Journal articles: 'Bottlenosed dolphins – Western Australia'

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Allen, Simon J., Daniele D. Cagnazzi, Amanda J. Hodgson, Neil R. Loneragan, and Lars Bejder. "Tropical inshore dolphins of north-western Australia: Unknown populations in a rapidly changing region." Pacific Conservation Biology 18, no. 1 (2012): 56. http://dx.doi.org/10.1071/pc120056.

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Australian Snubfin Orcaella heinsohni, Indo-Pacific Humpback Sousa chinensis and Indo-Pacific Bottlenose Dolphins Tursiops aduncus inhabit Australia’s tropical north-western coastline, a region undergoing extensive port development associated with the massive expansion of the oil, gas and mining industries. The current lack of data on dolphin population sizes or trends precludes impact assessments of developments on these protected species. Furthermore, the Western Australian and Commonwealth Government conservation listings of tropical inshore dolphins do not reflect their international listings. From April to July, 2010, we conducted ad hoc boat-based surveys (n=55) of inshore delphinids at seven sites across north-western Australia from Coral Bay in the south (23.1°S: 113.8°E) to Cable Beach in the north (17.9°S: 122.2°E). We documented the locations of these three species from which we obtained photoidentification and biopsy data, as well as reports of Australian Snubfin Dolphin sightings from researchers and community groups. The data from this limited field effort confirm that Indo-Pacific Humpback and Indo-Pacific Bottlenose Dolphins occur in the waters adjacent to each north-western Australian urban centre and show that the range of the Australian Snubfin Dolphin extends considerably further south-west than previously reported. Given the scale of coastal developments and the vulnerability of isolated cetacean populations to fragmentation or extirpation, assessments of the viability of dolphin populations are required. Our data suggest that the Australian Snubfin, Indo-Pacific Humpback and Indo-Pacific Bottlenose Dolphins need to be considered as likely to be impacted by coastal developments across north-western Australia.

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Smith, H. C., and K. R. Sprogis. "Seasonal feeding on giant cuttlefish (Sepia apama) by Indo-Pacific bottlenose dolphins (Tursiops aduncus) in south-western Australia." Australian Journal of Zoology 64, no. 1 (2016): 8. http://dx.doi.org/10.1071/zo15075.

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We report on observations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) feeding on giant cuttlefish (Sepia apama) from March 2007 to April 2013 in the temperate waters off Bunbury, south-western Australia. Seventeen feeding events were observed during the cooler months between July and September in relatively shallow coastal waters, with 12 dolphins identified as adult females. We observed behavioural sequences of complex prey-handling of cuttlefish where dolphins’ used multiple steps to remove the cuttlefish head, ink and cuttlebone before consuming the flesh of the cuttlefish mantle. Our study provides valuable information to the limited knowledge on the complex prey-handling by T. aduncus on cuttlefish in Australia, and is complementary to other known specialised foraging behaviours of bottlenose dolphins. This study also details a different behavioural sequence of cuttlefish prey-handling to that of the bottlenose dolphins in the Sado estuary, Portugal, where only the head is consumed, and to the Spencer Gulf, Australia, in that the dolphins in Bunbury carry the cuttlefish mantle over their rostrum before removing the cuttlebone. Information on S. apama in Bunbury is scarce, therefore studies on abundance, distribution and egg-laying sites are recommended in order to enable informed decision making and to understand the importance of S. apama to the diet of T. aduncus.

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Finn, Hugh, Rebecca Donaldson, and Michael Calver. "Feeding Flipper: a case study of a humandolphin interaction." Pacific Conservation Biology 14, no. 3 (2008): 215. http://dx.doi.org/10.1071/pc080215.

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We document a human-dolphin interaction involving the illegal feeding of wild Bottlenose Dolphins (Tursiops sp.) in Cockburn Sound, Western Australia from 1993-2003. In 1993 only one dolphin was considered conditioned to human interaction through food reinforcement. By 2001, 16% (n = 12) of the resident community of 74 adult dolphins were conditioned, and at least 14 dolphins were conditioned by 2003. Of the 13 conditioned dolphins of known sex, 11 (85%) were males. We observed conditioned dolphins initiating interactions by approaching recreational fishing boats and by residing for several hours at boat ramps and shore-based fishing sites. We only observed recreational fishers feeding dolphins, although anecdotal reports indicated additional feeding sources. We used belt transects to determine the densities of recreational boats and encounter rates for conditioned dolphins across habitats within Cockburn Sound. Encounter rates and boat densities were positively correlated, suggesting an association between recreational boat density and the ranging patterns of conditioned dolphins. This study demonstrates how illegal feeding interactions can intensify over time to affect a potentially biologically significant proportion of a local dolphin population. This emphasizes the need for early and pro-active intervention and demonstrates the value of longitudinal, individual-specific wildlife studies.

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Donaldson, R., H. Finn, and M. Calver. "Illegal feeding increases risk of boat-strike and entanglement in Bottlenose Dolphins in Perth, Western Australia." Pacific Conservation Biology 16, no. 3 (2010): 157. http://dx.doi.org/10.1071/pc100157.

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One reason for the legislative restrictions on feeding dolphins in many parts of the world is the putative increased risk of injury to dolphins conditioned to human interaction through food reinforcement. However, there are few empirical data to support this. Here, we present data for a population of Bottlenose Dolphins Tursiops sp. in Cockburn Sound, in the city of Perth, Western Australia, indicating higher incidence of boat strike injury and fishing line entanglement for dolphins conditioned to taking food from humans, compared to others in the population that were not conditioned. The data support prohibitions on feeding dolphins and rigorous enforcement of existing regulations.

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Stephens, Nahiid, Pádraig J. Duignan, Jianning Wang, John Bingham, Hugh Finn, Lars Bejder, Anthony P. Patterson, and Carly Holyoake. "Cetacean Morbillivirus in Coastal Indo-Pacific Bottlenose Dolphins, Western Australia." Emerging Infectious Diseases 20, no. 4 (April 2014): 672–76. http://dx.doi.org/10.3201/eid2004.131714.

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Nicholson, Krista, Lars Bejder, Simon J. Allen, Michael Krützen, and Kenneth H. Pollock. "Abundance, survival and temporary emigration of bottlenose dolphins (Tursiops sp.) off Useless Loop in the western gulf of Shark Bay, Western Australia." Marine and Freshwater Research 63, no. 11 (2012): 1059. http://dx.doi.org/10.1071/mf12210.

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Capture–recapture models were used to provide estimates of abundance, apparent survival and temporary emigration of Indo-Pacific bottlenose dolphins (Tursiops sp.) in a 226-km2 study area off Useless Loop in the western gulf of Shark Bay, Western Australia. Photo-identification data were collected during boat-based surveys in Austral autumn to early spring (April–September) from 2007 to 2011. Abundance estimates varied from 115 (s.e. 5.2, 95% CI 105–126) individuals in 2008 to 208 (s.e. 17.3, 95% CI 177–245) individuals in 2010. The variability in abundance estimates is likely to be a reflection of how individuals used the study area, rather than fluctuations in true population size. The best fitting capture–recapture model suggested a random temporary emigration pattern and, when coupled with relatively high temporary emigration rates (0.33 (s.e. 0.07) – 0.66 (s.e. 0.05)) indicated that the study area did not cover the entire ranges of the photo-identified dolphins. Apparent survival rate is a product of true survival and permanent emigration and was estimated annually at 0.95 (s.e. 0.02). Since permanent emigration from the study area is unlikely, true survival was estimated to be close to 0.95. This study provides a robust baseline for future comparisons of dolphin demographics, which may be of importance should climate change or increasing anthropogenic activity affect this population.

