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There were several wonderful figurative shoulders that lent inspiring views to my life. A select few belong to, in order of appearance, my papa Gerhard Würsig, Roy Tassava of Ohio State University, Charlie Walcott of Cornell University, Roger Payne then of Rockefeller University, and Ken Norris of University of California Santa Cruz. The shoulder that has been ever-present these past 50 years is that of my wife, Melany Carballeira Würsig. I thank them all. For you readers who may be in your approaching twilight years, I suspect you have similar mentors on whose shoulders you have relied for your own successes. If you are yet young (you lucky devils!), you will appreciate those shoulders ever more as time progresses all too rapidly. Let us now hope that the persons we have relied on will engender ever more shoulders to be relied on, of each gender, race, background. and belief relative to what culture, science, education, and philosophies of humanity may have to offer. [ABSTRACT FROM AUTHOR]

Fewer than 200 Indo-Pacific humpback dolphins (Sousa chinensis) occur in Hong Kong waters (though these are part of a much larger population in the Pearl River Estuary), with a decrease in the past about 10 years. They have partially overlapping individual ranges (mean = 100 km2), and two partially overlapping communities. Seasonal occurrence is higher in June-November than December-May, approximate wet and dry monsoon seasons, respectively. Group sizes tend to average three dolphins, a decrease from the past decade. Feeding often occurs in abruptly changing water depths and off rocky natural shores. The area immediately north of Hong Kong International Airport is largely used for travelling between locations to the west, east and further north. The area around Lung Kwu Chau Island in northwest Hong Kong is a "hot spot" for foraging and socializing. The area off Fan Lau, southwest Lantau Island, is largely used for foraging. A former foraging "hot spot" was located around the Brothers Islands east of the airport, now reduced, possibly due to increases in high-speed ferries (HSFs) and other activities. Sound recordings of dolphins from bottom-mounted hydrophones suggest that northwestern Hong Kong waters are used more at night than in daytime. Sexual activity and calving occur throughout the year, with a peak in late spring to autumn (wet monsoon season). Humpback dolphins communicate acoustically with each other and probably passively listen to prey in murky waters, and anthropogenic noises may be masking communication and affecting prey location. Increasing sounds of shipping, HSFs and industrial activities are likely to alter dolphin habitat use patterns and overall behaviours beyond the present already affected status. [ABSTRACT FROM AUTHOR]

Although seabirds frequently aggregate with feeding delphinids, the benefits to seabirds of feeding with dolphins have been rarely reported. We examined how dusky dolphins (Lagenorhynchus obscurus) influenced prey accessibility for seabirds in Admiralty Bay, New Zealand. Interactions of dusky dolphins and seabirds were characterized during 335 feeding bouts of dusky dolphins (52 video-recorded underwater). Dolphins increased prey accessibility for seabirds because they swam under the bottom half of prey balls for 59% of passes that were within 2 m of the prey ball. During feeding bouts by dolphins, 51% of prey balls ascended, whereas only 13% descended. Dolphins also influenced prey mobility; only 24% of stationary feeding bouts became mobile after dolphins began feeding, and 17% subsequently became stationary again. Significantly more Australasian gannets (Morus serrator) were near mobile than stationary prey balls after feeding, but not during feeding bouts. This suggests that feeding gannets increase mobility of prey balls, but that feeding dolphins counteract this effect. Seabirds also used dusky dolphins to locate prey. Numbers of gannets, shearwaters (Puffinus), and gulls (Larus) increased during the first 2 min of dolphin feeding, even when other seabirds were not present. Gannets fed with dolphins for 40% of gannet feeding observations and shearwaters fed with dolphins for 24% of shearwater feeding observations. [ABSTRACT FROM AUTHOR]

