More than 10 hours of chimp calls have just been cataloged, digitized and made available online, according to a paper in the latest issue of the journal Scientific Data.
The sound files, now stored in the Macaulay Library at Cornell University, come from the largest data set of audio recordings of free-living, young chimps. Frans Plooij of the International Research-institute on Infant Studies, who authored the new paper, and the late Hetty van de Rijt-Plooij made the recordings when they were at Gombe National Park, Tanzania, from 1971 to 1973.
The audio files feature the "grunts," "hoocalls," "barks," "squeals," and other vocalizations of 17 young chimps. The recordings have not yet been analyzed for their meaning, so the most extensive attempt to understand chimpanzee calls remains unfinished. The researchers did, however, rate the calls from one to five stars, with five given to the highest quality recordings. The files selected for this list all received five stars.
Here, a dominant male chimp works himself up into a vocal frenzy, becoming ever louder and punctuating his vocalizations by banging on a rock.