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Two species of Haploembia Ramburi (Oligotomidae: Embioptera), nonnative detritivores found in the western USA, display solitary tendencies, not typical for webspinners that usually share silk galleries. Reports from the 1960s based on native populations in Italy highlighted the impact of a gregarine that depressed male sterility and female survivorship in Haploembia solieri (Rambur). Sympatric asexual Haploembia tarsalis (Ross) lives a normal lifespan when parasitized, albeit suffering from reduced fecundity. Our goal is to characterize behavioral repertoires as individuals interact and to develop methods for future investigations focused on the impact of the little-known parasite. We quantified individual responses to conspecifics or other species in 10-min dyadic interactions and, in a 3-day trial, determined whether they aggregated when given dispersed resources. Replicated groups of four adult female H. solieri or H. tarsalis settled away from each other over the 3-day trials. In 10-min bouts of same or different species pairs, focal insects bolted back, retreated and attempted to escape when they encountered one another, especially when the opponent was H. tarsalis. Males courted conspecific females, but were dramatically repelled by H. tarsalis. Serving as a positive control, Oligotoma nigra (Hagen) (Oligotomidae) adult females paired with conspecifics displayed typical webspinner behaviors by sitting together, sharing silk. Haploembia solieri males did not respond negatively to O. nigra, not known to be parasitized by the gregarine, but did so when paired with H. tarsalis. Results align with the prediction that susceptibility to parasitism may have led to antisocial behaviors observed in two Haploembia species. [ABSTRACT FROM AUTHOR]

ABSTRACT: Dominance hierarchies are known for mitigating conflicts and guiding priority of access to limited resources in gregarious animals. The dominance hierarchy of dairy cows is typically investigated using agonistic interactions, often monitored at the feed bunk right after fresh feed delivery when competition is high, resulting in frequent interactions. Yet, the outcome of agonistic interactions during times of high competition may be more influenced by cows' high valuation of fresh feed than their intrinsic attributes, such that the dominance hierarchy constructed using agonistic interactions under high versus low competition times might differ. We tested how the structure of the dominance hierarchy changes in relation to different levels of competition in a dynamic group of 48 lactating dairy cows over 10 mo, with 6 cows exchanged every 16 d, for a total of 159 cows. Using a validated algorithm, we continuously detected the actor and reactor of replacement behaviors in 30 feed bins as cows competed for feed. We also calculated the percentage of occupied feed bins to characterize competition at the moment of each replacement. These data were combined to create hierarchies using Elo ratings, separately for 25 occupancy levels ranging from 13% to 100%. For each 1% rise in feeder occupancy, hierarchy steepness fell by 2.41 × 10−3 ± 9.71 × 10−5 (SE), and the percentage of dyads where both cows replaced each other rose by 0.13% ± 0.01%. At the highest feeder occupancy level in comparison to the lowest one, we observed 7.57% more dyads in which the dominant individual (those that won more interactions at the lowest feeder occupancy) started to lose proportionally more. The magnitude of decrease in the winning rate of the dominant individual in those dyads also got amplified by 1.06 × 10−3% ± 1.37 × 10−4% (SE) for each 1% increase in feeder occupancy. These findings illustrate how inferred hierarchies vary with competition, with high competition flattening the hierarchy due to increased success of subordinate animals. We suggest that during heightened competition, increased valuation of resources can affect competitive success more than the individual's intrinsic dominance attributes. We recommend against calculating dominance hierarchies based on agonistic interactions during periods of high competition alone, and more generally urge researchers to differentiate agonistic interactions based on context when constructing dominance hierarchies.

Edible crabs (Cancer pagurus) are an economically important species for Scottish inshore fisheries, with an estimated annual landing value of GBP 16 million (2023). Research into the behaviour, particularly agonistic behaviour, of this species is currently lacking. This paper aims to investigate behaviour, social interactions, potential hierarchies, and the impact of claw size on the outcomes of agonistic interactions of male C. pagurus through behavioural trials and retrials. Crabs were semi-randomly assigned to pairs (based on allocated condition index rating) and introduced to one another in trial tanks. Each pair underwent two trials, 24 h apart (the "trial" and "retrial"). Analyses of video records of agonistic bouts revealed that 77% of retrials were won by the initial victors, with a significant decrease in fight time between trials and retrials. Fight time was not correlated with weapon size (claw length, height, and depth). There were no differences in weapon size of winners and losers of bouts. Winners exhibited a significantly higher frequency of aggressive and dominant behaviours (approach, aggressive contact, threat displays, and mounting), and losers exhibited higher frequencies of submissive behaviours (withdrawal, retracting limbs, and remaining motionless). These results suggest that individual behaviour may play more of a role in dominance than size or other morphometric characteristics. [ABSTRACT FROM AUTHOR]

The decision to escalate aggression in a contest is based on the assessment of oneself and the opponent's capabilities, previous experiences and the asymmetries between contenders. Interestingly, there is increasing evidence that color polymorphism may also influence the result in a contest during agonistic encounters. Therefore, this research aimed to analyze, for the first time, the intra-sexual competition of adult males of the Mexican Rivulus Millerichthys robustus, testing the influence of color polymorphic variations during agonistic contests. The results of this study suggest that the aggressiveness between morphotypes is of orange and red over yellow. The orange morph was related to winning the greatest number of encounters, whereas yellow lost the most. The red morpho registered the greatest number of ties. Interestingly, in contests between more aggressive morphs (orange and red), fish tended to modulate and lower aggressiveness levels, possibly to avoid injuries. In contrast, the least aggressive morphotype (yellow) tended to raise its aggressiveness against the most successful morphotype and lower it in matches against its own color, changing to a scheme between contenders with symmetrical aggression levels. These results suggest that differential aggression between morphotypes can influence the evolution of color polymorphism in M. robustus, differentially influencing the fitness of the individuals. [ABSTRACT FROM AUTHOR]

Abstract Examples of symbiotic relationships often include cleaning mutualisms, typically involving interactions between cleaner fish and other fish, called the clients. While these cleaners can cooperate by removing ectoparasites from their clients, they can also deceive by feeding on client mucus, a behavior usually referred to as “cheating behavior” that often leads to a discernible jolt from the client fish. Despite extensive studies of these interactions, most research has focused on the visual aspects of the communication. In this study, we aimed to explore the role of acoustic communication in the mutualistic relationship between cleaner fishes and nine holocentrid client species across four regions of the Indo-Pacific Ocean: French Polynesia, Guam, Seychelles, and the Philippines. Video cameras coupled with hydrophones were positioned at various locations on reefs housing Holocentridae fish to observe their acoustic behaviors during interactions. Our results indicate that all nine species of holocentrids can use acoustic signals to communicate to cleaner fish their refusal of the symbiotic interaction or their desire to terminate the cooperation. These sounds were predominantly observed during agonistic behavior and seem to support visual cues from the client. This study provides a novel example of acoustic communication during a symbiotic relationship in teleosts. Interestingly, these vocalizations often lacked a distinct pattern or structure. This contrasts with numerous other interspecific communication systems where clear and distinguishable signals are essential. This absence of a clear acoustic pattern may be because they are used in interspecific interactions to support visual behavior with no selective pressure for developing specific calls required in conspecific recognition. The different sound types produced could also be correlated with the severity of the client response. There is a need for further research into the effects of acoustic behaviors on the quality and dynamics of these mutualistic interactions.

