Search

Emotions in animals may be expressed by arousal and understanding this often relies upon the monitoring of their behaviour. Under human care, animals' arousal states may be linked to husbandry decisions, whereby animals may display arousal responses to scheduled events such as feeding and human interaction. Here, we investigate vocal correlates of arousal associated with public presentations of bottlenose dolphins (Tursiops spp.) in human care by comparing vocal production rates and characteristics between high and low arousal contexts. Elevated arousal during the day compared with overnight was characterised by increased signature and non-signature whistle production. High intensity broadband crack vocalisations were produced less than whistles during the day and did not correlate with increased arousal around presentation times. Three of ten dolphins increased signature whistle production before and/or after presentation sessions, indicating elevated arousal and variation in individual responses. Many individuals elevated minimum frequency and suppressed maximum frequency of signature whistles in a way that correlated with higher arousal contexts, indicating that these may therefore be good indicators of changes in arousal state. Overall, our study demonstrates that passive acoustic monitoring can provide a useful indication of arousal linked to husbandry decisions, and that individual variation in vocal responses, likely linked to personality, is important to consider. [ABSTRACT FROM AUTHOR]

Keywords: cultural transmission; ecology of fear; human-wildlife conflict; livelihood impacts; predator-prey interactions EN cultural transmission ecology of fear human-wildlife conflict livelihood impacts predator-prey interactions 1 5 5 01/04/23 20230101 NES 230101 Killer whales ( I Orcinus orca i ) and white sharks ( I Carcharodon carcharias i ) are marine apex predators that shape prey behavior and even entire ecosystems through direct predation effects and indirect fear effects (e.g., Estes et al., [4]; Heithaus et al., [5]). " Predation on a White Shark (Carcharodon carcharias) by a Killer Whale (Orcinus orca) and a Possible Case of Competitive Displacement." Given the well-documented, predictable year-round presence of white sharks in Mossel Bay (Jewell et al., [7]; Ryklief et al., [13]), the sudden absence of white sharks for several weeks immediately after the predation event supports a flight response by surviving white sharks in the area. [Extracted from the article]

Sexing cetaceans typically requires extended periods of observation or expensive molecular methods. An alternative approach using photo‐identification may provide a cost‐effective, noninvasive method for assigning a sex to free‐ranging individuals. We investigated two methods for predicting the sex of common bottlenose dolphins (Tursiops truncatus) from Namibia, using the rate of change in dorsal fin (1) trailing edge marks or (2) surface features (scarring and lesions) and binary logistic regression models. Our results suggest animals with frequent and extensive changes to dorsal edge marks, or a high number/proportion of the dorsal fin covered in surface features are likely male, while those with little to no changes in dorsal edge marks or low numbers/proportion of surface features are likely female. Both sex prediction models performed reasonably well (accuracy: edge marks: 100%, surface features: 83%), with a high degree of consensus between models in sex predictions (78.6%). Our models are straightforward to implement and robust for the study population, providing useful insights into individuals' sex and population demographics. This reliable, inexpensive, and minimally invasive framework for assigning sex could be widely applicable, if population‐specific information of known sex individuals is included, due to the variable social systems and behaviors exhibited by Tursiops spp. [ABSTRACT FROM AUTHOR]

