I’m interested in the role that ecological and social factors play in shaping songbird vocal communication systems. I ask questions about how acoustic signals change as they transmit through the environment, and how birds communicating over distance process long-range signals. Sound (specifically birdsong) degrades predictably as it propagates from sender (singer) to receiver (listener), and I am investigating what effect that has on behavioral interactions, signal perception, song learning, and song evolution in birds.
By delving into the behavioral, neural, and developmental mechanisms underlying singing behavior in birds (proximate-level analysis), as well as the broader evolutionary processes shaping song evolution in birds (ultimate-level analysis), I aim to contribute to an integrative understanding of avian vocal communication.
In behavioral field trials, I am testing whether or not males use sound degradation cues to determine the position of their neighbors (rivals) across a landscape, and whether the extent of perceived acoustic degradation from competitors’ songs informs receiver responses. In analogous electrophysiological experiments, I am examining neural responses to variation in distance-degraded song stimuli. I here aim to identify an auditory processing mechanism that allows birds to perceive degradation cues, thus enabling acoustic distance assessment (and ultimately informing territorial behavior).
Song Development & Distant Song Models with Jeff Podos and Luke Remage-Healey
I am exploring how juvenile song development is affected by social variables during song learning. Young males in the wild learn by copying song models from adult tutors in their natal neighborhoods, but these tutors are spaced out across the landscape so that some are close and some are far. In the lab, I am raising male swamp sparrows (Melospiza melodia) and experimentally controlling the environment in which young birds are raised, to investigate the role of close vs. far song tutors on song development in two ways: 1) by comparing learning outcomes from acoustically clear (close) vs. acoustically degraded (far) song models, and 2) by comparing learning outcomes from visible, singing adult tutors (close) vs. tutors that are heard only and not visible (far). In subsequent electrophysiological experiments, I am examining the neural responses of these subjects as adults to their early tutor songs to determine how the brain (HVC) represents songs heard early in life from these different treatment categories. Through this work, I am examining how social relevance and perceptual mechanisms influence song learning and model choice by juvenile male songbirds.
Signal Evolution & Acoustic Adaptation with Jeff Podos
I am taking an ultimate-level approach to ask whether species’ songs evolve to match the acoustic properties of their environments. The acoustic adaptation hypothesis (AAH) posits that song structures can be acoustically adaptive, selected to maximize signal fidelity over biologically relevant transmission distances. I am investigating whether there is evidence that the AAH is contributing to song evolution in the Darwin’s finch radiation, a group of closely related, recently diverged species that occupy a range of habitats and sing a range of songs. Determining the relative contribution of acoustic adaptation (versus other factors) to shaping song differences across species may help explain both song divergence and speciation mechanisms within this group.
I’m involved in additional collaborative projects exploring birdsong, including investigating how early developmental experience shapes female song preferences (with Jeff Podos), and exploring song cultural evolution across spatially and temporally variable landscapes (with Tim Parker, Whitman College Biology).
Parker, T.H., Sousa, B., Leu, S.T., Edmondson, S., Foo, C., Strauss, A.V.H., Kahl, H., Ballinger, K., Ross, E., Ruse, M.G., Sandsten, M., Verheijen, B.H.F., & Jensen, W. Cultural conformity and persistence in dickcissel song are higher in locations in which males show high site fidelity. Ornithology (Accepted).
Podos, J., Moseley, D. L., Goodwin, S. E., McClure, J., Taft, B. N., Strauss, A. V. H., Rega-Brodsky, C., & Lahti, D.C. A Fine-Scale, Broadly-Applicable Index of Vocal Performance: Frequency Excursion. Animal Behaviour 116 (2016): 203-212.
Based in San Francisco, CA.