Spawning ecology of the Saint Paul's Gregory Stegastes sanctipauli, a damselfish endemic to the remote St Peter and St Paul's Archipelago.

We studied the spawning ecology of Stegastes sanctipauli, a damselfish endemic to the small and remote St Peter and St Paul's Archipelago (Brazil), aiming to determine the main correlates of reproductive success, as inferred from rates of egg losses along a spawning season. New clutches appeared mostly in the last quarter moon, when egg predation intensified. Predation by heterospecifics, particularly Halichoeres radiatus (Linnaeus, 1758), accounted for most egg losses, while filial cannibalism showed negligible influence. Predation pressure was highest for larger nests with higher initial density of eggs. Hatching of eggs occurred close to the new moon (i.e., ~5 days after spawning). Most nests occur in shallow reefs (<16 m depth), where main food resources for adults (turf algae) are concentrated, but abundance of egg predators, particularly H. radiatus, is also highest. This latter result suggests that the spawning activity of S. sanctipauli is influenced by the trade-offs between food accessibility by adults and egg predation risk. The patterns recorded here are similar to those known for other tropical damselfish species and may reflect strategies for attenuating predation pressure over new fry and eggs.

Factors affecting captive female giraffe stress response: Male presence, small enclosure, and low temperature.

To improve animal welfare based on suitable social housing conditions, it is important to understand the factors that trigger high-stress responses. Wild giraffes live in a fission-fusion society and males and females are rarely in the same herd for a long period. The captive condition of belonging to a herd with the same individuals for months or years is uncommon in nature. To understand the effect of male presence on female stress levels, fecal glucocorticoid metabolite (fGCM) levels and social interactions in two captive female giraffes were investigated. Additionally, the effect of enclosure size and temperature on fGCM level and social interactions were examined. The results showed no significant difference in the fGCM levels of females based on male presence. The frequency of agonistic behavior by the dominant female toward the subordinate female was significantly increased when a male was present. The subordinate female was significantly less likely to approach the dominant female and showed decreased affiliative and agonistic interactions toward the dominant female when a male was present. The frequencies of agonistic interactions between females were higher in the small enclosure regardless of male presence. Low temperature triggered higher fGCM levels and increased agonistic interaction in an aged female. The findings of this study suggest that these multiple factors should be considered individually to promote the welfare of captive giraffes.

Elevated aggression is associated with uncertainty in a network of dog dominance interactions.

Dominance hierarchies are widespread in animal societies and reduce the costs of within-group conflict over resources and reproduction. Variation in stability across a social hierarchy may result in asymmetries in the benefits obtained from hierarchy formation. However, variation in the stability and behavioural costs of dominance interactions with rank remain poorly understood. Previous theoretical models have predicted that the intensity of dominance interactions and aggression should increase with rank, but these models typically assume high reproductive skew, and so their generality remains untested. Here we show in a pack of free-living dogs with a sex-age-graded hierarchy that the central region of the hierarchy was dominated by more unstable social relationships and associated with elevated aggression. Our results reveal unavoidable costs of ascending a dominance hierarchy, run contrary to theoretical predictions for the relationship between aggression and social rank in high-skew societies, and widen our understanding of how heterogeneous benefits of hierarchy formation arise in animal societies.

Tyraminergic modulation of agonistic outcomes in crayfish.

Octopamine, a biogenic amine, modulates various behaviors, ranging from locomotion and aggression to learning and memory in invertebrates. Several studies recently demonstrated that tyramine, the biological precursor of octopamine, also affects behaviors independent of octopamine. Here we investigated the involvement of tyramine in agonistic interaction of the male crayfish Procambarus clarkii. When male crayfish fight, larger animals (3-7% difference in body length) are more likely to win. By contrast, direct injection of tyramine or octopamine counteracted the physical advantage of larger animals. Tyramine or octopamine-injected naive large animals were mostly beaten by untreated smaller naive animals. This pharmacological effect was similar to the loser effect in which subordinate larger animals are frequently beaten by smaller animals. Furthermore, loser effects were partly eliminated by either injection of epinastine, an octopamine blocker, or yohimbine, a tyramine blocker, and significantly diminished by injection of a mixture of both blockers. We also observed that tyramine levels in the subesophageal ganglion were remarkably increased in subordinate crayfish after losing a fight. These results suggest that tyramine modulates aggressive levels of crayfish and contributes to the loser effect in parallel with octopamine.