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Smolker, Rachel A., and Richard C. Connor. "'Pop' Goes the Dolphin: a Vocalization Male Bottlenose Dolphins Produce During Consortships." Behaviour 133, no. 9-10 (1996): 643–62. http://dx.doi.org/10.1163/156853996x00404.

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AbstractStudies of dolphin communication have been hindered by the difficulty of localizing sounds underwater and thus identifying vocalizing individuals. Male bottlenose dolphins (Tursiops sp.; speckled form) in Shark Bay, Western Australia produce a vocalization we call 'pops'. Pops are narrow-band, low frequency pulses with peak energy between 300 and 3000 Hz and are typically produced in trains of 3-30 pops at rates of 6-12 pops/s. Observations on the pop vocalization and associated behavior were made as part of a long-term study of bottlenose dolphins in Shark Bay. During 1987-88 seven dolphins, including three males, frequented a shallow water area where they were daily provisioned with fish by tourists and fishermen. The three males often produced pops when accompanied by single female consorts into the shallows. Fortuitously, the males often remained at the surface where pops were audible in air, enabling us to identify the popping individual. All 12 of the female consorts in the study turned in towards males at a higher rate when the males were popping than when they were not popping. All 19 occurrences of one form of aggression, 'head-jerks', were associated with pops. We conclude that pops are a threat vocalization which induces the female to remain close to the popping male during consortships.

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Chabanne, Delphine, Hugh Finn, Chandra Salgado-Kent, and Lars Bedjer. "Identification of a resident community of bottlenose dolphins (Tursiops aduncus) in the Swan Canning Riverpark, Western Australia, using behavioural information." Pacific Conservation Biology 18, no. 4 (2012): 247. http://dx.doi.org/10.1071/pc120247.

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Identifying appropriate management units is vital for wildlife management. Here we investigate one potential management unit — resident communities of bottlenose dolphins — using information from ranging, occupancy, and association patterns. We identify a resident community of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the Swan Canning Riverpark, Western Australia based on: ranging patterns, sighting rates, Lagged Identification Rates (LIR), and three measures of social affinity and structure (Simple Ratio Index, preferred dyadic association analyses, and Lagged Association Rates (LAR)). The analyses yielded an estimated ‘community size’ of 17–18 individuals (excluding calves). High seasonal sighting rates (> 0.75 sightings per season) and a long mean residence time (ca. nine years) indicated year-round residency. The model best-fitting the LIR (emigration and mortality) also supported this. The social structure of dolphins was species-typical, characterized by significant dyadic associations within agesex classes (permutation test; P < 0.001), stronger associations among adult males than among adult females (LAR males > LAR females), and temporally stable associations (LAR > null LAR). Constant companions or long-lasting association models best explained adult male and female LARs. While behavioural information identified a resident community in the Riverpark, genetic and demographic information is needed to assess its appropriateness as a management unit.

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Vollmer, Nicole L., Lee-Ann C. Hayek, Michael R. Heithaus, and Richard C. Connor. "Further evidence of a context-specific agonistic signal in bottlenose dolphins: the influence of consortships and group size on the pop vocalization." Behaviour 152, no. 14 (2015): 1979–2000. http://dx.doi.org/10.1163/1568539x-00003311.

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Pops are a low-frequency, pulsed vocalization produced by Indo-Pacific bottlenose dolphins (Tursiopscf.aduncus) in Shark Bay, Western Australia and are often heard when male alliances are consorting or ‘herding’ a female. Previous research indicated that pops produced in this context are an agonistic ‘come-hither’ demand produced by males and directed at female consorts. Here we examine pop occurrence during focal follows on bottlenose dolphin alliances with and without female consorts present. Regression analysis was conducted to determine if pop numbers were higher in the presence of female consorts, and if variables including group size alone and the interaction between presence/absence of a consortship and group size, influenced pop production. While the presence or absence of a consortship significantly affected the number of pops, average group size had no significant effect on pop production. Our research provides further evidence that the pop vocalization plays an important role in consortships.

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Kopps, Anna M., Corinne Y. Ackermann, William B. Sherwin, Simon J. Allen, Lars Bejder, and Michael Krützen. "Cultural transmission of tool use combined with habitat specializations leads to fine-scale genetic structure in bottlenose dolphins." Proceedings of the Royal Society B: Biological Sciences 281, no. 1782 (May 7, 2014): 20133245. http://dx.doi.org/10.1098/rspb.2013.3245.

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Socially learned behaviours leading to genetic population structure have rarely been described outside humans. Here, we provide evidence of fine-scale genetic structure that has probably arisen based on socially transmitted behaviours in bottlenose dolphins ( Tursiops sp.) in western Shark Bay, Western Australia. We argue that vertical social transmission in different habitats has led to significant geographical genetic structure of mitochondrial DNA (mtDNA) haplotypes. Dolphins with mtDNA haplotypes E or F are found predominantly in deep (more than 10 m) channel habitat, while dolphins with a third haplotype (H) are found predominantly in shallow habitat (less than 10 m), indicating a strong haplotype–habitat correlation. Some dolphins in the deep habitat engage in a foraging strategy using tools. These ‘sponging’ dolphins are members of one matriline, carrying haplotype E. This pattern is consistent with what had been demonstrated previously at another research site in Shark Bay, where vertical social transmission of sponging had been shown using multiple lines of evidence. Using an individual-based model, we found support that in western Shark Bay, socially transmitted specializations may have led to the observed genetic structure. The reported genetic structure appears to present an example of cultural hitchhiking of mtDNA haplotypes on socially transmitted foraging strategies, suggesting that, as in humans, genetic structure can be shaped through cultural transmission.

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Connor, Richard C., Jana J. Watson-Capps, William B. Sherwin, and Michael Krützen. "A new level of complexity in the male alliance networks of Indian Ocean bottlenose dolphins ( Tursiops sp.)." Biology Letters 7, no. 4 (November 3, 2010): 623–26. http://dx.doi.org/10.1098/rsbl.2010.0852.

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Male bottlenose dolphins in Shark Bay, Western Australia form two levels of alliances; two to three males cooperate to herd individual females and teams of greater than three males compete with other groups for females. Previous observation suggested two alliance tactics: small four to six member teams of relatives that formed stable pairs or trios and unrelated males in a large 14-member second-order alliance that had labile trio formation. Here, we present evidence for a third level of alliance formation, a continuum of second-order alliance sizes and no relationship between first-order alliance stability and second-order alliance size. These findings challenge the ‘two alliance tactics’ hypothesis and add to the evidence that Shark Bay male bottlenose dolphins engage in alliance formation that likely places considerable demands on their social cognition.

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Randić, Srđan, Richard C. Connor, William B. Sherwin, and Michael Krützen. "A novel mammalian social structure in Indo-Pacific bottlenose dolphins ( Tursiops sp.): complex male alliances in an open social network." Proceedings of the Royal Society B: Biological Sciences 279, no. 1740 (March 28, 2012): 3083–90. http://dx.doi.org/10.1098/rspb.2012.0264.