The antagonistic interaction between wasps and bees has long driven the attention of beekeepers and evolutionary entomologists. In the most classic reported interaction, Vespa velutina may invade the nest of honeybees and kill many of workers. Although this interaction has been registered to Asian honeybees, which was shown how to defend the nests, little or no attention has been given to similar interactions in the Neotropical region. Here, we report for the first time an antagonistic interaction between the wasp Polybia ignobilis and the stingless bees, Tetragonisca angustula. The wasp of this species was recorded killing and chewing guard bees near at the nest entrance of the stingless bee. Although our report is limited to answer evolutionary aspects of this interaction, it raises questions which may help to understand in the future the reasons this behavior evolved. [ABSTRACT FROM AUTHOR]

Changes in the behavior of free-living animals caused by natural and anthropogenic factors can influence their survival and reproduction. Tourist activities with sea lions in the wild have become an important attraction in various parts of the world. Although these animals appear to be habituated to human presence, in some cases, they have attacked humans, showing that they may be under a certain degree of stress. In this study, we analyzed California sea lions' maternal behavior under two contrasting scenarios of abundance and tourist activity in Los Islotes rookery, Mexico. We choose maternal behavior because it directly influences the pups' survival and the females' fecundity. The presence of tourist boats was not found to affect maternal behavior; however, behavior changes observed in the different scenarios were due to the number of females, the strong winds, and the increase in tide level due to the seasonality of the area. Although sea lions are apparently habituated to the presence of boats, it is recommended to continue monitoring the sea lion population and regulating tourism to be able to detect any change in the colony's population size and to rule out tourist activities as a possible cause. [ABSTRACT FROM AUTHOR]

Throughout their distribution range, sailfin and shortfin mollies of the genus Poecilia inhabit overlapping habitats; however, little is known about its behavioural coexistence. We first describe the ethogram of Poecilia velifera and P. mexicana in a mangrove of Yucatan. Furthermore, we identify behavioural strategies of each size morphotype/species. We describe reproductive, territorial, and cleaning behaviours in two sympatric species of mollies in their natural context, with emphasis of their behavioural interactions and coexistence. Specifically, here we document (i) specific reproductive strategies in male P. velifera morphotypes (large, intermediate-ornamented and 'cryptic-intermediate'), suggesting that cryptic-intermediate males have advantages that suggest consequences for their reproductive success; (ii) frequent courtship and sexual behaviours from P. mexicana males directed to P. velifera females, that deserve future attention to determine the possible generation of hybrids; and (iii) increased aggressive behaviour and territoriality of P. mexicana relative to those observed in P. velifera. [ABSTRACT FROM AUTHOR]

Social wasps are among the most curious non-ant insects known to harvest food bodies of Cecropia Loefl. The aim of this note is to describe for the first time: (1) interactions between wasp species which harvest food bodies; (2) interactions of these wasps with other insects associated to Cecropia (ants, assassin bugs); (3) the use of a food resource different from müllerian bodies; and (4) wasp species whose association with Cecropia was unknown until now. All records were made in Manaus region and in Uatumã Sustainable Development Reserve (Amazonas State, Brazil), with the aid of a digital camera. The wasp and ant species involved were captured for later identification. The recorded wasp species were: Charterginus xanthura Saussure, 1854, Protopolybia chartergoides Gribodo, 1891, Protopolybia minutissima Spinola, 1851, and Synoeca virginea Fabricius, 1804 (Hymenoptera: Vespidae). The findings corroborate the importance of food bodies not only for Azteca Forel, 1878 ants, but also for other social insects.

Adult female spiders lay batches of eggs in silken egg sacs, and after hatching, the spiderlings live for transient periods in their mother's web before dispersing. Sibling cannibalism is frequently observed among spiderlings of many species under conditions of food deprivation. Here, we conducted assays in small Petri dishes with different densities of newly hatched (second instar) spiderlings of the false widow spider, Steatoda grossa, using a split‐clutch design. Prey (freshly killed fruit flies) availability was manipulated both numerically and temporally. Offspring from 10 different females were separated as siblings into densities of two, four, or eight spiderlings per Petri dish and these were provided with either 0 flies (starvation control), two flies, four flies, or eight flies that were replenished weekly or every 3 weeks. A further control was conducted with solitary spiderlings in Petri dishes deprived of flies. The number of surviving spiderlings per Petri dish was counted every 3 days until only one remained (or until death of the solitary spiderling). Our results show that the rate of cannibalism was lower with increasing spiderling density and when fresh flies were replenished more frequently, whereas the number of flies that were provided did not affect cannibalism. In S. grossa, juvenile cannibalism occurs primarily under conditions of extreme food limitation, although in synanthropic habitats where the spider is abundant, it may be an adaptive strategy owing to the potential scarcity of prey. Under certain conditions, cannibalism in spiderlings is adaptive by eliminating competitors and providing nutrient‐rich food. [ABSTRACT FROM AUTHOR]

Birds may alter song structure in response to territorial challenges to convey information about aggressive intent or fighting ability. Professional and amateur ornithologists upload daily many birdsong recordings into acoustic data repositories, usually scoring whether songs were recorded in response to a conspecific playback or produced spontaneously. We analyzed recordings from these repositories to evaluate if song traits of Rufous-browed Peppershrikes (Cyclarhis gujanensis) vary between playback-elicited songs and spontaneous songs. For each recording after playback, we chose one spatially closer spontaneous recording to avoid geographic bias. Birds recorded after playback produced slightly longer songs than birds that were singing spontaneously. This result was accounted for by increases in the amount of sound and silence within a song after the playback instead of changes in the mean number or duration of elements. Playback did not alter song frequency parameters (bandwidth, minimum, mean, and maximum frequencies) or song rate. These results indicate that song duration might mediate aggressive interactions in Rufous-browed Peppershrikes. Even considering limitations such as unknown playback stimulus identity and possible pseudoreplication, acoustic data repositories give a unique yet unexplored opportunity to gather insights into the evolution of song flexibility during aggressive encounters.

Buffaloes are social animals and live in herds in natural settings. Under husbandry conditions, they are loosely housed in groups to allow them to express social behavior. The con struction of social hierarchy and knowledge of its determinants is warranted for determining the optimum group size and formulating strategies for shifting animals from one group to another. Social hierarchy is typically estimated by recording agonistic interactions among all animals for possession of limited resources. This study aimed to find the most limiting resource for estimating social hierarchy in riverine buffaloes. The study was conducted on 63 loose-housed (covered area=250m 2 ; open area=500m 2 ) with lactating Murrah buffaloes (BCS=3.25±0.16; 1-6 parity) maintained at ICAR-National Dairy Research Institute, Karnal, Haryana, India. Three limited resources considered for observing agonistic interactions were: i) seasonal green fodders, ii) concentrate mixture, and iii) possession of space under the foggers during the summer season (11:00, 07:00, and 14:00 hours, respectively). The manger length was restricted to allow 10% (length x width: 4.0 x 0.6 m) of animals to eat simultaneously, and 10% of foggers (3.7 m 2 space for two foggers) were operated to invite maximum aggression. Each restriction was carried out once daily in the same group. Access to resources was allowed from 10 m to ensure equal opportunity for possession. Agonistic interactions for each resource were recorded manually and by Closed Circuit Television recordings five times weekly by continuous sampling for 1 hour. A socio-metric matrix of all agonistic interactions was prepared, and pooled data was analyzed using one-way ANOVA in SPSS version 22. Participation of buffaloes for possession was higher (p

