Simon J. Allen

University of Zurich | UZH · Department of Evolutionary Anthropology

In 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...

Human‐caused mortality of wildlife is a pervasive threat to biodiversity. Assessing the population‐level impact of fisheries bycatch and other human‐caused mortality of wildlife has typically relied upon deterministic methods. However, population declines are often accelerated by stochastic factors that are not accounted for in such conventional me...

The prevalence of small cetacean (including dolphins, porpoises and small odontocete whales) bycatch in fisheries worldwide remains an ongoing conservation and welfare challenge. Various mitigation methods have been implemented in attempts to reduce bycatch. Two such methods involve gear modification: placement of Bycatch Reduction Devices (BRDs) w...

Bottlenose dolphins (Tursiops spp.) are found in waters around Australia, with T. trun-catus typically occupying deeper, more oceanic habitat, while T. aduncus occur in shallower, coastal waters. Little is known about the colonization history of T. aduncus along the Western Australian coastline; however, it has been hypothesized that ex-tant popula...

Aerial surveys are frequently used to estimate the abundance of marine mammals, but their accuracy is dependent upon obtaining a measure of the availability of animals to visual detection. Existing methods for characterizing availability have limitations and do not necessarily reflect true availability. Here, we present a method of using small, ves...

For over a century, the evolution of animal play has sparked scientific curiosity. The prevalence of social play in juvenile mammals suggests that play is a beneficial behavior, potentially contributing to individual fitness. Yet evidence from wild animals supporting the long-hypothesized link between juvenile social play, adult behavior, and fitne...

Vocal communication is an emblematic feature of group-living animals, used to share information and strengthen social bonds. Vocalizations are also used to coordinate group-level behaviours in many taxa, but little is known of the factors that may influence vocal behaviour during cooperative acts. Allied male Indo-Pacific bottlenose dolphins (Tursi...

The social intelligence hypothesis holds that complex social relationships are the major selective force underlying the evolution of large brain size and intelligence. Complex social relationships are exemplified by coalitions and alliances that are mediated by affiliative behavior, resulting in differentiated but shifting relationships. Male Indo-...

Knowledge of an animal's chronological age is crucial for understanding and predicting population demographics, survival and reproduction, but accurate age determination for many wild animals remains challenging. Previous methods to estimate age require invasive procedures, such as tooth extraction to analyse growth layers, which are difficult to c...

Social structuring from assortative associations may affect individual fitness, as well as population-level processes. Gaining a broader understanding of social structure can improve our knowledge of social evolution and inform wildlife conservation. We investigated association patterns and community structure of female Indo-Pacific bottlenose dolp...

The photo-identification of uniquely marked individuals has revealed much about mammalian behaviour and social structure in recent decades. In bottlenose dolphins ( Tursiops spp.), for example, the long-term tracking of individuals has unveiled considerable variation in social structure among populations and various spatio-temporal aspects of group...

Efforts to understand human social evolution rely largely on comparisons with nonhuman primates. However, a population of bottlenose dolphins in Shark Bay, Western Australia, combines a chimpanzee-like fission-fusion grouping pattern, mating system, and life history with the only nonhuman example of strategic multilevel male alliances. Unrelated ma...

Abstract: Assessing the population-level impact of human-caused mortality of wildlife typically relies upon deterministic methods. However, population declines are often accelerated by stochastic factors that are not accounted for in such conventional methods. Building upon the widely applied Potential Biological Removal (PBR) equation, we introduc...

This is the supplementary material for our article "A stochastic model for estimating sustainable limits to wildlife mortality in a changing world" published in Conservation Biology (Manlik et al. 2022). This can be cited as: Manlik, O., Lacy, R. C., Sherwin, W. B., Finn, H., Loneragan, N. R., & Allen, S. J. (2022). A stochastic model for estimatin...

Vocal interactions are intrinsic features of social groups and can play a pivotal role in social bonding. Dunbar’s social bonding hypothesis posits that vocal exchanges evolved to ‘‘groom at a distance’’ when social groups became too large or complex for individuals to devote time to physical bonding activities. Tests of this hypothesis in non-huma...

Understanding determinants of differential reproductive success is at the core of evolutionary biology because of its connection to fitness. Early work has linked variation in reproductive success to differences in age,¹ rank,² or size,³,⁴ as well as habitat characteristics.⁵ More recently, studies in group-living taxa have revealed that social rel...

