Article
| Article name | INVESTIGATING SOCIAL STRUCTURE OF TURSIOPS TRUNCATUS IN THE KARADAG STATE NATURE RESERVE (SOUTHEAST CRIMEA, BLACK SEA) USING INDIVIDUAL ACOUSTIC IDENTIFICATION DATA |
| Authors | Elena M. Panova, Researcher at the Marine Mammal Laboratory of the Shirshov Institute оf Oceanology, Russian Academy of Sciences (36 Nakhimovsky Prospekt, Moscow 117997, Russia); Research Associate at the Marine Mammal Laboratory of the T.I. Vyazemsky Karadag Scientific Station – Nature Reserve of RAS – Branch of А.О. Kovalevsky Institute of Biology of the Southern Seas of RAS (298188, Russia, Republic of Crimea, Feodosia, Kurortnoye, Nauki Street, 24); iD ORCID: https://orcid.org/0000-0002-9940-9855; e-mail: ye.panova@yandex.ru |
| Reference to article | Panova E.M., Logominova I.V., Litvin V.A. 2026. Investigating social structure of Tursiops truncatus in the Karadag State Nature Reserve (Southeast Crimea, Black Sea) using individual acoustic identification data. Nature Conservation Research 11(3): 73–83. https://dx.doi.org/10.24189/ncr.2026.020 |
| Section | Research articles |
| DOI | https://dx.doi.org/10.24189/ncr.2026.020 |
| Abstract | Alongside the traditional method of photo-identification, individual acoustic identification has emerged over the past decade as a useful tool in research on Tursiops truncatus (hereinafter – bottlenose dolphin). This approach relies on the recognition of individual animals via their unique calls, termed «signature whistles». To date, this method has been applied to several bottlenose dolphin populations to estimate their numbers and spatiotemporal distribution. In this study, we used three years (2022–2024) of individual acoustic identification data to investigate the social structure and individual associations within the Tursiops truncatus ponticus community, inhabiting the coastal waters of the Karadag State Nature Reserve in Southeast Crimea. Based on the encounter history of 114 unique signature whistle types, considered as individual «acoustic markers» of bottlenose dolphins, we calculated dyadic half-weight association indices using SOCPROG 2.10 software. This analysis was used to construct a social network, estimate the community's social differentiation, and investigate the temporal stability of associations within the study period. The social organisation of the bottlenose dolphin community in the Karadag State Nature Reserve showed a prevalence of low association indices among potential pairs; social differentiation within the community, including the presence of preferred and avoided associations; a combination of two types of social bonds, namely rapid dissociations and more long-lasting associations, likely represents short-term associations of relatively stable groups. The resulting mean association index of 0.06 is consistent with those in other coastal Tursiops sp. populations derived from photo-identification data. The three-year dynamics of association indices among signature whistle types suggest the existence of long-term bonds within the Karadag State Nature Reserve community, potentially lasting for months and possibly several years. Signature whistle types with association indices of 0.3 and higher appear to form the community's «core group», as well as individual dyads and triads. Currently, it remains unknown which individuals constitute these formations, as we lack information on the sex, age, and individual history of the animals producing these whistle types. Despite advantages of acoustic individual identification for bottlenose dolphins, such as its efficiency and cost-effectiveness, the scarcity of biological data on individuals keeps photo-identification studies highly relevant. A potential optimal solution may lie in the synergy of these two methods, creating a unified database of individually identified bottlenose dolphins. Expanding such research along the Crimean Peninsula's coast will enable us to investigate the community structure and inter-community connectivity of bottlenose dolphins inhabiting this region. |
| Keywords | association index, bottlenose dolphin, cetaceans, signature whistles, social network, social organisation, Tursiops sp. |
| Artice information | Received: 03.12.2025. Revised: 07.02.2026. Accepted: 18.04.2026. |