Exposure to Sublethal Ammonia Concentrations Alters the Duration and Intensity of Agonistic Interactions in the Crayfish, Orconectes rusticus.

Crayfish extract information from chemical stimuli during social interactions. Commercial fertilizers increase background ammonia concentrations which may interfere with chemical communication. Background pollution can disrupt perception of chemical stimuli in three ways: masking, sensory impairment, physiological impairment or in combination. We investigated whether exposure to ammonia alters agonistic behavior. Crayfish pairs exposed to 0.9 mg/L ammonia fought for a longer duration, while crayfish exposed to 9.0 mg/L ammonia fought for a shorter duration. Altering activity patterns of crayfish may alter crayfish populations leading to a nonproportional impact because of their importance to the structure and function of aquatic ecosystems.

Impact of Body-worn Sensors on Broiler Chicken Behavior and Agonistic Interactions.

Technology, like body-worn sensors, enables data collection from similar-looking individuals in large groups but may alter behavior. We aimed to evaluate the impact of body-worn sensors on broiler behavior. Broilers were housed in 8 pens (10 birds/m2). At 21 days-old, 10 birds/pen were fitted with a harness contained a sensor (HAR), while the remaining 10-birds were unharnessed (NON). Behaviors were recorded on days 22-26 using scan sampling (126 scans/day for 5 days). Percent of birds performing behaviors were calculated daily for each group (HAR-or-NON), and agonistic interactions were identified based on birds involved (two NON-birds (N-N), NON-aggressor to HAR-recipient (N-H), HAR-aggressor to NON-recipient (H-N), or two HAR-birds (H-H)). HAR-birds performed locomotory behavior and explored less often than NON-birds (p<0.05). Consummatory behavior was unaffected by treatment on any day (p>0.05). Agonistic interactions occurred more often between NON-aggressor and HAR-recipient birds than other categories on days 22 and 23 (p<0.05). HAR-broilers showed no behavioral differences when compared to NON-broilers after 2 days; thus, a similar acclimation period is required before using body-worn sensors to evaluate broiler welfare without altering behavior.

Social attributes shape antipredator behavior strategies in the ruddy ground-dove.

The cost-benefit of social behavior depends on group size and the social interaction. As group size increases, competition for resources increases, while individual vigilance may decrease due to the lower probability of individual predation or increased competition for resources. To test predictions of the "many eyes hypothesis" and the "competition hypothesis", we investigated the effects of social attributes on the vigilance, foraging, direct conflict and sex on social groups of ruddy ground-doves (Columbina talpacoti) in an urban area. We observed that the number of conspecifics did not influence individual foraging behavior, instead, the vigilance decreased as flock size increased. Moreover, the number of conflicts within the flock negatively affected individual vigilance. However, larger flocks exhibited more direct conflicts, and males were more frequently involved in social conflicts, regardless of the sex ratio of the flock. Finally, the investment in both vigilance and foraging was not influenced by the sex of the focal individual or the sex ratio of the flock. Our findings indicate that conspecific numbers and flock social organization significantly influence the cost-benefit dynamics of flocking behavior. Larger flocks enhance vigilance for predator detection but come at an individual cost due to increased resource competition and conflicts.

Individuality and function of chemical signals during conflict resolution of a mammal.

Individual recognition via communication signals is a critical component of social behavior, and provides the basis of conflict resolution, territorial behavior, and mate choice. However, the function of chemical signals in mammalian individual recognition and conflict resolution has largely been unexplored despite olfaction being a dominant sensory modality in many mammalian species. Here, we describe behavioral tests designed to evaluate the potential role of forehead gland secretions during conflict related to territorial defense in male Great Himalayan leaf-nosed bats. We used gas chromatography-mass spectrometry to quantify the chemical composition. Our results showed that forehead gland secretions contain 16 categories of compounds, including 84 volatile compounds. The concentrations of compounds and their categories differed significantly among individuals. Moreover, behavioral studies indicated that males can use chemical signals for individual recognition. Contests were staged between males with or without functioning forehead glands. Paired males without functioning forehead glands displayed more physical contact and longer contest duration compared with pairs with functioning glands. Moreover, males with a functioning gland were more likely to win in contests when paired with males without a functioning gland. These findings support a growing amount of evidence that chemical signals play a vital role in conflict resolution in mammals.