We are introducing a new population modelling approach for estimating sustainable limits to human-caused mortality. Our approach, termed ‘Maximum Sustainable Anthropogenic Mortality in Stochastic Environments’ (SAMSE), incorporates environmental and demographic stochasticity, including the dependency of offspring on their mothers.

Investigations into cooperative partner choice should consider both potential and realised partners, allowing for the comparison of traits across all those available. Male bottlenose dolphins form persisting multi-level alliances. Second-order alliances of 4-14 males are the core social unit, within which 2-3 males form first-order alliances to seq...

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 metropolit...

Increasing human activity along the coast has amplified the extinction risk of inshore delphinids. Informed selection and prioritisation of areas for the conservation of inshore delphinids requires a comprehensive understanding of their distribution and habitat use. In this study, we applied an ensemble species distribution modelling approach, comb...

Individuals and groups within the same population may differ in their use of resources. Also referred to as niche specialization, such differences can be documented through direct or indirect observation of resource or habitat use. Here, we examined selective habitat use in alliance-forming male Indo-Pacific bottlenose dolphins, Tursiops aduncus, i...

Cultural behavior, which is transmitted among conspecifics through social learning [1], is found across various taxa [2, 3, 4, 5, 6]. Vertical social transmission from parent to offspring [7] is thought to be adaptive because of the parental generation being more skilled than maturing individuals. It is found throughout the animal kingdom, particul...

Synchronous displays are hallmarks of many animal societies, ranging from the pulsing flashes of fireflies, to military marching in humans. Such displays are known to facilitate mate attraction or signal relationship quality. Across many taxa, synchronous male displays appear to be driven by competition, while synchronous displays in humans are tho...

Abstract: The viability of populations depends on metapopulation dynamics: the combination of reproduction and mortality within populations, as well as dispersal between populations. Population viability is also dependent on genetic diversity, which is essential for populations to adapt to environmental change. This study focuses on an Indo-Pacific...

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, mul-tilevel alliances to sequester estrus females. These alliances are therefore critical...

Coercive mate guarding, where males use aggression to control female movements, is a form of sexual coercion which functions to constrain female mate choice. Non-human primates, for example, herd females to keep them away from competing males, but male bottlenose dolphins (Tursiops aduncus) also herd females to keep them close to their alliance par...

Coalitions and alliances exemplify the core elements of conflict and cooperation in animal societies. Ecological influences on alliance formation are more readily attributed to within-species variation where phylogenetic signals are muted. Remarkably, male Indo-Pacific bottlenose dolphins in Shark Bay, Western Australia, exhibit systematic spatial...

The behavioral ecology of Tursiops aduncus (Indo-Pacific bottlenose dolphin) is usually reviewed alongside the much more widely studied T. truncatus (common bottlenose dolphin). However, the smaller, typically shallow water T. aduncus has been closely scrutinized in Australian and Japanese waters. As a result, there now exists a robust body of info...

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 'spongin...

Coercive mate guarding, where males use aggression to control female movements, is a form of sexual coercion which functions to constrain female mate choice. Non-human primates, for example, herd females to keep them away from competing males, but male bottlenose dolphins (Tursiops aduncus) also herd females to keep them close to their alliance par...

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 fora...

Manlik, O., Krützen, M., Kopps, A. M., Mann, J., Bejder, L., Allen, S. J., Frere, C., Connor, R.C., Sherwin, W. B. (2019). Data from: Is MHC diversity a better marker for conservation than neutral genetic diversity? A case study of two contrasting dolphin populations. Dryad Digital Repository. https ://doi.org/10.5061/dryad.73k278d

Genetic diversity is essential for populations to adapt to changing environments. Measures of genetic diversity are often based on selectively neutral markers, such as microsatellites. Genetic diversity to guide conservation management, however, is better reflected by adaptive markers, including genes of the major histocompatibility complex (MHC)....

This is the supplementary material to the article "Is MHC diversity a better marker for conservation than neutral genetic diversity? A case study of two contrasting dolphin population" (Manlik et al. 2019)

One of many challenges in the conservation of biodiversity is the recent trend in the frequency and intensity of extreme climatic events. The Shark Bay World Heritage Area, Western Australia, endured an unprecedented marine heatwave in 2011. Catastrophic losses of habitat-forming seagrass meadows followed, along with mass mortalities of invertebrat...

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, a...

The forecast for the viability of populations depends upon metapopulation dynamics: the combination of reproduction and mortality within populations, as well as dispersal between populations. This study focuses on an Indo‐Pacific bottlenose dolphin (Tursiops aduncus) population in coastal waters near Bunbury, Western Australia. Demographic modeling...