Human-controlled regimes can entrain behavioural responses and may impact animal welfare. Therefore, understanding the influence of schedules on animal behaviour can be a valuable tool to improve welfare, however information on behaviour overnight and in the absence of husbandry staff remains rare. Bottlenose dolphins (Tursiops spp.) are highly social marine mammals and the most common cetacean found in captivity. They communicate using frequency modulated signature whistles, a whistle type that is individually distinctive and used as a contact call. We investigated the vocalisations of ten dolphins housed in three social groups at uShaka Sea World dolphinarium to determine how patterns in acoustic behaviour link to dolphinarium routines. Investigation focused on overnight behaviour, housing decisions, weekly patterns, and transitional periods between the presence and absence of husbandry staff. Recordings were made from 17h00 – 07h00 over 24 nights, spanning May to August 2018. Whistle (including signature whistle) presence and production rate decreased soon after husbandry staff left the facility, was low over night, and increased upon staff arrival. Results indicated elevated arousal states particularly associated with the morning feeding regime. Housing in the pool configuration that allowed observation of staff activities from all social groups was characterised by an increase in whistle presence and rates. Heightened arousal associated with staff presence was reflected in the structural characteristics of signature whistles, particularly maximum frequency, frequency range and number of whistle loops. We identified individual differences in both production rate and the structural modification of signature whistles under different contexts. Overall, these results revealed a link between scheduled activity and associated behavioural responses, which can be used as a baseline for future welfare monitoring where changes from normal behaviour may reflect shifts in welfare state. [ABSTRACT FROM AUTHOR]

Abstract: The Indian Ocean humpback dolphin was recently uplisted to ‘Endangered’ in the recent South African National Red List assessment. Abundance estimates are available from a number of localized study sites, but knowledge of movement patterns and population linkage between these sites is poor. A national research collaboration, the SouSA project, was established in 2016 to address this key knowledge gap. Twenty identification catalogues collected between 2000 and 2016 in 13 different locations were collated and compared. Photographs of 526 humpback dolphins (all catalogues and photos) were reduced to 337 individuals from 12 locations after data selection. Of these, 90 matches were found for 61 individuals over multiple sites, resulting in 247 uniquely, well‐marked humpback dolphins identified in South Africa. Movements were observed along most of the coastline studied. Ranging distances had a median value of 120 km and varied from 30 km up to 500 km. Long‐term site fidelity was also evident in the data. Dolphins ranging along the south coast of South Africa seem to form one single population at the western end of the species' global range. Current available photo‐identification data suggested national abundance may be well below previous estimates of 1000 individuals, with numbers possibly closer to 500. Bearing in mind the poor conservation status of the species in the country, the development of a national Biodiversity Management Plan aimed at ensuring the long‐term survival of the species in South Africa is strongly recommended. At the same time, increased research efforts are essential, particularly to allow for an in‐depth assessment of population numbers and drivers of changes therein. The present study clearly indicates the importance of scientific collaboration when investigating highly mobile and endangered species. [ABSTRACT FROM AUTHOR]

Passive acoustic monitoring (PAM) is commonly used to generate information on the distribution, abundance, and behavior of cetacean species. In African waters, the utilization of PAM lags behind most other continents. This study examines whether the whistles of three coastal delphinid species (Delphinus delphis, Tursiops truncatus, and Tursiops aduncus) commonly encountered in the southern African subregion can be readily distinguished using both statistical analysis of standard whistle parameters and the automated detection and classification software PAMGuard. A first account of whistles recorded from D. delphis from South Africa is included. Using PAMGuard, classification to species was high with an overall mean correct classification rate of 87.3%. Although lower, high rates of correct classification were also found (78.4%) when the two T. aduncus populations were included separately. Classification outcomes reflected patterns observed in standard whistle parameters. Such acoustic discrimination may be useful for confirmation of morphologically similar species in the field. Classification success was influenced by training and testing the classifier with data from different populations, highlighting the importance of locally collected acoustic data to inform classifiers. The small number of sampling populations may have inflated the classification success, therefore, classification trials using a greater number of species are recommended. [ABSTRACT FROM AUTHOR]

