The conventional wisdom among animal scientists in the 1950s was that birds were genetically programmed to sing, that monkeys made noise to vent their emotions, and that animal communication, in general, was less like human conversation than like a bodily function.

Then Peter Marler, a British-born animal behaviorist, showed that certain songbirds not only learned their songs, but also learned to sing in a dialect peculiar to the region in which they were born. And that a vervet monkey made one noise to warn its troop of an approaching leopard, another to report the sighting of an eagle, and a third to alert the group to a python on the forest floor.

These and other discoveries by Dr. Marler, who died July 5 in Winters, Calif., at 86, heralded a sea change in the study of animal intelligence. At a time when animal behavior was seen as a set of instinctive, almost robotic responses to environmental stimuli, he was one of the first scientists to embrace the possibility that some animals, like humans, were capable of learning and transmitting their knowledge to other members of their species. His hypothesis attracted a legion of new researchers in ethology, as animal behavior research is also known, and continues to influence thinking about cognition.

Dr. Marler, who made his most enduring contributions in the field of birdsong, wrote more than a hundred papers during a long career that began at Cambridge University, where he received his Ph.D. in zoology in 1954 (the second of his two Ph.D.s.), and that took him around the world conducting field research while teaching at a succession of American universities.

Dr. Marler taught at the University of California, Berkeley, from 1957 to 1966; at Rockefeller University in New York from 1966 to 1989; and at the University of California, Davis, where he led animal behavior research, from 1989 to 1994. He was an emeritus professor there at his death.

Two technological breakthroughs were central to his field research — the portable tape recorder and the sonic spectrograph, a device developed in World War II for recording and graphing the signature sounds of enemy ships’ propellers.

Using both, Dr. Marler was one of the first ethologists to produce graphic snapshots of birdsong — streaks of ink on paper, like an electrocardiogram, showing the wave-frequency, modulation and pitch of various calls and songs.

From that data, Dr. Marler and his colleagues discovered that some species had repertoires of only a few songs while others had as many as 100. They found they could analyze and differentiate calls within the same species — calls for roosting, seeking food, mating, territory-marking, warning of danger and summoning help, known as mobbing, to ward off an intruder. (...)