Agonistic behavior in crayfish in relation to temperature and reproductive period

Summary I examined the relationship between temperature and agonistic behavior in the crayfish Cambarus latimanus LeConte a species which is reproductively active in winter. Crayfish were acclimated for 2 wks at 9.5, 14, 22 and 30°C in summer and at 9.5 and 22°C in winter. Agonistic behavior of pairs of the same sex was recorded for 1 h following acclimation. The entire acclimation, testing, and temperature-readjustment procedure was repeated until all crayfish pairs had been tested at each acclimation temperature.Published information on lobsters and catfish indicate that agonistic behavior is directly related to temperature. In contrast, for C. latimanus in the present study, duration of total agonistic behavior, maximum duration of a single agonistic interaction, and average length of a agonistic encounter were all inversely related to acclimation temperature. I hypothesized that for ectothermic species whose agonistic behavior is closely associated with reproductive processes (including competition for mates) the level of agonism will vary either directly or inversely depending upon whether the reproductive period is cued by increasing or decreasing seasonal temperatures, respectively.     

Seasonal changes in territoriality and frequency of agonistic behavior in two densities of juvenile brown bullhead,Ictalurus nebulosus

Synopsis Incidence of territoriality and frequency of six agonistic action patterns of juvenile brown bullhead, Ictalurus nebulosus, were observed in the laboratory over a two year period at two fish densities under conditions of constant light and temperature. High density fish showed little territoriality or agonistic behavior while low density fish displayed an annual cycle of agonistic behavior and territoriality. Agonistic behavior frequency and incidence of territoriality peaked in February and March and were higher the second year when compared with the first.     

Postconflict affiliative contacts between former opponents among wild moor macaques (Macaca maurus)

Agonistic interactions and postconflict behavior of moor macaques (Macaca maurus) were studied in their natural habitat, South Sulawesi, Indonesia. Individuals were involved in 0.28 agonistic interactions per hour. Forty-two percent of agonistic interactions were followed by affiliative contacts between the former opponents. Such affiliative contacts occurred within 2 minutes of the agonistic interaction and were most often initiated by the victim's approach to the aggressor. The most common postconflict behavior was grooming of the aggressor by the victim. The present study provides further evidence of a positive correlation between a high tendency for postconflict affiliative contact and a relaxed dominance style. Captivity might not alter the expression of postconflict behavior. The present study suggests that it is possible to demonstrate the occurrence of reconciliation a posteriori by using data obtained by general focal observation protocols. © 1996 Wiley-Liss, Inc.     

Sociality in Callithrix penicillata: II. Individual Strategies During Intergroup Encounters

In social animals, intergroup interactions, whether through agonistic and competitive behaviors or affiliative ones, can influence important parameters such as home range, territory sizes, and access to resources, which may directly affect both female and male fitness. We studied the intergroup interaction patterns of a wild group of black-tufted-ear marmosets (Callithrix penicillata) in central Brazil. Agonistic interactions occurred at low frequencies during intergroup encounters. The marmosets directed agonistic interactions without physical aggression primarily against same-sex individuals, suggesting that male and female aggression patterns are shaped by their sexual interests. However, females of the focal group also directed agonistic behavior toward extragroup males that attempted copulation. The marmosets appeared to use intergroup encounters to gather information about possible partners and extragroup reproductive opportunities. Intergroup sexual interactions occurred mainly in the form of copulations or attempted copulations by all adults, with the exception of the dominant female. Our results suggest that a possible reproductive strategy used by males is to attempt fertilization of extragroup females. Adult males copulated with the same extragroup female during several opportunities, which suggests sperm competition or the establishment of social bonds with neighboring females.     

Agonistic behavior in a transplanted troop of Japanese macaques: Arashiyama west

Arashiyama A troop was transplanted from Japan to Texas, U.S.A. in February 1972 and released into a large outdoor enclosure (42 ha) in a semi-free ranging condition. Agonistic behavior was quantified during the first six months after the release. Agonistic interactions occurred at about one incident per 100 monkeys every 2 to 9 minutes. In general, peaks in frequency of agonistic interactions coincided with peaks in feeding activity. 97.5% of all incidents were of a “mild” type, and 85.7% were simple one-to-one, unidirectional interactions. “Severe” forms of agonistic behavior occurred only during the first month and then only rarely. Adult females and juveniles were initiators in about 93% of all cases. In general, the more severe the form of attack, the more pronounced was the form of submission.     

