The freshwater dolphin <i>Inia geoffrensis geoffrensis</i> produces high frequency whistles

May‐Collado, Laura J.; Wartzok, Douglas

doi:10.1121/1.2404918

Cited by 36 publications

(30 citation statements)

References 44 publications

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“…2005). Peak frequency (PeakF) was also measured and is defined as the frequency at which maximum power occurs (Bazúa‐Durán & Au 2002, 2004; May‐Collado & Wartzok 2007, 2008; 2009). The contour for each selected whistle was grouped into one of the following categories upsweep, downsweep, constant, convex, concave, or sine (see Bazúa‐Durán & Au 2002).…”

Section: Methodsmentioning

confidence: 99%

Changes in Whistle Structure of Two Dolphin Species During Interspecific Associations

May‐Collado

2010

Ethology

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Dolphin communicative signals show great plasticity. Dolphins modify signal structure to cope with their environment, in response to stress, and in some species to mimic group members. Hence, whistle structure variations may offer insights to interspecific associations among dolphin species, which although temporal and opportunistic are common. In this study, I test the hypothesis that interspecific interactions influence dolphin whistle structure, particularly during social events. The study took place in the Southern Caribbean coast of Costa Rica, where interspecific associations of the distantly related Guyana and Bottlenose dolphins occur on daily basis. The results indicate that interspecific groups emit whistles that show intermediate whistle structure compared to whistles emitted in intraspecific groups. This pattern is seen during social interactions between species, but not when interspecific groups are traveling. Social events in interspecific groups were of antagonistic nature, where Bottlenose dolphins isolated and harassed one or two Guyana dolphins. Contour data suggest that the most vocal species during these encounters was the Guyana dolphin. Therefore, the observed modifications in whistles structure likely reflect a stress response by the Guyana dolphins. Another alternative explanation includes signal convergence between interacting species. However, to understand the nature of these potential modifications, future studies should combine acoustic tags and directional recording systems to follow the vocalizing animals. Despite the shortcomings of this study, it provides some of the first insights into dolphin interspecific communication, providing evidence of overall signal change during interspecific interactions.

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Section: Methodsmentioning

confidence: 99%

Changes in Whistle Structure of Two Dolphin Species During Interspecific Associations

May‐Collado

2010

Ethology

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“…, Lagenorhynchus albirostris whistles go up to 35 kHz (Rasmussen and Miller 2001) and up to 41 kHz in Tursiops truncatus (Boisseau 2005) or even higher, e.g. , Inia geoffrensis up to 48 kHz (May‐Collado and Wartzok 2007). All tonal sounds considered for baleen whales in this study were those referred to as exclusively tonal.…”

Section: Methodsmentioning

confidence: 99%

Reexamining the Relationship Between Body Size and Tonal Signals Frequency in Whales: A Comparative Approach Using a Novel Phylogeny

May‐Collado¹,

Agnarsson

Wartzok

2007

Marine Mammal Science

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A negative relationship between cetacean body size and tonal sound minimum and maximum frequencies has been demonstrated in several studies using standard statistical approaches where species are considered independent data points. Such studies, however, fail to account for known dependencies among related species—shared similarity due to common ancestry. Here we test these hypotheses by generating the most complete species level cetacean phylogeny to date, which we then use to reconstruct the evolutionary history of body size and standard tonal sounds parameters (minimum, maximum, and center frequency). Our results show that when phylogenetic relationships are considered the correlation between body size (length or mass) and minimum frequency is corroborated with approximately 27% of the variation in tonal sound frequency being explained by body size compared to 86% to 93% explained when phylogenetic relationships are not considered. Central frequency also correlates with body size in toothed whales, but for other tonal sound frequency parameters, including maximum frequency, this hypothesized correlation disappears. Therefore, constraints imposed by body size seem to have played a role in the evolution of minimum frequency but alternative hypotheses are required to explain variation in maximum frequency.

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“…These three frequency measurements are standard in Guyana dolphin whistle studies ͑see Azevedo and Van Sluys, 2005;Erber and Simão, 2004;Rossi-Santos and Podos, 2006͒. Peak frequency ͑PF͒ was also measured and is defined as the frequency at which maximum power occurs ͑Bazúa-Durán and Au, , 2004May-Collado and Wartzok, 2007͒ and number of harmonics ͑e.g., Wang et al, 1995;Erber and Simão, 2004͒. Whistle contours were categorized as ascending, descending, ascending-descending, descending-ascending, and constant in frequency, sine, and others ͑see Azevedo and Van Sluys, 2005; Erber and Simão, 2004͒.…”

Section: B Whistle Recordings and Analysismentioning

confidence: 99%

A characterization of Guyana dolphin (Sotalia guianensis) whistles from Costa Rica: The importance of broadband recording systems

May‐Collado

Wartzok

2009

The Journal of the Acoustical Society of America

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Knowledge of the whistle structure in Guyana dolphins comes mostly from Brazilian populations where recordings have been made using limited bandwidth systems (18 and 24 kHz). In Brazil, Guyana dolphin whistle frequency span is 1.34-23.89 kHz, but authors have suggested that limits of their recording system may underestimate frequency span. Whistles of Guyana dolphins from Costa Rica were studied using a broadband recording system. How bandwidth limitations affect the understanding of whistle structure and species classification between sympatric dolphin species was evaluated. In addition, whistles were compared to Brazilian populations. Guyana dolphin whistle frequency span was 1.38 up to 48.40 kHz, greater than previously reported. Bandwidth limitations explained 89% of the whistle variation between studies, and increase in bandwidth improved the whistle classification of Guyana dolphins. Whistle duration and minimum frequency were the most important variables in dolphin species classification. Finally, after accounting for differences in recording systems, Costa Rican Guyana dolphins whistled with significantly higher frequency than Brazilian populations, providing evidence for a postulated increase in frequency from south to north. The study concludes that equipment with an upper frequency limit of at least 50 kHz (150 kHz for harmonics) is required to capture the entire whistle repertoire of the Guyana dolphin.

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The freshwater dolphin Inia geoffrensis geoffrensis produces high frequency whistles

Cited by 36 publications

References 44 publications

Changes in Whistle Structure of Two Dolphin Species During Interspecific Associations

Changes in Whistle Structure of Two Dolphin Species During Interspecific Associations

Reexamining the Relationship Between Body Size and Tonal Signals Frequency in Whales: A Comparative Approach Using a Novel Phylogeny

A characterization of Guyana dolphin (Sotalia guianensis) whistles from Costa Rica: The importance of broadband recording systems

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