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Mammalia (2007): 147–149 2007 by Walter de Gruyter • Berlin • New York. DOI 10.1515/MAMM.2007.019

Short Note

Observations of an Indo-Pacific humpback carrying a sponge: object play or tool use?

Guido J. Parra the Indo-Pacific region from the eastern shores of South Africa to the northern coast of (Jefferson and Cetacean Ecology and Acoustics Laboratory, School of Karczmarski 2001, Parra et al. 2004). Two cases of epi- Veterinary Science, University of Queensland, St. Lucia, meletic behaviour involving humpback carrying Queensland 4072, Australia, dead calves have been observed in Hong Kong (Parsons e-mail: [email protected] 1998). In South Africa, humpback dolphins were seen carrying and throwing sea shells for short periods of time during social-play activities (Saayman and Tayler 1979). This paper describes a sponge carrying event by an adult Keywords: behaviour; object manipulation; play; Sousa Indo-Pacific humpback dolphin and discusses the poten- chinensis; tool use. tial functions of this behaviour in light of the observations made. The observations were made on November 9, 2006, Wild and captive delphinids are known to carry animate during boat based surveys of coastal dolphins in the and inanimate objects on their rostra, melons, fins and Hinchinbrook Channel (188169 S, 1468049 E), northeast tail flukes. Captive bottlenose dolphins (Tursiops spp.) Queensland, Australia. The Hinchinbrook Channel, part and pilot (Globicephala spp.) will often carry ran- of the Great Barrier Reef World Heritage Area, is a 44- dom objects such as seaweed, fish, and plastic toys in km long tidal channel that separates Hinchinbrook Island their tank (Brown and Norris 1956, Caldwell 1956, Tizzi from the mainland. The channel has a maximum depth et al. 2000). Free ranging bottlenose, Hector’s (Cepha- of 20 m and is fringed by one of the largest mangrove lorhynchus hectori, van Beneden 1881), and Atlantic forests in Australia. During dolphin surveys, systematic spotted dolphins ( frontalis, Cuvier 1829) have data collection was carried out through focal follows, been observed carrying seagrass, fish, sea cucumbers photo-identification, and scan and ad libitum behavioural and pieces of coral among others (Slooten and Dawson sampling. Further details of survey procedures are 1994, Mann and Smuts 1999, Miles and Herzing 2003). described by Parra (2006) and Parra et al. (2006). Most of these object carrying events are thought to be Four adult humpback dolphins were sighted at 08:43 related to play: the motor activity directed towards and followed for 2.3 h at distances ranging from 10 to the object appears to provide no obvious direct benefit 40 m. Observations took place in waters ranging from to the individual(s) involved (Martin and Caro 1985). 5.1 to 9.4 m deep (means6.9, SDs1.3, ns28). The The only object manipulation activities that have been school changed later to three adults and a juvenile (see suggested as non-play in delphinids are: 1) carrying of description below). All adults involved had distinctive dead calves, and 2) sponge carrying by some bottlenose marks on their dorsal fins. For most of the duration of dolphins in Shark Bay, Western Australia. The carrying of the sighting, dolphins were predominantly travelling dead calves has been hypothesised as a manifestation of epimeletic (care-giving) behaviour (Harzen and Santos northwards slowly (2–3 km/h) within 10 m of each other. 1992, Lodi 1992, Fertl and Schiro 1994, Palacios and Day At 08:56 one of the dolphins surfaced with a large 1995). Sponge carrying by bottlenose dolphins in Shark object on its rostrum (Figure 1). The object was dark Bay has been identified as a foraging specialisation brown in colour and covered the total length of the involving tool-use (Smolker et al. 1997). It is believed that dolphin’s rostrum. At first sight the object looked like the involved use sponges to protect their rostrum a marine sponge. Though the object could not be from shells, rocks and spines and stingers from noxious retrieved for further identification, Dr. John Hooper, an organisms while looking for prey in the sea bottom. expert in sponge with the Queensland Muse- Genetic and ecological data indicate that the use of um, inspected the sighting photographs and concluded sponges as tools is culturally transmitted mainly within a that the object resembled a sponge-algal complex matriline (Kru¨ tzen et al. 2005). The use of sponges as a (referred to from now on as a sponge). The sponge foraging tool has not been described in any other appeared to be held in place by its apparent conformity population of bottlenose dolphins or dolphin species, to the shape of the rostrum and by the water pressure although anecdotal evidence suggests that humpback as the dolphin moved forward. For the next 5 min, the dolphins in the Dampier Archipelago, Western Australia, dolphin swam at the surface with the sponge on its ros- also carry sponges (M.Kru¨ tzen, personal communication, trum following no specific direction and taking several July 2007). breaths interspersed with short dives less than 1 min Indo-Pacific humpback dolphins (Sousa chinensis, long. During this time the other three animals remained Osbeck 1765) are found throughout coastal waters of close to the sponger (-50 m). At 09:01 the dolphin per-