Dolphins live in complex social groupings with a wide variety of social strategies. In this chapter we investigate the role that differing habitats and ecological conditions have played in the evolution of delphinid social strategies. We propose a conceptual framework for understanding natural patterns of delphinid social structure in which the spatial and temporal predictability of resources influences the ranging patterns of individuals and communities. The framework predicts that when resources are spatially and temporally predictable, dolphins should remain resident in relatively small areas. Predictable resources are often found in complex inshore environments where dolphins may hide from predators or avoid areas with high predator density. Additionally, available food resources may limit group size. Thus, we predict that there are few benefits to forming large groups and potentially many benefits to being solitary or in small groups. Males may be able to sequester solitary females, controlling mating opportunities. Observations of inshore populations of bottlenose dolphins (Tursiops sp.) and island-associated spinner dolphins (Stenella Iongirostris) seem to fit this pattern well, along with forest-dwelling African antelope and primates such as vervets (Cercopithicus aethiops), baboons (Papio sp.), macaques (Macaca sp.) and chimpanzees (Pan troglodytes). In contrast, the framework predicts that when resources such as food are unpredictable, individuals must range further to find the necessary resources. Forming groups may be the only strategy available to avoid predation, especially in the open ocean. Larger home ranges are likely to support a greater number of individuals; however, prey is often sparsely distributed, which may act to reduce foraging competition. Cooperative foraging and herding of prey schools may be advantageous, potentially facilitating the formation of longterm bonds. Alternately, individuals may display many short-term affiliations. These large groups make it difficult for a male or a small group of males to sequester a female, and polygynandry is the most likely mating strategy. While it is difficult to study wide-ranging delphinids to examine these predictions, this ranging and behavioural pattern has been suggested for dusky dolphins (Lagenorhynchus obscurus), coastal bottlenose dolphins (Tursiops sp.) and mixed species of dolphins in the Eastern Tropical Pacific. These patterns also resemble the ranging and social strategies of open savannah African antelopes and desert-dwelling macropods. Resource availability exists in a range of complex distributions and we predict that delphinid ranging patterns will also vary. At intermediate-ranging patterns, the framework predicts that individuals should form mid-sized groups balancing intra-group competition with predation protection. Humpback dolphins (Sousa sp.) appear to fit this pattern, with some site fidelity over relatively large ranges. They display fluid associations with other individuals. Predation pressure is not sufficiently high to cause large groups to form, and individuals probably reduce predation pressure more by hiding whenever possible. This pattern is likely to prevent the formation of long-term complex bonds. In contrast, killer whales (Orcinus orca) also display intermediate-ranging patterns, but have extremely strong social bonds within familial groups. Cooperative and altruistic behaviour in killer whales facilitate the formation of life-long bonds, similar to those observations in sperm whales (Physetermacrocephalus) and elephants (Loxodonta africana). This conceptual framework remains largely untested, and for many species it is not currently possible to describe ranging behaviours, anti-predator tactics or social behaviour in sufficient detail for appropriate examination of these ideas.… [ABSTRACT FROM AUTHOR]

An array of four hydrophones arranged in a symmetrical star configuration was used to measure the echolocation signals of the dusky dolphin (Lagenorhynchus obscurus) near the Kaikoura Peninsula, New Zealand. Most of the echolocation signals had bi-modal frequency spectra with a low-frequency peak between 40 and 50 kHz and a high-frequency peak between 80 and 110 kHz. The low-frequency peak was dominant when the source level was low and the high frequency peak dominated when the source level was high. The center frequencies in the dusky broadband echolocation signals are among the highest of dolphins measured in the field. Peak-to-peak source levels as high as 210 dB re 1 mPa were measured, although the average was much lower in value. The levels of the echolocation signals are about 9-12 dB lower than for the larger white-beaked dolphin (Lagenorhynchus albirostris) which belongs to the same genus but is over twice as heavy as the dusky dolphins. The source level varied in amplitude approximately as a function of the one-way transmission loss for signals traveling from the animals to the array. The wave form and spectrum of the echolocation signals were similar to those of other dolphins measured in the field. [ABSTRACT FROM AUTHOR]