The distribution, movements and abundance of highly mobile marine species such as bottlenose dolphins Tursiops truncatus are best studied at large spatial scales, but previous research effort has generally been focused on relatively small areas, occupied by populations with high site fidelity., We aimed to characterize the distribution, movements and abundance of bottlenose dolphins around the coasts of Scotland, exploring how data from multiple sources could be integrated to build a broader-scale picture of their ecology., We reviewed existing historical data, integrated data from ongoing studies and developed new collaborative studies to describe distribution patterns. We adopted a Bayesian multi-site mark-recapture model to estimate abundance of bottlenose dolphins throughout Scottish coastal waters and quantified movements of individuals between study areas., The majority of sightings of bottlenose dolphins around the Scottish coastline are concentrated on the east and west coasts, but records are rare before the 1990s. Dedicated photo-identification studies in 2006 and 2007 were used to estimate the size of two resident populations: one on the east coast from the Moray Firth to Fife, population estimate 195 [95% highest posterior density intervals ( HPDI): 162-253] and the second in the Hebrides, population estimate 45 (95% HPDI: 33-66). Interaction parameters demonstrated that the dolphins off the east coast of Scotland are highly mobile, whereas those off the west coast form two discrete communities., We provide the first comprehensive assessment of the abundance of bottlenose dolphins in the inshore waters of Scotland. The combination of dedicated photo-identification studies and opportunistic sightings suggest that a relatively small number of bottlenose dolphins (200-300 individuals) occur regularly in Scottish coastal waters. On both east and west coasts, re-sightings of identifiable individuals indicate that the animals have been using these coastal areas since studies began. [ABSTRACT FROM AUTHOR]

Killer whales and leatherback turtles are infrequently sighted in the coastal waters of southern Africa. Year round observations in Walvis Bay, Namibia of killer whales (2003-2010) by multiple marine tour operators and opportunistic seasonal observations of leatherback turtles made during a cetacean research project in the area (2008-2010) have been collated. Visits to coastal waters by killer whales (n = 16) are sporadic and unpredictable but are slightly higher (n = 11) between late winter (August) and late summer (March). Leatherback turtles were only seen in the warmer periods of summer months (February-March) when the surface waters exceeded 15°C. Two interactions (one harassment and one probably predation) between killer whales and leatherback turtles have been recorded in Walvis Bay. This is the first report of killer whales eating leatherback turtles in the South Atlantic. These observations are noteworthy due to the low frequency of encounters of both species in the area, suggesting predation of turtles may be relatively common. Knowledge of the diet of killer whales is valuable due to the importance of dietary specialization in definition of ecotypes of the species. [ABSTRACT FROM AUTHOR]

The article examines the wounds and injuries as well as the subsequent healing of a propeller strike injury to a heaviside's dolphin (cephalorhynchus heavisidii). It says that the healing rates of dolphins vary with the severity of the injury. It adds that the scars resulting from deep wounds and mutilations along the edges of dorsal fins provide a useful set of marks which can be used to distinguish individuals. Moreover, the photographic capture-recapture techniques are also discussed.

The sympatric Heaviside's (Cephalorhynchus heavisidii) and dusky dolphins (Lagenorhynchus obscurus) are poorly studied in South Africa and are potentially at risk from anthropogenic threats including fisheries bycatch. As part of a larger study, shore-based observations were made in a small bay (~1000 m wide) in the Western Cape, South Africa, during the summer months of 1999-2001 to gather data on their nearshore movements and behavior. Heaviside's dolphins exhibited a diurnal onshore-offshore migration and the sighting rate varied significantly with time of day and brightness of the moon, with numbers being markedly higher before 12:00 and nearer a full moon. These patterns were presumed to be linked to the vertical migration of their principal prey, juvenile hake Merluccius species and Heaviside's dolphins appeared to be resting and not feeding inshore during the day. Sightings of dusky dolphin showed no predictable variation with time of day but their numbers inshore were significantly lower when upwelllng conditions existed offshore. Larger groups of Heaviside's dolphins (especially groups of four) were more active (leaps, etc.) than smaller groups, but behaviour was not linked to environmental factors. The dissimilar responses to environmental conditions suggest that sympatry in these two species is mediated by niche as well as prey differentiation. [ABSTRACT FROM AUTHOR]

