Dyadic Contests Research Articles

Perception of alarm cues influences the outcome of shelter competition in crayfish20

AbstractThe effects of predators on prey populations may significantly alter many aspects of prey biology, including spatial distribution, foraging activities, and social interactions. In aquatic habitats, chemosensation is an important mode of communication and has been shown for many taxa, including crayfish, to be used in detection of predator and/or conspecific alarm cues. Here, we report on an experiment to test the hypothesis that detection of alarm cues results in greater individual investment in contests over shelters. We tested this hypothesis through dyadic contests between sex‐ and size‐matched, non‐reproductive individuals of Faxonius virilis. We found that crayfish responded to exposure to alarm cues by spending more time inside a shelter. We also report that in contests between pairs in which one crayfish had been exposed to alarm cues and the other had not, exposed individuals were significantly more likely to win ownership of a single shelter. However, we did not detect any differences in the contest parameters we recorded between exposed and unexposed crayfish. These impacts on both individual and social behavior indicate that the presence of predators is likely to have large effects on the distribution and structure of crayfish populations.

Both sexes produce sounds in vocal fish species: testing the hypothesis in the pygmy gourami (labyrinth fishes).

In vocal fish species, males possess larger sound-generating organs and signal acoustically with pronounced sex-specific differences. Sound production is known in two out of three species of croaking gouramis (Trichopsis vittata and T. schalleri). The present study investigates sex-specific differences in sonic organs, vocalizing behaviour and sounds emitted in the third species, the pygmy gourami, T. pumila, in order to test the hypothesis that females are able to vocalize despite their less-developed sonic organs, and despite contradictory reports. Croaking gouramis stretch and pluck two enhanced (sonic) pectoral fin tendons during alternate fin beating, resulting in a series of double-pulsed bursts, termed croaking sound. We measured the diameter of the first and second sonic tendon and showed that male tendons were twice as large as in similar-sized females. We also determined the duration of dyadic contests, visual displays, number of sounds and buttings. Sexes differ in all sound characteristics but in no behavioural variable. Male sounds consisted of twice as many bursts, a higher percentage of double-pulsed bursts and a higher burst period. Additionally, male sounds had a lower dominant frequency and a higher sound level. In summary, female pygmy gouramis possessed sonic organs and vocalized in most dyadic contests. The sexual dimorphism in sonic tendons is clearly reflected in sex-specific differences in sound characteristics, but not in agonistic behaviour, supporting the hypothesis that females are vocal.

Collective displays as signals of relative colony size: meat ants, Iridomyrmex purpureus, are economical with the truth

Signals of resource-holding potential in dyadic (one-on-one) contests are relatively straightforward, typically reflected in the attributes of the individual, including body size and resource ownership. However, conveying this information is considerably more complex in social species: the outcome of collective contests will be influenced by both individual and group level effects, and the signal must be subsequently transmitted to the colony in order to elicit a colony response. Australian meat ants engage in collective displays where aggregations of many hundreds of pairs of workers from neighbouring colonies antennate one another while adopting a tip-toe posture with the abdomen raised. These displays rarely escalate into physical contests with their typically fatal consequences. A display between two workers may cease by one worker leaving or if one displaying worker is replaced by a nestmate. We asked whether these collective displays act to convey reliable information about relative colony size. Our field experiments and observations reveal that these displays do not necessarily convey precise information about relative colony size, and that it is possible for colonies to signal an exaggerated colony size, at least in the short term.

Dietary L-tryptophan modulates agonistic behavior and brain serotonin in male dyadic contests of a cichlid fish.

Although some studies have investigated the effects of dietary L-tryptophan on agonistic behavior, research on adult fish specimens is still lacking. Moreover, submissive behaviors have been generally overlooked. We focused on agonistic behavior between males of the cichlid fish Cichlasoma dimerus, in dyadic encounters held in a novel context after being fed or not with an L-tryptophan enriched diet (TRP) for 2weeks. We arranged three different dyads: control/control (control conditions: not TRP enriched), control/TRP, and TRP/TRP. We also registered the response of the brain serotonergic system in four brain regions. TRP/TRP dyads showed higher latencies to first attack, lower overall aggression, and lower proportions of bites and passive copings (submissive display) compared to control/control. TRP dominant males performed fewer bites with respect to controls, and subordinate males opposed to TRP males showed fewer passive copings. Higher serotonergic activities were found in subordinates' optic tectum and in the telencephalon and preoptic area/hypothalamus of TRP males. Altogether, results point out that dietary L-tryptophan reduced males' motivation to attack and dominant aggression, which consequently influenced subordinate agonistic repertory. In addition, males within TRP/TRP dyads showed a switch in their behavioral agonistic repertory. These behavioral outcomes were probably due to modifications at brain serotonergic functioning.

