scholarly journals Dominance in a socially dynamic setting: hierarchical structure and conflict dynamics in ravens' foraging groups

2022 ◽  
Vol 377 (1845) ◽  
Author(s):  
Palmyre H. Boucherie ◽  
Mario Gallego-Abenza ◽  
Jorg J. M. Massen ◽  
Thomas Bugnyar
Keyword(s):  
Dynamic Structure ◽  
First Year ◽  
Dominance Hierarchies ◽  
Dynamic Setting ◽  
Current State ◽  
Dominance Structure ◽  
In Captivity ◽  
In The Wild ◽  
Group Members ◽  
To Receive

Dominance hierarchies typically emerge in systems where group members regularly encounter and compete for resources. In birds, the ‘open’ and dynamic structure of foraging groups may prevent the emergence of structured hierarchies, although this assumption have hardly been tested. We report on agonistic data for ravens Corvus corax , collected over two 18-month periods for 183 marked individuals of a wild (fluid) population and 51 birds from six captive (stable) groups. We show that the dominance structure (steep and transitive) in wild foraging groups is strikingly similar to that found in captivity. In the wild, we found that higher ranks are mainly occupied by males, older and more aggressive individuals that also tend to receive fewer aggressions. Exploring the mechanisms sustaining the wild dominance structure, we confirmed that males are more aggressive than females and, with age, tend to receive fewer aggressions than females. Males that are about to leave the foraging groups for some months are less aggressive than newcomers or locals, while newcomers are specifically targeted by aggressions in their first year (as juveniles). Taken together, our results indicate that the socially dynamic conditions ravens face during foraging do not hinder, but provide opportunities for, using (advanced) social cognition. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.

Emergence of size-structured dominance hierarchies through size-dependent feedback

2022 ◽  
Vol 377 (1845) ◽  
Author(s):  
Ian M. Hamilton ◽  
Macie D. Benincasa
Keyword(s):  
Size Structure ◽  
Dynamic Game ◽  
Optimal Investment ◽  
Growth Suppression ◽  
Pecking Order ◽  
Dominance Hierarchies ◽  
Size Dependent ◽  
Current State ◽  
Dominance Structure ◽  
Competition For Food

Size-based dominance hierarchies influence fitness, group size and population dynamics and link dominance structure to evolutionary and ecological outcomes. While larger individuals often gain dominance, social status may influence growth and size in return, resulting in feedbacks among status, growth and size. Here, we present two models evaluating how these feedbacks influence the emergence of size structure in a dominance hierarchy. In the first, size influences competition for food and investment in suppressing growth of groupmates. Stable size differences emerged when suppression was greatest for similarly sized individuals and size had little effect on competition for food. The model predicted size divergence when size strongly affected competition for food. In the second model, we used a dynamic game to solve for optimal investment in growth suppression as a function of size structure. Investment in growth suppression was favoured only when dominants and subordinates were similar in size, generating size ratios different than those expected by chance. Variation in the feedbacks among growth, size and status can explain variation in emergent size structure of dominance hierarchies and its consequences for conflict within groups. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.

Cortisol responsiveness and dominance rank, but not baseline cortisol level, are repeatable traits in adult female guinea pigs

2021 ◽  
Author(s):  
Taylor Lynne Rystrom ◽  
Romy C. Prawitt ◽  
S. Helene Richter ◽  
Norbert Sachser ◽  
Sylvia Kaiser
Keyword(s):  
Social Behavior ◽  
Adult Female ◽  
Guinea Pigs ◽  
Dominance Rank ◽  
Dominance Hierarchies ◽  
Current State ◽  
Baseline Cortisol ◽  
Group Members ◽  
Endocrine Mechanism ◽  
Males And Females