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Terrestrial mammals with differentiated social relationships live in ‘semi-closed groups’ that occasionally accept new members emigrating from other groups. Bottlenose dolphins ( Tursiops sp.) in Shark Bay, Western Australia, exhibit a fission–fusion grouping pattern with strongly differentiated relationships, including nested male alliances. Previous studies failed to detect a group membership ‘boundary’, suggesting that the dolphins live in an open social network. However, two alternative hypotheses have not been excluded. The community defence model posits that the dolphins live in a large semi-closed ‘chimpanzee-like’ community defended by males and predicts that a dominant alliance(s) will range over the entire community range. The mating season defence model predicts that alliances will defend mating-season territories or sets of females. Here, both models are tested and rejected: no alliances ranged over the entire community range and alliances showed extensive overlap in mating season ranges and consorted females. The Shark Bay dolphins, therefore, present a combination of traits that is unique among mammals: complex male alliances in an open social network. The open social network of dolphins is linked to their relatively low costs of locomotion. This reveals a surprising and previously unrecognized convergence between adaptations reducing travel costs and complex intergroup–alliance relationships in dolphins, elephants and humans.

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Senigaglia, Valeria, and Lars Bejder. "Pregnancy Cravings: Visitation at a Food-Provisioning Site is Driven by the Reproductive Status of Bottlenose Dolphins." Tourism in Marine Environments 15, no. 3 (October 14, 2020): 237–48. http://dx.doi.org/10.3727/154427320x15943283422072.

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Marine wildlife tourism attractions often use food rewards to ensure close-up encounters with freeranging animals. In Bunbury, Western Australia, the Dolphin Discovery Centre (DDC) conducts a foodprovision program where bottlenose dolphins (N = 22; between 2000 and 2018) are offered food rewards to encourage their visitation at a beach in front of the DDC. We used historical records on individual beach visits by adult female dolphins collected by the DDC from 2000 to 2018 to develop generalized mixed effects models (GLMM) to test whether the frequency of beach visitation was influenced by their reproductive status (pregnant, lactating, nonreproductive) or climatic events (El Niño-Southern Oscillation phases) that could affect prey availability. We also quantified the behavioral budget of dolphins during food-provisioning sessions and documented intra- and interspecific aggressive behaviors using individual focal follows collected in 2017–2018. Provisioned females spend most of the time resting within the interaction area (66.3%) and aggressive interactions arise as a consequence of dominance behavior over food access. Visitation rates were most influenced by reproductive status with pregnant and lactating females visiting the provisioning area more frequently (z = 2.085, p = 0.037 and z = 2.437, p = 0.014, respectively). Females that frequently visit the provisioning area expose their dependent calves to regular human interactions at an early age when they are more susceptible to behavioral conditioning. Such experiences could cause the loss of awareness towards humans and promote maladaptive behaviors such as begging that increase risk of entanglement in fishing gear, boat strikes, and propeller injuries.

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Mann, Janet, Andrew F. Richards, Rachel A. Smolker, and Richard C. Connor. "Patterns of Female Attractiveness in Indian Ocean Bottlenose Dolphins." Behaviour 133, no. 1-2 (1996): 37–69. http://dx.doi.org/10.1163/156853996x00026.

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AbstractHormonal profiles of captive individuals show that bottlenose dolphins (Tursiops spp.) are seasonally polyoestrous, but little is known of reproductive behaviour among free-ranging bottlenose dolphins. In Shark Bay, Western Australia, we have documented for the first time patterns of female attractiveness that may correspond to multiple oestrous cycles. Male bottlenose dolphins in stable alliances of 2-3 individuals form temporary consortships with individual females. Consortships often are established and maintained by aggressive herding. Consortships are associated with reproduction and are a useful measure of a female's attractiveness. Following reproduction, females may become attractive to males when their surviving calf is about 2-2.5 years old or within 1-2 weeks of losing an infant. Individual females are attractive to males for variable periods extending over a number of months, both within and outside of the main breeding season. The duration of attractive periods is greater during breeding season months than during the preceding months. Males sometimes are attracted to females for periods exceeding the reported duration of rising estrogen levels during the follicular stage of the oestrous cycle. Males occasionally have consorted or otherwise been attracted to females in several unusual contexts, including late pregnancy, the first two weeks after parturition, and the day after the loss of a nursing infant. Individual females were consorted by up to 13 males during the season they conceived, supporting predictions of a promiscuous mating system in bottlenose dolphins. Thus, consorting is a strategy by males to monopolize females, but not a completely successful one. Multiple cycling by female bottlenose dolphins may be a strategy to avoid being monopolized by particular males. Given the duration and agonistic nature of many consortships, the benefits to females of such a costly strategy are not obvious. Multiple cycling may reduce the risk of infanticide by males or allow females to mate with preferred males after being monopolized by less desirable males.

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Bizzozzero, M. R., S. J. Allen, L. Gerber, S. Wild, S. L. King, R. C. Connor, W. R. Friedman, S. Wittwer, and M. Krützen. "Tool use and social homophily among male bottlenose dolphins." Proceedings of the Royal Society B: Biological Sciences 286, no. 1904 (June 12, 2019): 20190898. http://dx.doi.org/10.1098/rspb.2019.0898.

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Homophilous behaviour plays a central role in the formation of human friendships. Individuals form social ties with others that show similar phenotypic traits, independently of relatedness. Evidence of such homophily can be found in bottlenose dolphins ( Tursiops aduncus ) in Shark Bay, Western Australia, where females that use marine sponges as foraging tools often associate with other females that use sponges. ‘Sponging’ is a socially learned, time-consuming behaviour, transmitted from mother to calf. Previous research illustrated a strong female bias in adopting this technique. The lower propensity for males to engage in sponging may be due to its incompatibility with adult male-specific behaviours, particularly the formation of multi-level alliances. However, the link between sponging and male behaviour has never been formally tested. Here, we show that male spongers associated significantly more often with other male spongers irrespective of their level of relatedness. Male spongers spent significantly more time foraging, and less time resting and travelling, than did male non-spongers. Interestingly, we found no difference in time spent socializing. Our study provides novel insights into the relationship between tool use and activity budgets of male dolphins, and indicates social homophily in the second-order alliance composition of tool-using bottlenose dolphins.

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O'Brien, O., S. J. Allen, M. Krützen, and R. C. Connor. "Alliance-specific habitat selection by male Indo-Pacific bottlenose dolphins in Shark Bay, Western Australia." Animal Behaviour 164 (June 2020): 39–49. http://dx.doi.org/10.1016/j.anbehav.2020.03.014.

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Preen, A. R., H. Marsh, I. R. Lawler, R. I. T. Prince, and R. Shepherd. "Distribution and Abundance of Dugongs, Turtles, Dolphins and other Megafauna in Shark Bay, Ningaloo Reef and Exmouth Gulf, Western Australia." Wildlife Research 24, no. 2 (1997): 185. http://dx.doi.org/10.1071/wr95078.

