Differences in echolocation click patterns of the beluga (D e l p h i n a p t e r u s l e u c

Abstract

In an echolocation experiment, the target detection performance of a beluga and a bottlenose dolphin were similar, but each produced different patterns of echolocation click trains. The beluga emitted three different patterns of echolocation clicks. A pattern I click train started with low-amplitude clicks, followed by packets of clicks. A packet contained several clicks with interclick intervals less than the two-way travel time to the target; the interpacket intervals were greater than the two-way travel time. A pattern II click train consisted of a combination of individual clicks, some with intervals less than and some greater than the two-way travel time. This pattern did not contain packets. The third pattern of click trains consisted of individual clicks with interclick intervals less than the two-way travel time. However, the bottlenose dolphin always emitted clicks with interclick intervals greater than the two-way travel time. These differences in click patterns suggest that the beluga has a different echolocation strategy than the bottlenose dolphin.

Biosonar adjustments to target range of echolocating bottlenose dolphins(Tursiopssp.) in the wild

“…4B, filled squares). The relationship between ICIs and TWT displays similar levels of variation to raw data from target detection experiments with trained bottlenose dolphins (Turl and Penner, 1989).…”

“…Belugas trained for target detection tasks have even been shown to exhibit a unique type of echolocation in which clicks are sent out in packets with a high click repetition rate that does not allow the echoes to return before the next click is emitted (Turl and Penner, 1989). Thus, it seems that while the odontocete auditory and neural system may be flexible enough to handle biosonar range ambiguities that may arise when ICIs are lower than the TWT (Turl and Penner, 1989), the general approach phase for toothed whales in the wild involves processing the returning echoes before a new click is emitted.…”

Amazon river dolphins (Inia geoffrensis) modify biosonar output level and directivity during prey interception in the wild

“…For species where matching of click rate to target range has been shown (Penner, 1988;Au, 1993), it could be argued as acceptable to exclude clicks having either very long ICIs compared with TWTT or negative lag times to reduce the risk of including clicks emitted when the animals did not adjust biosonar gaze to an array. However, such criteria are certainly not applicable to all species Johnson et al, 2008) and this also introduces the pitfall that clicks from atypical biosonar patterns (Turl and Penner, 1989;Ivanov, 2004) may be ignored.…”

Social behaviour of captive belugas, Delphinapterus leucas

“…For example, belugas are better than bottlenose dolphins at detecting low amplitude signal echoes even in noisy and acoustically reflective environments. This may reflect an adaptation to the Arctic environment, which is highly reverberant and noisy (Turl 1990 Ford 1977;Mansfield 1983;Finley et aL 1990). However, there is still a need for research that will facilitate effective management of this species ; this need will only increase as human demands on the marine and coastal environments continue to grow.…”

“…Gurevich and Evans 1976;Au et aL 1985;Turl et aL 1987;Turl and Penner 1989). Experimental investigations and comparisons with bottlenose dolphins suggest that the beluga's echolocation system is well-suited to functioning in the Arctic environment (Turl 1990). For example, belugas are better than bottlenose dolphins at detecting low amplitude signal echoes even in noisy and acoustically reflective environments.…”