Social interactions among group members often lead to the formation of stable dominance hierarchies. Glucocorticoids (i.e. cortisol) have been proposed as an endocrine mechanism underlying social behavior, and previous studies have linked baseline as well as challenge glucocorticoid concentrations to dominance rank. Since the importance of rank on fitness differs between males and females, selection pressures acting on the underlying endocrine mechanisms may differ between the sexes. In male guinea pigs, for example, it is known that cortisol responsiveness mediates social behavior and that dominance rank and cortisol responsiveness are stable within individuals over time. It is unclear whether this is also the case for female guinea pigs. Thus the aim of this study was to investigate whether cortisol concentrations are repeatable in female guinea pigs and whether female rank is correlated to baseline cortisol concentrations or cortisol responsiveness. We show that cortisol responsiveness and dominance rank were significantly repeatable but not correlated in female guinea pigs. Furthermore, baseline cortisol was not repeatable and also did not correlate to dominance rank. Our results demonstrate that baseline cortisol and cortisol responsiveness represent different biological processes; cortisol responsiveness reflects a stable trait while baseline cortisol likely fluctuates with current state. Furthermore, cortisol responsiveness as a mediator of aggressive behavior and dominance acquisition might not be important for maintaining dominance hierarchies in stable groups of females displaying minimal aggression. Overall, this study reveals the remarkable stability of cortisol responsiveness and dominance rank in an adult female rodent and lays the groundwork for future investigations into the causes and consequences of this individual variation.

scholarly journals Growth and reproduction in captivity unveils remarkable life-history plasticity in the smallnose fanskate, Sympterygia bonapartii (Chondrichthyes: Rajiformes)

2018 ◽  
Vol 16 (4) ◽  
Author(s):  
Julieta A. Jañez ◽  
Fernando J. Meijide ◽  
Luis O. Lucifora ◽  
Carolina Abraham ◽  
Federico Argemi
Keyword(s):  
Logistic Function ◽  
First Year ◽  
Growth Data ◽  
Full Life Cycle ◽  
In Captivity ◽  
In The Wild ◽  
The Difference ◽  
The One ◽  
First Year Of Life ◽  
Growth And Reproduction

ABSTRACT We analyzed growth and reproduction of captive-born smallnose fanskates Sympterygia bonapartii. Egg cases were obtained from oviposition of two females caught in the wild and held at Temaikèn Aquarium. Following hatching, growth was analyzed in 13 females and 21 males until sexual maturity. Pattern of oviposition activity and reproductive performance were evaluated in six of the captive-reared females. Four models were fitted to growth data, among which the logistic function was the one attaining the best fit. The highest growth rate for both sexes was recorded during the first year of life, whereas growth was significantly higher in females than in males during the second year. Size at first oviposition was 61.7 ± 3.5 cm TL, similar to wild specimens. However, captive-reared females reached maturity before two years of age, i.e. much earlier than wild skates, implying a significant phenotypic plasticity in this species. The similarity in size at maturity and the difference in age at maturity between captive and wild specimens indicate that there is a decoupling of both parameters mediated through growth rates. Captive-born skates reproduced successfully and yielded viable offspring, indicating that the environment at Temaikèn Aquarium is suitable for S. bonapartii to attain its full life cycle.

scholarly journals Costs dictate strategic investment in dominance interactions

2022 ◽  
Vol 377 (1845) ◽  
Author(s):  
Tobit Dehnen ◽  
Danai Papageorgiou ◽  
Brendah Nyaguthii ◽  
Wismer Cherono ◽  
Julia Penndorf ◽  
...  
Keyword(s):  
Lower Cost ◽  
Social Groups ◽  
Theme Issue ◽  
Pecking Order ◽  
Dominance Hierarchies ◽  
Strategic Investment ◽  
Aggressive Interactions ◽  
Current State ◽  
Dominance Interactions ◽  
Group Members

Dominance is important for access to resources. As dominance interactions are costly, individuals should be strategic in whom they interact with. One hypothesis is that individuals should direct costly interactions towards those closest in rank, as they have most to gain—in terms of attaining or maintaining dominance—from winning such interactions. Here, we show that male vulturine guineafowl ( Acryllium vulturinum ), a gregarious species with steep dominance hierarchies, strategically express higher-cost aggressive interactions towards males occupying ranks immediately below themselves in their group's hierarchy. By contrast, lower-cost aggressive interactions are expressed towards group members further down the hierarchy. By directly evaluating differences in the strategic use of higher- and lower-cost aggressive interactions towards competitors, we show that individuals disproportionately use highest-cost interactions—such as chases—towards males found one to three ranks below themselves. Our results support the hypothesis that the costs associated with different interaction types can determine their expression in social groups with steep dominance hierarchies. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.

