To whistle or not to whistle? Geographic variation in the whistling behavior of small odontocetes

TitleTo whistle or not to whistle? Geographic variation in the whistling behavior of small odontocetes
Publication TypeJournal Article
Year of Publication2008
AuthorsOswald, Julie N., Rankin Shannon, and Barlow Jay
JournalAquatic Mammals
Volume34
Pagination288-302
ISBN Number0167-5427
EndNote Rec Number12264
Abstract


Whistles are used by odontocetes to varying degrees. During a visual and acoustic survey of dolphin abundance in the eastern tropical Pacific Ocean (ETP), whistles were heard from 66% of single species schools and from 98% of mixed species schools. In contrast, whistles were heard from only 24% of single species schools and 23% of mixed species schools during a survey of tem- perate waters off the western United States. The most common species encountered in the ETP were Stenella coeruleoalba, S. attenuata, and Tursiops truncatus, all of which whistled fre- quently. The most common species encountered in the temperate study area were Delphinus delphis, Phocoenoides dalli, Lissodelphis borealis, and Phocoena phocoena, only one of which whistled (D. delphis). Why do small odontocete species living in the ETP whistle more frequently than those living in colder waters farther north? Six hypotheses are explored: (1) predator avoidance, (2) group size, (3) school composition, (4) behav- ior state, (5) temporal variation, and (6) anatomi- cal differences. Multivariate logistic regression with whistling as the dependent variable and group size, school composition, time of day, pres- ence of a beak, and study area as independent variables showed that all variables were signifi- cant (p