Dolphin echolocation behaviour during active long-range target approaches

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

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Dolphin echolocation behaviour during active long-range target approaches. / Ladegaard, Michael; Mulsow, Jason; Houser, Dorian S; Jensen, Frants Havmand; Johnson, Mark; Madsen, Peter Teglberg; Finneran, James J.

In: The Journal of Experimental Biology, Vol. 222, No. 2, 189217 , 25.01.2019.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

Harvard

Ladegaard, M, Mulsow, J, Houser, DS, Jensen, FH, Johnson, M, Madsen, PT & Finneran, JJ 2019, 'Dolphin echolocation behaviour during active long-range target approaches', The Journal of Experimental Biology, vol. 222, no. 2, 189217 . https://doi.org/10.1242/jeb.189217

APA

Ladegaard, M., Mulsow, J., Houser, D. S., Jensen, F. H., Johnson, M., Madsen, P. T., & Finneran, J. J. (2019). Dolphin echolocation behaviour during active long-range target approaches. The Journal of Experimental Biology, 222(2), [189217 ]. https://doi.org/10.1242/jeb.189217

CBE

Ladegaard M, Mulsow J, Houser DS, Jensen FH, Johnson M, Madsen PT, Finneran JJ. 2019. Dolphin echolocation behaviour during active long-range target approaches. The Journal of Experimental Biology. 222(2). https://doi.org/10.1242/jeb.189217

MLA

Vancouver

Ladegaard M, Mulsow J, Houser DS, Jensen FH, Johnson M, Madsen PT et al. Dolphin echolocation behaviour during active long-range target approaches. The Journal of Experimental Biology. 2019 Jan 25;222(2). 189217 . https://doi.org/10.1242/jeb.189217

Author

Ladegaard, Michael ; Mulsow, Jason ; Houser, Dorian S ; Jensen, Frants Havmand ; Johnson, Mark ; Madsen, Peter Teglberg ; Finneran, James J. / Dolphin echolocation behaviour during active long-range target approaches. In: The Journal of Experimental Biology. 2019 ; Vol. 222, No. 2.

Bibtex

@article{1b861842bd784f19a9a228238216a820,
title = "Dolphin echolocation behaviour during active long-range target approaches",
abstract = "Echolocating toothed whales generally adjust click intensity and rate according to target range to ensure that echoes from targets of interest arrive before a subsequent click is produced, presumably facilitating range estimation from the delay between clicks and returning echoes. However, this click-echo-click paradigm for the dolphin biosonar is mostly based on experiments with stationary animals echolocating fixed targets at ranges below ∼120 m. Therefore, we trained two bottlenose dolphins instrumented with a sound recording tag to approach a target from ranges up to 400 m and either touch the target (subject TRO) or detect a target orientation change (subject SAY). We show that free-swimming dolphins dynamically increase interclick interval (ICI) out to target ranges of ∼100 m. TRO consistently kept ICIs above the two-way travel time (TWTT) for target ranges shorter than ∼100 m, whereas SAY switched between clicking at ICIs above and below the TWTT for target ranges down to ∼25 m. Source levels changed on average by 17log10(target range), but with considerable variation for individual slopes (4.1 standard deviations for by-trial random effects), demonstrating that dolphins do not adopt a fixed automatic gain control matched to target range. At target ranges exceeding ∼100 m, both dolphins frequently switched to click packet production in which interpacket intervals exceeded the TWTT, but ICIs were shorter than the TWTT. We conclude that the click-echo-click paradigm is not a fixed echolocation strategy in dolphins, and we demonstrate the first use of click packets for free-swimming dolphins when solving an echolocation task.",
keywords = "biosonar, click packet, Dtag, interclick interval, source level, toothed whale",
author = "Michael Ladegaard and Jason Mulsow and Houser, {Dorian S} and Jensen, {Frants Havmand} and Mark Johnson and Madsen, {Peter Teglberg} and Finneran, {James J}",
note = "{\circledC} 2019. Published by The Company of Biologists Ltd.",
year = "2019",
month = "1",
day = "25",
doi = "10.1242/jeb.189217",
language = "English",
volume = "222",
journal = "BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY",
issn = "0022-0949",
publisher = "The/Company of Biologists Ltd.",
number = "2",