Reconciliation in captive Guyanese squirrel monkeys (Saimiri sciureus)

The tendency for agonistic interaction to increase the probability of friendly interaction between social partners has been demonstrated across a range of Old World primates. While research on such post-conflict behavior proceeds into an hypothesis-testing phase, new comparative information must accumulate to provide full phylogenetic perspective on primate social behavior. Data from New World and prosimian primates are yet extremely limited. We studied captive squirrel monkeys (Saimiri sciureus) via post-conflict (PC) and matched control (MC) observations and analyzed results using both the PC-MC and time-rule methods. Former opponents maintaining affiliative relationships soon engaged in friendly interaction following large proportions of agonistic interactions, whereas non-affiliated individuals, including virtually all male-female pairs, reconciled conflicts rarely. Close-proximity approaching and huddling contact constituted the principal modes of post-conflict amicability. Agonistic interactions of relatively high intensity were most likely to be reconciled and most likely to be reconciled via physical contact. High vulnerability of Saimiri to predation may have favored this species' strong inclination to reconcile soon after agonistic interaction. Research on free-living populations of this and other primate species is needed to illuminate similarities and differences across taxa.     

Social Environment and Agonistic Interactions: Strategies in a Small Social Mammal

In group‐living species, the development of agonistic interactions among conspecifics may be affected by socio‐ecological factors, such as size and composition of social group, and availability of nests and food. We analysed the importance of size and composition of social groups on agonistic interactions among males in the Southern mountain cavy (Microcavia australis). We made behavioural observations in four social groups of different size and composition. We recorded two types of agonistic interactions: agonistic displays and direct agonistic behaviours; both types increased in the breeding season. A social group composed of a high number of males was associated with high frequency of agonistic displays. Direct agonistic behaviours were also influenced by the interaction of season and number of males per social group and number of females per social group. Agonistic interactions were also recorded among males of different socials groups in the breeding season. Agonistic displays were most frequent among males of the same social group, whereas direct agonistic behaviours were most common among males of different social groups. These results suggest that social factors affect agonistic interactions among males of Southern mountain cavy and that in a conflict situation, males develop different strategies, such as increased frequency of agonistic behaviours in breeding season and intragroup cooperation for defence of oestrous females.     

How boat noise affects an ecologically crucial behaviour: the case of territoriality in <Emphasis Type="Italic">Gobius cruentatus</Emphasis> (Gobiidae)

Gobius cruentatus emit sounds during agonistic interactions. In order to evaluate the effect of boat noise exposure on G. cruentatus territorial behaviour, we played a field-recorded diesel engine boat noise during aggressive encounters between an intruder and a resident fish in a laboratory-controlled tank. We tested two factors: role (resident vs. intruder) and condition (noisy vs. silent); the test animals underwent all the treatments in a round-robin design. Agonistic behavior of the residents was modified by boat noise: during the playback residents were more submissive and won less encounters than in the control (silent) condition. We suggest that sound production is an effective tool for territorial defense, since the impairment of acoustic communication due to the recreational boat noise diminished the ability of the resident to maintain its territory.     

Social behavior of the emperor tamarin in captivity: Components of agonistic display and the agonistic network

Agonistic behavior was studied longitudinally for 16 months in an intact family groups of captive emperor tamarins (Saguinus imperator subgrisescens) using methods from quantitative ethology and social network analysis. A motivational analysis of the components of agonistic display revealed the relative strength of each component along a continuum from strongly dominant to strongly subordinate. Tabulations of exchanges of strongly dominant and strongly subordinate components in interactions among the tamarins revealed an agonistic network (“dominance hierarchy”) that approached, but did not quite reach, the ideal state of a transitive order (“linear dominance hierarchy”). The frequency with which individual tamarins long called and scent marked was not closely correlated with their position (“dominance rank”) in the agonistic network. Instead, individuals undergoing change in status long called and scent marked frequently, irrespective of their rank.     

Agonistic behavior and dominance relationships in female Phayre's leaf monkeys -- preliminary results

Socioecological theory suggests a link between the strength of competition for food/safety, rates of agonism, structure of dominance hierarchies, and dispersal among group-living females. This study presents preliminary data on agonistic behavior and dominance relationships for female Phayre's leaf monkeys (Trachypithecus phayrei), a species in which females routinely disperse. Behavioral observations were conducted on two groups (four adult females, and five adult females plus two juvenile females, respectively) at Phu Khieo Wildlife Sanctuary, northeast Thailand. Rates of agonistic behavior were analyzed from focal continuous recordings, while dominance hierarchies were constructed from all agonistic behaviors (focal and ad libitum sampling). Overall, female-female agonistic behaviors (aggression, submission, and displacements) occurred at a rate of < 0.25 interactions per hour. Agonistic interactions involving food occurred more frequently than expected based on feeding time. Females in both groups exhibited linear dominance hierarchies with some reversals, and possibly an age-inversed hierarchical structure in the larger group. The results fit well with previous results for colobine monkeys regarding frequency of interactions, displacements predominating agonistic behavior, and the possibility of an age-inversed hierarchy. The results contradict the suggested link between linearity of hierarchies and female philopatry. Future studies should consider the notion that female dispersal may coexist with linear dominance hierarchies.     