Influence of temperature on intraspecific, unbalanced dyadic contests between crabs.

Intraspecific agonistic interactions are widespread across the animal kingdom, with many individual morphological and physiological characteristics playing important roles in the fate of disputes. Additionally, changes to environmental conditions can influence the outcomes of animal contests. The shore crab (Carcinus maenas) is a globally distributed species, present in numerous coastal and estuarine temperate systems around the world. Although shore crabs are highly tolerant to changes in temperature, this parameter has important physiological effects on the species’ ecology, while its effects on behavior are not fully understood. Our study aims to investigate how different individual characteristics (such as sex, color morphotype, carapace and chela morphology) and temperature conditions affect the dyadic interactions between shore crabs when disputing food resources. In general, the differences in carapace width between opponents, their sexes, color morphotypes and the temperature conditions interacted and were important predictors of the contest fate. We found that the body size and color morphotype of C. maenas determined the fate of dyadic disputes. However, the higher temperatures disrupted the well-established dominance of the larger red color morphotype individuals. Overall, the agonistic contest results suggest higher plasticity than previously acknowledged.

The role of social and/or ecological contexts influences assessment strategy use in Tilapia

AbstractAnimals engage in costly agonistic contests during which winners procure resources. During these interactions, the combatants obtain and use information to make decisions on whether to persist or to withdraw from the fight, which is termed assessment. Recent theory and work have suggested that the types of assessment employed may be more variable than previously thought, with the use of different strategies possibly being influenced by social and ecological conditions during priming. This study addresses the contextual components (social and ecological) that affect the utilization of one assessment strategy over another. Male tilapia were primed with different combinations of social (large and small animals) and ecological (resource rich or poor) contexts 24 hr prior to fighting in staged, dyadic contests. When opponents were primed with the same context, a clear assessment strategy emerged and differed as a function of priming treatment. Conversely, when fish were primed with different treatment contexts, there was no discernible assessment. In addition, priming conditions had differing effects for large and small fish. Thus, assessment strategies in cichlids are dependent upon a combination of social, ecological contexts and size of the animal. Since assessment strategies change as a function of both of these contexts, as well as others, future framework investigating assessment strategies should include both intrinsic and extrinsic factors that may shape fighting dynamics.

Repeatability in boldness and aggression among wild zebrafish (Danio rerio) from two differing predation and flow regimes.

Although flexibility in behavior is adaptive, this flexibility is limited, and the extent of variation and consistency of a trait could depend on the environment. In this study, we investigated repeatability in risk-taking during feeding among individuals and agonistic interactions among dyads of wild zebrafish, Danio rerio, collected from two habitats that differed in predation and flow regimes. We measured boldness as the latency to emerge from a shelter and feed in the presence of predators. We tested this for each individual from the two populations repeatedly across seven trials. We assessed aggression by subjecting size- and sex-matched pairs of fish to dyadic contests repeatedly across seven trials. Individuals from the high-predation stream population were bolder than individuals from the low-predation stagnant water population. Males were bolder than females, and in the low-predation population, larger individuals took greater risks to feed than smaller individuals. The high-predation stream population showed lower inter- and intraindividual variation in boldness than the low-predation stagnant water population. Further, both populations showed significant repeatability in risk-taking during feeding. The high-predation stream habitat fish were more aggressive than low-predation stagnant-water fish. Male dyads from the low-predation stagnant-water population were significantly more aggressive than female dyads. Most fish from the low-predation stagnant water population did not show aggressive behavior, resulting in low between-dyad but high within-dyad variation in aggression. The difference in behavioral responses between the populations and consistency in these traits within individuals is discussed in the light of confounding role of ecological and state-dependent factors. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Lateralization influences contest behaviour in domestic pigs

Cerebral lateralization, i.e. hemispheric asymmetries in structure and function, relates in many species to a preference to attack from their left. Lateralization increases cognitive capacity, enabling the simultaneous processing of multiple sources of information. Therefore, lateralization may constitute a component of fighting ability (Resource Holding Potential), and/or influence the efficiency of information-gathering during a contest. We hypothesized that lateralization will affect contest outcome and duration, with an advantage for more strongly lateralized individuals. In 52 dyadic contests between weight-matched pigs (Sus scrofa; n = 104; 10 wk age), the direction of orientation towards the opponent was scan sampled every 10 s. Laterality indexes (LI) were calculated for the direction and strength of lateralization. Up to 12.5% of the individuals showed significant lateralization towards either the right or left but lateralization was absent at the population level. In line with our hypothesis, animals showing strong lateralization (irrespective of direction) had a shorter contest duration than animals showing weak lateralization. Winners did not differ from losers in their strength or direction of lateralization. Overall the results suggest that cerebral lateralization may aid in conflict resolution, but does not directly contribute to fighting ability, and will be of value in the study of animal contests.