From whom do we learn group norms? Low-ranking group members are perceived as the best sources

2020 ◽  
Author(s):  
Jennifer E Dannals ◽  
Emily Reit ◽  
Dale T. Miller
Keyword(s):  
Social Norms ◽  
Correlation Study ◽  
Team Members ◽  
Norm Perception ◽  
Lower Ranking ◽  
Group Members ◽  
Groups And Teams ◽  
Or Team ◽  
And Behavior ◽  
To Receive

Social norm perception is ubiquitous in small groups and teams, but how individuals approach this process is not well understood. When individuals wish to perceive descriptive social norms in a group or team, whose ad- vice and behavior do they prefer to rely on? Four lab studies and one Teld survey demonstrate that when in- dividuals seek information about a team’s social norms they prefer to receive advice from lower-ranking indi- viduals (Studies 1–4) and give greater weight to the observed behavior of lower-ranking individuals (Study 5). Results from correlation (Study 3) and moderation (Study 4) approaches suggest this preference stems from the assumption that lower-ranking team members are more attentive to and aware of the descriptive social norms of their team. Alternative mechanisms (e.g., perceived similarity to lower-ranking team members, greater honesty of lower-ranking team members) were also examined, but no support for these was found.

scholarly journals Depression following traumatic brain injury: a comprehensive overview

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Marc Fakhoury ◽  
Zaynab Shakkour ◽  
Firas Kobeissy ◽  
Nada Lawand
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Health Concern ◽  
First Year ◽  
Comprehensive Overview ◽  
Symptoms Of Depression ◽  
Current State ◽  
Post Traumatic ◽  
Brain Changes

Abstract Traumatic brain injury (TBI) represents a major health concern affecting the neuropsychological health; TBI is accompanied by drastic long-term adverse complications that can influence many aspects of the life of affected individuals. A substantial number of studies have shown that mood disorders, particularly depression, are the most frequent complications encountered in individuals with TBI. Post-traumatic depression (P-TD) is present in approximately 30% of individuals with TBI, with the majority of individuals experiencing symptoms of depression during the first year following head injury. To date, the mechanisms of P-TD are far from being fully understood, and effective treatments that completely halt this condition are still lacking. The aim of this review is to outline the current state of knowledge on the prevalence and risk factors of P-TD, to discuss the accompanying brain changes at the anatomical, molecular and functional levels, and to discuss current approaches used for the treatment of P-TD.

scholarly journals On the modulation and maintenance of hibernation in captive dwarf lemurs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marina B. Blanco ◽  
Lydia K. Greene ◽  
Robert Schopler ◽  
Cathy V. Williams ◽  
Danielle Lynch ◽  
...  
Keyword(s):  
Food Restriction ◽  
Metabolic Disorders ◽  
Biological Rhythms ◽  
Food Ingestion ◽  
Ambient Temperatures ◽  
In Captivity ◽  
In The Wild ◽  
Cheirogaleus Medius ◽  
Save Energy ◽  
Metabolic Strategies

AbstractIn nature, photoperiod signals environmental seasonality and is a strong selective “zeitgeber” that synchronizes biological rhythms. For animals facing seasonal environmental challenges and energetic bottlenecks, daily torpor and hibernation are two metabolic strategies that can save energy. In the wild, the dwarf lemurs of Madagascar are obligate hibernators, hibernating between 3 and 7 months a year. In captivity, however, dwarf lemurs generally express torpor for periods far shorter than the hibernation season in Madagascar. We investigated whether fat-tailed dwarf lemurs (Cheirogaleus medius) housed at the Duke Lemur Center (DLC) could hibernate, by subjecting 8 individuals to husbandry conditions more in accord with those in Madagascar, including alternating photoperiods, low ambient temperatures, and food restriction. All dwarf lemurs displayed daily and multiday torpor bouts, including bouts lasting ~ 11 days. Ambient temperature was the greatest predictor of torpor bout duration, and food ingestion and night length also played a role. Unlike their wild counterparts, who rarely leave their hibernacula and do not feed during hibernation, DLC dwarf lemurs sporadically moved and ate. While demonstrating that captive dwarf lemurs are physiologically capable of hibernation, we argue that facilitating their hibernation serves both husbandry and research goals: first, it enables lemurs to express the biphasic phenotypes (fattening and fat depletion) that are characteristic of their wild conspecifics; second, by “renaturalizing” dwarf lemurs in captivity, they will emerge a better model for understanding both metabolic extremes in primates generally and metabolic disorders in humans specifically.

