The function of synchronisation in cicada swarms

Supervisor: James Herbert-Read

Co-Supervisor: Professor David Sumpter

Project Summary: 

The synchronised signals produced by animal aggregations provide some of the most spectacular examples of biological organisation. From flashing fireflies to chorusing insects, local interactions between individuals can generate coordinated displays involving hundreds or thousands of animals. Yet synchrony often occurs in mating aggregations in which males compete intensely for females. Why, then, should competing individuals coordinate their signals?

This project will use cicada choruses to investigate the evolutionary and behavioural functions of synchronisation. It will test whether synchrony arises through increasing male attractiveness to females, or provides protection from predators through dilution or reduced localisation of individual callers. The project will be primarily empirical, combining large-scale field observations with manipulative experiments. Behavioural observations and playback experiments will test the functions of synchrony, asking whether females prefer synchronous calls, or whether particular male timings within a chorus provide signalling advantages. Field observations and playback experiments will also test whether synchrony affects the ability of predators to detect, locate or target individual cicadas.

The student may complement this empirical work with theoretical or computational models exploring how competition, mate choice and predation interact to favour different signalling strategies. Overall, the project will reveal why competing animals coordinate their behaviour and how individual-level selection shapes synchrony.

Type of Work:

The student will investigate the function of synchronised calling in the Australian Razor-Grinder cicada (Henicopsaltria eydouxii). This species occurs along the east coast of Australia and emerges between late November and March. The project will involve seasonal fieldwork in Australia, with data processing, analysis and modelling conducted in Cambridge. 

The student will design and conduct field studies combining detailed behavioural observations with manipulative experiments. This will include making synchronised video and acoustic recordings of natural choruses; capturing, individually marking and releasing cicadas; and mapping the positions and movements of callers within aggregations. Speaker-based playback experiments will be used to manipulate the timing, location and composition of calls, allowing the student to test how males, females and predators respond to different patterns of synchrony.

Depending on the student’s interests, empirical results may be integrated with theoretical models examining when synchronised calling is favoured by selection and how different signalling strategies spread within populations. Applicants with a strong interest in animal behaviour, behavioural ecology and quantitative field research are therefore encouraged to apply. Experience of programming or mathematical modelling would be beneficial.

The student will receive training in the conceptual and theoretical foundations of the project, experimental design, fieldwork techniques, bioacoustics, animal behaviour, automated signal and behavioural analysis, programming, statistical analysis and, where appropriate, theoretical modelling. They will also receive training in scientific writing, presentation and research dissemination. The student will have weekly meetings with their supervisors, participate in weekly meetings of the Marine Behavioural Ecology Group and be supported to present their research at national and international conferences.

Importance of the area of research concerned:

Synchronised animal displays are among the most striking examples of collective behaviour, yet their evolutionary function remains poorly understood. This is particularly the case in mating aggregations, where males compete for female attention while coordinating their signals with those of their rivals. By testing how male competition, female choice, and predation shape synchronised calling, this project will reveal how individual-level selection produces complex group-level behaviour and provide broader insights into the evolution of animal communication and self-organised behaviour.

References: N/A