Abstract: Male genital diversification is likely the result of sexual selection. Female genital diversification may also result from sexual selection, although it is less well studied and understood. Female genitalia are complex among whales, dolphins, and porpoises, especially compared to other vertebrates. The evolutionary factors affecting the diversity of vaginal complexity could include ontogeny, allometry, phylogeny, sexual selection, and natural selection. We quantified shape variation in female genitalia using 2D geometric morphometric analysis, and validated the application of this method to study soft tissues. We explored patterns of variation in the shape of the cervix and vagina of 24 cetacean species (n = 61 specimens), and found that genital shape varies primarily in the relative vaginal length and overall aspect ratio of the reproductive tract. Extensive genital shape variation was partly explained by ontogenetic changes and evolutionary allometry among sexually mature cetaceans, whereas phylogenetic signal, relative testis size, and neonate size were not significantly associated with genital shape. Female genital shape is diverse and evolves rapidly even among closely related species, consistent with predictions of sexual selection models and with findings in invertebrate and vertebrate taxa. Future research exploring genital shape variation in 3D will offer new insights into evolutionary mechanisms because internal vaginal structures are variable and can form complex spirals. [ABSTRACT FROM AUTHOR]

Humpback dolphins (genus Sousa) use shallow, near-shore waters throughout their range. This coastal distribution makes them vulnerable to recreational and commercial disturbances, especially near heavily populated and industrialized areas. Most research focusing on Sousa and human activities has emphasized direct impacts and threats, involving injury and death, with relatively little focus on indirect effects on dolphins, such as changes in behaviour that may lead to deleterious effects. Understanding behaviour is important in resolving human-wildlife conflict and is an important component of conservation. This chapter gives an overview of animal behavioural responses to human activity with examples from diverse taxa; reviews the scientific literature on behavioural responses of humpback dolphins to human activity throughout their range, including marine vessel traffic, dolphin tourism, cetacean-fishery interactions, noise pollution, and habitat alteration; and highlights information and data gaps for future humpback dolphin research to better inform behaviour-based management decisions that contribute to conservation efforts. [ABSTRACT FROM AUTHOR]

Leaping is a highly conspicuous behavior in cetaceans that may function in cooperative hunting and social bonding, thereby converging with forms of intra-specific communication present in other social mammals. However, few studies have analyzed the ontogeny of leaping, an important aspect in determining the adaptive significance of this behavior. The objective of our study was to quantify the ontogeny of leaping in dusky dolphins, a highly acrobatic species that engages in a variety of aerial displays. We tested the hypotheses that: (1) leap frequency changes with calf age, (2) frequency of leap type varies with calf age and (3) frequency of leap type varies by behavioral state. Data were collected off Kaikoura, New Zealand through boat-based group focal follows of nursery groups from October 2006-May 2007. We analyzed data from 73 nursery group encounters according to age category (young calf, yearling) and season (early, late). Early young calves leapt less frequently than late young calves (p < 0.01), but leap frequency did not appear to differ among older calves. Calves learned noisy leaps first, followed by clean leaps, then coordinated leaps, and finally acrobatic leaps as indicated by the positive correlations between week (i.e., calf age) and frequency of clean (p < 0.01), acrobatic (p < 0.01) and coordinated (p < 0.05) leaps. The relationship between behavioral state and frequency of leap type was not significant. These results indicate that nursery groups represent an important environment for healthy physical and social development of calves. Furthermore, while calves appear to learn the mechanics of leaping individually, they appear to learn the context in which the leaps are performed from conspecifics. This indicates that, as for other socially-complex mammals such as other cetaceans, primates, and social carnivores, social learning may be an important component in the ontogeny of dusky dolphin behavior. [ABSTRACT FROM AUTHOR]

