Airborne and Underwater Vocalizations of the Antarctic Ross Seal (Ommatophoca Rossii)

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Stacey, Rita M.
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Western Illinois University
The Antarctic Ross seal (Ommatophoca rossii) is the least known of all the pinnipeds primarily due to the harsh environment they inhabit. On only three occasions have researchers been able to make recordings of sounds from this species. Audiocassette tapes were analyzed from three different collectors spanning 34 years: 1) in 1999/2000 Ian Stirling recorded aerial and underwater vocalizations in the Ross Sea, 2) in 1997 Tracy Rogers recorded underwater vocalizations off the back of a ship near Davis Station in the Davis Sea, and 3) in 1966 Carleton Ray recorded in both mediums in Robertson Bay near Cape Ad are and South Coulman Island in the Ross Sea. The objectives of this study on the recordings of Ross seal sounds were to: 1) classify airborne and underwater vocalizations, 2) identify frequency and time characteristics for each vocalization, 3) examine differences in vocalization characteristics by month/year, 4) examine differences in vocalization characteristics by location, and 5) examine differences in vocalization characteristics by sex of the seal. The Ross seals' vocal repertoire consists of 12 calls (6 aerial and 6 underwater). Three of the six underwater calls showed geographic variation, one underwater call showed differences over thirty years, and one aerial call varied by gender of the seal. The number of vocalizations in Antarctic seals varies with the mating system. The Ross seal has an intermediate number of sounds compared to other Antarctic species. More investigations are needed to understand the acoustic behavior and lifestyle of the elusive Ross seal.