Target Detection, Shape Discrimination, and Signal Characteristics of an Echolocationg False Killer Whale (Pseudorca crassidens)
Abstract
This study demonstrated the ability of a false killer whale (Pseudorca crassidens) to discriminate between two targets and investigated the parameters of the whale's emitted signals for changes related to test conditions. Target detection performance comparable to the bottlenose dolphin's (Tursiops truncatus) has previously been reported for echolocating false killer whales. No other echolocation capabilities have been reported. A false killer whale, naive to conditioned echolocation tasks, was initially trained to detect a cylinder in a go/no go procedure over ranges of 3 to 8 m. The transition from a detection task was readily achieved by introducing a spherical comparison tar- get. Finally, the cylinder was successfully compared to spheres of two different sizes and target strengths. Multivariate analyses were used to evaluate the parameters of emitted signals. Duncan's multiple range tests showed significant decreases (df = 185, p much much more 0.05) in both source level and bandwidth in the transition from detection to discrimination. Analysis of variance revealed a significant decrease in the number of clicks over test conditions F(5,26) = 5.23, p < 0.0001). These data suggest that the whale relied on cues relevant to target shape as well as target strength, that changes in source level and bandwidth were task-related, that the decrease in clicks was associated with learning experience, and that Pseudorca's ability to discriminate shapes using echolocation may be comparable to that of Tursiops truncatus.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1992
- Accession Number
- ADA262931
Entities
People
- D. A. Helweg
- J. L. Pawloski
- P. W. Moore
- R. L. Brill
- W. W. Au
Organizations
- Naval Command, Control and Ocean Surveillance Center