Cooperation between allied individuals and groups is ubiquitous in human societies, and vocal communication is known to play a key role in facilitating such complex human behaviors. In fact, complex communication may be a feature of the kind of social cognition required for the formation of social alliances, facilitating both partner choice and the...

Sexual displays enriched by object carrying serve to increase individual male fitness, yet are uncommon phenomena in the animal kingdom. While they have been documented in a variety of taxa, primarily birds, they are rare outside non-human mammals. Here, we document marine sponge presenting associated with visual and acoustic posturing found in sev...

Predation risk has a profound influence on the behavior of marine mammals, affecting grouping patterns and habitat use. Dolphins frequently bear evidence of shark bites, which can provide an indirect measure of predation pressure. Using photo-identification data, we investigated the prevalence of shark bites on three sympatric species of inshore do...

The incidental capture of wildlife in fishing gear presents a global conservation challenge. As a baseline to inform assessments of the impact of bycatch on bottlenose dolphins (Tursiops truncatus) interacting with an Australian trawl fishery, we conducted an aerial survey to estimate dolphin abundance across the fishery. Concurrently, we carried o...

This final report for the Western Australian Marine Science Institution (WAMSI) documents the findings of a collaborative project aiming to increase our understanding of the distribution, abundance and population connectivity of Australian snubfin (Orcaella heinsohni) and humpback (Sousa sahulenis) dolphins, including the development of new researc...

Within-species variation in social structure has attracted interest recently because of the potential to explore phenotypic plasticity and, specifically, how demographic and ecological variation influence social structure. Populations of bottlenose dolphins (Tursiops spp.) vary in male alliance formation, from no alliances to simple pairs to, in Sh...

The paucity of information on the recently described Australian humpback dolphin (Sousa sahulensis) has hindered assessment of its conservation status. Here, we applied capture-recapture models to photo-identification data collected during boat-based surveys between 2013 and 2015 to estimate the abundance, site fidelity and residence patterns of Au...

Two recent papers by Kuczaj et al. (Anim Cognit 18:543-550, 2015) and Eskelinen et al. (Anim Cognit 19:789-797, 2016) claim to have demonstrated that (i) bottlenose dolphins (Tursiops truncatus) cooperated to solve a novel task and (ii) vocal signals were important for coordinating these cooperative efforts. Although it is likely that bottlenose do...

The identification of species and population boundaries are important in both evolutionary biology and conservation. In recent years, new population genetic and computational methods for estimating population parameters and testing hypotheses in a quantitative manner have emerged. Using a Bayesian framework and a quantitative model-testing approach...

We present a Hierarchical Bayesian version of Pollock's Closed Robust Design for studying the survival, temporary migration, and abundance of marked animals. Through simulations and analyses of a bottlenose dolphin photo-identification dataset, we compare several estimation frameworks, including Maximum Likelihood estimation (ML), model-averaging b...

Inherent difficulties in determining the sex of free-ranging, sexually monomorphic species often prevents a sex-specific focus on estimating abundance, movement patterns and survival rates. This study provides insights into sex-specific population parameters of Indo-Pacific bottlenose dolphins (Tursiops aduncus). Systematic, boat-based photo-identi...

Assessing the abundance of wildlife populations is essential to their effective conservation and management. Concerns have been raised over the vulnerability of tropical inshore dolphins in waters off northern Australia to anthropogenic impacts on local populations, yet a lack of abundance data precludes assessment of their conservation status and...

An individual's fitness is determined by traits such as mate choice, reproductive output, resistance to parasites and survival to old age. The search for the genetic basis of fitness variation has until recently often relied on neutral genetic markers, including mitochondrial DNA and microsatellites. However, ecological and evolutionary processes r...

Marine tourism is a new frontier of late-capitalist transformation, generating more global revenue than aquaculture and fisheries combined. This transformation created whale-watching, a commercial tourism form that, despite recent critiques, has been accepted as non-consumptive activity. This paper uses four academic discourses to critique whale wa...

Determining the sex of free-ranging cetaceans can be challenging. Sexual dimorphism among external features may allow inferences on sex, but such patterns may be difficult to detect and are often confounded by age and geographic variation. Dorsal fin images of 107 female and 54 male Australian humpback dolphins, Sousa sahulensis, from Western Austr...