}

RIS

TY - JOUR

T1 - Dolphin echolocation behaviour during active long-range target approaches

AU - Ladegaard, Michael

AU - Mulsow, Jason

AU - Houser, Dorian S

AU - Jensen, Frants Havmand

AU - Johnson, Mark

AU - Madsen, Peter Teglberg

AU - Finneran, James J

N1 - © 2019. Published by The Company of Biologists Ltd.

PY - 2019/1/25

Y1 - 2019/1/25

N2 - Echolocating toothed whales generally adjust click intensity and rate according to target range to ensure that echoes from targets of interest arrive before a subsequent click is produced, presumably facilitating range estimation from the delay between clicks and returning echoes. However, this click-echo-click paradigm for the dolphin biosonar is mostly based on experiments with stationary animals echolocating fixed targets at ranges below ∼120 m. Therefore, we trained two bottlenose dolphins instrumented with a sound recording tag to approach a target from ranges up to 400 m and either touch the target (subject TRO) or detect a target orientation change (subject SAY). We show that free-swimming dolphins dynamically increase interclick interval (ICI) out to target ranges of ∼100 m. TRO consistently kept ICIs above the two-way travel time (TWTT) for target ranges shorter than ∼100 m, whereas SAY switched between clicking at ICIs above and below the TWTT for target ranges down to ∼25 m. Source levels changed on average by 17log10(target range), but with considerable variation for individual slopes (4.1 standard deviations for by-trial random effects), demonstrating that dolphins do not adopt a fixed automatic gain control matched to target range. At target ranges exceeding ∼100 m, both dolphins frequently switched to click packet production in which interpacket intervals exceeded the TWTT, but ICIs were shorter than the TWTT. We conclude that the click-echo-click paradigm is not a fixed echolocation strategy in dolphins, and we demonstrate the first use of click packets for free-swimming dolphins when solving an echolocation task.

AB - Echolocating toothed whales generally adjust click intensity and rate according to target range to ensure that echoes from targets of interest arrive before a subsequent click is produced, presumably facilitating range estimation from the delay between clicks and returning echoes. However, this click-echo-click paradigm for the dolphin biosonar is mostly based on experiments with stationary animals echolocating fixed targets at ranges below ∼120 m. Therefore, we trained two bottlenose dolphins instrumented with a sound recording tag to approach a target from ranges up to 400 m and either touch the target (subject TRO) or detect a target orientation change (subject SAY). We show that free-swimming dolphins dynamically increase interclick interval (ICI) out to target ranges of ∼100 m. TRO consistently kept ICIs above the two-way travel time (TWTT) for target ranges shorter than ∼100 m, whereas SAY switched between clicking at ICIs above and below the TWTT for target ranges down to ∼25 m. Source levels changed on average by 17log10(target range), but with considerable variation for individual slopes (4.1 standard deviations for by-trial random effects), demonstrating that dolphins do not adopt a fixed automatic gain control matched to target range. At target ranges exceeding ∼100 m, both dolphins frequently switched to click packet production in which interpacket intervals exceeded the TWTT, but ICIs were shorter than the TWTT. We conclude that the click-echo-click paradigm is not a fixed echolocation strategy in dolphins, and we demonstrate the first use of click packets for free-swimming dolphins when solving an echolocation task.

KW - biosonar

KW - click packet

KW - Dtag

KW - interclick interval

KW - source level

KW - toothed whale

U2 - 10.1242/jeb.189217

DO - 10.1242/jeb.189217

M3 - Journal article

C2 - 30478155

VL - 222

JO - BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY

JF - BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY

SN - 0022-0949

IS - 2

M1 - 189217

ER -