Sociable bluegill, Lepomis macrochirus, are selectively captured via recreational angling

Individuals often show considerable variance in social behaviour and aggression, leading to defined social roles. Removal of individuals with particular roles from groups may have impacts on group function, leaving those groups less able to locate critical resources and avoid danger. In recreational fisheries, capture by humans constitutes a mortality risk, and therefore angling has the potential to fundamentally alter social structure in exploited populations if individuals with defined social roles are disproportionately captured. However, little work has examined the linkage between social behaviour and angling vulnerability. To address this gap, we conducted a study on bluegill, Lepomis macrochirus, a freshwater fish known to be socially gregarious, and a common target of recreational anglers in North America. Fish were angled in a naturalistic pond setting, and a subset of captured and uncaptured fish was then assessed for sociability in a shoaling assay and aggression/dominance in paired dyadic contests. Results showed a significant effect of time spent in the social zone on capture status, with captured individuals spending significantly more time near a transparent divider separating it from a shoal of conspecifics compared to uncaptured fish. Dominance was not associated with angling vulnerability, and sociability was not linked with dominance. Collectively, these results show that more social bluegill are more likely to be captured by anglers. This could in turn lead to decreased social functionality in exploited populations as a result of the removal of particularly social individuals, as well as possible evolution of social behaviour in exploited populations due to this selection.

Predictors of contest outcome in males of two subspecies of Gallotia galloti (Squamata: Lacertidae)

In many species, male coloration signals aggressiveness and/or fighting ability. Males of the Tenerife lizard (Gallotia galloti) have conspicuous ultraviolet (UV)-blue cheek and lateral color patches that are brighter in the breeding season and larger than those of females. We analyzed experimentally the effect of morphological and behavioral traits, including spectral variables from UV-reflecting color patches, on the outcome of staged dyadic contests between males of two subspecies of G. galloti. We performed two experiments: (1) using pairs of unmanipulated males and (2) reducing the UV reflectance of the UV-blue patches of one of the contestants with sunscreen lotion. Results from experiment 1 showed no significant difference between subspecies in the effect of any variable on contest outcome. Overall, winners had larger body mass, head width, and fore-limb length and showed a higher rate of aggressive behavior patterns than losers, whereas losers showed a higher rate of “tail shake,” which is considered a submissive behavior. Winners also had lateral UV-blue patches with higher (more blue-biased) hue than losers, but no other spectral trait had a significant effect on contest outcome. Results from experiment 2 showed that reducing patch reflectance in the UV range had no effect in one subspecies but significantly increased fighting success in the other. The probability of winning was positively associated with the frequency of bites (irrespective of whether individuals had manipulated patches or not). Results from both experiments suggest that while multiple traits (morphometric, coloration, and behavioral) may influence the outcome of male contests in G. galloti, behavioral traits take prevalence over morphological, including coloration, traits. The effect of several traits on the outcome of contests has been previously analyzed in males of several lizard species. These analyses have commonly considered the effect of a single trait on contest outcome. However, as even males of the same age and experience often vary across multiple morphological (including coloration), performance, and behavioral traits, it has been suggested that contest outcome could be influenced by several interacting traits. We tested this hypothesis by staging dyadic contests between males of two subspecies of the Tenerife lizard. Results from a first experiment showed that larger body mass, head width, fore-limb lengths, higher frequency of bites, throat extension, and higher peak reflectance (hue) of UV-blue patches significantly affected the probability of winning, while a large frequency of tail shakes was associated with losing. Results from a second experiment, in which we experimentally manipulated patch UV reflectance in one of the contestant lizards, showed that bite frequency and reduction of UV reflectance affected the probability of winning; we discuss the complex effect of this latter trait on contest outcome.