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| References |
ACCOBAMS. 1996. Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic Area. Monaco: UNEP/CMS Secretariat. Available from https://accobams.org Bailey H., Fande A.D., Silva K., Gryzb E., McDonald E., Hoover A.L., Ogburn M.B., Rice A.N. 2021. Identifying and predicting occurrence and abundance of a vocal animal species based on individually specific calls. Ecosphere 12(8): e03685. DOI: 10.1002/ecs2.3685 Baker I., O'Brien J., McHugh K., Ingram S.N., Berrow S. 2018. Bottlenose dolphin (Tursiops truncatus) social structure in the Shannon Estuary, Ireland, is distinguished by age- and area-related associations. Marine Mammal Science 34(2): 458–487. DOI: 10.1111/mms.12462 Birkun A. 2012. Tursiops truncatus ssp. ponticus. In: The IUCN Red List of Threatened Species 2012: e.T133714A17771698. Available from https://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T133714A17771698.en Caldwell M.C., Caldwell D.K. 1965. Individualized whistle contours in bottle-nosed dolphins (Tursiops truncatus). Nature 207(4995): 434–435. DOI: 10.1038/207434a0 Caldwell M.C., Caldwell D.K. 1979. The whistle of the Atlantic bottlenosed dolphin (Tursiops truncatus) – Ontogeny. In: H.E. Winn, B.L. Olla (Eds.): Behavior of Marine Animals. Boston: Springer. P. 369–401. DOI: 10.1007/978-1-4684-2985-5_11 Caldwell M.C., Caldwell D.K., Tyack, P.L. 1990. Review of the signature-whistle hypothesis for the Atlantic bottlenose dolphin. In: S. Leatherwood, R.R. Reeves (Eds.): The Bottlenose Dolphin. San Diego: Academic Press. P. 199–234. Chernetsky A.D., Krasnova V.V., Boltunov A.N., Panova E.M., Agafonov A.V., Belikov R.A., Belikova E.A. 2021. Occurrence and distribution of cetaceans in the northeastern part of the Black Sea. Oceanology 61(4): 488–498. DOI: 10.1134/S0001437021040020 CITES. 2026. Convention on International Trade in Endangered Species of Wild Fauna and Flora: Appendices I, II and III valid from 5 March 2026. Geneva, Switzerland. Available from https://cites.org/eng/app/appendices.php CMS. 2015. Convention on the Conservation of Migratory Species of Wild Animals: Appendices I and II. Bonn, Germany. Available from http://www.cms.int/en/species Collier M.A., Jacoby A.M., Foroughirad V., Patterson E.M., Krzyszczyk E., Wallen M.M., Miketa M.L., Karniski C., Wilkin S., Mann J., Bansal S. 2025. Breathing synchrony shapes respiratory disease risk in bottlenose dolphins. Communications Biology 8(1): 870. DOI: 10.1038/s42003-025-08161-1 Connor R.C., Smolker R.A., Richards A.F. 1992. Two levels of alliance formation among male bottlenose dolphins (Tursiops sp.). Proceedings of the National Academy of Sciences of the United States of America 89(3): 987–990. DOI: 10.1073/pnas.89.3.987 Connor R.C., Wells R.S., Mann J., Read A.J. 2000. The bottlenose dolphin: Social relationships in a fission-fusion society. In: J. Mann, R.C. Connor, P.L. Tyack, H. Whitehead (Eds.): Cetacean societies: Field studies of dolphins and whales. Chicago: University of Chicago Press. P. 91–126. Council of Europe. 1979. Convention on the Conservation of European Wildlife and Natural Heritage. Bern, Switzerland. Available from http://conventions.coe.int/Treaty/EN/Treaties/Html/104.htm Edwards C.M., Syme J., Parra G.J. 2025. Association patterns of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in waters off the North West Cape, Western Australia. Marine Mammal Science 41(3): e70017. DOI: 10.1111/mms.70017 Fearey J., Elwen S., Dines S., James B.S. 2021. Using signature whistles to investigate population dynamics of locally threatened bottlenose dolphins (Tursiops truncatus) in Namibia. Namibia Scientific Society Journal 68: 89–101. Fearey J., Elwen S.H., Distiller G., Gridley T. 2022. Improving detectability of dolphin signature whistles for capture-recapture analysis: an examination of array configuration using real-world data. Marine Mammal Science 38(4): 1489–1507. DOI: 10.1111/mms.12941 Félix F., Van Bressem M.F., Van Waerebeek K. 2019. Role of social behaviour in the epidemiology of lobomycosis-like disease (LLD) in estuarine common bottlenose dolphins from Ecuador. Diseases of Aquatic Organisms 134(1): 75–87. DOI: 10.3354/dao03356 Fisher D.N., Cheney B.J. 2023. Dolphin social phenotypes vary in response