title: Echolocation parameters of Australian humpback dolphins (Sousa sahulensis) and Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the wild.
abstract: Echolocation is a key sensory modality for toothed whale orientation, navigation, and foraging. However, a more comparative understanding of the biosonar properties of toothed whales is necessary to understand behavioral and evolutionary adaptions. To address this, two free-ranging sympatric delphinid species, Australian humpback dolphins (Sousa sahulensis) and Indo-Pacific bottlenose dolphins (Tursiops aduncus), were studied. Biosonar clicks from both species were recorded within the same stretch of coastal habitat in Exmouth Gulf, Western Australia, using a vertical seven element hydrophone array. S. sahulensis used biosonar clicks with a mean source level of 199 ± 3 dB re 1 μPa peak-peak (pp), mean centroid frequency of 106 ± 11 kHz, and emitted at interclick intervals (ICIs) of 79 ± 33 ms. These parameters were similar to click parameters of sympatric T. aduncus, characterized by mean source levels of 204 ± 4 dB re 1 μPa pp, centroid frequency of 112 ± 9 kHz, and ICIs of 73 ± 29 ms. These properties are comparable to those of other similar sized delphinids and suggest that biosonar parameters are independent of sympatric delphinids and possibly driven by body size. The dynamic biosonar behavior of these delphinids may have, consequently, allowed for adaptations to local environments through high levels of control over sonar beam properties.
authors.affiliation: Zoophysiology, Department of Bioscience, Aarhus University, Building 1131, C.F. Moellers Alle 3, DK-8000 Aarhus C, Denmark.
authors.forename: Mafalda
authors.initials: M
authors.lastname: de Freitas
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Frants H
authors.initials: FH
authors.lastname: Jensen
authors.affiliation: Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia.
authors.forename: Julian
authors.initials: J
authors.lastname: Tyne
authors.affiliation: Murdoch University Cetacean Research Unit, School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia.
authors.forename: Lars
authors.initials: L
authors.lastname: Bejder
authors.affiliation: Zoophysiology, Department of Bioscience, Aarhus University, Building 1131, C.F. Moellers Alle 3, DK-8000 Aarhus C, Denmark.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Madsen
mesh_terms: D000162:Acoustics; D000818:Animals; D000835:Animals, Wild; D049628:Body Size; D050681:Bottle-Nosed Dolphin / Q000145:classification / Q000502:physiology / Q000523:psychology*; D004289:Dolphins / Q000145:classification / Q000502:physiology / Q000523:psychology*; D004455:Echolocation / Q000145:classification; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013045:Species Specificity; D013997:Time Factors; D014828:Vocalization, Animal / Q000145:classification