Sustenance and Performance: Nutritional Reserves, Longevity, and Contest Outcomes of Fed and Starved Adult Parasitoid Wasps

Dyadic contests for possession of resources occur across a wide range of animal taxa, with contest outcome often being heavily influenced by the energetic reserves of the competitors. The majority of studied parasitoid wasps lack de novo lipogenesis, with adult lipid reserves being limited to those acquired throughout larval development. Carbohydrate- and lipid-rich adult diets can increase adult parasitoid lifespan and fecundity by potentially acting as a maintenance energy store. However, the effects of such diets on fat reserve compositions and some aspects of parasitoid behaviour contest outcome dynamics have not been examined. This study assesses the effect of a carbohydrate rich diet (honey) on the longevity, metabolic state and contest performance of Goniozus legneri, a bethylid wasp. The longevity of honey-fed diet adults was typically more than twice that of starved wasps. Compared to similarly-aged starved wasps, honey feeding increased concentrations of common haemolymph sugars and amino acids in a 3-day old and 7-day old wasps, and higher concentrations of stored lipid in7-day old wasps. However, nutritional status did not affect the outcome of dyadic contests over host possession when both contestants were either 3 days or 7 days old. While contest dynamics outcome may be unaffected by diet, it remains possible that an enhancing effect of feeding on contest ability is matched by an effect of higher value being placed on winning by starved wasps.

Mutual assessment during ritualized fighting in mantis shrimp (Stomatopoda).

Safe and effective conflict resolution is critical for survival and reproduction. Theoretical models describe how animals resolve conflict by assessing their own and/or their opponent's ability (resource holding potential, RHP), yet experimental tests of these models are often inconclusive. Recent reviews have suggested this uncertainty could be alleviated by using multiple approaches to test assessment models. The mantis shrimp Neogonodactylus bredini presents visual displays and ritualistically exchanges high-force strikes during territorial contests. We tested how N. bredini contest dynamics were explained by any of three assessment models-pure self-assessment, cumulative assessment and mutual assessment-using correlations and a novel, network analysis-based sequential behavioural analysis. We staged dyadic contests over burrow access between competitors matched either randomly or based on body size. In both randomly and size-matched contests, the best metric of RHP was body mass. Burrow residency interacted with mass to predict outcome. Correlations between contest costs and RHP rejected pure self-assessment, but could not fully differentiate between cumulative and mutual assessment. The sequential behavioural analysis ruled out cumulative assessment and supported mutual assessment. Our results demonstrate how multiple analyses provide strong inference to tests of assessment models and illuminate how individual behaviours constitute an assessment strategy.

Olfactory signaling of aggressive intent in male-male contests of cave crickets (Troglophilus neglectus; Orthoptera: Rhaphidophoridae).

In animal contests, communicating aggressive motivation is most often mediated by visual or acoustic signals, while chemical signals are not expected to serve such a function since they are less able to be modulated by the sender during the changing behavioral context. We describe a rare example of ephemeral olfactory signals in terrestrial animals, signals that are emitted via protrusive scent glands in male cave crickets Troglophilus neglectus (Orthoptera, Rhaphidophoridae) to reflect the state of the signaler’s aggression. We correlate the intensity of behaviorally expressed aggression of the individuals in dyadic contests with the frequency and extent of their gland tissue protrusion, the latter serving as an indication of the amount of released odor. We detected large amounts of odor release during brief gland protrusions, and the absence of its release during gland retraction. Males protruded the glands during and after encountering a rival, with the degree of protrusion increasing with the intensity of the signalers’ aggression. During the encounters, the degree of gland protrusion increased most strongly with the occurrence of the elevated body posture, directly preceding the attack. This degree was significantly higher in encounter winners than in losers displaying such posture, suggesting the highly important role of the released odor for contest resolution. After the encounters, glands were protruded almost exclusively by winners, apparently announcing victory. We tested for the function of the olfactory signals also directly, by preventing gland tissue protrusion in symmetric and asymmetric treatments of the contestants. Treating only the dominant individuals decreased the percentage of encounters they won by over 60%, while treating both contestants elicited a significant increase in the frequency and duration of fights. During contests, the olfactory signals of T. neglectus apparently function as a highly effective threat, which prevents maximal contest escalation and decreases the conflict-related costs.

