The Anderson Lab
Our laboratory studies behavioral ecology, animal communication,
and bioacoustics
Birdsong and Behavioral Ecology
Birdsong is a dual-function signal, functioning in both intrasexual competition and intersexual mate attraction. In this way, bird song is an important component in understanding songbird behavior. Our research examines song to answer questions regarding behavioral ecology. One of the focuses of our current work is to understand the evolution of communication systems. Why do some species have small vocal repertoires of simple song types, while other species have large repertoires? Why do some species evolve multiple categories of singing modes? What selective pressures drive the evolution of this complexity? To address these questions, we study the behavioral and evolutionary ecology of the Bachman's sparrow (Peucaea aestivalis), a species in which males have 35-45 song types, as well as a variety of other types of songs and calls. Females also sing and produce a variety of call types.
In previous studies on intrasexual competition, we have studied how birdsong is used in aggressive and territorial interactions between male songbirds. To elicit aggressive signaling from a male subject, we use playback of song combined with a conspecific model, either taxidermic or 3D printed, on his territory, and record his aggressive signaling behavior. We compare which signals elicit attack, how consistent aggressiveness is over time, and whether aggressiveness relates to territorial characteristics.
Our lab has studied how male song repertoires are structured and used in both male-male aggressive communication and male-female courtship, and how singing behaviors such as song type matching, low-amplitude "quiet song" and "excited song" are used during male-male contests. We are also interested how this species' behavior and natural history may be shaped by the fires (prescribed burns) that are critical for suitable habitat. Future work will include hormone and neuroendocrine studies to examine the physiological mechanisms that underlie social behavior and response to extreme environmental challenges in this species.
Graduate students Hans Gonzembach and Billy Abbott running a behavioral trial with a male Bachman's sparrow.
Most of our studies have focused on the Bachman’s sparrow, which is unique for its large repertoire size. We have found that low-amplitude “whisper” songs predict attack (Ali and Anderson 2018), and that aggressiveness changes over time and relates to some aspects of territory quality.
Additionally, we explore how intra- and intersexual selection have shaped the repertoire sizes of songbirds. Many hypotheses have been proposed to explain the evolution of large and elaborate repertoires. The most prominent hypothesis is the mate choice hypothesis, which states that large repertoires evolved due to female preference similar to the peacock’s elaborate tail. However, large repertoires may have evolved under intrasexual competition to allow males to match their songs to multiple rivals. We found some support of the latter in Bachman’s sparrow, but likely this songbird’s relatively large repertoire is due to the mate choice hypothesis.​
