Lysanne Snijders

Song Trait Similarity in Great Tits Varies with Social Structure

For many animals, long-range signalling is essential to maintain contact with conspecifics. In territorial species, individuals often have to balance signalling towards unfamiliar potential competitors (to solely broadcast territory ownership) with signalling towards familiar immediate neighbours (to also maintain so-called “dear enemy” relations). Hence, to understand how signals evolve due to these multilevel relationships, it is important to understand how general signal traits vary in relation to the overall social environment. For many territorial songbirds dawn is a key signalling period, with several neighbouring individuals singing simultaneously without immediate conflict. In this study we tested whether sharing a territory boundary, rather than spatial proximity, is related to similarity in dawn song traits between territorial great tits (Parus major) in a wild personality-typed population. We collected a large dataset of automatized dawn song recordings from 72 unique male great tits, during the fertile period of their mate, and compared specific song traits between neighbours and non-neighbours. We show here that both song rate and start time of dawn song were repeatable song traits. Moreover, neighbours were significantly more dissimilar in song rate compared to non-neighbours, while there was no effect of proximity on song rate similarity. Additionally, similarity in start time of dawn song was unrelated to sharing a territory boundary, but birds were significantly more similar in start time of dawn song when they were breeding in close proximity of each other. We suggest that the dissimilarity in dawn song rate between neighbours is either the result of neighbouring great tits actively avoiding similar song rates to possibly prevent interference, or a passive consequence of territory settlement preferences relative to the types of neighbours. Neighbourhood structuring is therefore likely to be a relevant selection pressure shaping variation in territorial birdsong.

Dawn song predicts behaviour during territory conflicts in personality-typed great tits

Territorial animals settle territory disputes and discourage conspecific intrusion via close-range confrontations as well as nonconfrontational long-range signalling. Since individuals often differ consistently in general aggression and risk taking, the relative use of either close- or long-range territorial defence behaviour is likely to vary with the personality of the territory owner. Here we quantified the relationship between dawn song, a well-studied long-range signal, and responses to a close-range confrontation as well as how individuals in a territorial population vary in this relationship. For this we recorded dawn song and experimentally simulated territory intrusions via playbacks in wild personality-typed male great tits, Parus major. We show that males that sang at a higher rate at dawn also showed stronger vocal responses towards a simulated intruder, but spent less time in proximity to the intruder. Moreover, males with a higher exploration score, an established proxy for personality traits, showed the strongest vocal and spatial responses during the confrontation, yet exploration behaviour did not predict the dawn song rate. These findings highlight the importance of both confrontational and nonconfrontational territorial behaviours as well as personality for the social and territorial dynamics of animal populations.

Information transmission via movement behaviour improves decision accuracy in human groups

A major advantage of group living is increased decision accuracy. In animal groups information is often transmitted via movement. For example, an individual quickly moving away from its group may indicate approaching predators. However, individuals also make mistakes which can initiate information cascades. How responsive should individuals then be to escaping group members? Increasing responsiveness increases true positives (i.e. escape when a predator is present) but at the cost of increased false positives (i.e. escape when a predator is absent). Conversely, reducing responsiveness decreases not only false positives but also true positives, resulting in a fundamental trade-off in decision accuracy. Here we investigated how socially responsive individuals are to information transmission via movement. We performed a simulated predator detection task using human groups in which humans stepped forward if they wanted to escape. We confirm that this simple movement mechanism allows individuals in groups to simultaneously increase true positives and decrease false positives. The increase in the number of escapees over time during collective decisions depended on the personal information of the group members. Individual predator detection by only a few group members rarely resulted in anyone stepping forward. Individual predator detection by a quarter of the group often resulted in the entire group escaping. Finally, individual predator detection by at least half of the group led to a rapid escape of the whole group. Overall, the increase in the number of escapees over time followed a linear response. Since information transmission via movement is widespread in animal groups, this mechanism is expected to be relevant for many animal groups to improve decision accuracy.

Animal Social Network Theory Can Help Wildlife Conservation

Many animals preferentially associate with certain other individuals. This social structuring can influence how populations respond to changes to their environment, thus making network analysis a promising technique for understanding, predicting, and potentially manipulating population dynamics. Various network statistics can correlate with individual fitness components and key population-level processes, yet the logical role and formal application of animal social network theory for conservation and management have not been well articulated. We outline how understanding of direct and indirect relationships between animals can be profitably applied by wildlife managers and conservationists. By doing so, we aim to stimulate the development and implementation of practical tools for wildlife conservation and management and to inspire novel behavioral research in this field.

Chapter Eight – Communication in Animal Social Networks: A Missing Link?

Animal social networks and animal communication networks are key disciplines for understanding animal social behavior, yet these disciplines remain poorly integrated. In this review, we show how communication and social networks are inherently linked, with social signals reflecting and affecting social networks. Signals carry key information on the quality and direction of social connections and reveal social connections over long distances. Moreover, social signals can directly affect proximity among conspecifics, by facilitating social attraction and repulsion. Social signals thus mediate many of the social networks we observe. Throughout, we discuss a broad range of signal types and interactions, yet with a focus on acoustic signals and show how they reflect and affect social relationships. With this review we aim to inspire further integration of the social network and communication network disciplines, expecting that it will lead to new insights into the dynamics and evolution of animal social behavior.Animal social networks and animal communication networks are key disciplines for understanding animal social behavior, yet these disciplines remain poorly integrated. In this review, we show how communication and social networks are inherently linked, with social signals reflecting and affecting social networks. Signals carry key information on the quality and direction of social connections and reveal social connections over long distances. Moreover, social signals can directly affect proximity among conspecifics, by facilitating social attraction and repulsion. Social signals thus mediate many of the social networks we observe. Throughout, we discuss a broad range of signal types and interactions, yet with a focus on acoustic signals and show how they reflect and affect social relationships. With this review we aim to inspire further integration of the social network and communication network disciplines, expecting that it will lead to new insights into the dynamics and evolution of animal social behavior.