A coffee agroecosystem model: III. Parasitoids of the coffee berry borer (Hypothenemus hampei)

Parasitoids native to tropical Africa have been released in the Americas for the biological control of the coffee berry borer (CBB), but their establishment has been checkered. A tritrophic distributed maturation time model for the coffee plant – CBB – three parasitoids (Phymastichus coffea, Cephalonomia stephanoderis, Prorops nasuta) system was proposed by Gutierrez et al. (1998). Based on this pioneering work, and improved models for coffee and CBB (Rodríguez et al., 2011, 2013), we present an updated version of the parasitoid models. The new elements in this analysis include:1.New data on the biology and behavior of the parasitoids are added.2.A fourth parasitoid (Cephalonomia hyalinipennis) is added to the system.3.Interspecific competitive interactions among parasitoids (e.g., dyadic contests, intra-guild predation and hyperparasitism) and their effects on the control of CBB are explored.Because field data on the effectiveness of the parasitoids on CBB control is sparse, we assessed the efficacy of the parasitoids for control of CBB heuristically. The results are compared to prior analyses, and are related to field observations. Specifically, we found:1.Control of CBB by betilid parasitoids (Cephalonomia stephanoderis, Cephalonomia hyalinipennis and Prorops nasuta) is ineffective because of their low reproductive capacity relative to CBB, their host-feeding behavior, and phenological mismatches with CBB life stages.2.Of the parasitoids, the eulophid P. coffea has the greatest potential to suppress CBB infestation levels, though the fungal pathogen B. bassiana and insecticides are reported to have detrimental effects on its establishment and dynamics.

Opposite effects of nonapeptide antagonists on paternal behavior in the teleost fish Amphiprion ocellaris

The nonapeptides isotocin (IT) and arginine vasotocin (AVT), along with their mammalian homologs oxytocin and arginine vasopressin, are well known regulators of social behaviors across vertebrate taxa. However, little is known about their involvement in paternal care. Here, we measured the effect of an IT and an AVT V1a receptor antagonist on paternal behaviors in the primarily paternal teleost Amphiprion ocellaris. We also measured the effect of the IT receptor antagonist on aggression in dyadic contests between two non-reproductive fish to assess specificity of the effect on paternal behaviors. Individual differences in levels of paternal behaviors (nips, fanning the eggs, and proportion of the time in the nest) were consistent across spawning cycles when no treatments were administered. The IT receptor antagonist severely reduced paternal behaviors but had no effect on aggression, whereas the AVT V1a receptor antagonist increased paternal behaviors. These results support the idea that IT signaling is crucial for the expression of paternal behavior in A. ocellaris. Based on a previous study showing that the AVT V1a antagonist decreases aggression in dyadic contests, we hypothesize that the antagonist enhances paternal behavior indirectly by reducing vigilance and aggression, thereby alleviating effort directed towards other competing behaviors and allowing for the increased expression of paternal behaviors.

Parentally acquired differences in resource acquisition ability between brown trout from alternative life history parentage

AbstractDominance hierarchies, where they exist, affect individual food acquisition ability and fitness, both of which have the potential to influence life history pathways. Juvenile salmonids exhibit clear dominance hierarchies in early life. As one of the drivers for the adoption of alternative life histories in salmonids is the relative rate of resource acquisition, there is potential for juvenile behaviour to influence the subsequent life history strategy of the individual. Lacustrine brown trout, Salmo trutta, exhibit a multitude of life histories which includes among others the piscivorous (ferox) life history where individuals grow to large size and have delayed maturity and benthivorous and pelagic life histories where individuals grow to much smaller sizes, however mature earlier. Using a number of observable characteristics of dominance, this study compared differences in behaviour between size‐matched pairs of progeny, reared under common garden conditions which are derived from alternative, co‐existing life history strategy parents. We found that first‐generation progeny of ferox trout were more aggressive, acquired more food, had lighter skin pigmentation and held more desirable positions than the progeny of benthivorous brown trout in an experimental stream system. Ferox trout progeny were dominant over benthivorous brown trout progeny in 90% of trials in dyadic contests. Given such clear differences in dominance, this study indicates that parentally acquired dominance‐related differences, passed through either, or both, of genetic and nongenetic (e.g. maternal effects) means, are likely a contributing factor to the continued maintenance of distinct life history strategies of brown trout.