scholarly journals Previously unknown behavior in parasitic cuckoo females: male-like vocalization during migratory activity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Swetlana G. Meshcheryagina ◽  
Alexey Opaev
Keyword(s):  
Vocal Communication ◽  
Harmonic Spectrum ◽  
Common Cuckoo ◽  
Neck Extension ◽  
Migratory Activity ◽  
Call Production ◽  
In Captivity ◽  
In The Wild ◽  
Combined Features ◽  
Female Call

Abstract Background In the last decade, enigmatic male-like cuckoo calls have been reported several times in East Asia. These calls exhibited a combination of vocal traits of both Oriental Cuckoo (Cuculus optatus) and Common Cuckoo (Cuculus canorus) advertising calls, and some authors therefore suggested that the enigmatic calls were produced by either Common × Oriental Cuckoo male hybrids or Common Cuckoo males having a gene mutation. However, the exact identity of calling birds are still unknown. Methods We recorded previously unknown male-like calls from three captive Oriental Cuckoo females, and compared these calls with enigmatic vocalizations recorded in the wild as well as with advertising vocalizations of Common and Oriental Cuckoo males. To achieve this, we measured calls automatically. Besides, we video-recorded captive female emitting male-like calls, and compared these recordings with the YouTube recordings of calling males of both Common and Oriental Cuckoos to get insight into the mechanism of call production. Results The analysis showed that female male-like calls recorded in captivity were similar to enigmatic calls recorded in the wild. Therefore, Oriental Cuckoo females might produce the latter calls. Two features of these female calls appeared to be unusual among birds. First, females produced male-like calls at the time of spring and autumn migratory activity and on migration in the wild. Because of this, functional significance of this call remained puzzling. Secondly, the male-like female call unexpectedly combined features of both closed-mouth (closed beak and simultaneous inflation of the ‘throat sac’) and open-mouth (prominent harmonic spectrum and the maximum neck extension observed at the beginning of a sound) vocal behaviors. Conclusions The Cuculus vocalizations outside the reproductive season remain poorly understood. Here, we found for the first time that Oriental Cuckoo females can produce male-like calls in that time. Because of its rarity, this call might be an atavism. Indeed, female male-like vocalizations are still known in non-parasitic tropical and apparently more basal cuckoos only. Therefore, our findings may shed light on the evolution of vocal communication in avian brood parasites.

scholarly journals Reintroduction of the Golden Conure (Guaruba guarouba) in Northern Brazil: Establishing a Population in a Protected Area

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 198
Author(s):  
Marcelo Rodrigues Vilarta ◽  
William Wittkoff ◽  
Crisomar Lobato ◽  
Rubens de Aquino Oliveira ◽  
Nívia Gláucia Pinto Pereira ◽  
...  
Keyword(s):  
Power Lines ◽  
Food Supplementation ◽  
Territorial Disputes ◽  
Amazon Forest ◽  
Nest Boxes ◽  
In Captivity ◽  
Viable Population ◽  
In The Wild ◽  
Northern Brazil ◽  
Native Foods

Brazil has the highest number of parrots in the world and the greatest number of threatened species. The Golden Conure is endemic to the Brazilian Amazon forest and it is currently considered as threatened by extinction, although it is fairly common in captivity. Here we report the first reintroduction of this species. The birds were released in an urban park in Belem, capital of Para State, where the species was extinct more than a century ago. Birds were trained to recognize and consume local food and to avoid predators. After the soft-release, with food supplementation and using nest boxes, we recorded breeding activity in the wild. The main challenges before the release were the territorial disputes within the aviary and the predation by boa snakes. During the post-release monitoring the difficulties were the fast dispersion of some individuals and the dangers posed by anthropic elements such as power lines that caused some fatalities. Released birds were very successful at finding and consuming native foods, evading predators, and one pair reproduced successfully. Monitoring continues and further releases are programmed to establish an ecologically viable population.

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