Sex-specific responses to territorial intrusions in a communication network: evidence from radio-tagged great tits

Abstract Signals play a key role in the ecology and evolution of animal populations, influencing processes such as sexual selection and conflict resolution. In many species, sexually selected signals have a dual function: attracting mates and repelling rivals. Yet, to what extent males and females under natural conditions differentially respond to such signals remains poorly understood, due to a lack of field studies that simultaneously track both sexes. Using a novel spatial tracking system, we tested whether or not the spatial behavior of male and female great tits (Parus major) changes in relation to the vocal response of a territorial male neighbor to an intruder. We tracked the spatial behavior of male and female great tits (N = 44), 1 hr before and 1 hr after simulating territory intrusions, employing automatized Encounternet radio‐tracking technology. We recorded the spatial and vocal response of the challenged males and quantified attraction and repulsion of neighboring males and females to the intrusion site. We additionally quantified the direct proximity network of the challenged male. The strength of a males vocal response to an intruder induced sex‐dependent movements in the neighborhood, via female attraction and male repulsion. Stronger vocal responders were older and in better body condition. The proximity networks of the male vocal responders, including the number of sex‐dependent connections and average time spent with connections, however, did not change directly following the intrusion. The effects on neighbor movements suggest that the strength of a males vocal response can provide relevant social information to both the males and the females in the neighborhood, resulting in both sexes adjusting their spatial behavior in contrasting ways, while the social proximity network remained stable. This study underlines the importance of “silent” eavesdroppers within communication networks for studying the dual functioning and evolution of sexually selected signals.

Dominance rank and boldness predict social attraction in great tits

Social relationships can have important fitness consequences, and how well an individual is socially connected often correlates with other behavioral traits. Whether such correlations are caused by underlying individual differences in social attraction usually remains unclear, because to identify effects of individual traits on social attraction, it is essential to experimentally exclude the influence of the social partner. Using standardized high-definition video playback on captive great tits (Parus major), we effectively demonstrate the influence of individual traits on the motivation to be near a conspecific. We show that social attraction varied contrastingly with boldness and stimulus novelty. Shyer birds tended to show stronger social attraction when they were confronted with the stimulus bird for the first time. Lower ranked birds showed the overall strongest social attraction. This rank effect remained after experimentally changing dominance ranks by altering group compositions. Moreover, preference for social association tended to increase with a decrease in dominance rank, suggesting that birds plastically change their social preference in relation to their within-group dominance status. Our results provide insight into how social relations can form and change, processes that are key for understanding the long-term consequences of the social environment, and the role individuals might play in influencing this environment themselves.

Individual- and population-level drivers of consistent foraging success across environments

Individual foraging is under strong natural selection. Yet, whether individuals differ consistently in their foraging success across environments, and which individual- and population-level traits might drive such differences, is largely unknown. We addressed this question in a field experiment, conducting over 1,100 foraging trials with subpopulations of guppies, Poecilia reticulata, translocated across environments in the wild. We show that individuals consistently differed in reaching and acquiring food resources, but not control ‘resources’, across environments. Social individuals reached and acquired more food resources than less-social ones and males reached more food resources than females. Yet, overall, individuals were more likely to join females at resources than males, which might explain why individuals in subpopulations with relatively more females reached and acquired, on average, more food resources. Our results provide rare evidence for individual differences in foraging success across environments, driven by individual- and population-level (sex ratio) traits.Whether individual behaviours remain consistent across environments is unclear. Here the authors show that guppies translocated into different environments consistently differ in their ability to acquire food resources, which is also modified by sociality and sex.

Systematic reviews and maps as tools for applying behavioral ecology to management and policy

&NA; Although examples of successful applications of behavioral ecology research to policy and management exist, knowledge generated from such research is in many cases under‐utilized by managers and policy makers. On their own, empirical studies and traditional reviews do not offer the robust syntheses that managers and policy makers require to make evidence‐based decisions and evidence‐informed policy. Similar to the evidence‐based revolution in medicine, the application of formal systematic review processes has the potential to invigorate the field of behavioral ecology and accelerate the uptake of behavioral evidence in policy and management. Systematic reviews differ from traditional reviews and meta‐analyses in that their methods are peer reviewed and prepublished for maximum transparency, the evidence base is widened to cover work published outside of academic journals, and review findings are formally communicated with stakeholders. This approach can be valuable even when the systematic literature search fails to yield sufficient evidence for a full review or meta‐analysis; preparing systematic maps of the existing evidence can highlight deficiencies in the evidence base, thereby directing future research efforts. To standardize the use of systematic evidence syntheses in the field of environmental science, the Collaboration for Environmental Evidence (CEE) created a workflow process to certify the comprehensiveness and repeatability of systematic reviews and maps, and to maximize their objectivity. We argue that the application of CEE guidelines to reviews of applied behavioral interventions will make robust behavioral evidence easily accessible to managers and policy makers to support their decision‐making, as well as improve the quality of basic research in behavioral ecology.