The long-term goal of my primary research program is to investigate the communication function of different learning strategies in birds. We are studying the banded wren, a moderately age-restricted learner, and the mockingbird, an open-ended learner. This project focuses on the signal function and delivery patterns of different learned song types during male-male countersinging interactions and courtship/mate attraction.

Neuroscientists studying the process of song learning and memory in songbirds have been limited to three species that are easily kept in the lab: sparrows, zebra finches, and canaries. These species exhibit very different patterns in the timing and duration of learning and their tendency to copy whole song types. Very little is know about why these different learning strategies have evolved. We are studying the communication consequences of different song learning strategies in wild songbirds. This research relates to recent work on human language learning showing that some aspects of acquisition occur and are restricted to early ages, whereas other aspects of acquisition are accommodated by the social environment experienced by adults.

We are taking advantage of new bioacoustic technology, including microphone array recording and interactive sound playback, to quantify how males use their complex song repertoires to communicate aggressive intentions to other males and their attractiveness to females. For the banded wren, our playback experiments, recordings, and field observations are leading us to the conclusion that males learn most of their song types during the first year of life. However, new evidence shows that males improve the precision of their songs as they get older, making repeated notes in trills more consistent. Males can detect the difference between playback of young and old male songs. The branded wren is a highly territorial species with dynamic boundaries; countersinging serves the primary function of mediating boundary disputes between males. As for the mockingbird, repertoire size is very large and song learning continues throughout adulthood; we believe female preference for large repertoires, improved precision of notes as in the wren, and rapid matching during competitive singing bouts is driving song learning in this species.

This basic research project has no direct economic or medical impact. It does, however, lead to a deeper understanding of the evolution of vocal communication strategies in birds and other animals, and ultimately asks whether and how animal signals provide honest information to receivers. Our fieldwork does take place in sensitive tropical habitats and contributes to a fuller understanding of community structure and diversity in these rich environments.

Behavioral ecology

• Selvino de Kort (Lab of Ornithology)
• Erin Bohman (Lab of Ornithology)