Comparison of managed care and wild walrus source characteristics

Abstract

Male Pacific walruses perform acoustic displays while in rut. The purpose of these displays is unknown but are hypothesized to be for territory defense or mate advertisement. Understanding source characteristics will allow the estimation of perceptibility by conspecifics. The displays occur in the Bering Sea in late winter where direct human observation is difficult. Working with an animal in managed care provided the ability to make direct observations of a male producing breeding vocalizations and the direct calculation of source level. Source characteristics from recordings of managed care and wild walruses were analyzed. The mean peak source level of the impulsive knocks produced by the managed care male was 183 dB (re: 1 μPa). The mean peak source level from the wild recordings was 177 dB (re: 1 μPa). For both wild and managed care vocalizations, a significant relationship between ambient noise level and source level was identified. An increase of approximately 5 dB in source level was found for an i...