Assemblage structure and acquisition of high‐value resources will usually be affected by changes in resource availability and differential competitive abilities of assemblage members. In fragmented habitats where carrying capacity limits are exceeded due to high population densities and biomass, interspecific interactions can be expected to occur at a high frequency, potentially turning into an important cost for coexistence. We studied assemblage‐ and guild‐level patterns of interspecific interactions in two highly diverse isolated primate assemblages in southern Amazonia. Specifically, we assessed the effects of temporal variation in fruit availability on the rates of interspecific interactions between gray woolly monkeys (Lagothrix lagotricha cana), one of the largest tree‐dwelling mammals of the Amazon forests, and nine syntopic primate species. We found that fruit availability positively predicted rate of intraguild interactions in contrast to overall assemblage interaction rate. We did not find statistical evidence for the effect of fruit availability on the assemblage rates of type‐dependent (i.e., agonistic or non‐agonistic) and context‐dependent (i.e., feeding or non‐feeding) interactions. However, there was a clear trend toward increased feeding‐related and agonistic‐related interactions as fruit availability increased, with agonistic interactions mostly occurring at guild‐level. These results provide support for a significant role of fruit availability in structuring spatial–temporal intraguild interactions at our study sites. Costly interspecific interactions and spatial habitat overlap can be expected to occur at a high frequency in highly diverse assemblages living in human‐modified landscapes, which in turn, can have potentially negative impacts to the species involved. [ABSTRACT FROM AUTHOR]

The interest in the welfare of zoo animals, from both the public and the scientific community, has long been biased towards mammals. However, growing evidence of the complex behavioural repertoires of less charismatic animals, such as reptiles, reveals the necessity to better comply with their welfare needs in captivity. Here, we present the effects of an enclosure change towards a more natural habitat in captive Galapagos tortoises (Chelonoidis spp.) held at ZSL London Zoo. Using behavioural observations, we found that the tortoises habituated to their new enclosure in six days. This represents the first quantification of habituation latency to a new enclosure in a reptile model to our knowledge—which is important information to adapt policies governing animal moves. The tortoises expressed time budgets more similar to those of wild individuals after their transition to the new enclosure. Interestingly, the hierarchy between the individuals was inverted and more stable after this change in environment. The tortoises interacted less often, which led to a decrease in the frequency of agonistic encounters. We also found that higher ambient sound volume was associated with increased likelihood of interactions turning into fights. Taken together, our results demonstrate the potential of appropriate enclosure design to improve reptile welfare.

Numerous fishes produce sounds and their transmission and detection may be hindered by increasing levels of anthropogenic noise. We investigated acoustic communication during dyadic contests between male croaking gouramis (Trichopsis vittata, Osphronemidae) in the presence and absence of white noise. We hypothesised that fish modify acoustic signalling in the presence of noise in order to maintain intraspecific communication. Under controlled laboratory settings we compared agonistic behaviour, visual and acoustic signalling between noise and no-noise conditions. Trichopsis vittata produced sounds that were significantly lower in level and higher in dominant frequency under noise treatments. No difference was found in visual signalling or temporal sound characteristics. This study indicates that noise does not affect the amount of signalling during agonistic behaviour in a highly vocal fish. No increase in sound level was observed in croaking gouramis, indicating that a Lombard effect is not present in all vocalising fish. The lack of a Lombard effect shows that sound communication is potentially hindered by (human-made) noise in fish, which may affect territory maintenance and reproduction. [ABSTRACT FROM AUTHOR]

Simple Summary: Professional and amateur ornithologists might use conspecific playback to attract or study birds, record their songs, and then archive these songs in acoustic data repositories. This allows us to explore whether birdsong varies after simulated aggressive encounters. We investigated this idea in Rufous-browed Peppershrikes (Cyclarhis gujanensis), a widespread Neotropical bird. When accounting for geographic variation in song traits, we found that males recorded after playback produce longer songs than males recorded singing spontaneously. In contrast, playback usage neither altered song rate nor song frequency. Despite the limitations derived from unstandardized playback designs, data from acoustic repositories can provide hints about signal flexibility in aggressive contexts. Birds may alter song structure in response to territorial challenges to convey information about aggressive intent or fighting ability. Professional and amateur ornithologists upload daily many birdsong recordings into acoustic data repositories, usually scoring whether songs were recorded in response to a conspecific playback or produced spontaneously. We analyzed recordings from these repositories to evaluate if song traits of Rufous-browed Peppershrikes (Cyclarhis gujanensis) vary between playback-elicited songs and spontaneous songs. For each recording after playback, we chose one spatially closer spontaneous recording to avoid geographic bias. Birds recorded after playback produced slightly longer songs than birds that were singing spontaneously. This result was accounted for by increases in the amount of sound and silence within a song after the playback instead of changes in the mean number or duration of elements. Playback did not alter song frequency parameters (bandwidth, minimum, mean, and maximum frequencies) or song rate. These results indicate that song duration might mediate aggressive interactions in Rufous-browed Peppershrikes. Even considering limitations such as unknown playback stimulus identity and possible pseudoreplication, acoustic data repositories give a unique yet unexplored opportunity to gather insights into the evolution of song flexibility during aggressive encounters. [ABSTRACT FROM AUTHOR]

The interest in the welfare of zoo animals, from both the public and the scientific community, has long been biased towards mammals. However, growing evidence of the complex behavioural repertoires of less charismatic animals, such as reptiles, reveals the necessity to better comply with their welfare needs in captivity. Here, we present the effects of an enclosure change towards a more natural habitat in captive Galapagos tortoises (Chelonoidis spp.) held at ZSL London Zoo. Using behavioural observations, we found that the tortoises habituated to their new enclosure in six days. This represents the first quantification of habituation latency to a new enclosure in a reptile model to our knowledge—which is important information to adapt policies governing animal moves. The tortoises expressed time budgets more similar to those of wild individuals after their transition to the new enclosure. Interestingly, the hierarchy between the individuals was inverted and more stable after this change in environment. The tortoises interacted less often, which led to a decrease in the frequency of agonistic encounters. We also found that higher ambient sound volume was associated with increased likelihood of interactions turning into fights. Taken together, our results demonstrate the potential of appropriate enclosure design to improve reptile welfare. [ABSTRACT FROM AUTHOR]

The neuroendocrine regulation of rabbit maternal behaviour has been explored in detail. However, little is yet known about the hormonal regulation of aggression in concurrently pregnant-lactating does, a reproductive condition that prevails during group housing of rabbits on farms. Therefore, in this study we determined the relation between a) the levels of progesterone, testosterone, and oestradiol during lactation; b) the anogenital distance at artificial insemination; and c) the timing of grouping with the intensity of agonistic behaviour, published previously. We performed four consecutive trials, where three groups of eight does each were artificially inseminated on day 10 postpartum (pp) and grouped on either day 12, 18 or 22 pp. Using Dipetalogaster maxima, a reduviid blood-sucking bug, we collected blood samples during the pregnant-lactating phase (days 13, 15, 17, 19, 21, 23 pp) on one or two randomly chosen does per treatment group. Testosterone levels varied little across the pregnant-lactating phase, agreeing with results from pregnant-only rabbits, while progesterone levels increased from day 3 (=13 dpp) to day 7 (=17 dpp) and remained unchanged until day 13 (=23 dpp) of pregnancy. All oestradiol concentrations fell below the limit of detection. Overall, all concentrations were slightly lower in comparison to rabbit studies with pregnantonly does. The agonistic behaviour was not related to the respective hormonal concentrations at grouping. In conclusion, the time point of grouping does after artificial insemination (AI) in the semi-group housing system only had a weak influence on aggression and the hormonal profile did not indicate an optimum time for grouping.

