Professor Emeritus Peter Marler, researcher of songbird learning, dies

by WYNNE PARRY

Professor Emeritus Peter Robert Marler, whose work in songbird learning established a foundation for understanding how animals communicate, died July 5 at the age of 86 in Winters, California. Dr. Marler joined Rockefeller’s faculty in 1966 and helped establish the Millbrook Field Research Center about 80 miles north of Manhattan, serving as its founding director from 1972 to 1981.

Born in England, Dr. Marler received his first doctorate in botany from University College, London. But since childhood, birds had always had his attention. In his spare time, while conducting vegetation surveys, he noted the song of common birds known as chaffinches varied geographically, like dialects of a language. Dr. Marler earned a second doctorate, this one in zoology, at Cambridge University under William Thorpe, whose own work established that young birds must learn their species’ songs by listening to adults during a critical period of their development.

In 1957, Dr. Marler joined the faculty at the University of California, Berkeley, and in 1966 he moved to Rockefeller, which had launched a new program in behavioral research. He remained at Rockefeller until 1989 when he went back west to the University of California, Davis. He retired in 1994, and since has held the emeritus rank at both Rockefeller and UC-Davis.

Building upon Dr. Thorpe’s work, Dr. Marler found that young birds learn song dialects; and that when they are ready to learn, young birds prefer the song from their own species. This observation and others lead him to develop the concept of an innate program with its own built-in guidelines, which he referred to as an “instinct to learn,” an alternative to learning by trial-and-error that he proposed applied to human speech as well. Dr. Marler also examined the progression of song learning, beginning with babble-like subsong and then plastic song. In this phase, he found, birds often acquire a greater diversity of sounds than they later produce as adults.

Dr. Marler’s work also looked at content, and helped to establish that animal calls could encode specific meanings. After one of his students observed that African monkeys known as vervets had specific alarm calls for snakes, eagles and leopards, Dr. Marler and his colleagues followed up by playing back recorded calls to free-ranging vervets and observing how the monkeys responded. The vervets’ responses were appropriate to the inferred nature of the threat: They looked intently at the ground around them when the snake alarm was played back, scrutinized the sky when they heard the eagle call, and climbed to the tree tops when hearing the leopard alarm call.

While Dr. Marler’s primary expertise was birdsong, he encouraged his students to follow their interests wherever they led. “While I was his student at Berkeley, a woman in his lab was studying the motor behavior of tarantulas, how they integrated those eight legs, and another young lady was interested in the wing vibrations and sounds of courting flies,” says Fernando Nottebohm, Dorothea L. Leonhardt Professor and head of the Laboratory of Animal Behavior. All these projects got Marler’s enthusiastic support. He believed in allowing full independence to his students. Dr. Marler later invited Dr. Nottebohm to join him at Rockefeller.

“What characterized his science was a very systematic approach that took into account the physical nature of the signal, how the signal travelled and was detected, its context, who produced it and what kind of response it elicited. By bringing all of those together, you could make a catalog as well as broad theories of how animals communicated,” Dr. Nottebohm says. “In this way, Peter organized the field for people who later pursued issues of animal communication at other levels of analysis, such as neurophysiology, anatomy, cell and molecular biology. When I became interested in the neurobiology of bird song, he had already set up the behavioral frame in such a way to make the central questions clear.”

Dr. Marler’s honors included membership in the Royal Society of London and the National Academy of Sciences.