In fission-fusion social systems with scramble competition between males, multiple males join mating groups while surrounding an oestrous female. If male decisions to join a mating group have been shaped by natural selection, then there should be an optimal group size resulting from the trade-offs between the benefits of monopolizing a female in small groups and the energy lost in defending her from rivals in large groups. Male dusky dolphins ( Lagenorhynchus obscurus) off Kaikoura, New Zealand, provide a unique opportunity to assess the optimum mating group size because they join transient mating groups not confounded by foraging or predator evasion. Within aggregations of up to 1000 individuals, males search for oestrous females, encountering choices of staying with a large mating group or leaving to find a smaller group. Mating groups typically involve multiple males mating with a single female. We conducted focal follows of mating groups (N = 44) by vessel from November 2011 through January 2012. We used video and a GPS to record group size, behaviour and movement. For each group, we measured potential costs ( Swim Speed, Loss of Monopolization Potential) and benefits ( Copulation Rate and Duration, Energy Savings). Only Loss of Monopolization Potential was positively correlated with group size, while Energy Savings was negatively correlated. Using these two factors as utility functions, we constructed an optimality model and predicted the optimal mating group size to be seven individuals with a range of 4-11 individuals due to variance. The observed modal mating group size was five dolphins, with a range of 2-15. We compare variation in mating group currencies and sizes to past studies. We discuss potential limitations of applying optimality models to predict mating group size for socially complex and behaviourally plastic species such as dolphins. [ABSTRACT FROM AUTHOR]

Dusky dolphin (Lagenorhynchus obscurus) acoustic sounds were characterized by analyzing narrowband recordings [0-16 kHz in New Zealand (NZ) and 0-24 kHz in Argentina], and sounds in broadband recordings (0-200 kHz) were compared to their counterparts in down-sampled narrowband recordings (0-16 kHz). The most robust similarity between sounds present in broadband recordings and their counterparts in the down-sampled narrowband recordings was inter-click interval (ICI); ICI was therefore primarily used to characterize click sounds in narrowband recordings. In NZ and Argentina, distribution of ICIs was a continuum, although the distribution of ICIs in NZ had a somewhat bimodal tendency. In NZ, sounds that had smaller mean ICIs were more likely to have constant ICIs, and less likely to have increasing or decreasing ICIs. Similar to some other delphinids, dusky dolphins may use single, short duration sounds that have a constant ICI and closely spaced clicks for communication. No whistles were documented at either study site. Temporally structured sequences of burst pulses (i.e., sounds with ICI < about 10 ms) also occurred at both study sites, and these sequences contained 2-14 burst pulses that appeared closely matched aurally and in spectrograms and waveforms. [ABSTRACT FROM AUTHOR]

Background: Commercial viewing and swimming with dusky dolphins (Lagenorhynchus obscurus) near Kaikoura, New Zealand began in the late 1980s and researchers have previously described changes in vocalisation, aerial behaviour, and group spacing in the presence of vessels. This study was conducted to assess the current effects that tourism has on the activity budget of dusky dolphins to provide wildlife managers with information for current decision-making and facilitate development of quantitative criteria for management of this industry in the future. Methodology/Principal Findings: First-order time discrete Markov chain models were used to assess changes in the behavioural state of dusky dolphin pods targeted by tour vessels. Log-linear analysis was conducted on behavioural state transitions to determine whether the likelihood of dolphins moving from one behavioural state to another changed based on natural and anthropogenic factors. The best-fitting model determined by Akaike Information Criteria values included season, time of day, and vessel presence within 300 m. Interactions with vessels reduced the proportion of time dolphins spent resting in spring and summer and increased time spent milling in all seasons except autumn. Dolphins spent more time socialising in spring and summer, when conception occurs and calves are born, and the proportion of time spent resting was highest in summer. Resting decreased and traveling increased in the afternoon. Conclusions/Significance: Responses to tour vessel traffic are similar to those described for dusky dolphins elsewhere. Disturbance linked to vessels may interrupt social interactions, carry energetic costs, or otherwise affect individual fitness. Research is needed to determine if increased milling is a result of acoustic masking of communication due to vessel noise, and to establish levels at which changes to behavioural budgets of dusky dolphins are likely to cause long-term harm. Threshold values from these studies would allow managers to set appropriate operational conditions based on quantifiable criteria. [ABSTRACT FROM AUTHOR]