Impact of a Dietary Citrus Extract on the Behavior and Production of Lactating Dairy Cows Following Regrouping: A Preliminary Study.

Exposure of lab animals, humans, and pigs to olfactory sensory feed additives may reduce response to stress and anxiety. The objective of this preliminary study was to determine if feeding a citrus-based olfactory sensory functional feed extract (derived from Citrus sinensis) reduces the negative impact of regrouping of lactating dairy cows. Thirty-two (parity = 2.0 ± 1.2; mean ± SD), mid-lactation Holstein dairy cows (169.8 ± 16.8 DIM) were enrolled as focal cows in this study and housed individually in a tie-stall facility where they were randomly assigned to 1 of 2 treatment diets: (1) control total mixed ration (TMR) (control; n = 16; primiparous = 7; multiparous = 9), or (2) control TMR with 4 g/d of citrus extract (CE) (Phodé, Terssac, France) (CE; n = 16; primiparous = 7; multiparous = 9). Cows were fed their experimental diets for 7 d in the tie-stall facility (baseline), then moved to 1 of 2 experimental free-stall pens (containing 29 other cows) for a period of 7 d, where they remained on the same treatment diet as before. Compared with their baseline, primiparous control cows had decreased rumination time on d 1 and 2, had decreased lying time on d 1, and tended to have decreased lying time on d 2 and 3 following regrouping. In contrast, primiparous cows fed the CE diet did not experience a change in rumination and lying time. Primiparous CE cows had greater feeding time on d 1 and tended to have greater feeding time on d 2 after regrouping compared to primiparous control cows. Primiparous control cows had greater idle standing time, as compared to the CE cows, across the 7 d after regrouping. Primiparous CE cows initiated less total competitive behavior after regrouping, but were also displaced more frequently from the feed bunk and from the free stalls on d 1 after regrouping, as compared to the primiparous control cows. For multiparous cows, CE supplementation was not consistently associated with any benefits to behavior or production after regrouping, possibly because these cows were more experienced with social stressors. Results indicate that feeding CE to mid-lactation naïve primiparous dairy cows may reduce the initiation of competitive interactions and lessen the reduction in rumination and lying time after regrouping. These results need to be verified in further studies where potential confounding effects (e.g., pen social dynamics, pen location) are minimized.

Exposure paradigm of fluoxetine impacted the Faxonius virilis agonistic behavior differently.

Pharmaceutically active compounds are major contaminants of aquatic environments. The effects on aquatic organisms have been assessed mostly through eco-toxicological tests performed using static exposure systems or flow through systems with constant concentrations. Yet, constant concentration exposures ignore the spatio-temporal dynamics of chemicals in flowing environments. In dynamic systems, a chemical's effect on an organism will vary due to fluctuations in the frequency, magnitude, and duration of the chemical concentration within the plume, which develops due to turbulence interacting with the geomorphology of habitat. The aim of this study was to analyze how different exposure dynamics to the antidepressant fluoxetine might alter the agonistic behavior of aquatic organisms. Male crayfishes, Faxonius virilis, were subjected to 23 h exposures at different concentrations of fluoxetine (control, 0.05, 0.5, 1, 10 and 100 µg/l) in both static and dynamic mesocosm systems. After exposure, size-matched crayfishes, from the same exposure system and fluoxetine concentration, underwent a fifteen minute fight trial. The aggressive intensities and duration of agonistic interactions were quantified. The time spent performing a tailflip was significantly longer for fluoxetine concentrations of 1, 10, 100 µg/l in the static exposure than in the dynamic exposure. On other hand, the time spent at higher intensities and the time to escalate to the highest intensity of interactions in control treatments were significantly lower in the dynamic exposure than in the static exposure. Whereas, in elevated fluoxetine concentrations, these times were significantly higher in the dynamic than in static treatments. Therefore, we could conclude that the fight dynamics and duration of agonistic behavior in crayfish were affected by static and dynamic exposure paradigms differently. Despite these behavioral changes, serotonin levels in fluoxetine-exposed crayfish did not differ significantly between exposure paradigms. Future research should incorporate different exposure methods that more accurately represent chemical exposure in natural habitats.

Body Contacts and Social Interactions in Captive Odontocetes Are Influenced by the Context: An Implication for Welfare Assessment.