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Strip-transect aerial surveys of Shark Bay, Ningaloo Reef and Exmouth Gulf were conducted during the winters of 1989 and 1994. These surveys were designed primarily to estimate the abundance and distribution of dugongs, although they also allowed sea turtles and dolphins, and, to a lesser extent, whales, manta rays and whale sharks to be surveyed. Shark Bay contains a large population of dugongs that is of international significance. Estimates of approximately 10000 dugongs resulted from both surveys. The density of dugongs is the highest recorded in Australia and the Middle East, where these surveys have been conducted. Exmouth Gulf and Ningaloo Reef are also important dugong habitats, each supporting in the order of 1000 dugongs. The estimated number of turtles in Shark Bay is comparable to the number in Exmouth Gulf plus Ningaloo Reef (7000–9000). The density of turtles in Ningaloo Reef and, to a lesser extent, Exmouth Gulf is exceptionally high compared with most other areas that have been surveyed by the same technique. Shark Bay supports a substantial population of bottlenose dolphins (2000–3000 minimum estimate). Exmouth Gulf and Ningaloo Reef were not significant habitats for dolphins during the winter surveys. Substantial numbers of whales (primarily humpbacks) and manta rays occur in northern and western Shark Bay in winter. Ningaloo Reef is an important area for whale sharks and manta rays in autumn and winter. The Shark Bay Marine Park excludes much of the winter habitats of the large vertebrate fauna of Shark Bay. In 1989 and 1994, more than half of all the dugongs were seen outside the Marine Park (57·4 and 50·7%, respectively). Approximately one-third to one-half of turtles and dolphins were seen outside the Marine Park (in 1989 and 1994 respectively: turtles, 43 and 27%; dolphins, 47 and 32%). Almost all the whales and most of the manta rays were seen outside the Marine Park. Expansion of the Shark Bay Marine Park, to bring it into alignment with the marine section of the Shark Bay World Heritage Area, would facilitate the appropriate management of these populations. This would also simplify the State– Commonwealth collaboration necessary to meet the obligations of World Heritage listing. The coastal waters of Western Australia north of the surveyed area (over 6000 km of coastline) are relatively poorly known and surveys of their marine megafauna are required for wise planning and management.

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Gerber, Livia, Richard C. Connor, Stephanie L. King, Simon J. Allen, Samuel Wittwer, Manuela R. Bizzozzero, Whitney R. Friedman, et al. "Affiliation history and age similarity predict alliance formation in adult male bottlenose dolphins." Behavioral Ecology 31, no. 2 (November 28, 2019): 361–70. http://dx.doi.org/10.1093/beheco/arz195.

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Abstract Male alliances are an intriguing phenomenon in the context of reproduction since, in most taxa, males compete over an indivisible resource, female fertilization. Adult male bottlenose dolphins (Tursiops aduncus) in Shark Bay, Western Australia, form long-term, multilevel alliances to sequester estrus females. These alliances are therefore critical to male reproductive success. Yet, the long-term processes leading to the formation of such complex social bonds are still poorly understood. To identify the criteria by which male dolphins form social bonds with other males, we adopted a long-term approach by investigating the ontogeny of alliance formation. We followed the individual careers of 59 males for 14 years while they transitioned from adolescence (8–14 years of age) to adulthood (15–21 years old). Analyzing their genetic relationships and social associations in both age groups, we found that the vast majority of social bonds present in adolescence persisted through time. Male associations in early life predict alliance partners as adults. Kinship patterns explained associations during adolescence but not during adulthood. Instead, adult males associated with males of similar age. Our findings suggest that social bonds among peers, rather than kinship, play a central role in the development of adult male polyadic cooperation in dolphins.

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Sargeant, B. L., J. Mann, P. Berggren, and M. Krützen. "Specialization and development of beach hunting, a rare foraging behavior, by wild bottlenose dolphins (Tursiops sp.)." Canadian Journal of Zoology 83, no. 11 (November 1, 2005): 1400–1410. http://dx.doi.org/10.1139/z05-136.

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Foraging behaviors of bottlenose dolphins vary within and among populations, but few studies attempt to address the causes of individual variation in foraging behavior. We examined how ecological, social, and developmental factors relate to the use of a rare foraging tactic by wild bottlenose dolphins (Tursiops sp. Gervais, 1855) in Shark Bay, Western Australia. Beach hunting involves partial and nearly complete stranding on beach shores. Over 10 years of observation, only four adults and their calves were observed beach hunting in more than 1 year. Of two adult beach hunters observed in detail, one was more specialized in beach hunting than the other, indicating substantial flexibility in degree of use. Only calves born to beach hunters developed the tactic, although complete stranding was not observed at least up to 5 years of age. Beach hunters used shallow, inshore habitats significantly more than others and were more likely to hunt during incoming tide. Mitochondrial DNA haplotypes were not consistent with strict matrilineal transmission. Thus, beach hunting likely involves vertical social learning by calves, while individual, horizontal, and (or) oblique learning may occur among individuals who frequent coastal habitats.

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Ward, Rhianne, Iain Parnum, Christine Erbe, and Chandra Salgado-Kent. "Whistle Characteristics of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in the Fremantle Inner Harbour, Western Australia." Acoustics Australia 44, no. 1 (January 26, 2016): 159–69. http://dx.doi.org/10.1007/s40857-015-0041-4.

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Smolker, Rachel A., Andrew F. Richards, Richard C. Connor, and John W. Pepper. "Sex Differences in Patterns of Association Among Indian Ocean Bottlenose Dolphins." Behaviour 123, no. 1-2 (1992): 38–69. http://dx.doi.org/10.1163/156853992x00101.

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AbstractPatterns of association among bottlenose dolphins resident in Shark Bay, Western Australia were analyzed using party membership data. Parties contained an average of 4.8 individuals, but party size and composition were unstable. While these temporary parties often contained both males and females, long term consistent associations generally were between members of the same sex. The highest association coefficients, resulting from very frequent co-occurrence within parties were between males and between mothers and offspring. Males formed subgroups of two or three individuals who consistently associated with each other, and these were stable over periods of at least seven years in some cases. Male subgroups preferentially associated with particular other male subgroups. Females associated most consistently with other females, although not to the same extent as some males. Female associations were better described as a network rather than discrete subgroups. Male-female associations were generally inconsistent and depended in part on female reproductive state. Mothers and their offspring associated very consistently for at least 4 years.

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Kopps, Anna M., Michael Krützen, Simon J. Allen, Kathrin Bacher, and William B. Sherwin. "Characterizing the socially transmitted foraging tactic “sponging” by bottlenose dolphins (Tursiopssp.) in the western gulf of Shark Bay, Western Australia." Marine Mammal Science 30, no. 3 (December 10, 2013): 847–63. http://dx.doi.org/10.1111/mms.12089.

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Allen, S. J., L. Bejder, and M. Krützen. "Why do Indo-Pacific bottlenose dolphins (Tursiops sp.) carry conch shells (Turbinella sp.) in Shark Bay, Western Australia?" Marine Mammal Science 27, no. 2 (August 26, 2010): 449–54. http://dx.doi.org/10.1111/j.1748-7692.2010.00409.x.

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Heithaus, Michael R. "SHARK ATTACKS ON BOTTLENOSE DOLPHINS (TURSIOPS ADUNCUS) IN SHARK BAY, WESTERN AUSTRALIA: ATTACK RATE, BITE SCAR FREQUENCIES, AND ATTACK SEASONALITY." Marine Mammal Science 17, no. 3 (July 2001): 526–39. http://dx.doi.org/10.1111/j.1748-7692.2001.tb01002.x.

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Erbe, Christine, Chandra Salgado-Kent, Simone de Winter, Sarah Marley, and Rhianne Ward. "Matching Signature Whistles with Photo-Identification of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in the Fremantle Inner Harbour, Western Australia." Acoustics Australia 48, no. 1 (February 4, 2020): 23–38. http://dx.doi.org/10.1007/s40857-020-00178-2.

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Coscarella, Mariano A., Silvana L. Dans, Mariana Degrati, Griselda V. Garaffo, and Enrique A. Crespo. "Bottlenose dolphins at the southern extreme of the south-western Atlantic: local population decline?" Journal of the Marine Biological Association of the United Kingdom 92, no. 8 (December 6, 2011): 1843–49. http://dx.doi.org/10.1017/s0025315411001901.

