RUI: Honesty, Learning Biases, and Complexity in the Cultural Evolution of Bird Songs

Bird songs provide an excellent model for studying cultural development, especially when the songs of known individuals in a wild population are recorded over a long period of time and can provide a record of generational changes. This research will ask how new forms of Savannah sparrow song arise, how sensory and learning predispositions affect choices of which song to copy, and how constraints on a communication system can result in forms of cultural development.

In cultural development, in contrast to natural selection, socially learned behaviors, rather than genes, are transmitted between individuals. Behaviors can be innovated to respond to specific situations, while changes in genes arise only as random mutations. Behaviors can be learned from anyone, whether younger or older, related or unrelated – in contrast to genes, which are transmitted from parent to offspring.

As a consequence, behaviors that provide advantages to the learners can spread quickly, allowing a population to adapt more rapidly to a changing environment. Here, an integrated approach will be used that draws on mathematical modeling and field studies in a natural population to explore the possibility that female choice favors the elaboration of some components of male songs.

This research will also provide meaningful experiences directed at increasing engagement with and appreciation for the scientific approach to understanding bird songs and the value of that research both for the public and for grade school and undergraduate students.

Drawing on long-term demographic and song recording data from two Savannah sparrow study sites, this research will track cultural development of songs at the population level. Key outcomes will be: 1) understanding the tradeoffs between the efficacy of a song in attracting mates and a given singer’s ability to perform it consistently; 2) the implications for signal honesty when innovations make songs easier to perform while still maintaining attractiveness; and 3) how the interplay between limits on vocal performance and selection for increasingly complex songs might give rise to cycles between behavioral complexity and simplicity.

An integrated approach that draws on mathematical modeling and field studies in a natural population will be used to explore the possibility that female choice favors the elaboration of some components of male songs. Such elaboration might be limited by the performer’s vocal virtuosity, and some males may learn to subvert the honesty of the system by learning novel song features that are easier to perform.

Modeling these processes may provide insight into the processes that drive cyclic changes between simplicity and complexity in behavior. A better understanding of the factors that drive the cultural development of new forms of socially learned behavior can inform processes of speciation where vocal signals play a role and can also provide insights that may help conserve species whose environments are changing rapidly.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.