to food availability but not the North Atlantic Oscillation index. Proceedings of the Royal Society B: Biological Sciences 290(2008): 20231187. DOI: 10.1098/rspb.2023.1187 Gladilina E., Shpak O., Serbin V., Kryukova A., Glazov D., Goldin P. 2018. Individual movements between local coastal populations of bottlenose dolphins (Tursiops truncatus) in the northern and eastern Black Sea. Journal of the Marine Biological Association of the United Kingdom 98(2): 223–229. DOI: 10.1017/S0025315416001296 Janik V.M. 1999. Pitfalls in the categorization of behaviour: a comparison of dolphin whistle classification methods. Animal Behaviour 57(1): 133–143. DOI: 10.1006/anbe.1998.0923 Janik V.M., Sayigh L.S. 2013. Communication in bottlenose dolphins: 50 years of signature whistle research. Journal of Comparative Psychology A 199(6): 479–489. DOI: 10.1007/s00359-013-0817-7 Janik V.M., Slater P.J.B. 1998. Context-specific use suggests that bottlenose dolphin signature whistles are cohesion calls. Animal Behaviour 56(4): 829–838. DOI: 10.1006/anbe.1998.0881 Janik V.M., Sayigh L.S., Wells R.S. 2006. Signature whistle shape conveys identity information to bottlenose dolphins. Proceedings of the National Academy of Sciences of the United States of America 103(21): 8293–8297. DOI: 10.1073/pnas.0509918103 Janik V.M., King S.L., Sayigh L.S., Wells R.S. 2013. Identifying signature whistles from recordings of groups of unrestrained bottlenose dolphins (Tursiops truncatus). Marine Mammal Science 29(1): 109–122. DOI: 10.1111/j.1748-7692.2011.00549.x Kovacs C.J., Perrtree R.M., Cox T.M. 2017. Social differentiation in common bottlenose dolphins (Tursiops truncatus) that engage in human-related foraging behaviors. PLoS ONE 12(2): e0170151. DOI: 10.1371/journal.pone.0170151 Leatherwood S., Reeves R.R. 1982. Bottlenose dolphin Tursiops truncatus and other toothed cetaceans. In: J.A. Chapman, G.A. Feldhamer (Eds.): Wild mammals of North America: biology, management, and economics. Baltimore: John Hopkins University Press. P. 369–414. Logominova I.V., Agafonov A.V. 2019. Spatiotemporal dynamics of the local population of Black Sea bottlenose dolphins (Tursiops truncatus ponticus Barabash, 1940): Visual and acoustic description methods. Oceanology 59(1): 99–106. DOI: 10.1134/S0001437019010119 Logominova I.V., Agafonov A.V. 2021. Local community of bottlenose dolphins (Tursiops truncatus ponticus Barabash, 1940) in waters of Southeastern Crimea: number and formation of associations of individuals in groups. Oceanology 61(5): 677–686. DOI: 10.1134/S0001437021040093 Logominova I.V., Agafonov A.V., Litvin V.А. 2023a. Ethological and acoustic studies of bottlenose dolphins (Tursiops truncatus ponticus Barabash, 1940) at the Karadag Reserve, Southeastern Crimea. Oceanology 63(6): 845–855. DOI: 10.1134/S0001437023060097 Logominova I.V., Agafonov A.V., Litvin V.А. 2023b. Spatio-temporal distribution of the Black Sea bottlenose dolphin (Tursiops truncatus ponticus Barabash, 1940) in coastal waters of Crimea. Simferopol: Arial. 105 p. [In Russian] Longden E.G., Elwen S.H., McGovern B., James B.S., Embling C.B., Gridley T. 2020. Mark-recapture of individually distinctive calls – a case study with signature whistles of bottlenose dolphins (Tursiops truncatus). Journal of Mammalogy 101(5): 1289–1301. DOI: 10.1093/jmammal/gyaa081 Louis M., Gally F., Barbraud C., Béesau J., Tixier P., Simon-Bouhet B., Le Rest K., Guinet C. 2015. Social structure and abundance of coastal bottlenose dolphins, Tursiops truncatus, in the Normano-Breton Gulf, English Channel. Journal of Mammalogy 96(3): 481–493. DOI: 10.1093/jmammal/gyv053 Lusseau D., Schneider K., Boisseau O.J., Haase P., Slooten E., Dawson S.M. 2003. The bottlenose dolphin community of Doubtful Sound features a large proportion of long-lasting associations: Can geographic isolation explain this unique trait?. Behavioral Ecology and Sociobiology 54(4): 396–405. DOI: 10.1007/s00265-003-0651-y Möller L.M., Harcourt R.G. 2008. Shared reproductive state enhances female associations in dolphins. International Journal of Ecology 2008: 498390. DOI: 10.1155/2008/498390 Notarbartolo-di-Sciara G., Tonay A.M. (Eds.). 2021. Conserving whales, dolphins and porpoises in the Mediterranean Sea, Black Sea and adjacent areas: an ACCOBAMS status report. Monaco: ACCOBAMS. 