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The management scheme of Marine Protected Areas (MPAs) includes monitoring protocols but such activities are not always carried out. This is the case for Golfo San José, a MPA in northern Patagonia, Argentina. It was created in 1975 for the protection of the southern right whale (Eubalaena australis) breeding grounds. Other components of the system, such as dolphin populations have received little attention. This study is the first attempt to estimate sighting rates, group size and overall abundance of a bottlenose dolphin (Tursiops truncatus) population in Golfo San José and adjacent areas after 30 years. An analysis of the seasonal sighting rates indicates that bottlenose dolphins were present in the study area throughout the year but a decline in group size and abundance and major shift in distribution was detected when compared with previous published reports. The settlement of the MPA failed to secure the persistence of the bottlenose dolphin population within its boundaries. Possible explanations for the detected decline are addressed including increased natural mortality, human induced mortality and disturbance, resources depletion and environmental shift.

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Krutzen, Michael, William B. Sherwin, Per Berggren, and Nick Gales. "POPULATION STRUCTURE IN AN INSHORE CETACEAN REVEALED BY MICROSATELLITE AND mtDNA ANALYSIS: BOTTLENOSE DOLPHINS (TURSIOPS SP.) IN SHARK BAY, WESTERN AUSTRALIA." Marine Mammal Science 20, no. 1 (January 2004): 28–47. http://dx.doi.org/10.1111/j.1748-7692.2004.tb01139.x.

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Krützen, Michael, Lynne M. Barré, Richard C. Connor, Janet Mann, and William B. Sherwin. "‘O father: where art thou?’- Paternity assessment in an open fission-fusion society of wild bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia." Molecular Ecology 13, no. 7 (April 22, 2004): 1975–90. http://dx.doi.org/10.1111/j.1365-294x.2004.02192.x.

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Machado, R., LR de Oliveira, PH Ott, M. Haimovici, LG Cardoso, L. Milmann, MA Romero, RA dos Santos, and M. Borges-Martins. "Trophic overlap between marine mammals and fisheries in subtropical waters in the western South Atlantic." Marine Ecology Progress Series 639 (April 2, 2020): 215–32. http://dx.doi.org/10.3354/meps13284.

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Marine mammals and humans are apex predators and both may compete for fish in ecosystems under continuous fishing pressure. We assessed the degree of trophic overlap between prey species found in the diet of 5 marine mammals (39 specimens of sea lion Otaria flavescens, 61 fur seals Arctocephalus australis, 76 franciscana dolphins Pontoporia blainvillei, 25 bottlenose dolphins Tursiops truncatus and 28 Lahille’s bottlenose dolphins T. gephyreus) and the catches of the 6 main commercial fishing gears used in southern Brazil (coastal gillnets, oceanic gillnets, purse seine, demersal pair trawling, bottom [single] trawl and double-rig trawling) between 1993 and 2016. An adjusted general overlap index indicated an overall moderate to high overlap. Specific overlap analysis showed that O. flavescens and T. truncatus presented high trophic relationships with fisheries, followed by T. gephyreus. Smaller interactions were observed for A. australis and P. blainvillei, even though they also exploit commercial fishing resources. Coastal gillnet and pair bottom trawling are the fisheries that most target the fish species favoured by O. flavescens, T. gephyreus and T. truncatus. The information presented in this study on trophic interactions may assist decision making for both fishery management and conservation measures for these apex predators. Commercial fishing activities are a major threat to marine mammals both regionally and globally. Current levels of fishing or its intensification may lead to dramatic changes in the coastal marine food web, including additional threats to coastal marine mammal populations in southern Brazil.

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Watson-Capps, Jana J., and Janet Mann. "The effects of aquaculture on bottlenose dolphin (Tursiops sp.) ranging in Shark Bay, Western Australia." Biological Conservation 124, no. 4 (August 2005): 519–26. http://dx.doi.org/10.1016/j.biocon.2005.03.001.

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Connor, R. C., and R. S. Smolker. "Habituated Dolphins (Tursiops sp.) in Western Australia." Journal of Mammalogy 66, no. 2 (May 31, 1985): 398–400. http://dx.doi.org/10.2307/1381260.

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Möller, LM, SJ Allen, and RG Harcourt. "Group Characteristics, Site Fidelity And Seasonal Abundance Of Bottlenosed Dolphins (Tursiops Aduncus) In Jervis Bay And Port Stephens, South-Eastern Australia." Australian Mammalogy 24, no. 1 (2002): 11. http://dx.doi.org/10.1071/am02011.

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Social organisation and abundance of bottlenose dolphins (Tursiops aduncus) in Jervis Bay (JB) and Port Stephens (PS), NSW, were investigated through behavioural/photo-identification surveys between May 1997 and April 2000. Mean group size was significantly larger at JB (12.3 � 0.87, n =167) compared to PS (6.8 � 0.37, n = 218). At both sites, groups were significantly larger when calves were present. Group size varied with activity, being smallest when feeding and largest when socialising. While mean group size of feeding dolphins did not vary between sites, travelling and socialising groups were significantly larger in JB. Site fidelity was assigned based on sighting rates and presence across seasons. Sighting rates varied significantly between areas, but the proportion of dolphins categorised as residents, occasional visitors and transients did not. Minimum abundance by season, based on mark-resighting of recognisable individuals, ranged from 61 � 3.2 to 108 � 7.1 in JB and 143 � 8.1 to 160 � 8.1 in PS. Differences in group size at the two sites may relate to social factors and/or human impacts, while differences in abundance may be associated with habitat size and complexity. The lack of dolphin matches between areas suggests that they represent distinct populations.

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Wild, Sonja, Simon J. Allen, Michael Krützen, Stephanie L. King, Livia Gerber, and William J. E. Hoppitt. "Multi-network-based diffusion analysis reveals vertical cultural transmission of sponge tool use within dolphin matrilines." Biology Letters 15, no. 7 (July 2019): 20190227. http://dx.doi.org/10.1098/rsbl.2019.0227.

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Behavioural differences among social groups can arise from differing ecological conditions, genetic predispositions and/or social learning. In the past, social learning has typically been inferred as responsible for the spread of behaviour by the exclusion of ecological and genetic factors. This ‘method of exclusion’ was used to infer that ‘sponging’, a foraging behaviour involving tool use in the bottlenose dolphin ( Tursiops aduncus ) population in Shark Bay, Western Australia, was socially transmitted. However, previous studies were limited in that they never fully accounted for alternative factors, and that social learning, ecology and genetics are not mutually exclusive in causing behavioural variation. Here, we quantified the importance of social learning on the diffusion of sponging, for the first time explicitly accounting for ecological and genetic factors, using a multi-network version of ‘network-based diffusion analysis'. Our results provide compelling support for previous findings that sponging is vertically socially transmitted from mother to (primarily female) offspring. This research illustrates the utility of social network analysis in elucidating the explanatory mechanisms behind the transmission of behaviour in wild animal populations.

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Brown, Alex, Lars Bejder, Daniele Cagnazzi, Guido J. Parra, and Simon J. Allen. "The North West Cape, Western Australia: A Potential Hotspot for Indo-Pacific Humpback Dolphins Sousa chinensis?" Pacific Conservation Biology 18, no. 4 (2012): 240. http://dx.doi.org/10.1071/pc120240.

