This research will examine a model system of vocal learning, bird song learning. The research will concentrate on the role of social factors, and will contrast several different hypotheses about these factors. According to the direct interaction hypothesis, young birds learn songs by interacting with older birds. According to the social eavesdropping hypothesis, the young bird learns primarily by extracting information from interactions among other birds that he observes or overhears. According to the social dominance hypothesis, the key information concerns the dominance relationships of those birds, while according to the singing rules hypothesis, the key information concerns which songs are appropriate replies to other songs. These hypotheses will be tested using the newly-developed 'virtual tutor' system which can both simulate interacting singers and interact directly with the subject. This system also captures many of the features of live counter-singing birds while permitting the investigator more experimental control than is possible with live birds. Parallel studies will be carried out in the field.
Song learning in songbirds has been analyzed extensively in the laboratory and, in part because of its many parallels with human language learning, it has become a major model system for studying the neurobiology and genetics of learning. It is only recently that another parallel with human language learning has been recognized; i.e., the role of social factors in vocal learning. This research will further develop the utility of this model system of learning. The research will support both graduate and undergraduate students. It will also play a role in public education, featuring the field research which takes place at Discovery Park, a 532-acre natural area park operated by Seattle Parks & Recreation.
The use of elaborate acoustic vocalizations, or song, in communication is common in a wide variety of animal groups. In the oscines (songbirds), song has one additional, intriguing aspect: it is learned, with much of that learning occurring very early in life. Although many animals use vocal signals, in only a few (humans, songbirds, whales and dolphins, parrots and a few other species) is the vocal communication system learned. Vocal learning in songbirds has been extensively analyzed in the laboratory and has become a major model system especially for studying the neurobiology and genetics of learning. Bird song learning has received additional attention because of its many parallels with human language learning; these parallels include an early sensitive period for learning, an innate predisposition for species-typical signals, a sensory-memorization stage which begins well before vocal production, an early subsong or babbling stage, and the necessity of auditory feedback for early development but not for adult maintenance of vocal production. Yet another parallel between vocal learning in songbirds and humans has only been recognized in recent years: the importance of social factors in vocal learning. The role of social factors in bird song learning was not fully appreciated until relatively recently, primarily because the method commonly used to study bird song learning eliminates the social context in order to achieve greater experimental control of the song stimuli used for song tutoring. This ‘tape tutoring’ method isolates the bird from social contact and presents tape-recorded tutor song from a loudspeaker. This paradigm has generated most of what we know about song learning, but workers in the field became aware of the importance of social factors with the discovery that birds learned more readily from singing birds than from tape-recorded song. In fact, many of the rules of song learning derived from tape tutor studies appeared to bend, if not break, when the song tutors were actual live birds. For this reason we embarked on a program for studying song learning under natural conditions, in the field; we have supplemented this work with some laboratory studies, and also with related field studies examining how birds use song to communicate. Here we focus on the role of song learning in the bird’s life. Young song sparrows begin learning their songs as soon as they disperse from the area where they hatched (thus they do not learn songs from their father). They begin memorizing songs during the late spring and early summer months but do not sing until fall or the next spring, and do not ‘crystallize’ their final repertoire of 8 or 9 different songs until the following spring, their first breeding season. Although the young bird starts his song learning early, for the most part he only learns, or retains, songs of adults who have, like him, survived into the spring. Virtually all young birds learn the songs of their springtime neighbors, even though they may have started learning the previous summer (note: the population is non-migratory, and birds stay on their territories year around for as long as they survive). Young birds are not more likely to learn from aggressive birds (a popular theory) . Instead, a common strategy seems to be learn most of your songs from your neighbors, and about half the birds learn primarily from one special neighbor, with whom he may form a partially cooperative relationship. The song control system of the songbird brain is one of the major model systems in neurobiology, and research on this system has led to many insights into brain function in humans, especially pertaining to learning and plasticity in adulthood. Field studies of the function of bird song are necessary to complement and guide neurobiological studies of this model system. A basic understanding of the role of song in the animal’s life, and the normal process by which song is learned, form the basis for neurobiological studies that will advance our basic understanding of brain function and ultimately lead to important medical applications. Broader impacts of the research program: Several undergraduate assistants worked on this project. They learned to work in a scientific team, coordinating their activities with other members of the team. The skills they learned translate well to skills they will use in the future, regardless of the specific environment they work in. A good problem-solver who can function effectively within a group context is a valuable resource for any organization. In addition, our research site, a large public park in Seattle, provides an excellent, unique base for outreach where we interact with the public daily as we carry out our research. We also provide talks and workshops for the general public. Our research has generated considerable local interest and this past May it was described in a front-page article in the Seattle Times.
