female preference for dominant males was active rather than the 'passive' result of an enhanced willingness or ability by the dominant males to copulate. (3) The preference exhibited during mating was not apparent outside the period of receptivity: females neither spent more time with odours of dominant males nor with these individuals themselves, outside oestrus. Females began to spend more time with dominant males only two hours before the start of mating. (4) Females were indiscriminate in their choice of male during the first mating session. Instead, they mated with the preferred male last. (5) Finally, there was evidence that the males' mating patterns were, in turn, influenced by the females' preference (exhibited a few hours before mating). Subordinate males, which had less access to females, tended to ejaculate as soon as possible, whereas the mating pattern of dominant males was more consistent with mate guarding.

The evolution of social dominance II: Multi-player models

Abstract: The social hierarchies observed in natural systems often show a high degree of transitivity. Transitive hierarchies do not only require rank differentiation within pairs of individuals but also a higher level ordering of relations within the group. Several authors have suggested that the formation of linear hierarchies at the group level is an emergent property of individual behavioural rules, referred to as winner and loser effects. Winner and loser effects occur if winners of previous conflicts are more likely to escalate the current conflict, whereas the losers of previous conflicts are less likely to do so. According to this idea, an individual's position in a hierarchy may not necessarily reflect its fighting ability, but may rather result from arbitrary historical asymmetries, in particular the history of victories and defeats. However, if this is the case, it is difficult to explain from an evolutionary perspective why a low ranking individual should accept its subordinate status. Here we present a game theoretical model to investigate whether winner and loser effects giving rise to transitive hierarchies can evolve and under which conditions they are evolutionarily stable. The main version of the model focuses on an extreme case in which there are no intrinsic differences in fighting ability between individuals. The only asymmetries that may arise between individuals are generated by the outcome of previous conflicts. We show that, at evolutionary equilibrium, these asymmetries can be utilized for conventional conflict resolution. Several evolutionarily stable strategies are based on winner and loser effects and these strategies give rise to transitive hierarchies.

Substitution of silk stabilimenta for egg sacs by Allocyclosa bifurca (Araneae: Araneidae) suggests that silk stabilimenta function as camouflage devices

Abstract: The matching form and orientation of egg sacs and spiders, the match between egg sac color and that of the spider, ontogenetic changes in spider coloration that occur when egg sacs begin to be produced, differences in the positions of the spiders' legs during the day and at night, and coordinated changes in spider and egg sac colors in different populations all indicated that the egg sac and detritus stabilimenta near the hub function as camouflage in Allocyclosa bifurca. Silk stabilimentum construction was induced by experimental removal of egg sac stabilimenta, and was inhibited by addition of egg sacs. This implies that silk stabilimenta also function as camouflage devices.

The evolution of social dominance I: Two-player models

Abstract: A difference in dominance rank is an often-used cue to resolve conflicts between two animals without escalated fights. At the group level, adherence to a dominance convention efficiently reduces the costs associated with conflicts, but from an individual's point of view, it is difficult to explain why a low ranking individual should accept its subordinate status. This is especially true if, as suggested by several authors, dominance not necessarily reflects differences in fighting ability but rather results from arbitrary historical asymmetries. According to this idea, rank differentiation emerges from behavioural strategies, referred to as winner and loser effects, in which winners of previous conflicts are more likely to win the current conflict, whereas the losers of previous conflicts are less likely to do so. In order to investigate whether dominance, based on such winner and loser effects, can be evolutionarily stable, we analyse a game theoretical model. The model focuses on an extreme case in which there are no differences in fighting ability between individuals at all. The only asymmetries that may arise between individuals are generated by the outcome of previous conflicts. By means of numerical analysis, we find alternative evolutionarily stable strategies, which all utilize these asymmetries for conventional conflict resolution. One class of these strategies is based on winner and loser effects, thus generating evolutionarily stable dominance relations even in the absence of differences in resource holding potential.

Dynamic changes in alarm call structure: A strategy for reducing conspicuousness to avian predators?

Abstract: The design of many animal signals reflects the need to maximize signal efficacy while minimizing conspicuousness to eavesdroppers. The aerial alarm calls of birds have been a useful model system for exploring such evolutionary tradeoffs at the level of general call structure, but much less is known about changes in fine-scale signal characteristics over the course of an encounter with a potential predator. We analyzed variation in the alarm calls that male fowl, Gallus gallus, produced in response to raptor silhouettes moving overhead. Spectrogram cross-correlation was used to test for changes in structure over the course of a call bout. This analysis revealed that aerial alarm calls are individually distinctive and that they vary significantly from the first call to the second. We then measured single acoustic parameters, including the duration, dominant frequency and frequency bandwidth of each component in successive calls. Males almost invariably began the first call in a bout with a high amplitude broad-band pulse, which was followed by a much longer and highly variable sustained element. They then selectively reduced or eliminated the introductory pulse, while leaving other aspects of alarm structure unchanged. Recent work has shown that the introductory pulse is potentially costly because it has attributes that are readily localized by raptors. We suggest that male fowl have adaptive plasticity in alarm call structure, allowing them to manage short-term predation risk while continuing to signal to companions.

Assessing relationship quality and social anxiety among wild chimpanzees using self-directed behaviour

Abstract: Current theory on primate social relationships implies that relationship quality consists of three factors: value, security, and compatibility. The relationship security of each group member can be determined using the level of social anxiety found when that individual is in the proximity of other individuals. I studied social anxiety by measuring the rate of rough selfscratching behaviour (RSS), a self-directed behaviour, in wild chimpanzees in Mahale Mountains National Park, Tanzania. The RSS rate drastically differed across individual activities; RSS was rare when the focal individual was foraging or moving, but frequent during resting. The male RSS rate while resting was inversely correlated with dominance rank, particularly when males were with other group members; higher-ranking males performed RSS less often than lower-ranking males. The RSS frequency of males did not vary with the proximity of group members or the association level of the individuals in proximity. In contrast, close proximity of group members increased the female RSS rate. In addition, females performed RSS more frequently when a non-affiliative group member was in their proximity than with an affiliative group member. The relative dominance rank of the individuals in close proximity did not affect the RSS rate in either males or females. Furthermore, infant contact or separation from the mother did not influence the maternal RSS rate. These results suggest that anxietyinducing situations differ between sexes in this species, and that for female chimpanzees, relationship security is related to association level. The results are discussed in terms of interspecific variation in social dominance style and inter-individual tolerance within primates.