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Indo-Pacific Humpback Dolphins Sousa chinensis (Humpback Dolphins hereafter) are listed as ‘near threatened’ on an international level and ‘migratory’ in Australian waters. There is limited information on Humpback Dolphins in Western Australian State waters, where the species remains unlisted. This lack of knowledge hinders the management and conservation of the species in a region of rapidly increasing coastal development. We conducted opportunistic boat-based surveys in April 2010 and present data on the location, size and composition of Humpback Dolphin groups encountered in the near-shore waters around the North West Cape, Western Australia. A total of 42 groups were encountered in a variety of habitats during 145 h on the water over ca. 80 km coastline. Group size ranged from 1 to 15, with a mean (± SE) of 5.3 (± 0.48) individuals. A total of 54 Humpback Dolphins were identified from photographs of the unique markings on their dorsal fins. The lack of a plateau in the cumulative discovery curve of identified individuals over the duration of the study suggests that only a subset of dolphins in the area was identified. This region is close to the south-western limit of the species’ Australian distribution and appears to represent an important location for Western Australian Humpback Dolphins. In light of increasing anthropogenic activity around the North West Cape and Exmouth Gulf, these preliminary findings from a limited survey effort indicate that further research into this population is required.

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Bejder, Lars, Amanda Hodgson, Neil Loneragan, and Simon Allen. "Coastal dolphins in north-western Australia: The need for re-evaluation of species listings and short-comings in the Environmental Impact Assessment process." Pacific Conservation Biology 18, no. 1 (2012): 22. http://dx.doi.org/10.1071/pc120022.

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LITTLE is known about the distribution, abundance and behavioural ecology of dolphins in the tropical north-west of Australia. This region is remote, and until recently, has had a relatively low human population. Two of Australia’s tropical coastal dolphin species, the Australian Snubfin Orcaella heinsohni and Indo-Pacific Humpback Dolphins Sousa chinensis (“Snubfin Dolphin” and “Humpback Dolphin”, hereafter) are known to occur in the region. Australia-wide, the only scientific publications on these two species come from a few studies from eastern Queensland, where both species live in “populations” of 50–100 individuals (Parra et al. 2006a; Cagnazzi et al. 2009) that are genetically isolated from one another (Parra 2011); have small home ranges; and are found in near-shore areas, typically within 3- 5 km of the coastline (Parra 2006; Parra et al. 2002, 2004, 2006a,b; Cagnazzi et al. 2009). In eastern Australia, both species forage on coastal/estuarine fish and cephalopods, which is further evidence of their reliance on the near-shore environment (Parra and Jedensjö 2009). According to population sizes in Queensland, and the extent of potentially suitable habitat along the north-west coast, the total numbers in Western Australia are likely to be in the low thousands of individuals (i.e., < 5000). The combination of these life-history characteristics may render Snubfin and Humpback Dolphins particularly vulnerable to local extinctions due to human activities such as habitat modification and increased shipping and boating activity (Frankham 2005; O’Grady et al. 2006). In this Essay, we review the current extent of coastal developments in the waters of north-west Australia. Then we discuss the conservation and management implications of this in relation to coastal dolphins, particularly Snubfin and Humpback Dolphins. We also appraise the current, non-targeted methods being used to survey marine mammal populations for environmental impact assessments (EIAs), highlighting their inadequacy for coastal dolphins. Finally, we make recommendations that should improve government decision making processes for the long term conservation of these two species.

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Sleeman, Jai C., Mark G. Meekan, Steven G. Wilson, Curt K. S. Jenner, Micheline N. Jenner, Guy S. Boggs, Craig C. Steinberg, and Corey J. A. Bradshaw. "Biophysical correlates of relative abundances of marine megafauna at Ningaloo Reef, Western Australia." Marine and Freshwater Research 58, no. 7 (2007): 608. http://dx.doi.org/10.1071/mf06213.

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Changes in the relative abundance of marine megafauna (whales, dolphins, sharks, turtles, manta rays, dugongs) from aerial survey sightings in the waters adjacent to Ningaloo Reef between June 2000 and April 2002 are described. Generalised linear models were used to explore relationships between different trophic guilds of animals (based on animal sighting biomass estimates) and biophysical features of the oceanscape that were likely to indicate foraging habitats (regions of primary/secondary production) including sea surface temperature (SST), SST gradient, chlorophyll-a (Chl-a), bathymetry (BTH) and bathymetry gradient (BTHg). Relative biomass of krill feeders (i.e. minke whales, whale sharks, manta rays) were related to SST, Chl-a and bathymetry (model [AICc] weight = 0.45) and the model combining these variables explained a relatively large amount (32.3%) of the variation in relative biomass. Relative biomass of fish/cephalopod feeders (dolphins, sharks) were weakly correlated with changes in SST, whereas that of other invertebrate/macroalgal feeders (turtles, dugong) was weakly correlated with changes in steepness of the shelf (bathymetry gradient). Our results indicate that biophysical variables describe only a small proportion of the variance in the relative abundance and biomass of marine megafauna at Ningaloo reef.

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Bell, CH, CM Kemper, and JG Conran. "Common Dolphins (Delphinus Delphis) In Southern Australia: A Morphometric Study." Australian Mammalogy 24, no. 1 (2002): 1. http://dx.doi.org/10.1071/am02001.

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Examination of 211 Delphinus specimens from the coasts of Western Australia to New South Wales, including Tasmania, was conducted using 62 quantitative and 11 qualitative variables. After refining the dataset, multivariate analyses were performed on 130 cranially mature specimens using 21 cranial variables. MANOVA showed males to be slightly larger than females, but with substantial overlap, allowing analyses to combine genders. UPGMA Cluster Analysis and MDS Ordination showed three largely overlapping groups based on a size gradient. K-means analysis of these groups found no significant differences and confirmed a size gradient. Discriminant analysis of specimens grouped by geography and water depth showed a tendency for large skulls to be from coasts adjacent to deep water and small skulls from shallow water coasts. Cranial measurements were significant, postcranial measurements and features were not. Tooth counts were within the range for D. delphis for all specimens examined. This study confirms genetic evidence for a single continuously variable species (Delphinus delphis Linnaeus, 1758) in southern Australian waters. Compared with either D. delphis or D. capensis from the eastern North Pacific, the skulls of D. delphis in southern Australia were more variable for many characters.

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Frère, Céline H., Peter T. Hale, Lindsay Porter, Victor G. Cockcroft, and Merel L. Dalebout. "Phylogenetic analysis of mtDNA sequences suggests revision of humpback dolphin (Sousa spp.) taxonomy is needed." Marine and Freshwater Research 59, no. 3 (2008): 259. http://dx.doi.org/10.1071/mf07120.

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Humpback dolphins (Sousa spp.) have a wide distribution in the tropical Atlantic and Indo-Pacific Oceans and a confused taxonomy. Morphological assessments suggest three species groupings – Sousa teuszii (eastern Atlantic), Sousa plumbea (western Indo-Pacific), and Sousa chinensis (eastern Indo-Pacific) – but most taxonomies recognise only two species – S. chinensis (Indo-Pacific), and S. teuszii (Atlantic). To investigate phylogenetic relationships, mitochondrial DNA control region sequences (338 base pairs) from 72 Sousa representing three populations in the Indo-Pacific (South Africa: S. plumbea, n = 23; China: S. chinensis, n = 19; and Australia: S. chinensis, n = 28), and S. teuszii in the Atlantic (Mauritania, n = 2) were generated. All three Indo-Pacific populations formed robust, monophyletic clades with high bootstrap (BS) and Bayesian posterior probability (BPP) scores. Surprisingly, humpback dolphins from South Africa and China formed a strongly-supported clade with the Atlantic S. teuszii (BS 63%, BPP 0.92) to the exclusion of animals from Australia. Genetic divergence between animals from China and Australia (DA = 8.4% ± 2.47%) was greater than between China and South Africa (DA = 5.1% ± 1.80%). These results strongly suggest that Australian humpback dolphins are not S. chinensis but may represent a distinct species in their own right.