Heaviside's dolphins, Cephalorhynchus heavisidii, are endemic to southwestern Africa, where they are exposed to unknown levels of anthropogenic threats, including inshore set netting. Using photo-ID data collected over 3 yr on the west coast of South Africa, we calculated Chapman's-modified Petersen estimates of the number of distinctive individuals at three spatial scales. Sample sizes were small and recapture rates low resulting in high variance. Total population abundance was extrapolated from the proportion of well-marked animals in the population (14%–17%) with between-year estimates adjusted for mortality using data from Commerson's dolphin. The total population size was calculated as 527 animals (CV = 0.35, CI 272–1,020) in the 1999 study area (20 km of coastline, within season), 3,429 animals (CV = 0.36, CI 1,721–6,828) in the central study area (150 km of coastline, 3 yr), and 6,345 animals (CV = 0.26, CI 3,573–11,267) in the full study area (390 km of coastline, 2 yr). Dolphins fitted with satellite transmitters varied in their use of the inshore photographic study area from 39.5% to 94.7% of transmission days (38–51 total). Given the known or suspected biases in the data, these abundance estimates are likely to be biased downward. [ABSTRACT FROM AUTHOR]

The recently published book, I Ethology and Behavioural Ecology of Odontocetes i , is the first in a series of six books exploring the topic in relation to the major groups of marine mammals. Minor niggles with the book, which may be off-putting to the reader, include inconsistencies in formatting; for example, some chapters include a summary/discussion/conclusion section at the end, others do not. Paragraphing and section header format (use of headers, numbering scheme, and font size) vary from chapter to chapter. [Extracted from the article]

Environmental factors are thought to strongly influence the distribution and predictability of the coastal distribution of southern right whales (Eubalaena australis) off South Africa. Preferred habitat had generally shallow sloping sedimentary floors and was characteristically protected from open ocean swell and prevalent seasonal winds. This study investigated whether habitat choices at smaller scales (within bays) were similar. Fine scale distribution patterns (GPS) from three years' surveys (1997, 1999, 2000) were analyzed separately within the three main concentration areas St Sebastian Bay, De Hoop, and Walker Bay (containing ∼73% of cow-calf pairs and ∼49% of unaccompanied adults in the whole survey region). Whale density at this scale of within particular bays did not correlate well with predicted variables, but Chi-squared analysis strongly supported results at broader scales, in all bays. Post-hoc "choice" tests between similar areas differing in only one variable revealed that cow-calves preferred (presumed) sandy substrates and especially protection from swell. The strength and predictability of preferences shown at fine scale (where individual movement and weather variability could have great influence) provide strong support for findings at larger scales and emphasize the importance of environmental factors in the habitat choice of wintering right whales. [ABSTRACT FROM AUTHOR]

Aerial surveys over the last 32 yr have shown that the distribution of southern right whales Eubalaena australis along the south coast of South Africa is markedly discontinuous, but highly predictable. A GIS was used at a variety of scales to investigate whether this pattern was related to environmental characteristics. Whale distribution was analyzed as density per 20-min bin of longitude over two temporal and spatial scales, namely 15 bins for 32 yr, and a wider scale but shorter time period, 23 bins for 19 yr, as well as using three years of GPS accuracy data (15 bins) for finer scale analysis. Environmental factors tested were depth, distance from shore, sea floor slope, protection from swell, protection from wind, and shore type. The majority of whales were concentrated in areas that provided reasonable protection from open ocean swell and seasonal winds, and had sedimentary floors with gentle slopes. They generally avoided exposed rocky shorelines. Cow-calf pairs were found significantly closer to shore and in shallower water than unaccompanied whales, particularly off sandy beaches. Habitat choice at this time of year may be related both to energy conservation for calves and lactating females (calm sea conditions) and to protection of the new-born. [ABSTRACT FROM AUTHOR]