Research on the welfare of captive odontocetes has increased in recent years, but has been mostly focused on bottlenose dolphins (Tursiops truncatus). Few studies investigated potential welfare indicators using quantitative data linked to a range of conditions or stimuli that are thought to impact the animals' emotional state. Since odontocetes are social animals that engage in various social interactions, these interactions might inform us on their welfare state. We investigated pectoral contact laterality and the effect of the context on several social behaviors in three groups of captive odontocetes (Yangtze finless porpoises, YFPs: Neophocaena asiaeorientalis asiaeorientalis; East-Asian finless porpoises, EAFPs: N. a. sunameri, and bottlenose dolphins, BDs). Animals exhibited patterns depending on the time of the day for most of the social behaviors we analyzed; social separation was associated with lower rates of social behaviors for the two analyzed groups (YFPs and BDs), the accessibility to several pools was associated with higher rates of social behaviors for BDs. The effect of enrichment, disturbances and public presence was less clear and strongly depended on the group, the type of enrichment and disturbance. Our results confirm that captive odontocetes' social behaviors are influenced by the context, and that, depending on the group, some of them, such as pectoral contacts, other body contacts, agonistic interactions or social play exhibit consistent patterns across contexts. Monitoring these behaviors might be useful to adapt the captive management to each species and group. The different responses among the three studied groups confirm that species and groups react differently to a stimulus and therefore, management decisions should be species/group specific. We recommend that more studies should be conducted to validate our findings in other groups of odontocetes under human care.

Agonistic Interactions in Pigs-Comparison of Dominance Indices with Parameters Derived from Social Network Analysis in Three Age Groups.

Dominance indices are often calculated using the number of won and lost fights of each animal focusing on dyadic interactions. Social network analysis provides new insights into the establishment of stable group structures going beyond the dyadic approach. Thus, it was investigated whether centrality parameters describing the importance of each animal for the network are able to capture the rank order calculated by dominance indices. Therefore, two dominance indices and five centrality parameters based on two network types (initiator-receiver and winner-loser networks) were calculated regarding agonistic interactions observed in three mixing events (weaned piglets, fattening pigs, gilts). Comparing the two network types, the winner-loser networks demonstrated highly positive correlation coefficients between out-degree and outgoing closeness and the dominance indices. These results were confirmed by partial least squares structural equation modelling (PLS-SEM), i.e., about 60% of the variance of the dominance could be explained by the centrality parameters, whereby the winner-loser networks could better illustrate the dominance hierarchy with path coefficients of about 1.1 for all age groups. Thus, centrality parameters can portray the dominance hierarchy providing more detailed insights into group structure which goes beyond the dyadic approach.

All by myself? Meta-analysis of animal contests shows stronger support for self than for mutual assessment models.

Since the 1970's, models based on evolutionary game theory, such as war of attrition (WOA), energetic war of attrition (E-WOA), cumulative assessment model (CAM) and sequential assessment model (SAM), have been widely applied to understand how animals settle contests. Despite the important theoretical advances provided by these models, empirical evidence indicates that rules adopted by animals to settle contests vary among species. This stimulated recent discussions about the generality and applicability of models of contest. A meta-analysis may be helpful to answer questions such as: (i) is there a common contest rule to settle contests; (ii) do contest characteristics, such as the occurrence of physical contact during the fight, influence the use of specific contest rules; and (iii) is there a phylogenetic signal behind contest rules? To answer these questions, we gathered information on the relationship between contest duration and traits linked to contestants' resource holding potential (RHP) for randomly paired rivals and RHP-matched rivals. We also gathered behavioural data about contest escalation and RHP asymmetry. In contests between randomly paired rivals, we found a positive relationship between contest duration and loser RHP but did not find any pattern for winners. We also found a low phylogenetic signal and a similar response for species that fight with and without physical contact. In RHP-matched rivals, we found a positive relationship between contest duration and the mean RHP of the pair. Finally, we found a negative relation between contest escalation and RHP asymmetry, even though it was more variable than the other results. Our results thus indicate that rivals settle contests following the rules predicted by WOA and E-WOA in most species. However, we also found inconsistencies between the behaviours exhibited during contests and the assumptions of WOA models in most species. We discuss additional (and relatively untested) theoretical possibilities that may be explored to resolve the existing inconsistencies.

Interactions between Invasive Monk Parakeets (Myiopsitta monachus) and Other Bird Species during Nesting Seasons in Santiago, Chile.

