Day and night sounds of the Guiana dolphin, Sotalia guianensis (Cetacea: Delphinidae) in southeastern Brazil

Deconto, Lucimary S.; Monteiro‐Filho, Emygdio L. A.

doi:10.1007/s10211-015-0223-y

Cited by 15 publications

(10 citation statements)

References 27 publications

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“…These may have important implications in understanding dolphin habitat-use, however, hours or seasons with lower detection rates may simply indicate reduced movement into the study area, fewer individuals, or transitory occupancy potentially determined by changes in foraging opportunities [54]. Diel patterns are reported in several studies, which revealed that dolphin acoustic activity generally decreases during daytime [26,32,55] and is greater during nighttime, when possibly foraging [29,[56][57][58]. However, whistle detection rate outcomes from around the world are heterogeneous, showing in some areas an absence of temporal trends, while elsewhere a general decrease during daytime [26,32,57].…”

Section: Discussionmentioning

confidence: 99%

Acoustic Presence of Dolphins through Whistles Detection in Mediterranean Shallow Waters

Gregorietti

Papale

Ceraulo

et al. 2021

JMSE

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The evaluation of acoustic temporal rhythms in wide-ranging cetaceans can reveal patterns in animal spatial presence and the occurrence of periodical phenomena. Here, we aimed at assessing the temporal patterns of dolphin’s acoustic presence in a shallow-water area in the Sicily Strait (Mediterranean Sea). Whistles were collected continuously for 14 months from an acoustic monitoring station installed aboard of an elastic seamark. Over a total of 6955 h of recording, 14,048 signals were identified using both automatic and visual methods. Three parameters were analyzed: hourly presence (HP), used as a proxy of the presence of dolphins in the area; detection rate (DR), indicating the acoustic activity rate of dolphins measured per hour in the entire dataset; and detection rate in presence of dolphins (DRD), indicating the acoustic activity rate of dolphins considering only the hours when whistles were recorded. The highest values of both HP and DR were reached during the night, and the Autumn and Winter months, suggesting an increase in the dolphin’s occurrence and a possible moving away and towards the monitoring station potentially following prey. DRD, instead, showed an almost uniform distribution throughout the day implying that when the animals are close to the monitoring station, the acoustic activity does not show any pattern. However, possible changes in the communication exchange along the seasons were suggested. This study complements other work on this subject, improving the knowledge of dolphins’ acoustic activity in the area.

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Section: Discussionmentioning

confidence: 99%

Acoustic Presence of Dolphins through Whistles Detection in Mediterranean Shallow Waters

Gregorietti

Papale

Ceraulo

et al. 2021

JMSE

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“…In conclusion, despite the evidence strongly pointing to habitat‐dependent characteristics (such as wind/sea conditions and bathymetry), future studies should continue to investigate these, and other, factors that may be promoting divergence in Guiana dolphin whistles among populations. Thus, it is important to consider environmental conditions, sample vocalizations associated with different socio‐behavioral states at a higher frequency (at least up to 96 kHz), pulsed signals analysis and compare diurnal and nocturnal sound emissions (see Deconto and Monteiro‐Filho , ). The variation in Guiana dolphin whistles is probably associated with many other variables besides latitude, resulting from a more complex interaction of evolutionary, ecological, and social factors yet to be studied.…”

Section: Discussionmentioning

confidence: 99%

Whistle variability of Guiana dolphins in South America: Latitudinal variation or acoustic adaptation?

Moron

Lopes

Reis

et al. 2018

Marine Mammal Science

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A previous comparison of whistles using data sampled at 48 kHz suggested that certain frequency parameters vary along a latitudinal gradient. This geographical pattern may be biased because whistles sampled at higher frequencies could potentially have very different frequency contents. The current study compared the acoustic parameters of Guiana dolphin (Sotalia guianensis) whistles recorded at a higher sampling rate (96 kHz) and from groups occupying two never before sampled sites, Benevente Bay, Espírito Santo, Brazil, and Formosa Bay, Rio Grande do Norte, Brazil, with recordings of other populations in South America. By only considering data sampled at a rate of at least 96 kHz, we aimed to detect differences in whistles across locations. Contrary to previous findings, our analyses do not indicate any clear separation between northern and southern populations based on whistles, and do not corroborate the hypothesis of latitudinal acoustic variation in this species. The variation in Guiana dolphin whistle parameters found here appears to be influenced by latitude to some extent, but several other factors, including sampling method, environmental fluctuations, and social influence on vocal learning, may be confounding the detection of a geographic pattern in these whistle samples.

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“…Passive acoustic monitoring has become popular for studying dolphin diel patterns, which seem to vary across and within taxa. Several studies have found that dolphins are most vocally active at night (Deconto et al, 2016;Dede et al, 2014;Frouin-Mouy, 2022;Hodge et al, 2013), while others found that dolphins are most vocally active during the day (Gauger et al, 2022;McElligott & Lammers, 2021) or during twilight hours (Goold, 2000), or showed no observable diel pattern in vocalization rates (Philpott et al, 2007). One study found different diel patterns for different types of vocalizations (Cascão et al, 2020), while another found a nocturnal diel pattern in the vocalizations of smaller dolphin species while larger species were vocally active throughout the diel cycle (Howe & Lammers, 2021).…”

Section: Introductionmentioning

confidence: 99%

Seasonal and diel patterns in Pacific white‐sided dolphin (Lagenorhynchus obliquidens) pulsed calls near Barkley Canyon

Kanes,

Dosso,

Insua

et al. 2023

Marine Mammal Science

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Evaluation of temporal patterns in offshore marine mammal activity through visual data collection can be impaired by light and weather conditions and the cost of ship time. The conditions‐independence and cost‐efficacy of acoustic data collection make it popular for researching the temporal patterns of wild dolphins. However, Pacific white‐sided dolphins (PWSDs) north of Southern California remain under‐researched. This study evaluates diel and seasonal patterns in PWSD communication signals detected in 480 days of near‐continuous passive acoustic data collected over 20 months from the Barkley Canyon node of Ocean Networks Canada's NEPTUNE observatory, offshore Vancouver Island, British Columbia, Canada. In this study, a random forest classifier is used to identify PWSD pulsed calls and false positives are manually removed. The resulting acoustic presence‐absence data set is evaluated for seasonal and diel patterns using generalized additive mixed models, considering masking effects from ambient noise. PWSDs are found to be vocally active during all diel periods year‐round, with high summer and low spring activity. Seasonally dependent diel patterns are identified, with PWSD pulsed calls exhibiting no diel pattern in spring, a slight increase in vocal activity during dusk and night in fall and winter, and a notable increase during night and dawn in summer.

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Day and night sounds of the Guiana dolphin, Sotalia guianensis (Cetacea: Delphinidae) in southeastern Brazil

Cited by 15 publications

References 27 publications

Acoustic Presence of Dolphins through Whistles Detection in Mediterranean Shallow Waters

Acoustic Presence of Dolphins through Whistles Detection in Mediterranean Shallow Waters

Whistle variability of Guiana dolphins in South America: Latitudinal variation or acoustic adaptation?

Seasonal and diel patterns in Pacific white‐sided dolphin (Lagenorhynchus obliquidens) pulsed calls near Barkley Canyon

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