Intersexual dominance, which is measured by the probability that members of one sex elicit submission of members of the other sex during agonistic interactions, is often skewed in favor of males. However, even in sexually dimorphic species, several factors may influence intersexual dominance. Here, we use an 8-year dataset to examine the dynamics of intersexual dominance in wild-living mandrills (Mandrillus sphinx). Mandrills exhibit an extreme male-biased sexual size dimorphism but females show pronounced kin-differentiated social relationships and occasionally form coalitions against males. We established intersexual hierarchies across consecutive 6-month time blocks, representing either mating or birth seasons. Although females appeared to outrank 11% of males, they elicited male submission in only 2% of agonistic interactions against males. This discrepancy is likely due to the temporary residency of most males in the exceptionally large mandrill groups, the sexually coercive male mating strategies and the scarce number of agonistic interactions within most dyads, that may limit hierarchical inferences. In a second step, we found that the intersexual hierarchy mixes the intrasexual ones respecting their respective order. Females outranked mostly young and old males during the mating (vs. birth) season and social integration was positively correlated to dominance status in both sexes. In a third step, we found that females win more conflicts against young or old males which are closer to them in the intersexual hierarchy. These results extend our understanding of female-male dominance relationships by indicating that female mandrills occasionally outrank males who are considerably larger than them, and that a combination of demographic and social factors can influence the intersexual hierarchy.

Multimodal communication in animals is common, and is particularly well studied in signals that include both visual and auditory components. Multimodal signals that combine acoustic and olfactory components are less well known. Multimodal communication plays a crucial role in agonistic interactions in many mammals, but relatively little is known about this type of communication in nocturnal mammals. Here, we used male Great Himalayan leaf-nosed bats Hipposideros armiger to investigate multimodal signal function in acoustic and olfactory aggressive displays. We monitored the physiological responses (heart rate [HR]) when H. armiger was presented with 1 of 3 stimuli: territorial calls, forehead gland odors, and bimodal signals (calls + odors). Results showed that H. armiger rapidly increased their HR when exposed to any of the 3 stimuli. However, the duration of elevated HR and magnitude of change in HR increased significantly more when acoustic stimuli were presented alone compared with the presentation of olfactory stimuli alone. In contrast, the duration of elevated HR and magnitude of change in HR were significantly higher with bimodal stimuli than with olfactory stimuli alone, but no significant differences were found between the HR response to acoustic and bimodal stimuli. Our previous work showed that acoustic and chemical signals provided different types of information; here we describe experiments investigating the responses to those signals. These results suggest that olfactory and acoustic signals are non-redundant signal components, and that the acoustic component is the dominant modality in male H. armiger , at least as it related to HR. This study provides the first evidence that acoustic signals dominate over olfactory signals during agonistic interactions in a nocturnal mammal. [ABSTRACT FROM AUTHOR]

As group housing of horses can be associated with increased injury risk especially when there are limited resources, the aim of this study was to allow initial, scientifically based recommendations regarding the positioning and design of straw feeders. Data collection took place in a Hinrichs Innovation + Technik (HIT) active stable with 50–62 horses kept in one single group. Occupancy, feeding distances, prevalence of agonistic interactions (AIS) as well as the percentage of feeding disturbances at two different straw feeders were analysed. Equine behaviour was recorded for 6 h/day on 15 summer and 15 winter days. Using generalised linear mixed models, considering the fixed effects of feeder, a fresh straw supply and the interaction of observation day and time period delivered the best prediction for the number of feeding events/h and the prevalence of AIS/h. Here, both feeders differed (p < 0.05) with twice as many feeding events/h, but threefold more AIS/h respectively twice as many AIS/horse at the larger feeder, where conspecifics fed side by side. Sixty-five % of the AIS with low risk of injury and 92 % of the AIS with high risk of injury led to feeding disturbances. The latter made up 25 % of all AIS in total with no differences between both feeders. Feeding distances did not differ either. The horses tended to use only every third opening space when feeding simultaneously. This knowledge should be taken into account when making assumptions about the de facto animal:feeding place ratio and the design of straw feeders in the future. Moreover, regarding the smaller feeder, the horses preferred to feed simultaneously with the feeder edge between them, so that the actual animal distances were smaller. Additional research is needed to investigate, how feeding in rectangular position to each other influences threatening behaviour inside a feeder. In this study, a central positioning within a paddock was beneficial with respect to feeder usage, but disadvantageous regarding AIS and displacements. However, the investigation of further straw feeders and farms is essential to allow general statements, as the study also proves that many factors such as season and rank order stability potentially influence equine behaviour at straw feeders. • Group-housed horses´ behaviour at straw feeders is studied. • At two feeders occupancy and agonistic interactions were observed for 30 days. • At least three feeder openings were necessary to deliver one feeding place. • 25 % of agonistic interactions were associated with a high injury risk. • A central feeder positioning promotes occupancy, but also agonistic interactions. [ABSTRACT FROM AUTHOR]

Bite force in lizards is involved in key behaviours such as intrasexual agonistic and intersexual interactions. The relationship between morphology and function is dynamic and sexual pressures can affect bite performance differently between sexes, especially considering the biting position and temporal changes related to the reproductive cycle. The Achala copper lizard (Pristidactylus achalensis) is a highly dimorphic lizard with a short reproductive season. Both sexes present bite scars; however, scar position varies between sexes implying different bite functions. We studied factors influencing bite force such as sex, body size, head morphology and seasonality. We also compared the maximum bite force at two biting positions (frontal and lateral) related to different behaviours (copulation and fighting), and quantified the incidence and scar pattern between sexes. Overall, males bite harder than females and lateral bites were harder than frontal ones. Although bite force did not vary seasonally in males, bite force in females decreased after the reproductive period. Harder bites may confer advantages in mating competition related to the body size in males, while females may benefit from seasonal enhancement of bite force for mate rejection in cases of unwanted copulation. [ABSTRACT FROM AUTHOR]

Aggressive interactions help individuals to gain access to and defend resources, but they can be costly, leading to increased predation risk, injury, or death. Signals involving sounds and color can allow birds to avoid the costs of intraspecific aggressive encounters, but we know less about agonistic signaling between species, where fights can be frequent and just as costly. Here, we review photographic and video evidence of aggressive interactions among species of birds (N = 337 interactions documenting the aggressive signals of 164 different bird species from 120 genera, 50 families, and 24 orders) to document how individuals signal in aggressive encounters among species, and explore whether these visual signals are similar to those used in aggressive encounters with conspecifics. Despite the diversity of birds examined, most aggressively signaling birds displayed weapons (bills, talons, wings) used in fighting and placed these weapons closest to their heterospecific opponent when signaling. Most species oriented their bodies and heads forward with their bills pointing towards their heterospecific opponent, often highlighting their face, throat, mouth, and bill. Many birds also opened their wings and/or tails, increasing their apparent size in displays, consistent with the importance of body size in determining behavioral dominance among species. Aggressive postures were often similar across species and taxonomic families. Exceptions included Accipitridae and Falconidae, which often highlighted their talons in the air, Columbidae, which often highlighted their underwings from the side, and Trochilidae, which often hovered upright in the air and pointed their fanned tail downward. Most species highlighted bright carotenoid-based colors in their signals, but highlighted colors varied across species and often involved multiple colors in combination (e.g., black, white, and carotenoid-based colors). Finally, birds tended to use the same visual signals in aggressive encounters with heterospecifics that they use in aggressive encounters with conspecifics, suggesting that selection from aggressive interactions may act on the same signaling traits regardless of competitor identity. [ABSTRACT FROM AUTHOR]