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148 G.J. Parra: Sponge carrying by a humpback dolphin

direction and made steep dives, resembling activities involved during foraging behaviour in humpback dolphins (Parra 2006). Moreover, sediment clouds, such as the ones observed while the sponger was underwater, are often observed during foraging activities of humpback dolphins (personal observations) and are consistent with observations of benthic feeding in other delphinids (Rossbach and Herzing 1997, Visser 1999). Could the humpback dolphin be using a sponge as a foraging tool in a similar way to bottlenose dolphins in Shark Bay? The ecological setting and the behaviour dis- played by the humpback dolphin in Hinchinbrook Chan- Figure 1 Adult Indo-Pacific humpback dolphin, Sousa chinen- nel is similar to that of the bottlenose dolphins carrying sis, carrying a sponge on its rostrum. sponges in Shark Bay. Regular sponge carriers in Shark Bay are mainly observed in deep water channels formed a steep fluke-up dive, still with the sponge on its (8–10 m), carrying the sponge on their rostrum, taking rostrum, while the other animals swam at the surface. several breaths at the surface and performing fluke-up The dolphin stayed underwater for approximately 3 min dives (Smolker et al. 1997). Humpback dolphins are before surfacing again still with the sponge beacon on known to feed on a wide variety of estuarine fish. Impor- its rostrum. Comparison of photographs taken at the sur- tant prey includes bottom-dwelling species including cat- face indicated the animal was carrying the same sponge. fish, sciaenid and croakers (Barros et al. 2004). Catfish Owing to the turbidity of the water, it was not possible to possess serrated spines composed of dense bone tissue observe the animal underwater. However, the animal was with the ability to harm and kill dolphins (Barros and tracked through a trail of sediment clouds rising from the Cockcroft 1999). Stingray barbs are also known to pose bottom. as a threat to dolphins (Duignan et al. 2000, Spanier et The dolphin repeated this diving behaviour several al. 2000), and have been found embedded in the bodies times: several breaths at the surface with the sponge of dead Australian humpback dolphins (Bowater et al. beacon on its rostrum followed by a long dive. None of 2003). Thus, it is feasible that the humpback dolphin may the other animals in the school were observed carrying have used the sponge as a ‘‘protective glove’’ while or interacting with the sponge. At 09:18 the dolphin sur- searching for food in the sea bottom. faced without the sponge. The dolphin continued to trav- It is clear that more observations are needed before el north slowly with the other three members of the we can discern if the behaviour described here is an iso- school until 09:28, when it separated from them and lated/random case. The preliminary observations suggest swam towards another school of humpback dolphins the humpback dolphin was using the sponge, in some with two adults and a juvenile. From this time onwards unknown way, while foraging. Future research conducted this new school became the focus of the focal follow. in the Hinchinbrook region over the next few years should These animals were also travelling slowly in a north direc- provide additional information on sponge carrying by humpback dolphins. tion. At 9:50 the same dolphin was observed again at the surface with a sponge on its rostrum. From the photo- graphs available, it was not clear if this sponge was the Acknowledgements same one as before. The dolphin was then seen several times at the surface with the sponge before diving again Many thanks to Maria Jedensjo¨ , Maayan Cohen, Maeve Lee, with the rest of the school. At this time, the animals were Deirdre McElligott and Meagan Dewar for contributing a lot of their time to help me out with the boat surveys and collection lost from sight until 10:05 when they were spotted again. of data. I am grateful to P. Corkeron, M. Noad and two anony- The same dolphin was still carrying a sponge on its ros- mous reviewers for valuable comments on the manuscript. Spe- trum. The dolphin was last observed carrying the sponge cial thanks to M. Noad for providing the boat to conduct the at 10:09. After this, the animals travelled slowly until surveys. Funding for this project was provided by Sea World 11:00 when the weather conditions deteriorated and the Research and Rescue Foundation, Ian Potter Foundation and a animals were lost from sight. postdoctoral fellowship from The University of Queensland. What was the humpback dolphin doing with this Fieldwork was carried out under permits from the Great Barrier sponge? Object play by dolphins and other is Reef Marine Park, the Environmental Protection Agency and mainly, but not exclusively, accompanied by splashing, approval from the Animal Ethics Committee of The University of aerial displays, social interactions and a wide variety of Queensland. postures with objects been thrown into the air, chased and captured, bitten to pieces, shaken and transferred between different body parts (Smolker et al. 1997, Hall References 1998, Mann and Smuts 1999). The humpback dolphin carrying the sponge did not engage in any of these dis- Barros, N.B. and V.G. Cockcroft. 1999. Prey resource partition- ing between Indo-Pacific humpback dolphins (Sousa chinen- plays and neither of the other dolphins participated nor sis) and bottlenose dolphins (Tursiops truncatus) off South interacted physically with the sponge or the sponger dur- Africa exclusion or mutual tolerance? wAbstractx In: 13th ing the focal follow. The sponger, on the contrary, swam Biennial Conference on the Biology of Marine Mammals, in a stereotyped manner at the surface with no apparent Wailea, Maui, Hawaii.

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G.J. Parra: Sponge carrying by a humpback dolphin 149

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