Innovative social behavior in chimpanzees (Pan troglodytes)

We present evidence of agonistic buffering in captive chimpanzees, recorded from 1993 until 2005, mainly from ad libitum sampling in over 2000 hr of observation. A total of 33 agonistic buffering episodes were analyzed for context and effects of this complex social behavior. Agonistic buffering was directed at the whole chimpanzee colony as they supported an individual who initially received aggression from the alpha male, independently of the victim's age, sex or social rank. Chimpanzee agonistic buffering behavior is compared with that in other nonhuman primate species, and we describe some particularities of chimpanzee agonistic buffering: the status of the buffers used-socially important offspring such as those from the alpha female-and the social rank of the adult male responsible for the buffering episode-alpha male. Possible functions for this behavior in chimpanzees are suggested as appeasement of group members in a particularly crowded captive setting, and/or as a "forced reconciliation" mechanism. Chimpanzees exhibit behavioral flexibility by adapting themselves to new social and physical situations and use novel behavior to achieve social benefits.     

A qualitative investigation of major urinary proteins in relation to the onset of aggressive behavior and dispersive motivation in male wild house mice (<Emphasis Type="Italic">Mus musculus domesticus</Emphasis>)

The physiological basis for population differentiation of dispersal timing during individual development in male wild house mice is still unknown. As major urinary proteins (MUPs) are known to convey information about competitive ability in male mice, we examined individual MUP profiles defined by isoelectric-focusing (IEF) patterns in relation to developmental timing of dispersive motivation. As an experimental paradigm marking the development of the dispersal propensity, we used agonistic onset between litter mate brothers when kept in pairs under laboratory conditions. Agonistic onset is known to reflect the initiation of dispersive motivation. Hence, we compared individual MUP IEF patterns between fraternal pairs that did or did not develop agonistic relationships before the age of 2 months. Urine was collected on the day of weaning and at the beginning of adulthood. We investigated whether there was a significant co-occurrence of particular MUP IEF patterns with the agonistic onset in male mice. We assumed that, based on this co-occurrence, particular MUP IEF patterns and/or a particular dynamic of MUP IEF expression from weaning to adulthood may be considered a physiological predictor of a specific behavioral strategy in male mice (i.e. submissive-philopatric or agonistic-dispersive strategy). We found that agonistic males expressed more MUP IEF bands than amicable ones at weaning, but these differences disappeared later on. The presence of two particular IEF bands at weaning was significantly associated with early agonistic onset. Our study suggests that MUPs could have a predictive value for the onset of aggressive behavior and dispersal tendency in male wild house mice.     

Field observations of intraspecific agonistic behavior of two crayfish species,Orconectes rusticus and Orconectes virilis,in different habitats

Agonistic behavior is a fundamental aspect of ecological theories on resource acquisition and sexual selection. Crustaceans are exemplary models for agonistic behavior within the laboratory, but agonistic behavior in natural habitats is often neglected. Laboratory studies do not achieve the same ecological realism as field studies. In an attempt to connect laboratory results to field data and investigate how habitat structure affects agonistic interactions, the nocturnal behavior of two crayfish species was observed by scuba diving and snorkeling in two northern Michigan lakes. Intraspecific agonistic interactions were analyzed in three habitats: two food resources-macrophytes and detritus-and one sheltered habitat. The overall observations reinforce the concept that resources influence agonistic bouts. Fights in the presence of shelters were longer and more intense, suggesting that shelters have a higher perceived value than food resources. Fights in the presence of detritus patches had higher average intensities and ended with more tailflips away from an opponent, suggesting that detritus was a more valuable food resource than macrophytes. In addition, observations of aggressive behavior within a natural setting can add validity to laboratory studies. When fights in nature are compared with laboratory fights, those in nature are shorter, less intense, and less likely to end with a tailflip, but do show the fundamental fight dynamics associated with laboratory studies. Extrinsic and intrinsic factors affect intraspecific aggression in many ways, and both should always be recognized as having the potential to alter agonistic behavior.     

A review of shark agonistic displays: comparison of display features and implications for shark–human interactions

Agonistic displays in 23 species of sharks of six families are described and illustrated. These displays are reviewed in terms of ethological concepts and shark hydrodynamic models. Shark agonistic displays feature many common elements rendering them readily distinguishable from normal swimming and pseudodisplays caused by sharksucker irritation. Shark agonistic displays are most readily elicited by rapid, direct diver approach when food is absent and potential escape routes restricted. Such displays appear to be motivated by defence of self or the immediately surrounding space rather than defence of territory or resources. Costs and benefits of display versus attack in shark–shark and shark–diver contests are evaluated using payoff matrices and optimal strategies are identified. Shark–human interactions are modelled in terms of a system of nested critical approach distances. For divers faced with a displaying shark, responses which may decrease the likelihood of defensive attack are suggested. Recommendations for future work on shark agonistic behaviour are offered.     

