skip to main content


Title: Group chorusing as an intragroup signal in the greater ani, a communally breeding bird
Abstract

Group living often requires maintaining dynamic and varied relationships with fellow group members, while simultaneously monitoring and interacting with external competitors. Group members in many social species vocalize together to produce duets or choruses—coordinated, often conspicuous vocal displays—that may play a role in these interactions. Compared with male–female duets, however, relatively little research exists on the function and adaptive significance of group choruses, which involve three or more individuals. Here we investigate chorusing behavior in the greater ani (Crotophaga major), a communally breeding cuckoo that nests in stable social groups of four to eight unrelated individuals. Groups may remain together for several years on the same nesting territory, and groups occasionally destroy each other's clutches in conflicts over high‐quality territories. We asked whether the raucous, highly stereotyped choruses performed by ani groups are primarily used for intra‐ or intergroup communication, and whether they contain information about the identity of the social group and the number of birds vocalizing. Behavioral observations and acoustic recordings from three breeding seasons revealed that choruses typically occurred during social interactions within the group (78% of choruses) or in response to a predator or extra‐group individual (17%) and only rarely in intergroup interactions (4%). Consistent with this finding, choruses did not reliably reflect the number of birds vocalizing, and we found only limited evidence for group‐specific acoustic signatures (driven by a single group whose choruses were highly distinct). These results suggest that group choruses play an important role in intra‐group signaling, potentially in contexts such as group formation, reinforcement of social bonds within the group, and/or collective decision‐making, and they motivate new research questions about the role of collective signaling in social evolution.

 
more » « less
NSF-PAR ID:
10389264
Author(s) / Creator(s):
 ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Ethology
Volume:
129
Issue:
2
ISSN:
0179-1613
Page Range / eLocation ID:
p. 63-73
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Coalitions among individuals and between groups, which have had critical evolutionary benefits for humans, play an important role in contemporary life. One key element of the processes of assessing potential allies is how they may contribute to the perceived physical formidability – fighting ability or the capacity to inflict costs on others – of the alliance. In three studies, focused for the first time on intergroup coalitions, we investigated how qualities of the groups such as status (social prestige) and the relationship between them influence the perceived physical formidability of a coalition (i.e., European Union, EU). Study 1 found that the inclusion of a group with higher or similar (but not lower) status increased the perceived formidability of the EU. Studies 2 and 3 showed that learning that ingroup members recategorized a low‐status group within a common‐group identity increased the perceived formidability of the EU including that group, compared with the conditions in which either outgroup members recategorized or no information was provided. Study 3 also revealed mediation by fusion – a visceral connection – with outgroup members, which has been relatively unexplored. Taken together, these studies reveal that both, status and social identity processes, may significantly affect the estimations of coalitional formidability.

     
    more » « less
  2. Abstract

    Collective phenotypes, which arise from the interactions among individuals, can be important for the evolution of higher levels of biological organization. However, how a group’s composition determines its collective phenotype remains poorly understood. When starved, cells of the social amoeba Dictyostelium discoideum cooperate to build a multicellular fruiting body, and the morphology of the fruiting body is likely advantageous to the surviving spores. We assessed how the number of strains, as well as their genetic and geographic relationships to one another, impact the group’s morphology and productivity. We find that some strains consistently enhance or detract from the productivity of their groups, regardless of the identity of the other group members. We also detect extensive pairwise and higher-order genotype interactions, which collectively have a large influence on the group phenotype. Whereas previous work in Dictyostelium has focused almost exclusively on whether spore production is equitable when strains cooperate to form multicellular fruiting bodies, our results suggest a previously unrecognized impact of chimeric co-development on the group phenotype. Our results demonstrate how interactions among members of a group influence collective phenotypes and how group phenotypes might in turn impact selection on the individual.