Sexual selection influences both genital diversity and mating behaviors, yet the integrated coevolution of pre- (behavioral) and postcopulatory (anatomical) traits in both sexes has received little attention. Traits could potentially evolve through an arms race model of escalations in male persistence and female resistance, and/or through a tradeoff model of inverse correlations between investments in pre- and postcopulatory traits. Preand postcopulatory traits of dusky dolphins (Lagenorhynchus obscurus) were compared with bottlenose dolphins (Tursiops spp.) and harbor porpoises (Phocoena phocoena). Relative testes size and vaginal complexity were measured from dissected specimens. Behavioral traits were analyzed from video recordings of individuals in free-ranging populations. Female precopulatory and male postcopulatory traits were associated, whereas female and male postcopulatory traits or female pre- and postcopulatory traits were not associated. Dusky dolphins differed substantially in several behavioral traits including longer durations of mating group interactions, lower rates of copulation attempts, more males per group, and higher female behavioral resistance. To explore complex processes of integrative coevolution, we recommend future research incorporate pre- and postcopulatory traits and focus on alternative measures of female resistance and male persistence. [ABSTRACT FROM AUTHOR]

The challenges of monitoring fully aquatic and long-living mammals have limited research on cetaceans that spans several decades to only a few populations. We report the first long-term assessment of association and residency patterns of dusky dolphins (Lagenorhynchus obscurus) off Kaikoura, New Zealand. Dorsal fin images, spanning 30 years of data collection, were used for photo-identification and social structure analyses. A total of 4,022 uniquely marked individuals were identified. Most (80%) were sighted only one time. The population of dusky dolphins off Kaikoura appears to be open, with the possibility of immigration and emigration. Dusky dolphins showed preferences for assembly into either large or small groups, which appear to drive association patterns. They did not demonstrate significant preferred or avoided associations with each other, and had overall weak association patterns. Individuals reside in the Kaikoura area for approximately eight years, and also have temporallv stable associations lasting approximately eight years. Dusky dolphins fit the model of a fission-fusion societv, and their association patterns may reflect unique local ecological conditions and foraging opportunities. [ABSTRACT FROM AUTHOR]

The article reports on the observation of mother and calve behavior among dusky dolphins via the use of an unmanned aerial vehicle (UAV). Particular attention was given to swimming speed, inter-adult distance, and respiration and suckling rates in the area between the Kaikoura Peninsula and the Haumuri Bluffs, New Zealand.

In the early 1970s. Roger Payne and colleagues developed a non-invasive, shore-based method for collecting data on free-ranging marine mammals in their natural environments. By using a theodolite, or surveyor's transit, they were able to collect data on nearshore marine mammal movement patterns, habitat use, and behavior without any disruption to the animals. As technology advanced, theodolite data collection progressed from analog machines requiring manual data entry to digital equipment linked to computer software that facilitated data management and automated calculations of marine mammal positional information. There are limitations associated with theodolite use, and concurrent data collection methods can contribute information that may not be possible with shore-based research alone. Since the first published research in 1978 using a theodolite to describe the behavioral ecology of dolphins off Argentina, at least 46 species of marine mammals in 36 countries have been tracked by theodolite, and the method continues to be used globally to contribute to non-invasive marine mammal research, conservation, and management. [ABSTRACT FROM AUTHOR]

The article discusses the use of underwater passive acoustic monitoring (PAM) and theodolite tracking to study Indo-Pacific humpback dolphin behavior and sound production. The PAM and shore-based theodolite tracking findings are compared. It is noted that three Ecological Acoustic Recorders (EARs) were deployed on the monitoring site of Lung Kwu Tan (LKT).