Assessments of incidental wildlife mortality resulting from fishing rarely account for unobserved by-catch. We assessed by-catch of protected and vulnerable wildlife species in an Australian trawl fishery by comparing in-trawl video footage with data collected by an on-board observer. Data were obtained from 44 commercial trawls with two different...

Little is known about the Australian snubfin (Orcaella heinsohni) and Indo-Pacific humpback (Sousa chinensis) dolphins ('snubfin' and 'humpback dolphins', hereafter) of north-western Australia. While both species are listed as 'near threatened' by the IUCN, data deficiencies are impeding rigorous assessment of their conservation status across Austr...

Culturally transmitted tool use has important ecological and evolutionary consequences and has been proposed as a significant driver of human evolution. Such evidence is still scarce in other animals. In cetaceans, tool use has been inferred using indirect evidence in one population of Indo-Pacific bottlenose dolphins (Tursiops sp.), where particul...

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 transm...

The bycatch of small cetaceans in commercial fisheries is a global wildlife management problem. We used data from skippers' logbooks and independent observers to assess common bottlenose dolphin (Tursiops truncatus) bycatch patterns between 2003 and 2009 in the Pilbara Trawl Fishery, Western Australia. Both datasets indicated that dolphins were cau...

Cetaceans have long held great significance in the lives of humans. This significance has been both practical and spiritual and is reflected in artefacts dating back some 10,000 years, in spoken myths and legends, in the writings of Greek and Roman philosophers and many more recent chroniclers of the encounters between humans and wildlife (Alpers,...

The incidental capture of common bottlenose dolphins (Tursiops truncatus) is an ongoing protected species management problem in the Pilbara Fish Trawl Interim Managed Fishery, Western Australia. We investigated this issue using four approaches: the analysis of skippers’ logbook and independent observer data on bycatch; underwater video of dolphins...

Little is known of inshore dolphin populations, particularly snubfin (Orcaella heinsohni) and humpback (Sousa chinensis) dolphins, in tropical north-western Australia. Studies elsewhere suggest that they are sensitive to habitat modification and vulnerable to localised extinctions. Both species are listed ‘near-threatened’ by the IUCN. In north-wes...

Individual foraging tactics are widespread in animals and have ecological and evolutionary implications. Indo-Pacific bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia, exhibit a foraging tactic involving tool use, called “sponging". Sponging is vertically, socially transmitted through the matriline and, to date, has been described...

Most studies of delphinid-trawler interactions have documented the surface behavior of dolphins feeding on discarded bycatch, but not their subsurface behavior around demersal trawl gear. Using video cameras mounted inside trawl nets, we recorded the subsurface behavior of common bottlenose dolphins (Tursiops truncatus) in a demersal fish trawl fis...

The Murdoch University Cetacean Research Unit is conducting research into marine mammal biology and ecology within a number of broad programs across Australia’s north-western bioregion. These programs include assessing: population dynamics and behaviour (abundance estimation, social structure, genetic structure and population connectivity); anthrop...

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 conse...

In Shark Bay, Western Australia, bottlenose dolphins Tursiops sp. carry conical sponges Echinodictyum mesenterinum on their rostra in the only documented cetacean foraging behaviour using a tool (‘sponging’). In this study, we examined the influence of various ecological factors on live sponge distribution and the occurrence of sponging in parts of...

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 c...

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 popul...

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 earl...

Indo-Pacific bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia, exhibit a remarkable array of foraging tactics within a single population (Mann and Sargeant 2003). Those described in some detail to date include: “kerplunking,” whereby dolphins scare fish out from vegetative cover with a percussive, bubbleforming tail slap in shallo...

An estimated 350 dolphins were incidentally caught between late 2003 and 2009 in the Pilbara trawl fishery of north-western Australia. Data from skipper logbooks and independent observers were used to assess spatial and temporal patterns of dolphin bycatch in this fishery. Both datasets indicated that dolphins were caught throughout all four of the...

Executive Summary Introduction Although Indo-Pacific bottlenose dolphins (Tursiops aduncus) are a valued component of the Swan-Canning Estuary and the Swan Canning Riverpark, little is known about the health and ecology of the small community of dolphins inhabiting the estuary. To improve the scientific basis for management, we examined the popula...

Remote video systems can be expensive, slow to deploy and the data recorded may not be available until the system has been retrieved. To overcome these issues, a rapid, non-destructive and cost-effective remote video and data management system was developed to record benthic habitats in Shark Bay, Western Australia. This system comprises a downward...