Songlike vocalizations and infrasound from the Sumatran rhinoceros

Abstract

Within the last ten years the Sumatran rhino (Dicermoceros sumatrensis) population has dropped 50%, and only 200–300 individuals are left in the world. The oldest living species of rhino in evolutionary terms, Sumatran rhinos are solitary, although males and females are seen together during courtship. Their native habitat is dense tropical forest and mountain moss forest. They are the smallest living rhino, standing 0.09–1.5 m tall, and are covered in course, reddish-brown hair. Three Sumatran rhinos, housed at the Cincinnati Zoo, were recorded from 1–3 m. Two Statham Radio microphones, and two Sony TCD-D8 DAT recorders recorded from 9 Hz to 22 KHz. Analysis, including FFTs, spectrographs, and filtering, were performed using National Instrument’s Polynesia. The rhinos proved to be extremely vocal, producing signals almost constantly. Distinct calls, including several types of ‘‘eeps,’’ 70 Hz–4 kHz (57–92 dB); ‘‘whales,’’ 100 Hz–3.2 kHz (87 dB); and ‘‘whistle-blows,’’ 17 Hz–8 kHz (100 dB) were discovered. The ‘‘whistle-blow’’ has high dB infrasound that would be advantageous for use in the rhino’s forest habitat. Some Sumatran rhino vocalizations sound similar to and resemble (under analysis) some humpback whale signals.