Risso's dolphin (Rissos; Grampus g behavior is little described given then-riseus) rvpical offshore distribution where research access is inherently challenging. We conducted focal group behavior follows of 51 Rissos groups from a circling, small, fixed-wing Partenavia aircraft in the Southern California Bight from 2008 through 2012 (15 aerial surveys; 72,647 km: 86 d).Instantaneous scan sampling of group heading and behavior state (rest/slow travel, medium-fast [mf]travel, and mill), and maximum nearest neighbor distance (MNND) estimated in adult body lengths(BLs) were noted once per 30 s. Focal follows occurred for 5 to 59 min (n = 51, mean 21.6, standard deviation [SD] = 12.9). Mean group size was 25.8(n = 51.SD±23.62.range3tol20).Atotalof 1,446 usable headings, 1,275 MNND, and 1,359 behavior state data points were used to calculate response variables of reorientation, splitting-joining, and behavior state transition rates relative to explanatory variables using standard multiple-linear-regression, logistic regression, or multi-linear-regressio nomial logistic regression models. Reorientation rates tended to be higher when other species were present. No explanatory variables were found to influence the splitting-joining rate. Rissos behavior state was significantly affected by calf presence and time of day. Rissos groups spent most (60%) time engaged in rest/slow travel followed by mf travel (33%) and milling (7%), and rarely changed behavior state. Transitions from one behavior state to another were more common in groups with calf presence, which were 4.3 times more likelv to continue mf travel than non-calf groups. During early afternoon. Rissos were six times more likelv to continue mf travel versus early morning and late afternoon. Preponderance of daytime rest/slow travel likely reflects presumed need for diurnal rest prior to apparent nocturnal foraging, a pattern associated with other nocturnal foraging dolphin species. Observations from aircraft facilitate a unique birds eye view on social interactions and spacing of individuals, which are less available from the low-vantage perspective of other platforms. [ABSTRACT FROM AUTHOR]

The article investigates mixed-species associations among marine mammals in California waters. Topics discussed include the frequency of mixed-species associations in the area, particularly those involving Risso's dolphins, the factors behind the change in the frequency of mixed-species associations involving Risso's dolphins in the waters of California between the 1950s and 2010s and the reasons for mixed-species associations among marine mammals.

Complex foldings of the vaginal wall are unique to some cetaceans and artiodactyls and are of unknown function(s). The patterns of vaginal length and cumulative vaginal fold length were assessed in relation to body length and to each other in a phylogenetic context to derive insights into functionality. The reproductive tracts of 59 female cetaceans (20 species, 6 families) were dissected. Phylogenetically-controlled reduced major axis regressions were used to establish a scaling trend for the female genitalia of cetaceans. An unparalleled level of vaginal diversity within a mammalian order was found. Vaginal folds varied in number and size across species, and vaginal fold length was positively allometric with body length. Vaginal length was not a significant predictor of vaginal fold length. Functional hypotheses regarding the role of vaginal folds and the potential selection pressures that could lead to evolution of these structures are discussed. Vaginal folds may present physical barriers, which obscure the pathway of seawater and/or sperm travelling through the vagina. This study contributes broad insights to the evolution of reproductive morphology and aquatic adaptations and lays the foundation for future functional morphology analyses. [ABSTRACT FROM AUTHOR]

Long-term passive acoustic monitoring (PAM) was conducted to study Indo-Pacific humpback dolphins, Sousa chinensis, as part of environmental impact assessments for several major coastal development projects in Hong Kong waters north of Lantau Island. Ecological acoustic recorders obtained 2711 days of recording at 13 sites from December 2012 to December 2014. Humpback dolphin sounds were manually detected on more than half of days with recordings at 12 sites, 8 of which were within proposed reclamation areas. Dolphin detection rates were greatest at Lung Kwu Chau, with other high-occurrence locations northeast of the Hong Kong International Airport and within the Lung Kwu Tan and Siu Ho Wan regions. Dolphin detection rates were greatest in summer and autumn (June-November) and were significantly reduced in spring (March-May) compared to other times of year. Click detection rates were significantly higher at night than during daylight hours. These findings suggest high use of many of the proposed reclamation/development areas by humpback dolphins, particularly at night, and demonstrate the value of long-term PAM for documenting spatial and temporal patterns in dolphin occurrence to help inform management decisions. [ABSTRACT FROM AUTHOR]

