Retamosa was in the midst of replacing the batteries in a tape recorder when she heard the call of a bellbird for the very first time. Standing amidst the forest canopy, she gazed upward, trying to locate the source of its striking metallic and powerful sound, searching for the bird for half an hour without success. The bellbird sings from high in the treetops, visible to its peers but hidden from those on the ground. Nonetheless, Retamosa beamed with joy: she nurtures ecosystems in Costa Rica’s AmistOsa Biological Corridor, connecting with them through her careful listening.
In the natural world, living organisms depend on sound for virtually everything. They produce calls to attract mates, communicate their identities, issue warnings, navigate, and assist in both hunting and defense. For decades, researchers have been tracking species while holding recorders, and continue to do so, though they increasingly employ remote recording technology. The analysis of the sounds produced by organisms is termed bioacoustics. Retamosa has been engaged in this field for a decade.
Through the use of bioacoustic recordings, studies have revealed that certain birds amplify their calls to be heard in urban environments, while sea turtle hatchlings communicate from their nests to time their hatching. Furthermore, when bioacoustics is combined with other sound elements—those produced by humans as well as the natural sounds of the environment, like the crashing of ocean waves—it enables a deeper ecological interpretation. This broader sound analysis is referred to as ecoacoustics, and it represents the very work taking place in Costa Rica.