The monk parakeet (Myiopsitta monachus) is considered to be one of the most invasive bird species because its unique ability among parrots to build their own communal nests. Currently, they are considered an invasive species in 19 countries and a pest-even in their native distribution-because of economic losses derived from their impacts. During the reproductive seasons of 2017 and 2018, we registered interactions between invasive monk parakeets and resident bird species in Santiago, Chile. We observed agonistic and affiliative interactions, and further, we described monk parakeets' nest occupancy by nine bird species, two invasive and seven native. For this reason, we consider that the monk parakeet is an allogenic ecosystem engineer with the potential to shape distribution and richness of sympatric species in urban environments. Our results contribute to an assessment of the implications of the monk parakeet's ecological invasion to other synanthropic species, and raise concern of other potential impacts, such as pathogen transmission derived from these interactions.

Great Himalayan leaf-nosed bats modify vocalizations to communicate threat escalation during agonistic interactions.

Bats vocalize extensively within various social contexts. Nevertheless, studies of agonistic interactions, associating vocalizations signalling the emotional state of a caller with individual signatures during aggressive vocalizations remain scarce. Here, we examined whether male Great Himalayan leaf-nosed bats (Hipposideros armiger) modify their aggressive vocalizations during agonistic interactions depending on the level of aggression, and whether these vocalizations encode individual signatures. We applied a cost-benefit analysis to audio-video recordings of 50 dyadic agonistic interactions to categorize displays into two levels of aggression intensity (low aggression: bared teeth, slightly pulled up body and/or wings; high aggression: rapidly flapping wings, punching, biting). Male H. armiger used graded visual agonistic displays accompanied by bent upward frequency modulation (bUFM) vocalizations to defend their roosting territories. At high aggression intensities, males decreased the minimum frequency of aggressive calls and increased the frequency bandwidth. Males also transferred energy from the second harmonic to the first harmonic as the threat escalated. These systematic modifications of acoustic parameters as aggressive intensity fluctuated corresponded to prosodic modifications in human speech, indicating that emotion-related acoustic cues are a common feature of acoustic communication in mammals. In addition, we found that the aggressive calls of eight adult males encoded discriminable signatures, and that males could discriminate among individuals based on these aggressive calls. Such discrimination is probably useful for individual identification among rival neighbours.

Does MCH play a role on establishment or maintenance of social hierarchy in Nile tilapia?

Body coloration has a fundamental role in animal communication by signaling sex, age, reproductive behavior, aggression, etc. Nile-tilapia exhibits dominance hierarchy and the dominants are paler than subordinates. During social interactions in these animals, these color changes occur rapidly, and normally the subordinates become dark. In teleosteans, from the great number of hormones and neurotransmitters involved in color changes, melanocyte hormone stimulates (α-MSH) and melanin concentrates hormone (MCH) are the most remarkable. The aim of this project was to investigate the role of MCH in the establishment of hierarchical dominance of the Nile-tilapia. We analyzed the effect of background coloration in the dominance hierarchy. It was then compared to the melanophore sensibility of dominants and subordinates' fishes to MCH; finally, it was checked if the social rank affects the number of these pigment cells in dominants and subordinated fishes. Fishes which have a social hierarchy established and adjusted individually to the background exhibits paler body coloration when a visual contact was possible, independently of previous social rank and background color. Probably, even recognizing each other, fishes could be defending their new territory. Melanophores of the subordinate fishes were more sensible to MCH than dominants. It suggests that dominants fishes, which are paler than subordinates, could be under a chronic effect of MCH, which could be due a desensitization of melanophores to this hormone. The opposite effect seems to be occurring on subordinate fishes. It was not observed a significant change in the number of melanophores when the fishes were exposed to a prolonged period of agonistic interaction. It is possible that the exposure time for this interaction might not have been sufficient to have any change in the number of these cells of dominants and subordinate fishes.

Novelty of the arena impairs the cortisol-related increase in the aggression of matrinxã (Brycon amazonicus).