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Young, EJ, J. Bannister, NB Buller, RJ Vaughan-Higgins, NS Stephens, SD Whiting, L. Yeap, TL Miller, and KS Warren. "Streptococcus iniae associated mass marine fish kill off Western Australia." Diseases of Aquatic Organisms 142 (December 17, 2020): 197–201. http://dx.doi.org/10.3354/dao03545.

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Streptococcus iniae causes high mortality in cultured and wild fish stocks globally. Since the first report in captive Amazon river dolphins Inia geoffrensis in 1976, it has emerged in finfish across all continents except Antarctica. In March 2016, an estimated 17000 fish were observed dead and dying along a remote 70 km stretch of the Kimberley coastline north of Broome, Western Australia. Affected species included finfish (lionfish Pterois volitans, angelfish Pomacanthus sp., stripey snapper Lutjanus carponotatus, sand bass Psammoperca waigiensis, yellowtail grunter Amniataba caudavittata, damselfish Pomacentridae sp.), flatback sea turtles Natator depressus, and olive (Aipysurus laevis) and black-ringed (Hydrelaps darwiniensis) sea snakes. Moribund fish collected during the event exhibited exophthalmia and abnormal behaviour, such as spiralling on the surface or within the water column. Subsequent histopathological examination of 2 fish species revealed bacterial septicaemia with chains of Gram-positive cocci seen in multiple organs and within brain tissue. S. iniae was isolated and identified by bacterial culture, species-specific PCR, Matrix-Assisted Laser Desorption Ionisation Time-Of-Flight (MALDI-TOF) and biochemical testing. This is the first report of S. iniae associated with a major multi-species wild marine fish kill in Australia. Extreme weather events in the region including a marked decrease in water temperatures, followed by an extended period of above-average coastal water temperatures, were implicated as stressors potentially contributing to this outbreak.

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Leslie, Matthew S., and Phillip A. Morin. "Structure and phylogeography of two tropical predators, spinner ( Stenella longirostris ) and pantropical spotted ( S. attenuata ) dolphins, from SNP data." Royal Society Open Science 5, no. 4 (April 2018): 171615. http://dx.doi.org/10.1098/rsos.171615.

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Little is known about global patterns of genetic connectivity in pelagic dolphins, including how circumtropical pelagic dolphins spread globally following the rapid and recent radiation of the subfamily delphininae. In this study, we tested phylogeographic hypotheses for two circumtropical species, the spinner dolphin ( Stenella longirostris ) and the pantropical spotted dolphin ( Stenella attenuata ), using more than 3000 nuclear DNA single nucleotide polymorphisms (SNPs) in each species. Analyses for population structure indicated significant genetic differentiation between almost all subspecies and populations in both species. Bayesian phylogeographic analyses of spinner dolphins showed deep divergence between Indo-Pacific, Atlantic and eastern tropical Pacific Ocean (ETP) lineages. Despite high morphological variation, our results show very close relationships between endemic ETP spinner subspecies in relation to global diversity. The dwarf spinner dolphin is a monophyletic subspecies nested within a major clade of pantropical spinner dolphins from the Indian and western Pacific Ocean populations. Population-level division among the dwarf spinner dolphins was detected—with the northern Australia population being very different from that in Indonesia. In contrast to spinner dolphins, the major boundary for spotted dolphins is between offshore and coastal habitats in the ETP, supporting the current subspecies-level taxonomy. Comparing these species underscores the different scale at which population structure can arise, even in species that are similar in habitat (i.e. pelagic) and distribution.

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Isaac, Jo. "The North West Cape, Western Australia: A Potential Hotspot for Indo-Pacific Humpback Dolphins Sousa chinensis?" Pacific Conservation Biology 18, no. 4 (2012): 239. http://dx.doi.org/10.1071/pc120239.

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SAVING A Million Species is an emotive title for a book, and immediately raises a number of questions, including “Are a million species really at risk from climate change?”, “Which species are they?” and “How can we save them?”. This book attempts to tackle these critical questions, and more. Organized into six key parts, and with 20 chapters authored by many of the pre-eminent researchers in climate change and biodiversity science, Saving A Million Species is an ambitious book that addresses the most significant conservation crisis of our time. As a reference and a starting point for further chapters, Part I begins by introducing and dissecting the well-known paper by Thomas et al., “Extinction Risk from Climate Change”, published in Nature in 2004. Chris Thomas returns to arguably the most important paper of his career, and scrutinizes the methodologies and limitations of that first analysis. Chapter 3 goes on to discuss the implications and fallout from the paper, including subsequent changes in policy around the world and the incorporation of extinction risk from climate change into threatened species listings.

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Brown, Alexander M., Anna M. Kopps, Simon J. Allen, Lars Bejder, Bethan Littleford-Colquhoun, Guido J. Parra, Daniele Cagnazzi, Deborah Thiele, Carol Palmer, and Celine H. Frère. "Population Differentiation and Hybridisation of Australian Snubfin (Orcaella heinsohni) and Indo-Pacific Humpback (Sousa chinensis) Dolphins in North-Western Australia." PLoS ONE 9, no. 7 (July 2, 2014): e101427. http://dx.doi.org/10.1371/journal.pone.0101427.

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Hunt, Tim N., Simon J. Allen, Lars Bejder, and Guido J. Parra. "Assortative interactions revealed in a fission–fusion society of Australian humpback dolphins." Behavioral Ecology 30, no. 4 (March 12, 2019): 914–27. http://dx.doi.org/10.1093/beheco/arz029.

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Abstract Understanding individual interactions within a community or population provides valuable insight into its social system, ecology, and, ultimately, resilience against external stimuli. Here, we used photo-identification data, generalized affiliation indices, and social network analyses to investigate dyadic relationships, assortative interactions, and social clustering in the Australian humpback dolphin (Sousa sahulensis). Boat-based surveys were conducted between May 2013 and October 2015 around the North West Cape, Western Australia. Our results indicated a fission–fusion society, characterized by nonrandom dyadic relationships. Assortative interactions were identified both within and between sexes and were higher among members of the same sex, indicating same-sex preferred affiliations and sexual segregation. Assortative interactions by geographic locations were also identified, but with no evidence of distinct social communities or clusters or affiliations based on residency patterns. We noted high residency among females. Models of temporal patterns of association demonstrated variable levels of stability, including stable (preferred companionships) and fluid (casual acquaintances) associations. We also demonstrated some social avoidance. Our results point to greater social complexity than previously recognized for humpback dolphins and, along with knowledge of population size and habitat use, provide the necessary baseline upon which to assess the influence of increasing human activities on this endemic, Vulnerable species.

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Smith, Holly, Amy Samuels, and Stuart Bradley. "Reducing risky interactions between tourists and free-ranging dolphins (Tursiops sp.) in an artificial feeding program at Monkey Mia, Western Australia." Tourism Management 29, no. 5 (October 2008): 994–1001. http://dx.doi.org/10.1016/j.tourman.2008.01.001.