Static acoustic monitoring is a cost-effective, low-effort means of gathering large datasets on echolocation click characteristics and habitat use by odontocetes. Heaviside's dolphins (Cephalorhynchus heavisidii) were monitored using an acoustic monitoring unit, the T-POD, in July 2008 at a site of known high abundance for this species in Walvis Bay, Namibia. The T-POD successfully detected clicks from Heaviside's dolphins, and these clicks were detected in the 120 to 140 kHz frequency range. A distinct diel pattern to the hourly mean inter-click interval was observed, with higher values during daylight hours than at night, suggesting that click trains are produced at faster rates at night time. There was no apparent diel pattern in the proportion of buzz trains produced, however. A diel pattern in click activity was observed, with many more detection-positive minutes per hour recorded between dusk and dawn, and vocalization activity dropping to low levels in the middle of the day. This corresponded with visual observations made on abundance of dolphins in the study area. These results suggest that Heaviside's dolphins use this site primarily during the night. Static acoustic monitoring proved to be an effective technique for monitoring patterns of habitat use by Heaviside's dolphins. [ABSTRACT FROM AUTHOR]

The Cape fur seal (Arctocephalus pusillus pusillus) is one of the most colonial mammals, with colonies of up to hundreds of thousands of individuals during the breeding season. During the lactation period, mothers and pups are regularly separated as females undertake multi-day foraging trips at sea. Mothers and pups use a mutual vocal recognition system to reunite after separation. Such communication is highly constrained by both high background noise and risk of individual confusion owing to the density of seals. This study aimed to experimentally assess the acoustic features relevant for mother-pup vocal identification and the propagation properties of their calls. Playback experiments revealed that mother and pup individual vocal signatures rely on both temporal and frequency parameters: amplitude and frequency modulations, timbre and fundamental frequency (f0). This is more parameters than in any colonial species studied so far. The combinational use of acoustic features reinforces the concept that both environmental and social constraints may have acted as selective pressures on the individual vocal recognition systems. Theoretical propagation distances of mother and pup vocalisations were estimated to be below the range of distances at which mother-pup reunions can occur. This suggests that Cape fur seals may have strong abilities to extract vocal signals from the background noise, as previously demonstrated in the highly colonial king penguin. Investigating the transmission of information throughout the propagation of the signal as well as the ability of the receiving individual to decipher vocal signatures is crucial to understanding vocal recognition systems in the wild., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

We use genomics to identify the natal origin of a grey whale found in the South Atlantic, at least 20 000 km from the species core range (halfway around the world). The data indicate an origin in the North Pacific, possibly from the endangered western North Pacific population, thought to include only approximately 200 individuals. This contributes to our understanding of Atlantic sightings of this species known primarily from the North Pacific, and could have conservation implications if grey whales have the potential for essentially global dispersion. More broadly, documenting and understanding rare extreme migration events have potential implications for the understanding of how a species may be able to respond to global change.

Dwarf sperm whales ( Kogia sima ) are small toothed whales that produce narrow-band high-frequency (NBHF) echolocation clicks. Such NBHF clicks, subject to high levels of acoustic absorption, are usually produced by small, shallow-diving odontocetes, such as porpoises, in keeping with their short-range echolocation and fast click rates. Here, we sought to address the problem of how the little-studied and deep-diving Kogia can hunt with NBHF clicks in the deep sea. Specifically, we tested the hypotheses that Kogia produce NBHF clicks with longer inter-click intervals (ICIs), higher directionality and higher source levels (SLs) compared with other NBHF species. We did this by deploying an autonomous deep-water vertical hydrophone array in the Bahamas, where no other NBHF species are present, and by taking opportunistic recordings of a close-range Kogia sima in a South African harbour. Parameters from on-axis clicks ( n =46) in the deep revealed very narrow-band clicks (root mean squared bandwidth, BW RMS , of 3±1 kHz), with SLs of up to 197 dB re. 1 µPa peak-to-peak (μPa pp ) at 1 m, and a half-power beamwidth of 8.8 deg. Their ICIs (mode of 245 ms) were much longer than those of porpoises (<100 ms), suggesting an inspection range that is longer than detection ranges of single prey, perhaps to facilitate auditory streaming of a complex echo scene. On-axis clicks in the shallow harbour ( n =870) had ICIs and SLs in keeping with source parameters of other NBHF cetaceans. Thus, in the deep, dwarf sperm whales use a directional, but short-range echolocation system with moderate SLs, suggesting a reliable mesopelagic prey habitat., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)