The dichotomic effect of a cortisol level rise in vertebrate behavior has been widely observed. Generally, a chronic increase of the hormone level inhibits aggression, while an acute rise increases aggression. However, in this study, we show that this increase in aggression through an acute rise of cortisol also depends on the context in which the agonistic interaction occurs in the tropical fish matrinxã, Brycon amazonicus. We combined two factors: the type of housing (resident or non-resident in the trial arena) and the level of cortisol at the beginning of the fight (normal level - control, or high level - hydrocortisone-treated fish). The cortisol treatment increased the aggressiveness in the resident fish, but this effect was not observed in the non-resident fish, which fought in an unknown arena. The novelty of the arena may have elicited an "alerted state" in the non-resident fish; in this situation the fight was not the priority, and the cortisol effect in aggression could be impaired by a conflict between motivational systems (fear and aggression). In our knowledge, in fish, the increase of aggression promoted by an acute rise in cortisol levels was always tested and observed in a resident context, and the inhibition of cortisol effect in the agonist behavior is demonstrated for the first time. As the cortisol effect in aggression is observed in several taxa, the inhibition of aggressiveness increased by the novelty of the arena should be investigated in other groups to clarify the dynamics of this effect of cortisol in animal behavior.

First records of preorbital gland opening in rare wild barasingha (Rucervus duvaucelii) in social contexts may help to explain this phenomenon in cervids.

The opening of the preorbital gland in deer serves as a visual communication and has been linked to a wide variety of behavioural situations. As we reported recently, all previous long-term studies on preorbital gland opening were carried out on only one species, whereas case reports on six other rarely studied species have shown associations with different behaviours, thus greatly increasing our overall understanding of the real function of this gland in animal visual communication. Here, we report for the first time preorbital gland opening in the barasingha (Rucervus duvaucelii) in social contexts as observed in a wild population in Kanha National Park, India. We observed this behaviour in two different contexts: agonistic and sexual. Moreover, our record of preorbital gland opening during copulation is the first one amongst cervids. Our findings of preorbital gland opening in both contexts in wild barasingha indicate that the gland was opened only when the individual was highly excited. We suggest that preorbital gland opening may be an important behavioural indicator of an individual involved in a serious intraspecific interaction, and thus a useful tool with which to distinguish between playful and serious behaviours, especially in agonistic and sexual situations.

Experimental assessment of social interactions in two species of the genus Teratoscincus (Gekkota).

Social organization of many reptile species that are rare in the wild remains rather unexplored due to difficulties when setting experiments in the field. Behavioral analysis of standard social situations in laboratory conditions is considered an indirect method to reveal social behavior in the field. We studied two rare species of geckos, Teratoscincus scincus and Teratoscincus keyserlingii, inhabiting sand dunes of Uzbekistan and Eastern Iran. A series of experiments was carried out to quantify responses in social interactions among conspecific adults as well as reactions of these towards conspecific/heterospecific subadults and juveniles. We also assessed the effect of species and sex on recorded behavior. Finally, the reaction to threat stimuli simulating predator attack was analyzed. The species effect was recorded only in the response to a simulated predatory attack: T. scincus typically escaped whereas larger T. keyserlingii attacked the stimulus. In accordance with the sexual competition hypothesis, agonistic interactions were nearly exclusively confined to male-male encounters while females were tolerant to each other. Male-female encounters regularly resulted in mating attempts, which suggests that females are not strongly selective in choosing partners. Therefore, male aggression can be linked to mate guarding or territoriality. Adults' lack of interest in immature geckos may indicate generalized tolerance of adults towards young.

Does fin coloration signal social status in a dominance hierarchy of the livebearing fish Xiphophorus variatus?

In each population of the livebearing fish Xiphophorus variatus, only a small portion of the adult males develop bright yellow-red (YR) coloration on the dorsal and caudal fins. Here we characterized the dominance hierarchy in X. variatus and tested whether YR coloration is related to a male's position in the hierarchy and can therefore serve as a reliable cue to rival males. Populations varied considerably in the frequency of YR males. Across all populations, males with YR coloration were significantly larger than the rest of the males in the population. Observations of aggressive interactions among males in small groups in the laboratory revealed a sized-based dominance hierarchy with YR males at the top. Aggression was more common among males of a similar size and fighting increased as male body size differences decreased. However, despite the reliability of YR coloration as a signal of dominance status, males at lower social ranks did not avoid aggression with YR males and YR males did not experience fewer aggressive attacks compared to non-YR males. Our findings demonstrate that fin coloration is a reliable cue of a male's social status but rival males appear to not use this information to avoid potentially costly interactions with dominant males, suggesting that YR fin coloration has not evolved as a cue in agonistic interactions.