     
    more » « less
  3. Abstract

    In group‐living species, integrating into a new social group after dispersal is an important life history milestone associated with physical and social challenges. Generally, this process seems to be accompanied by heightened glucocorticoid (GC) concentrations; however, most studies of physiological responses to group transfer have been conducted on species with despotic social relationships, where integrating individuals are often targets of frequent aggression. Here we present data on fecal glucocorticoid (fGC) concentrations during periods of unstable group membership for male woolly monkeys (Lagothrix lagotricha poeppigii), a species with extremely low rates of male–male aggression and generally tolerant male–male associations. We collected data on males in four study groups at the Tiputini Biodiversity Station, Ecuador, and observed three attempted transfer events, involving a total of four adult males, in one study group. We observed only three instances of overt aggression (chases) between males across the entire study period, though male display behaviors were more frequent. We tested whether rates of displays were higher during periods of unstable group membership using a generalized linear mixed model (LMM). We also examined whether male status, group stability, and the occurrence of intergroup encounters affected fGC concentrations using LMMs. Contrary to our predictions, rates of display behaviors were not higher during periods of unstable group membership. However, both transient/integrating males and those who were already group members showed elevated fGC concentrations during these unstable periods. Our results suggest that even in species with tolerant male–male relationships, the integration of unfamiliar individuals can provoke an increase in GCs.

     
    more » « less
  4. Understanding the factors that facilitate the emergence of cooperation among organisms is central to the study of social evolution. Spotted hyenas Crocuta crocuta frequently cooperate to mob lions Panthera leo, approaching the lions as a tightknit group while vocalizing loudly in an attempt to overwhelm them and drive them away. Whereas cooperative mobbing behavior has been well documented in birds and some mammals, to our knowledge it has never been described during interactions between 2 apex predators. Using a 27-year dataset, we characterize lion–hyena encoun- ters, assess rates of mobbing behavior observed during these interactions, and inquire whether mobbing results in successful acquisition of food. Lions and hyenas interacted most often at fresh kills, especially as prey size and the number of hyenas present increased. Possession of food at the beginning of an interaction positively affected retention of that food by each predator species. The presence of male lions increased the probability of an interspecific interaction but decreased the likelihood of hyenas obtaining or retaining possession of the food. Hyena mobbing rates were high- est at fresh kills, but lower when adult male lions were present. The occurrence of mobbing was pre- dicted by an increase in the number of hyenas present. Whether or not mobbing resulted in acquisi- tion of food from lions was predicted by an increase in the number of mobs formed by the hyenas present, suggesting that cooperation among hyenas enhances their fitness. 
    more » « less
  5. his project is supported by an NSF BPE grant. Career choices, such as engineering, are influenced by a number of factors including personal interest, ability, competence beliefs, prior work-related experience, and financial and social supports. However, financial and social support, a particularly significant factor for rural students’ career decisions, is often overlooked in the literature exploring career choice. Moreover, little work has explored how communities serve as key influencers for supporting or promoting engineering as a career choice. Therefore, the goal of this study is to explore the ways in which communities provide support to students deciding to pursue engineering as a college major. To better understand how students from selected rural area high schools choose engineering as a major, we conducted focus group discussions consisting of 4-6 students each from selected schools to talk collectively about their high school experiences and their choice to major in engineering. Choosing focus group participants from different schools enabled us to elicit tacit perceptions and beliefs that may not be evident when students from the same community talk with one another. That is, as students share their experiences across schools, they may recognize differences in their experiences that, though otherwise unconscious or unacknowledged, proved significant in their choice of college and major. We expect that certain community programs and the individuals involved will have some influence on students’ decisions to study engineering at [University Name]. We anticipate that the results will yield two key outcomes: 1. A holistic understanding of the communities that effectively support and encourage engineering major choice for rural students. 2. Locally driven, contextually relevant recommendations for policies and programs that would better enable economically disadvantaged, rural schools in southwestern Virginia to support engineering as a career choice for high school students. By understanding the ways some economically-disadvantaged rural communities support engineering as a career choice and linking a broad spectrum of rural communities together around this issue, this project will broaden participation in engineering by increasing support for students from these areas. By shifting our focus from students to communities, this research broadens our understanding of career choice by capturing the perspectives of community members (including not only school personnel, but also community leaders, students’ families, business owners and others) who often play a key role in students’ decisions, particularly in rural communities. Our research will bring these voices into the conversation to help scholars learn from and respond to these essential community perspectives. In doing so, we will provide a more nuanced model of engineering career choice that can then be explored in other rural contexts. This work thus contributes to the research on career choice, rural education, and engineering education. © 2018 American Society for Engineering Education 
    more » « less