Aggressive interactions help individuals to gain access to and defend resources, but they can be costly, leading to increased predation risk, injury, or death. Signals involving sounds and color can allow birds to avoid the costs of intraspecific aggressive encounters, but we know less about agonistic signaling between species, where fights can be frequent and just as costly. Here, we review photographic and video evidence of aggressive interactions among species of birds (N = 337 interactions documenting the aggressive signals of 164 different bird species from 120 genera, 50 families, and 24 orders) to document how individuals signal in aggressive encounters among species, and explore whether these visual signals are similar to those used in aggressive encounters with conspecifics. Despite the diversity of birds examined, most aggressively signaling birds displayed weapons (bills, talons, wings) used in fighting and placed these weapons closest to their heterospecific opponent when signaling. Most species oriented their bodies and heads forward with their bills pointing towards their heterospecific opponent, often highlighting their face, throat, mouth, and bill. Many birds also opened their wings and/or tails, increasing their apparent size in displays, consistent with the importance of body size in determining behavioral dominance among species. Aggressive postures were often similar across species and taxonomic families. Exceptions included Accipitridae and Falconidae, which often highlighted their talons in the air, Columbidae, which often highlighted their underwings from the side, and Trochilidae, which often hovered upright in the air and pointed their fanned tail downward. Most species highlighted bright carotenoid-based colors in their signals, but highlighted colors varied across species and often involved multiple colors in combination (e.g., black, white, and carotenoid-based colors). Finally, birds tended to use the same visual signals in aggressive encounters with heterospecifics that they use in aggressive encounters with conspecifics, suggesting that selection from aggressive interactions may act on the same signaling traits regardless of competitor identity.

Predation is an important ecological constraint that influences communication in animals. Fish respond to predators by adjusting their visual signaling behavior, but the responses in calling behavior in the presence of a visually detected predator are largely unknown. We hypothesize that fish will reduce visual and acoustic signaling including sound levels and avoid escalating fights in the presence of a predator. To test this we investigated dyadic contests in female croaking gouramis (Trichopsis vittata , Osphronemidae) in the presence and absence of a predator (Astronotus ocellatus , Cichlidae) in an adjoining tank. Agonistic behavior in T. vittata consists of lateral (visual) displays, antiparallel circling, and production of croaking sounds and may escalate to frontal displays. We analyzed the number and duration of lateral display bouts, the number, duration, sound pressure level, and dominant frequency of croaking sounds as well as contest outcomes. The number and duration of lateral displays decreased significantly in predator when compared with no-predator trials. Total number of sounds per contest dropped in parallel but no significant changes were observed in sound characteristics. In the presence of a predator, dyadic contests were decided or terminated during lateral displays and never escalated to frontal displays. The gouramis showed approaching behavior toward the predator between lateral displays. This is the first study supporting the hypothesis that predators reduce visual and acoustic signaling in a vocal fish. Sound properties, in contrast, did not change. Decreased signaling and the lack of escalating contests reduce the fish's conspicuousness and thus predation threat. [ABSTRACT FROM AUTHOR]

Interference competition over food and territory can shape population structure and habitat use within and between species. The introduction of invasive species often leads to novel competitive interactions over shared resources and invaders can eventually exclude the native species from preferred habitats. Invasive brook trout (Salvelinus fontinalis) introduced to northern Europe have excluded native brown trout (Salmo trutta) from numerous headwater streams. The fact that invasive brook trout can displace the more aggressive brown trout is puzzling. However, the earlier spawning and hatching of brook trout, compared to brown trout, may lead to unequal competition due to size advantage and prior resident status of brook trout at the fry stage. In this study, we examine the effect of competition between brown trout and brook trout using the natural size distribution of the two species. In two consecutive experiments, we first measured space use and feeding of a fry (age 0+) in the presence of a juvenile (age 1+). In experiment 2, we assessed territorial interactions between the species at the fry stage (age 0+) and if smaller brown trout could compensate the disadvantage by manipulating residence duration. Fry of brook trout feed sooner and spend more time close to the larger individual than brown trout fry. We also found that brook trout fry won most territorial contests against brown trout, and that increased residence duration led to longer and more aggressive interactions. The results suggest that smaller brown trout are displaced to suboptimal habitats in the presence of a larger brook trout. Therefore, the later emergence from gravel beds resulting in the naturally occurring size disadvantage of brown trout at the fry stage may lead to unequal territorial interactions that could explain why brown trout are displaced from preferred habitats in sympatry with brook trout. [ABSTRACT FROM AUTHOR]

We report a visual display, leg-stretching, in the nocturnal Ryukyu Kajika frog (Buergeria japonica) on Iriomote Island in southern Okinawa, Japan. This visual display is produced by males before, during, or after a vocalization and involves the extension of one or both hindlimbs outwards at substrate level. Leg-stretches in this species are performed during male-male agonistic interactions in choruses, and almost exclusively in concert with aggressive vocalizations. These observations are one of the first reports of visual displays for the Rhacophoridae family and provide insights into why visual displays evolve in frogs, especially in nocturnal species. We discuss our observations in the context of underlying mechanisms and selective pressures driving the evolution of anuran visual displays. [ABSTRACT FROM AUTHOR]

The neuroendocrine regulation of rabbit maternal behaviour has been explored in detail. However, little is yet known about the hormonal regulation of aggression in concurrently pregnant-lactating does, a reproductive condition that prevails during group housing of rabbits on farms. Therefore, in this study we determined the relation between a) the levels of progesterone, testosterone, and oestradiol during lactation; b) the anogenital distance at artificial insemination; and c) the timing of grouping with the intensity of agonistic behaviour, published previously. We performed four consecutive trials, where three groups of eight does each were artificially inseminated on day 10 postpartum (pp) and grouped on either day 12, 18 or 22 pp. Using Dipetalogaster maxima, a reduviid blood-sucking bug, we collected blood samples during the pregnant-lactating phase (days 13, 15, 17, 19, 21, 23 pp) on one or two randomly chosen does per treatment group. Testosterone levels varied little across the pregnant-lactating phase, agreeing with results from pregnant-only rabbits, while progesterone levels increased from day 3 (=13 dpp) to day 7 (=17 dpp) and remained unchanged until day 13 (=23 dpp) of pregnancy. All oestradiol concentrations fell below the limit of detection. Overall, all concentrations were slightly lower in comparison to rabbit studies with pregnantonly does. The agonistic behaviour was not related to the respective hormonal concentrations at grouping. In conclusion, the time point of grouping does after artificial insemination (AI) in the semi-group housing system only had a weak influence on aggression and the hormonal profile did not indicate an optimum time for grouping. [ABSTRACT FROM AUTHOR]