When males engage in scramble competition, are females non-evasive recipients of male coercion or evasive? Small groups of male dusky dolphins (Lagenorhynchus obscurus) engage in exploitative (non-interference) scramble competition for access to oestrous females near Kaikoura, New Zealand. We conducted behavioural sequence analyses of videos of 48 mating groups with continuous records and focal individual follows of females. We determined (1) the frequency and type of behaviours (non-evasive vs. evasive), (2) the variation in simple transition probabilities of behaviours leading to a copulatory position associated with female resistance and non-resistance and (3) the variation in female responses to male behaviours throughout focal follows. Females exhibited frequent active evasive manoeuvers following male behaviours. Copulation sequences were highly variable and most complex when terminated by females. Females altered responses to male signals, one aspect of mate choice potentially favouring male endurance. [ABSTRACT FROM AUTHOR]

A combination of autonomous acoustic recorders and visual surveys was used to determine the seasonal and spatial distribution of dolphins on the West Florida Shelf (WFS), Gulf of Mexico, USA. Acoustic detection rates were calculated using a model that adjusted the theoretical detection range for variations in ambient noise, which was found to be highly variable. Both acoustic and visual techniques indicated dolphins were present on the WFS year-round. Acoustic detections were not identified to species, but bottlenose dolphins (Tursiops truncatus), Atlantic spotted dolphins (Stenella frontalis), and a single group of rough-toothed dolphins (Steno bredanensis) were visually sighted, with the highest sighting rates for bottlenose dolphins. Both dolphin acoustic detection rates and bottlenose dolphin visual sighting rates decreased from inshore to offshore waters, and were especially high in waters adjacent to Tampa Bay, a major estuary. Dolphin acoustic detection rates and bottlenose dolphin visual sighting rates also suggested a habitat shift from deeper to shallower water in summer and/or autumn. Atlantic spotted dolphins were rarely observed in water shallower than 20 m, and appeared to move into shallower and more northerly waters during the summer. Both spatial and temporal variations in dolphin acoustic detection and visual sighting rates can potentially be explained by the habitat preferences and seasonal movements of their prey. This study is the first investigation of dolphin distribution on the WFS using both visual and acoustic methodologies over a synoptic scale, and the combined techniques allowed for a more complete assessment of the temporal and spatial patterns of WFS dolphins. [ABSTRACT FROM AUTHOR]

Highlights: [•] We characterized dolphin feeding behaviors at two study sites, and related behaviors to dolphin group and prey ball sizes. [•] Dolphins fed on larger prey balls in Argentina (maximum size >74m2) than they did in NZ (maximum size 33m2). [•] Dolphins in larger groups more often swam under prey balls during herding passes. [•] When dolphins fed on larger prey balls, they more often swam through prey balls to capture fish. [•] Coordination of prey-capture behaviors appeared to make it easier for dolphins to capture fish due to entrapment. [Copyright &y& Elsevier]

The article discusses the impact of vessel traffic on movements of Sousa chinensis in Lantau Island, Hong Kong. It is evident that human-related recreation and commercial disturbances affect marine mammals with near-shore distributions. It has been informed that Sousa chinensis are protected under the Wild Animals Protection Ordinance and a code of conduct for vessels in Hong Kong.