Complex contests and the influence of aggressiveness in pigs

Animal contests vary greatly in behavioural tactics used and intensity reached, with some encounters resolved without physical contact while others escalate to damaging fighting. However, the reasons for such variation remains to be fully explained. Aggressiveness, in terms of a personality trait, offers a potentially important source of variation that has typically been overlooked. Therefore, we studied how aggressiveness as a personality trait influenced escalation between contestants matched for resource-holding potential (RHP), using detailed observations of the contest behaviour, contest dynamics and escalation levels. We predicted that winner and loser behaviour would differ depending on personality. This was tested by examining 52 dyadic contests between pigs, Sus scrofa. Aggressiveness was assayed in resident–intruder tests prior to the contest. Contests were then staged between pigs matched for RHP in terms of body weight but differing in their aggressiveness. In 27% of the contests a winner emerged without escalated physical fighting, demonstrating that a fight is not a prerequisite between RHP-matched contestants. However, the duration of contests with or without fighting was the same. In contests without a fight, opponents spent more time on mutual investigation and noncontact displays such as parallel walking, which suggests that ritualized display may facilitate assessment and decision making. Winners low in aggressiveness invested more time in opponent investigation and display and showed substantially less aggression towards the loser after its retreat compared to aggressive winners. Aggressiveness influenced contest dynamics but did not predict the level of escalation. Prominent behavioural differences were found for the interaction between personality and outcome and we therefore recommend including this interaction in models where personality is considered. Analyses based on contest duration only would miss many of the subtleties shown here and we therefore encourage more detailed analyses of animal contests, irrespective of the level of contest escalation.

Do weaponless males of the hermit crab Pagurus minutus give up contests without escalation? Behavior of intruders that lack their major cheliped in male-male contests.

In dyadic contests, theoretical studies have predicted that weaker contestants are less likely to engage in fights to minimize the cost of aggression. Since the major cheliped of decapod crustaceans is critically important as a weapon, contestants without a major cheliped should be more likely to give up the contests. We therefore examined whether loss of the major cheliped by the hermit crab Pagurus minutus would affect their decision to escalate male–male contests over guarded females. Intruders without a major cheliped showed no difference in the frequency of escalation compared with intact intruders, and the decision to give up was affected by the body size difference between the contestants. After escalation, compared with intact intruders, intruders without a major cheliped had significantly decreased success of takeover of a female from opponents, suggesting a strong disadvantage of losing their major cheliped. Although the decision of weaponless intruders to escalate seems irrational, several factors, such as poor accuracy of resource holding potential assessment, the influence of body size, and a high benefit to cost ratio of male–male contests, may have affected their behavior.

Can outcomes of dyadic interactions be consistent across contexts among wild zebrafish?

Winner–loser relations among group-living individuals are often measured by the levels of aggressive interactions between them. These interactions are typically driven by competition for resources such as food and mates. It has been observed in recent studies on zebrafish that dominant males generally have higher total reproductive success than their less aggressive subordinate counterparts. This study aimed to test whether males who monopolized a food resource (winners) also displayed higher levels of aggression than the males who were unsuccessful (losers). Further, the study also tested whether the same ‘winner’ males were also able to monopolize interactions with females during courtship. The results from these experiments showed that while males monopolizing food resources (winners) demonstrated higher levels of agonistic interactions than the losers, the average number of courtship interactions initiated by either of the males (i.e. winners/losers) with a female was not significantly different. A significant relationship was obtained between the number of aggressive interactions and feeding latencies of males in the context of food monopolization. This indicated that there could be a linkage between boldness defined by feeding latency in a novel environment and agonistic responses. The probable role of nature of resources, resource availability and distribution in determining the outcomes of dyadic contests is discussed.

The role of pigment based plumage traits in resolving conflicts

The role of melanin ‘badges of status’, in male–male competition has been well‐studied, in contrast, carotenoid based plumage has largely been examined in the context of female mate choice. Recent work has shown that carotenoid signals can also function in male–male competition, although the functions of the two types of signals is currently unclear. Here, we examine the relationships between colouration, dominance and aggression in the crimson finch Neochmia phaeton, a species where males have both conspicuous red carotenoid plumage and a black melanin patch. We examined the importance of carotenoid and melanin based signals in three contexts: 1) among free‐living birds interacting at a feeding station: we found that neither colour signal influenced the outcome of interactions; 2) in staged dyadic contest in captivity: we found that coloration from carotenoid pigments was positively related to the probability of winning a contest, while the size of the melanin plumage patch was not related to winning; and 3) in staged dyadic contests where male plumage colour had been masked: we found that the number of interactions required to determine dominance increased. While the underlying natural plumage colour was still important in these contests, birds with more intense carotenoid colouration were now more likely to lose. These results confirm carotenoid‐based signalling in male–male contests. However this signal is used in conjunction with other factors such as self‐assessment and body condition. Contrary to traditional expectations, the black melanin patch was not found to be important in this context.