In general, one animal is considered dominant over another animal if it has won more fights than its opponent. Whether this difference in won and lost fights is significant is neglected in most studies. Thus, the present study evaluates the impact of two different calculation methods for dyadic interactions with a significant asymmetric outcome on the results of social network analysis regarding agonistic interactions of pigs in three different mixing events (weaned piglets, fattening pigs and gilts). Directly after mixing, all animals were video recorded for 17 (fattening pigs, gilts) and 28 h (weaned piglets), documenting agonistic interactions. Two calculation methods for significant dyads, that is, dyadic interactions with a clear dominant subordinate relationship in which one animal has won significantly more fights than its encounter, were proposed: pen individual limits were calculated by a sign test considering the differences of won and lost fights of all dyadic interactions in each pen; dyad individual limits were determined by a one-sided sign test for each individual dyad. For all data sets (ALL, including all dyadic interactions; PEN or DYAD, including only significant dyads according to pen or dyad individual limits), networks were built based on the information of initiator and receiver with the pigs as nodes and the edges between them illustrating attacks. General network parameters describing the whole network structure and centrality parameters describing the position of each animal in the network were calculated. Both pen and dyad individual limits revealed only a small percentage of significant dyads for weaned piglets (12.4% or 8.8%), fattening pigs (4.2% or 0.6%) and gilts (3.6% or 0.4%). The comparison between the data sets revealed only high Spearman’s rank correlation coefficients (rS) for the density, that is, percentage of possible edges that were actually present in the network, whereas the centrality parameters showed only moderate rS values (0.37 to 0.75). Thus, the rank order of the animals changed due to the exclusion of insignificant dyads, which shows that the results obtained from social network analysis are clearly influenced if insignificant dyads are excluded from the analyses. Due to the fact that the pen individual limits consider the overall level of agonistic interactions within each pen, this calculation method should be preferred over the dyad individual limits. Otherwise, too many animals in the group became isolated nodes with zero centrality for which no statement about their position within the network can be made.

Cases of mutual relations of beavers with 16 species of mammals and 8 species of birds are described and analysed. Beavers have different contacts with lots of species of animals around the water complex, which can be often regular in different situation. The beaver can respond both indifferently and aggressively to the same situation to the same species. For small and medium-sized birds, beavers do not pay any attention at all, especially if they do not show any interest to them. Similar indifference beavers show to much larger birds — herons, goose and swans. Beavers and birds get mutual benefit from the disturbing signals of each other, by which they announce danger. Beavers react immediately to the wings of the birds that take off and their alarming screams, and immediately dive into the water, not even trying to find out what threatens them. Other animals persistent interest to beavers accompanied by sounds in addition irritates beavers of course and they try to get rid it. The sudden appearance and rapid movement of other animals are perceived by beavers as a threat and they try to hide in water at once. Large animals, greatly exceeding beavers in size, are perceived by them as a potential threat. Beavers-migrants are much more alerted to other animals than beavers living on their territory for a long time. Beavers’ attitude towards other mammals (and birds) may largely depend on the presence of cubs nearly very nearby. In such situations the beavers may attempt to drive out other animals even of larger in size or being a real threat to them from their water body or its water-side. When driving other animals out of their territory the beavers use the following techniques: swimming near the enemy, loud blows with the tail on the water, aggressive attacks against the potential enemy and provocation of an attack by the predator followed by a fight. A specific beavers reaction to small dogs is described — unfolding towards with their back to them and flapping with their tail on the ground.

Social hierarchy affects the access of animals to feed resources. On daily rotational pasture systems, supplementation time may influence feeding behavior. This trial was designed to test the effect of grain delivery time on the feeding behavior of heifers. Heifers divided into two groups according to breed (n = 15 Braford and n = 19 Jersey) were tested in a crossover design with two treatments: INITIAL—supplement at 8 am (entry time to a fresh paddock), and MIDDLE—supplement at 4 pm (middle time of paddock use). Animals entered a new paddock every morning, and grain supplement at 2 kg/animal/day was offered at the fence line (1 m/animal). Then, ingestive and other behaviors were registered by direct visual observation through scan sampling at 2-min intervals for 1 h after grain supply. Agonistic interactions were recorded continuously (instigator–victim) to build a social matrix whereby each heifer was defined as dominant, intermediate, or subordinate. Weekly pasture samples were collected according to the order that animals left the feeding area, using the hand-plucking technique, to determine crude protein and fiber content. Heifers spent more time grazing on the INITIAL treatment (p < 0.0001) but exhibited more behaviors on the MIDDLE treatment (p < 0.0001). Dominant heifers spent more time eating grain (p = 0.0008), whereas subordinate heifers spent more time grazing along the paddock (p = 0.0067), but not along the fence (p = 0.0008). The crude protein content of pasture samples was higher for the INITIAL treatment (p < 0.0001). Behavioral interaction occurred with respect to the order of leaving the feeding area, social rank, and crude protein consumed (p = 0.04). Subordinate heifers consistently grazed more and ate less grain supplement than dominant and intermediate heifers. However, when grain supplement was offered at the time animals entered the paddock, more grazing activity took place during supplement feeding, and subordinate heifers could select a high-protein diet. In the INITIAL treatment, this means that subordinate animals could benefit from the better pasture available, keeping a distance from dominant heifers, reducing agonistic interactions and likely improving their welfare.

Understanding the association between an individual's position within a social network and its sex and age across seasons can be useful information for conservation management. For example, identifying the social position of females within a group can provide insights into reproductive potential, while the position of juveniles may be related to survival and hence recruitment potential. In the present study, we used social network analysis to investigate the effects of season, sex, age and reproductive partner on social interactions in the endangered Northern Bald Ibis (Geronticus eremita). Via focal sampling we recorded the social behaviour of 39 individually marked, free-flying birds for 4 months over two seasons (autumn, winter). We observed the occurrence of affiliative and agonistic interactions and estimated proximity between colony members. We found that (1) individuals were in proximity with more colony members in winter than in autumn, and affiliative interactions occurred more often in winter, (2) older individuals occupied more central positions in the proximity network irrespective of sex, (3) males engaged more than females in agonistic interactions, whereas females received more affiliative interactions than males irrespective of age, and (4) most affiliative interactions occurred between former or potentially prospective reproductive partners. Our findings suggest that social relationships could modulate inter-individual distance and there may be sex-related differences in the investment into pair bond maintenance. Overall the findings of sex- and age-related differences in behaviour and social position contribute to understanding factors associated with breeding success and mortality risk in an endangered bird species. [ABSTRACT FROM AUTHOR]

The benthic assemblage of reefs provides an important resource of food and habitat for reef fishes. However, how benthic composition mediates reef fishes' biotic interactions at isolated environments such as oceanic islands remains largely unknown. Here, we aimed to investigate the role of four different reef microhabitats over biological interactions of fishes in an understudied oceanic island, Príncipe Island. For that, we recorded a total of 46 Underwater Remote Videos (RUVs) to document benthic composition and fishes' trophic and agonistic interactions. We used benthic cover estimates to group the samples into four microhabitats (dominated by epilithic algal matrix [EAM], sand/rock, corals and sponges), then quantified fishes' trophic and agonistic interactions in each microhabitat. All microhabitats presented a different structure of trophic and agonistic interactions of the fish assemblage. Feeding pressure (FP) and agonistic interactions were higher on the EAM microhabitat and lower in coral microhabitat. Herbivores were the main responsible group for the FP in all microhabitats. Territorial damselfishes used microhabitats differently for both trophic and agonistic interactions. We demonstrated that reef fish diversity and intensity of biotic interactions varied according the spatial distribution of benthic resources, which suggests that benthic composition plays an important role on structuring biological interactions at isolated reef systems. [ABSTRACT FROM AUTHOR]

