Began working on bat social behavior and communication in Trinidad in 1965, and spent 18 months on projects in Trinidad 1968-9. Worked largely on emballonurids in Costa Rica 1972-1974. In summers of 1969-1972, 1974, and 1977, worked out of Makokou and later the Ipassa Field station in Gabon studying Hypsignathus monstrosus and Epomops franqueti lek behavior. In 1980's jointly worked on lek mating in sage grouse in California, to compare with findings on bats, and both emballonurid and phyllostomatid social behavior in Trinidad and Costa Rica. In 1990's worked on spatial dispersion in Kenya antelope and began a decade of studies on wild parrot vocal behavior. Am co-author with Sandra Vehrencamp of two editions of a textbook, Principles of Animal Communication. Was a faculty member at University of California, San Diego 1975-1998, and then professor and Director of the Macaulay Library at the Cornell University Lab of Ornithology, 1999-2009. Am currently retired.