Year of Award


Document Type


Degree Type

Doctor of Philosophy (PhD)

Degree Name

Organismal Biology and Ecology

Department or School/College

Division of Biological Sciences

Committee Chair

Erick Greene

Commitee Members

Douglas Emlen, Ray Callaway, Jon Graham, Mike Webster


University of Montana


Communication is often set up as a simple dyadic exchange between one sender and one receiver. However, in reality, signaling systems have evolved and are used with many forms and types of information bombarding multiple senders, who in turn send multiple signals of different modalities, through various environmental spaces, finally reaching multiple receivers. In order to understand both the ecology and evolution of a signaling system, we must examine all the facets of the signaling system.

My dissertation focused on the alarm call signaling system in birds. Alarm calls are acoustic signals given in response to danger or predators. My first two chapters examine how information about predators alters alarm calls. In chapter one I found that chickadees make distinctions between predators of different hunting strategies and appear to encode information about predators differently if they are heard instead of seen. In my second chapter, I test these findings more robustly in a non-model bird, the Steller’s jay. I again found that predator species matters, but that how Steller’s jays respond if they saw or heard the predator depends on the predator species. In my third chapter, I tested how habitat has influenced the evolution of mobbing call acoustic structure. I found that habitat is not a major contributor to the variation in acoustic structure seen across species and that other selective pressures such as body size may be more important. In my fourth chapter I present a new framework to understand the evolution of multimodal communication across species. I identify a unique constraint, the need for overlapping sensory systems, thresholds and cognitive abilities between sender and receiver in order for different forms of interspecific communication to evolve. Taken together, these chapters attempt to understand a signaling system from both an ecological and evolutionary perspective by examining each piece of the communication scheme.



© Copyright 2017 Alexis Chandon Billings