All songbirds have their own species-specific song, and vocal variety among individuals of the same species is used for communication. Some aspects of vocal variety have been shown to relate to sender characteristics and thus to convey a potential message to receivers. During playback experiments, individuals show different response patterns, which provide evidence for perception, and thus meaning, of the vocal variety. Here, we tested the impact of two types of vocal variety: syllable diversity and syllable switching in the common chiffchaff, Phylloscopus collybita , in two separate playback experiments. We found that syllable diversity was a relatively fixed trait and that variation among individuals was likely to reflect some male quality triggering responses of different intensity. Higher rates of syllable switching did not elicit different responses but songs after playback showed that it is a dynamic trait, potentially contributing to motivational signalling together with other song parameters. The resolution of analyses in our experiments revealed subtle changes in vocal features over time in unprecedented detail. This approach unveiled an intricate combination of various vocal features during the response that may complement each other during vocal interactions. We believe future studies would benefit from the same resolution, through which one can explore advanced levels in animal communication. • Syllable diversity is likely to be a fixed trait signalling male quality. • Syllable switching may be a dynamic trait related to motivation. • Birdsong is highly dynamic during vocal interactions. • Some parameters follow opposite patterns during vocal interactions. • Studying behaviour at high temporal resolution offers advanced insights. [ABSTRACT FROM AUTHOR]

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Agonistic behavioural interactions play a decisive role in the competition for food, space, mating opportunities, and establishing social rank. We used pelt biting (number of bites on an animal’s body) as a proxy for assessing the intensity of agonistic animal interactions and how it responded to social, population, and heat stress factors. We modelled a 14-year time series of pelt biting records and observational data of agonistic interactions on a population of captive Iberian red deer (Cervus elaphus). We found that (i) the higher the social rank of deer, the lower the number of pelt bites received; (ii) increasing heat stress conditions caused deer to suffer more pelt bites; (iii) males received more bites than females; (iv) the heavier the deer, the lower the number of bites on their bodies; (v) the bigger the group, the more bites exhibited on its members; (vi) deer 5–6 years old suffered greater rate of pelt biting than younger or older deer; and (vii) hinds that gave birth earlier in the parturition period suffered less pelt biting than those that gave birth around the peak of the parturition season (p < 0.01 for all effects). Pelt biting is useful to predict management situations in which deer welfare could be at stake.

In general, one animal is considered dominant over another animal if it has won more fights than its opponent. Whether this difference in won and lost fights is significant is neglected in most studies. Thus, the present study evaluates the impact of two different calculation methods for dyadic interactions with a significant asymmetric outcome on the results of social network analysis regarding agonistic interactions of pigs in three different mixing events (weaned piglets, fattening pigs and gilts). Directly after mixing, all animals were video recorded for 17 (fattening pigs, gilts) and 28 h (weaned piglets), documenting agonistic interactions. Two calculation methods for significant dyads, that is, dyadic interactions with a clear dominant subordinate relationship in which one animal has won significantly more fights than its encounter, were proposed: pen individual limits were calculated by a sign test considering the differences of won and lost fights of all dyadic interactions in each pen; dyad individual limits were determined by a one-sided sign test for each individual dyad. For all data sets (ALL, including all dyadic interactions; PEN or DYAD, including only significant dyads according to pen or dyad individual limits), networks were built based on the information of initiator and receiver with the pigs as nodes and the edges between them illustrating attacks. General network parameters describing the whole network structure and centrality parameters describing the position of each animal in the network were calculated. Both pen and dyad individual limits revealed only a small percentage of significant dyads for weaned piglets (12.4% or 8.8%), fattening pigs (4.2% or 0.6%) and gilts (3.6% or 0.4%). The comparison between the data sets revealed only high Spearman's rank correlation coefficients (rS) for the density, that is, percentage of possible edges that were actually present in the network, whereas the centrality parameters showed only moderate rS values (0.37 to 0.75). Thus, the rank order of the animals changed due to the exclusion of insignificant dyads, which shows that the results obtained from social network analysis are clearly influenced if insignificant dyads are excluded from the analyses. Due to the fact that the pen individual limits consider the overall level of agonistic interactions within each pen, this calculation method should be preferred over the dyad individual limits. Otherwise, too many animals in the group became isolated nodes with zero centrality for which no statement about their position within the network can be made. [ABSTRACT FROM AUTHOR]

Objectives: Although conflicts between groups over valuable resources are common in the animal kingdom, an individual's strategy toward out‐group individuals may differ according to the benefits and costs received from inter‐group interactions. Groups of bonobos encounter each other frequently and may mingle and range together from a few hours to a few days. During these inter‐group associations, individuals across groups exhibit both aggressive and affiliative interactions. This study aimed to examine the strategies that bonobos employ with other groups, by comparing the patterns of within‐ and inter‐group aggression. Materials and methods: We observed the aggressive interactions within a group of wild bonobos and between the group and three neighboring groups in Wamba, Luo Scientific Reserve, DR Congo. Results: Bonobos increased the level of cooperation to attack out‐group individuals more than they do to attack within‐group individuals. Additionally, they reduced the aggression between within‐group members during inter‐group associations, compared to that when not associated with other groups. Males selectively and cooperatively attacked out‐group males. Inter‐group aggression among females was rare. Furthermore, females sometimes formed coalitions with out‐group individuals to attack a common target. Discussion: Our results support the hypothesis that inter‐group competition occurs in bonobos, with males across groups competing over mates. Females across groups were tolerant and even cooperative with each other. Regardless of the ideal male strategy, female tolerant and cooperative relationships across groups and female within‐group superiority over males could preserve tolerant inter‐group relationships in bonobos. [ABSTRACT FROM AUTHOR]

Although the popularity of domestic donkeys is increasing, the scientific literature on their behavior is still limited. This study investigated the social behavior of a group of 13 donkeys (10 females, 3 geldings, aged 3–13 years) stabled in an Animal Assisted Interventions facility in the North of Italy. Our first aim was to assess the distribution of donkeys' intraspecific social behaviors during daytime and the second aim was to characterize affiliative and agonistic social interactions during peak activity times. Social behaviors were expressed more between 8 and 9 AM than the rest of daytime, mainly reflecting the expression of affiliative behavior. The latter consisted mostly of proximity (55.0% of all affiliative) and following (29.2%). In most cases affiliative behavior was expressed within preferential dyads, composed of either a mother and her offspring or two adult donkeys. This supports the idea that dyadic relationships are a predominant feature of the social organization of the species. However, dyadic interactions were not observed in the oldest sub-adults, suggesting that social preferences undergo a change around the time donkeys reach full growth. Agonistic behaviors were much less common than affiliative ones. The most expressed agonistic behavior was threat (51%), followed by displacement and bite (both 18.5%). They were less expressed by donkeys who were part of an affiliative pair, suggesting that limited expression of agonistic behavior is associated with an actual change in social preferences, not a mere consequence of fewer occasions of conflict over resources. While the study has limitations, the results provide insight into the social behavior of domestic donkeys which could represent a starting point for further research as well as relevant information for donkeys farming. • Intraspecific social behavior was studied in a group of 13 donkeys. • Affiliative interactions were more common than agonistic interactions. • Affiliative behaviors were expressed less by sub-adults than adults. • Most affiliative interactions occurred within preferential pairs. • Donkeys in preferential affiliative pairs expressed fewer agonistic interactions. [ABSTRACT FROM AUTHOR]

