Peter Marler was an outstanding leader in the study of animal communication. He was born in Slough, England, on 14 February 1928. As a child he enjoyed the songs of birds and first kept a pet bird, a Rook Corvus frugilegus, at the age of eight. The study of bird song was to become his major interest. Peter graduated from University College, London, with a BSc degree in 1948. Doubtful that his interest in birds would lead to employment, he studied plant ecology at University College, obtaining his PhD in 1952. His first job was with the newly created Nature Conservancy surveying natural areas in the Scottish Highlands. He used the opportunity to increase his large collection of song patterns of the Chaffinch Fringilla coelebs and discovered that they changed from valley to valley, resulting in local dialects. Peter thought these dialects must be learned from neighbours, a novel idea at the time. When offered a position as assistant to William Thorpe at the University of Cambridge, he was unable to resist and gave up his tenured position to follow his passion for birds. It was an opportune time to be there. Thorpe and his associate Robert Hinde had recently established an ornithological field station at Madingley, with aviaries housing a variety of finches. Thorpe was studying the development of song in the Chaffinch. Peter soon became his first graduate student in ornithology, electing to concentrate on the vocal behaviour of the Chaffinch in the field. He obtained his second PhD in 1955. This was an exciting time in the early stages of the newly minted study of animal behaviour known as ethology, led by Konrad Lorenz, Niko Tinbergen and William Thorpe. Tinbergen was Peter's external examiner. While at Cambridge Peter had access to the extensive BBC collection of bird song recordings and Thorpe's newly arrived audio-spectrograph that made possible graphic analysis of recorded sounds. Fifty years later he wrote ‘I was in heaven’. The spectrograph and portable tape recorder became his main tools in the study of bird song. He took advantage of these new opportunities to point out convergences in the structure and function of vocalizations of several species, ranging from easily located songs and mobbing calls to cryptic alarm signals. This led to one of his most widely cited publications (1957 Behaviour 11:13–39). In 1957 he took up his first faculty position at Berkeley, California, and spent the rest of his long career in the United States. He brought with him the focus on structure and function of behaviour that characterized European ethology. Just as he had been in awe of the erudition of Thorpe and Hinde Peter impressed those who met him in America. One of his early students, and later a distinguished colleague, Fernando Nottebohm wrote ‘he was in a straight line of descent from Darwin, and his blend of field biologist (naturalist), experimentalist and deep thinker will always be rare’. For his new research Peter chose the White-crowned Sparrow Zonotrichia leucophrys which, like the Chaffinch, showed regional song dialects. He began his life's work studying the development of song in captive birds brought into his lab at an early age. Thorpe had started such research but Peter and his students took it to new levels. The basic pattern they discovered began with the memorization of the songs of adult birds to which young were exposed during a sensitive period, followed somewhat later by production of song. Song production occurred in three stages: subsong (unstructured vocalizations), plastic song (many variable song patterns) and crystallized song (a limited repertoire of stereotyped songs influenced by the social context in which the bird found itself). It was clear from the beginning that conspecific songs were more readily incorporated into the repertoire than were those of other species. Experiments with isolated or deafened birds showed the extent to which normal songs developed without exposure to adult songs, and the need for a bird to hear itself sing in order to produce a normal song. This model revolutionized our understanding of how birds acquire their songs. In 1980 Peter moved to Rockefeller University and became Director of the newly established field station at Millbrook, New York. He continued his research on song development in more detail. Comparative studies showed that the timing of different stages, and the features of song that were readily learned, varied even among closely related species. It was becoming clearer to what extent inheritance or learning determined the final outcome; bird song proved to be good material to resolve questions of ‘nature versus nurture’. Peter felt that it was inappropriate to treat behaviours as one or the other, since both were involved. He developed the concept of a ‘species-specific instinct to learn’. Peter hoped to link animal communication and human language. He undertook a variety of studies of primate vocalizations, beginning with a sabbatical in Uganda in 1964. Armed with a tape recorder, he compiled call repertoires of several forest monkeys and noted parallels among species in their form and function. Later with primatologist Jane Goodall in Tanzania he recorded and analysed the vocal repertoire of the chimpanzee for the first time. He found sufficient variation in calls to allow for individual recognition. Observation of vervet monkeys by his student Tom Strusaker revealed distinct calls warning of different predators such as a leopard, an eagle or a snake. At Peter's suggestion, recordings of these calls were played in the wild by post-docs Dorothy Cheney and Robert Seyfarth and the vervet troops reacted appropriately to each signal. Peter concluded from all his studies that while mammals and birds produced both general (affective) signals and, as in the vervet monkeys, specific (symbolic) signals, they fell far short of the complexity and inventiveness of human language. Nevertheless, he found parallels between the developmental stages of bird song and human speech. Peter was much sought after and a willing participant in conferences and books bringing together researchers in different fields of behaviour. In each case he brought his carefully reasoned arguments based on his own observations and broad knowledge of the relevant literature. He was never dogmatic but presented his views in a tentative manner that encouraged others to interact. His nomination to the Royal Society refers to ‘his far-reaching impact on studies of development in behaviour, linguistics, and psychology’. In 1989 he moved to the Davis campus of the University of California as professor of Neurobiology, Physiology and Behavior. As a colleague remarked ‘he was a giant in the whole field of communication’. He taught courses in Animal Behaviour and Ornithology and helped establish the Center for Neurosciences. He retired in 1994 as Professor Emeritus and continued to publish articles and books. One of his last major publications, edited with Hans Slabbekoorn, drew together invited chapters representing recent research into a book entitled Nature's Music: the Science of Bird Song (Elsevier Academic Press 2004). In his opening chapter ‘The Good Old Days’ Peter recalled much of his own career and expressed the hope that new research would finally lay to rest the false dichotomy between nature and nurture. Peter was kind, helpful and stimulating to both his students and his colleagues. When we visited Millbrook in the 1980s, my wife and I found a lively group that worked and played together enthusiastically. Peter was devoted to his wife Judith and their family. She in turn ran nurseries for young birds and described herself as ‘den mother’ to his students. The dedication to him of two volumes entitled Acoustic Communication in Birds edited by Donald Kroodsma and Edward Miller (Academic Press 1982) reads in part, ‘Peter has touched many workers individually, as graduate students, post-doctoral researchers and peers, whereby his influence upon research and thinking on animal communication has carried yet further’. Among members of his ‘work group’ in addition to those mentioned earlier were: Mark Konishi, Susan Peters, Don Kroodsma, Bill Searcy, Steve Nowicki, Ken Yasukawa, John Wingfield and Douglas Nelson. Peter Marler received many awards, notably a Guggenheim Fellowship in 1964, membership in the National Academy of Sciences in 1971 and Foreign Member of the Royal Society in 2008. He suffered a stroke in 2008 and died of pneumonia at age 86 on 10 July 2014. He is survived by his wife Judith, son Christopher, and daughters Catherine and Marianne. Peter Marler's papers are held at The Special Collections Department, University Library, University of California, Davis.