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Haughey, Rebecca, Timothy N. Hunt, Daniella Hanf, Cecilia Passadore, Ryan Baring, and Guido J. Parra. "Distribution and Habitat Preferences of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) Inhabiting Coastal Waters With Mixed Levels of Protection." Frontiers in Marine Science 8 (June 29, 2021). http://dx.doi.org/10.3389/fmars.2021.617518.

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Assessments of species distributions are crucial for informing conservation and management action. In this study, we used ensemble modelling to explain the distribution of Near Threatened Indo-Pacific (IP) bottlenose dolphins (Tursiops aduncus) in coastal waters at the North West Cape (NWC), Western Australia (WA), an area encompassing a marine protected area (MPA) and adjacent unprotected coastal waters. Analyses used dolphin sighting data collected during boat-based surveys conducted from 2013 to 2015 and 2018 to 2019. Overall, the distribution of IP bottlenose dolphins was best explained by distance to coast (up to 2,000 m) and distance to boat ramp (up to 7,000 m). Areas of high probability of occurrence for dolphins extended from the tip and down the eastern side of the NWC and overlapped with designated sanctuary zones as well as waters beyond the boundaries of the Ningaloo Marine Park (NMP). Distribution and habitat preferences varied slightly with season. In autumn, dolphin distribution was best explained by distance to coast and water depth with a higher likelihood of observing dolphins 1,000–2,000 m from the coast and in water depths of 7–10 m deep. During winter months, distance to coast (1,000–2,000 m) and sea surface temperature (SST) (21.5–23.5°C) were the most important explanatory variables, with presence in coastal lagoons to the west of the NWC more likely than other seasons. During spring, areas of moderate to high probability of dolphin occurrence were mainly located outside the NMP, with marine park zone (outside the NMP and Sanctuary zones within the NMP, the two zones with the highest probability of IP bottlenose dolphin occurrence) and water depth (waters 7–13 m deep) best explaining dolphin distribution. This study highlights the importance of inshore areas of the NWC for IP bottlenose dolphins and the potential vulnerability of this species to increasing and cumulative anthropogenic stressors associated with these areas. Results of this study should be considered in future zoning reviews and adaptive management efforts of the NMP allowing for effective management of this Near Threatened species.

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Marley, Sarah A., Christine Erbe, and Chandra P. Salgado Kent. "Underwater recordings of the whistles of bottlenose dolphins in Fremantle Inner Harbour, Western Australia." Scientific Data 4, no. 1 (September 12, 2017). http://dx.doi.org/10.1038/sdata.2017.126.

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King, Stephanie L., Richard C. Connor, Michael Krützen, and Simon J. Allen. "Cooperation-based concept formation in male bottlenose dolphins." Nature Communications 12, no. 1 (April 22, 2021). http://dx.doi.org/10.1038/s41467-021-22668-1.

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AbstractIn Shark Bay, Western Australia, male bottlenose dolphins form a complex nested alliance hierarchy. At the first level, pairs or trios of unrelated males cooperate to herd individual females. Multiple first-order alliances cooperate in teams (second-order alliances) in the pursuit and defence of females, and multiple teams also work together (third-order alliances). Yet it remains unknown how dolphins classify these nested alliance relationships. We use 30 years of behavioural data combined with 40 contemporary sound playback experiments to 14 allied males, recording responses with drone-mounted video and a hydrophone array. We show that males form a first-person social concept of cooperative team membership at the second-order alliance level, independently of first-order alliance history and current relationship strength across all three alliance levels. Such associative concepts develop through experience and likely played an important role in the cooperative behaviour of early humans. These results provide evidence that cooperation-based concepts are not unique to humans, occurring in other animal societies with extensive cooperation between non-kin.

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Senigaglia, V., F. Christiansen, K. R. Sprogis, J. Symons, and L. Bejder. "Food-provisioning negatively affects calf survival and female reproductive success in bottlenose dolphins." Scientific Reports 9, no. 1 (June 20, 2019). http://dx.doi.org/10.1038/s41598-019-45395-6.

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AbstractFood-provisioning of wildlife can facilitate reliable up-close encounters desirable by tourists and, consequently, tour operators. Food-provisioning can alter the natural behavior of an animal, encouraging adverse behavior (e.g. begging for food handouts), and affect the reproductive success and the viability of a population. Studies linking food-provisioning to reproductive success are limited due to the lack of long-term datasets available, especially for long-lived species such as marine mammals. In Bunbury, Western Australia, a state-licensed food-provisioning program offers fish handouts to a limited number of free-ranging bottlenose dolphins (Tursiops aduncus). Coupled with long-term historical data, this small (<200 individuals), resident dolphin population has been extensively studied for over ten years, offering an opportunity to examine the effect of food-provisioning on the reproductive success of females (ntotal = 63;nprovisioned females = 8). Female reproductive success was estimated as the number of weaned calves produced per reproductive years and calf survival at year one and three years old was investigated. The mean reproductive success of provisioned and non-provisioned females was compared using Bayes factor. We also used generalized linear models (GLMs) to examine female reproductive success in relation to the occurrence of food-provisioning, begging behavior and location (within the study area). Furthermore, we examined the influence of these variables and birth order and climatic fluctuations (e.g. El Niño Southern Oscillation) on calf survival. Bayes factor analyses (Bayes factor = 6.12) and results from the best fitting GLMs showed that female reproductive success and calf survival were negatively influenced by food-provisioning. The negative effects of food-provisioning, although only affecting a small proportion of the adult females’ population (13.2%), are of concern, especially given previous work showing that this population is declining.

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Chabanne, Delphine B. H., Simon J. Allen, William Bruce Sherwin, Hugh Finn, and Michael Krützen. "Inconsistency Between Socio-Spatial and Genetic Structure in a Coastal Dolphin Population." Frontiers in Marine Science 7 (January 14, 2021). http://dx.doi.org/10.3389/fmars.2020.617540.

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Identifying population structure and boundaries among communities of wildlife exposed to anthropogenic threats is key to successful conservation management. Previous studies on the demography, social and spatial structure of Indo-Pacific bottlenose dolphins (Tursiops aduncus) suggested four nearly discrete behavioral communities in Perth metropolitan waters, Western Australia. We investigated the genetic structure of these four communities using highly polymorphic microsatellite markers and part of the hypervariable segment of the mitochondrial control region. Overall, there was no evidence of spatial genetic structure. We found significant, yet very small genetic differentiation between some communities, most likely due to the presence of highly related individuals within these communities. Our findings of high levels of contemporary migration and highly related individuals among communities point toward a panmictic genetic population with continuous gene flow among each of the communities. In species with slow life histories and fission-fusion dynamics, such as Tursiops spp., genetic and socio-spatial structures may reflect different timescales. Thus, despite genetic similarity, each social community should be considered as a distinct ecological unit to be conserved because they are exposed to different anthropogenic threats and occur in different ecological habitats, social structure being as important as genetic information for immediate conservation management. The estuarine community, in particular, is highly vulnerable and appropriate conservation measures are needed in order to maintain its connectivity with the adjacent, semi-enclosed coastal communities.

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Haughey, Rebecca, Tim Hunt, Daniella Hanf, Robert William Rankin, and Guido J. Parra. "Photographic Capture-Recapture Analysis Reveals a Large Population of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) With Low Site Fidelity off the North West Cape, Western Australia." Frontiers in Marine Science 6 (January 28, 2020). http://dx.doi.org/10.3389/fmars.2019.00781.

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Journal articles on the topic 'Bottlenosed dolphins – Western Australia'

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