This study aimed to investigate how farrowing and rearing systems affect skin lesions, serum cortisol, and aggressive behavior as indicators for weaning stress of piglets. Between May 2016 and March 2018, in total 3144 weaning piglets from three different farrowing systems were examined: farrowing crates (FC), single-housing free-farrowing pens (FF), and group-housing of lactating sows and litters (GH). After weaning and regrouping, piglets were relocated to conventional rearing pens (conv; 5.7 m2) or to wean-to-finish pens (w-f; 12.4 m2). Skin lesions were scored 24 h after weaning. Blood samples were taken one week before and 24 h after weaning to analyze the individual difference in serum cortisol. Behavior was observed for 24 h after relocation. Animals raised in FC and FF had significantly more skin lesions than that of GH animals. Piglets born in GH showed lower cortisol differences and fought less and for shorter periods compared to FC and FF piglets. Piglets weaned to w-f pens showed greater cortisol changes and fought significantly longer than piglets in conv pens. Group housing during the suckling period reduced weaning stress for piglets in terms of skin lesions, serum cortisol, and aggressive behavior. Greater space allowance (w-f vs. conv) was not beneficial with regard to the investigated parameters.

Abstract Group housing provides horses with social contact, a lack of which is associated with health and behavior problems. Despite the benefits of group housing for horses, horse owners are concerned about aggression and resulting injuries. This study focused on agonistic and affiliative interactions in a focal group of (originally) 12 horses with short-term and longer term changes in composition, variation in available area, and presence of periparturient mares. Age and density had no significant effect on agonistic or affiliative behavior. However, when agonistic behavior was considered within 3 subcategories, density did have a significant positive effect on contact and threat aggression but not on passive aggression (avoid and displace). When analyzing only the days without the most aggressive horse, age and density had a positive effect on agonistic interactions, and density had a negative effect on affiliative interactions. Days with and without the most aggressive horse showed no significant overall differences in either category of social interactions. Agonistic and affiliative interactions were not significantly correlated, but agonistic interactions had a significant linear and quadratic effect on affiliative interactions. Relative level of aggressiveness was used instead of a formal measure of dominance rank as aggression level is the main issue for horse owners. Comparing interactions with more and less aggressive horses, there was no overall effect for affiliative interactions. However, overall, horses in the focal group were on average 3.7 times more aggressive toward less aggressive horses, compared to more aggressive horses. Relationships between agonistic and affiliative interactions, density, age, and the role of relative aggressiveness are complicated, and more research is needed to clarify the most relevant factors under particular sets of circumstances and their contribution to intraspecific aggression in various contexts. [ABSTRACT FROM AUTHOR]

Seed dispersal effectiveness (SDE) is related to the role of seed dispersal agents in realizing the reproductive potential of plants through seed dispersal and subsequent plant recruitment. The SDE of a given seed disperser may vary spatially and temporally, with important implications for our understanding of the mutualistic relationships involving plants and frugivores. Here we observed 22 frugivorous bird species visiting an individual tree (Cabralea canjerana) over a 9-y period in a fragment of Atlantic forest in south-eastern Brazil to document the temporal variation in SDE. The quantitative (that takes into account the frequency of feeding visits to the focal plant and the number of fruits removed per visit) and qualitative (that considers the probability of seed deposition on a suitable site for plant recruitment) components of SDE varied in two and one order of magnitude both among bird species and among years within bird species, respectively. As a result, the SDE of bird species fluctuates over the years, especially for a migratory species that is the main seed disperser of C. canjerana (Chivi vireo Vireo chivi) whose quantitative component (i.e. the product of visit and fruit intake rates) varied from 3.0 to 7.1. This study illustrates the dynamic nature of the seed-dispersal environment to which a plant is subjected to over the course of its life, which has important consequences for the plant's individual fitness. [ABSTRACT FROM AUTHOR]

The article presents information on the feeding procedure of fishes through self-feeding and enhancement of the learning ability of the fishes including tilapia, and rainbow trouts. Topics include the different categories of animal personality development, the dominance of the glycoprotein ependymin in cerebrospinal fluid, and fish growth.

Abstract: Many animal social structures are organized hierarchically, with some individuals monopolizing resources. Dominance hierarchies have received great attention from behavioural and evolutionary ecologists. There are many methods for inferring hierarchies from social interactions. Yet, there are no clear guidelines about how many observed dominance interactions (i.e. sampling effort) are necessary for inferring reliable dominance hierarchies, nor are there any established tools for quantifying their uncertainty. We simulate interactions (winners and losers) in scenarios of varying steepness (the probability that a dominant defeats a subordinate based on their difference in rank). Using these data, we (1) quantify how the number of interactions recorded and the steepness of the hierarchy affect the performance of five methods for inferring hierarchies, (2) propose an amendment that improves the performance of a popular method, and (3) suggest two easy procedures to measure uncertainty and steepness in the inferred hierarchy. We find that the ratio of interactions to individuals required to infer reliable hierarchies is surprisingly low, but depends on the steepness of the hierarchy and the method used. We show that David's score and our novel randomized Elo‐rating are the best methods when hierarchies are not extremely steep, where the original Elo‐rating, the I&SI and the recently described ADAGIO perform less well. In addition, we show that two simple methods can be used to estimate uncertainty at the individual and group level, and that the randomized Elo‐rating repeatability provides researchers with a standardized measure valid for comparing the steepness of different hierarchies. We provide several worked examples to guide researchers interested in studying dominance hierarchies. Methods for inferring dominance hierarchies are relatively robust. We recommend that a ratio of observed interactions to individuals of at least 10 (for steep hierarchies), and ideally 20 serves as a good benchmark. Our simple procedures for estimating uncertainty in the observed data will facilitate evaluating whether sufficient data have been collected, while plotting the shape of the hierarchy will provide new insights into the social structure of the study organism. [ABSTRACT FROM AUTHOR]

Communication is essential during social interactions including animal conflicts and it is often a complex process involving multiple sensory channels or modalities. To better understand how different modalities interact during communication, it is fundamental to study the behavioural responses to both the composite multimodal signal and each unimodal component with adequate experimental protocols. Here we test how an African cichlid, which communicates with multiple senses, responds to different sensory stimuli in a social relevant scenario. We tested Maylandia zebra males with isolated chemical (urine or holding water coming both from dominant males), visual (real opponent or video playback) and acoustic (agonistic sounds) cues during agonistic interactions. We showed that (1) these fish relied mostly on the visual modality, showing increased aggressiveness in response to the sight of a real contestant but no responses to urine or agonistic sounds presented separately, (2) video playback in our study did not appear appropriate to test the visual modality and needs more technical prospecting, (3) holding water provoked territorial behaviours and seems to be promising for the investigation into the role of the chemical channel in this species. Our findings suggest that unimodal signals are non-redundant but how different sensory modalities interplay during communication remains largely unknown in fish.