Acoustic communication in choughs and a changing world

: From functions to fitness

Abstract

Acoustic communication fulfils vital functions in many animals, including attracting mates, mediating conflict, coordinating social behaviours and warning about predators. However, rising levels of anthropogenic noise disrupt acoustic communication, impairing signal detection and interfering with receiver responses; consequently, many animals adjust acoustic signals to noise. In Chapter 1 of this thesis, I give a general introduction to the evolution and function of acoustic communication, describe impacts of noise on wildlife and state the thesis aims. In Chapter 2, I investigate the function of ‘peep’ calls in white-winged choughs (Corcorax melanorhamphos), a cooperatively breeding passerine bird. I use a combination of field observations and experimental testing to demonstrate that peep calls function in recruiting group members to food. Furthermore, I show that choughs give a higher rate of peep calls for divisible rather than whole food, associated with a lower tendency to monopolise divisible food. Contrary to expectation, juveniles do not respond more strongly than adults to peep calls, despite the former having a lower foraging success. I discuss possible evolutionary explanations for peep calling, including group augmentation and inclusive fitness benefits. In Chapter 3, I present a systematic review investigating how adjustments of acoustic communication to noise can affect behaviour, physiology, signal transmission and fitness. Given that evidence is relatively recent and dispersed across taxa and disciplines, I use a systematic approach to maximise the inclusion of relevant studies and ensure future repeatability. The review summarises major trends in findings, identifies significant research biases and knowledge gaps, and makes recommendations for future research. My thesis therefore advances our understanding of the role of acoustic communication in both food sharing and coordinating group-living, and highlights important downstream consequences of acoustic adjustments to noise.

Date of Award	17 Mar 2026
Original language	English
Awarding Institution	University of Bristol
Supervisor	Andrew N Radford (Supervisor) & Joshua Arbon (Supervisor)