160 p. Papale E., Ceraulo M., Giardino G., Buffa G., Filiciotto F., Grammauta R., Maccarrone V., Mazzola S., Buscaino G. 2017. Association patterns and population dynamics of bottlenose dolphins in the Strait of Sicily (Central Mediterranean Sea): implication for management. Population Ecology 59(1): 55–64. DOI: 10.1007/s10144-016-0566-x Papale E., Ceraulo M., Gregorietti M., De Vita C., Buscaino G. 2025. Assessing the effectiveness of acoustic signals in mark-recapture studies to estimate dolphins' population size. Current Zoology 71(4): 409–418. DOI: 10.1093/cz/zoae079 Pleslić G., Rako‐Gospić N., Miočić‐Stošić J., Blazinić Vučur T., Radulović M., Mackelworth P., Frleta‐Valić M., Holcer D. 2019. Social structure and spatial distribution of bottlenose dolphins (Tursiops truncatus) along the Croatian Adriatic coast. Aquatic Conservation: Marine and Freshwater Ecosystems 29(12): 2116–2132. DOI: 10.1002/aqc.3213 Quick N.J., Janik V.M. 2012. Bottlenose dolphins exchange signature whistles when meeting at sea. Proceedings of the Royal Society B: Biological Sciences 279(1738): 2539–2545. DOI: 10.1098/rspb.2011.2537 Red Data Book of Krasnodar Territory. Animals. 3rd ed. Krasnodar: Administration of Krasnodar Krai, 2017. 720 p. [In Russian] Red Data Book of the Republic of Crimea. Vol. 1: Animals. 3rd ed. Kaliningrad: Polygraphych, 2025. 480 p. [In Russian] Red Data Book of the Russian Federation. Vol. Animals. 2nd ed. Moscow: VNII Ekologiya, 2021. 1128 p. [In Russian] Sayigh L.S., Tyack P.L., Wells R.S., Scott M.D. 1990. Signature whistles of free-ranging bottlenose dolphins Tursiops truncatus: stability and mother-offspring comparisons. Behavioral Ecology and Sociobiology 26(4): 247–260. DOI: 10.1007/BF00178318 Sayigh L.S., Esch H.C., Wells R.S., Janik V.M. 2007. Facts about signature whistles of bottlenose dolphins, Tursiops truncatus. Animal Behaviour 74(6): 1631–1642. DOI: 10.1016/j.anbehav.2007.02.018 Sharpe M., Berggren P. 2025. A comparison of photo-ID and signature whistle based capture-recapture abundance estimates of common bottlenose dolphin. Marine Mammal Science 41(3): e13218. DOI: 10.1111/mms.13218 Smolker R.A., Richards A.F., Connor R.C., Pepper J.W. 1992. Sex differences in patterns of association among Indian Ocean bottlenose dolphins. Behaviour 123(1): 38–69. DOI: 10.1163/156853992X00101 Watwood S.L., Owen E.C.G., Tyack P.L., Wells R.S. 2005. Signature whistle use by temporarily restrained and free-swimming bottlenose dolphins, Tursiops truncatus. Animal Behaviour 69(6): 1373–1386. DOI: 10.1016/j.anbehav.2004.08.019 Wells R.S., Scott M.D. 2017. Bottlenose dolphin, Tursiops truncatus, Common bottlenose dolphin. In: B. Wursig, J.G.M. Thewissen, K.M. Kovacs (Eds.): Encyclopedia of Marine Mammals. London: Academic Press. P. 118–125. DOI: 10.1016/B978-0-12-804327-1.00072-8 Wells R.S., Irvine A.B., Scott M.D. 1980. The social ecology of inshore odontocetes. In: L.M. Herman (Ed.): Cetacean Behavior: Mechanisms and Functions. New York: J. Wiley & Sons. P. 263–317. Wells R.S., Scott M.D., Irvine A.B. 1987. The social structure of free-ranging bottlenose dolphins. In: H.H. Genoways (Ed.): Current Mammalogy. Boston: Springer. P. 247–305. DOI: 10.1007/978-1-4757-9909-5_7 Whitehead H. 1995. Investigating structure and temporal scale in social organizations using identified individuals. Behavioral Ecology 6(2): 199–208. DOI: 10.1093/beheco/6.2.199 Whitehead H. 2007. Selection of models of lagged identification rates and lagged association rates using AIC and QAIC. Communications in Statistics – Simulation and Computation 36(6): 1233–1246. DOI: 10.1080/03610910701569531 Whitehead H. 2008. Analyzing animal societies: quantitative methods for vertebrate social analysis. Chicago: University of Chicago Press. 336 p. Whitehead H. 2009. SOCPROG programs: analysing animal social structures. Behavioral Ecology and Sociobiology 63(5): 765–778. DOI: 10.1007/s00265-008-0697-y Whitehead H. 2019. SOCPROG: Programs for analyzing social structure. Nova Scotia, Canada: Dalhousie University. 91 p. Würsig B., Würsig M. 1977. The photographic determination of group size, composition, and stability of coastal porpoises (Tursiops truncatus). Science 198(4318): 755–756. DOI: 10.1126/science.198.4318.755 |