title: Your attention please: increasing ambient noise levels elicits a change in communication behaviour in humpback whales (Megaptera novaeangliae).
abstract: High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background noise. Humpback whale communication signals comprise two different types: vocal signals, and surface-generated signals such as 'breaching' or 'pectoral slapping'. We found that humpback whales gradually switched from primarily vocal to primarily surface-generated communication in increasing wind speeds and background noise levels, though kept both signal types in their repertoire. Vocal signals have the advantage of having higher information content but may have the disadvantage of loosing this information in a noisy environment. Surface-generated sounds have energy distributed over a greater frequency range and may be less likely to become confused in periods of high wind-generated noise but have less information content when compared with vocal sounds. Therefore, surface-generated sounds may improve detection or enhance the perception of vocal signals in a noisy environment.
authors.affiliation: School of Veterinary Science, University of Queensland, Gatton, Queensland 4343, Australia. r.dunlop@uq.edu.au
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Dunlop
authors.forename: Douglas H
authors.initials: DH
authors.lastname: Cato
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Noad
mesh_terms: D000162:Acoustics; D000819:Animal Communication; D000818:Animals; D050640:Humpback Whale / Q000502:physiology*; D009622:Noise; D012919:Social Behavior; D014919:Wind
references.citation: Proc Natl Acad Sci U S A. 2009 Oct 20;106(42):18010-5
references.pmid: 19805199
references.citation: Anim Behav. 1999 Jun;57(6):1175-1183
references.pmid: 10373249
references.citation: J Acoust Soc Am. 2007 Dec;122(6):3725-31
references.pmid: 18247780
references.citation: Proc Biol Sci. 2007 Apr 22;274(1613):1057-62
references.pmid: 17264059
references.citation: Trends Ecol Evol. 1986 Dec;1(6):144-50
references.pmid: 21227802
references.citation: J Acoust Soc Am. 1986 Sep;80(3):735-40
references.pmid: 3760326
references.citation: J Exp Biol. 2004 Jan;207(Pt 3):443-8
references.pmid: 14691092
references.citation: Nature. 2006 Mar 16;440(7082):333-6
references.pmid: 16541072
references.citation: Science. 1971 Aug 13;173(3997):585-97
references.pmid: 17833100
references.citation: J Acoust Soc Am. 2007 Nov;122(5):2893-905
references.pmid: 18189579
references.citation: J Acoust Soc Am. 2009 Jan;125(1):EL27-32
references.pmid: 19173379
references.citation: J Acoust Soc Am. 2000 Sep;108(3 Pt 1):1197-208
references.pmid: 11008820
references.citation: J Acoust Soc Am. 2008 Mar;123(3):1747-52
references.pmid: 18345862
references.citation: Anim Behav. 1998 Jul;56(1):107-13
references.pmid: 9710467
references.citation: J Exp Biol. 2008 Oct;211(Pt 19):3174-80
references.pmid: 18805817