Delphinids frequently coordinate behaviors to contain or capture schooling fishes, but we know little about how these behaviors relate to prey escape behaviors, and corresponding costs and benefits. In this study, we described prey ball escape behaviors and investigated how prey ball behaviors related to dusky dolphin, Lagenorhynchus obscurus, prey herding and capturing behaviors using above-water and underwater video methods. Prey balls exhibited horizontal and vertical movements, both of which would have increased feeding costs for dolphins compared with feeding on stationary prey at the surface. The only prey ball behavior that we observed to precede escape was 'funneling' or the brief formation of a prey ball shape where the height was at least twice the width. Funneling was observed most often for large prey balls, immediately before they descended. When prey balls ascended, there was an insignificant trend for dolphins to do a greater proportion of herding passes that did not include a prey capture (p = 0.094), and dolphins did a larger proportion of prey-capture attempts on the sides of prey balls (p = 0.017) and a smaller proportion through the edges of prey balls (p = 0.037). When prey balls ascended, dolphins also did a smaller proportion of attempts with a dorsal body orientation (p = 0.037); there were insignificant trends for them to do a smaller proportion with a side orientation (p = 0.100) but a larger proportion with a ventral body orientation (p = 0.081). Thus, funneling is an effective behavior by which large prey balls are able to vertically escape, and dolphins may counter vertical prey escape behaviors by doing herding passes that do not include a prey-attempt, and changing location or body orientation of prey-capture behaviors. [ABSTRACT FROM AUTHOR]

The study presents a description of the monthly changes in dusky dolphin Lagenorhynchus obscurus feeding tactics and multi-species associations in Admirality Bay and Current Basin in New Zealand. The concurrent changes found in dusky dolphins including abundance, prey characteristics, and locations of feeding bouts, were found to be different from May through July. The intra-annual differences suggest that changes in prey species or behavior, influence dolphin feeding tactics, and influence which species benefit from feeding with dolphins.

There is increasing evidence that culture is an important determinant of behavior in some non-human species including great apes and cetaceans (whales and dolphins). In some cases, there may be repercussions for population biology and conservation. Rapidly evolving “horizontal” cultures, transmitted largely within generations, may help animals deal with anthropogenic change and even allow them to exploit it, sometimes with negative consequences for both the animals and humans. In contrast, stable “vertical” or “oblique” cultures, transmitted principally between generations, may impede adaptation to environmental change, and confound range recovery, reintroductions and translocations. Conformist stable cultures can lead to maladaptive behavior, which may be mistaken for the results of anthropogenic threats. They can also structure populations into sympatric sub-populations with distinctive cultural variants. Such structuring is common among cetaceans, among which sympatric sub-populations may face different anthropogenic threats or respond to the same threat in different ways. We suggest that non-human culture should be integrated into conservation biology when considering populations with such attributes, and also more generally by refining definitions of evolutionarily significant units and considering how cultural attributes may change our perspectives of non-humans. [Copyright &y& Elsevier]

The article argues against the assertion of researchers G. Yang and colleagues that the Lipotes vexillifer or baiji in China has been a conservation cause celebre. The authors disagree with the proposal of Yang's group to just let the species go extinct. They recognize that the chance of saving the baiji of the Yangtze River from extinction is not great but they believe the potential of establishing an ex situ program are worth the risks and costs. No species should suffer the indignity of extinction simply because people consciously choose not to try and save it.

Vocalizations of Indo-Pacific humpback dolphins (Sousa chinensis) in west Hong Kong waters were described from 12 recordings in 2010. A broadband hydrophone system recorded sounds. Vocalizations were characterized as broadband click trains, burst pulses, and narrowband frequency modulated sounds, including whistles generally similar to those of some other delphinid cetaceans. A comparison of results to previous humpback dolphin sound descriptions for Moreton Bay, Australia found broad similarities except for the apparent absence of 'quacks' and 'grunts' in the present study, which are of low frequency and thus were possibly masked by anthropogenic and other low frequency noise in the Hong Kong habitat. [ABSTRACT FROM AUTHOR]