Triadic interactions in captive Barbary macaques (Macaca sylvanus,Linnaeus, 1758): “Agonistic buffering”?

This study presents data on the expression of male-immature triadic interactions, previously termed agonistic buffering, in a captive Macaca sylvanus group. Agonistic buffering has been hypothesized as inhibiting or modifying the expression of aggression. This was tested by examining (1) the dominance ranks of the animals involved in the triadic interactions, (2) the events preceding and following the triadic interactions, and (3) the presence of an infant in nonagonistic encounters between juvenile, subadult, and adult males. The results obtained do not support the hypothesis of agonistic buffering as the single explanation for triadic interactions, but emphasize the contextual variability in the expression of these triadic interactions.     

Parallel changes in agonistic and non-agonistic behaviors during dominance hierarchy formation in crayfish

Agonistic and non-agonistic behaviors were studied before, during, and after the formation of social status in crayfish. Differences in the expression of a non-agonistic behavior by dominant and subordinate crayfish developed in parallel with the differences in agonistic behaviors that indicate the animals' social status. An increase in burrowing behavior marked the ascendancy of the dominant animal, while an immediate suppression of burrowing paralleled the inhibition of aggressive behavior in the new subordinate. The strikingly similar changes in both agonistic and non-agonistic behaviors following the decision on status suggest related underlying neural mechanisms.     

Within-group social relationships among females and adult males in wild western lowland gorillas (Gorilla gorilla gorilla)

Within-group female relationships, and relationships between females and adult males have not been described for wild western lowland gorillas. New data are presented here from Mbeli Bai in the Nouabale-Ndoki National Park, Republic of Congo. Nine groups were observed over a continuous 2-year period, and affiliative and agonistic interactions, as well as time spent by females and adult males in proximity to each other were recorded. Affiliative behavior was extremely rare in the bai, and measures of proximity between individuals were inconclusive because of the small sample sizes. Rates of agonistic interaction among females were highly variable between groups. The majority of agonistic interactions were undecided, and the supplant rate was low. Evidence for an agonistic dominance hierarchy is weak. The data do not support hypotheses that increased frugivory in western lowland gorillas raises levels of within-group contest competition; however, the need for intersite comparisons is stressed. In contrast, rates of agonistic behavior between females and silverback males were higher and more consistent between groups. Agonistic relationships between males and females conformed with patterns seen in mountain gorillas, where male protection from intraspecific aggression is important. The benefit females gain by forming long-term cooperative alliances appears to be small, and is likely outweighed by reproductive advantages associated with male protection.     

Agonistic stress in early adolescence and its effects on reproductive effort in young adulthood

Agonistic stress (AS) is normally associated with the suppression of fertility behavior; however, there are conditions under which the association is reversed. In this article, we investigate the effects of AS using longitudinal data from a large sample (n=9731) of young adults in the United States. We find that repeated exposure to AS is associated with early fertility, higher fertility over a 10-year period, and low investment in long-term mating relationships. The association of AS with early fertility and mating behavior is mediated by antisocial preferences. However, the positive association between AS and fertility behavior over the long run is robust with respect to the controls in the model. We believe that our findings align well with studies showing increased reproductive effort in response to agonistic interactions with conspecifics.     

Acoustic threat displays and agonistic behaviour in the red-finned loach <Emphasis Type="Italic">Yasuhikotakia modesta</Emphasis>

Agonistic behaviour and the significance of acoustic threat displays were investigated in juvenile red-finned loaches, Yasuhikotakia modesta. This species produced two different vocalizations during agonistic encounters—clicks and butting sounds. Clicks were produced at some distance from the opponent whereas butting sounds were emitted when one fish touched the other with its mouth. This occurred primarily during circling. Both sound types were short broadband signals with the main energies concentrated at about 230 Hz, but clicks were longer in duration and lower in sound level. Agonistic behaviour usually started when one fish approached the other, spread its fins and produced clicks (threat displays), which was followed by parallel displaying, circling and chasing. All fish approached a mirror quickly and displayed aggressively in a parallel position. The number and duration of the threat displays in front of the mirror image were significantly elevated compared with control experiments (rear of the mirror). When playing back click trains in the presence of a mirror image, loaches vocalized significantly less often than during the silent periods, whereas the amount of lateral displaying remained similar. These data indicate that agonistic sounds reduced acoustic displays in red-finned loaches.