Measuring sperm whales from their clicks: stability of interpulse intervals and validation that they indicate whale length.

摘要: Multiple pulses can often be distinguished in the clicks of sperm whales (Physeter macrocephalus). Norris and Harvey [in Animal Orientation Navigation, NASA SP-262 (1972), pp. 397–417] proposed that this results from reflections within head, thus interpulse interval (IPI) is an indicator head length, by extrapolation, total length. For idea to hold, IPIs must stable individuals, but differ systematically among individuals different size. IPI stability was examined photographically identified recorded repeatedly over dives, days, years. variation dives a single day days year statistically significant, although small magnitude (it would change length estimates <3%). As expected, varied significantly individuals. Most showed significant increases several years, suggesting growth. Mean lengths calculated published regressions were 13.1 16.1 m, longer than photogrammetric same (12.3 15.3 m). These discrepancies probably arise paucity large (12–16 m) data used regressions. A new regression offered for size range.