Cooperation or dolphin ‘tug-of-war’? Comment on Kuczaj et al.and Eskelinen et al
Stephanie L. King, Simon J. Allen, Richard C. Connor & Kelly Jaakkola
Two recent papers by Kuczaj et al. (2015) and Eskelinen et al. (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 dolphins may share communicative signals in order to achieve a common goal, we suggest that this has not been demonstrated in the aforementioned studies. Here, we discuss the two main problems that preclude any definitive conclusions being drawn on cooperative task success and vocal communication from these studies. The first lies in the experimental design. The ‘cooperative task’, involving an apparatus that requires two dolphins to pull in opposite directions in order to achieve a food reward, is not conducive to cooperation, but could instead reflect a competitive ‘tug-of-war’. It is therefore of questionable use in distinguishing competitive from cooperative interactions. Second, the suggestion that the occurrence of burst-pulsed signals in this task was indicative of cooperation is disputable, as (i) this study could not determine which dolphins were actually producing the signals, and (ii) this sound-type is more commonly associated with aggressive signalling in dolphins. We commend the authors for investigating this exciting and topical area in animal communication and cognition, but the question of whether dolphins cooperate and communicate to solve a cooperative task remains as yet unanswered.
It was a quick trip back to Perth for me this week as I was presenting at the UWA Faculty of Science Rising Star Awards 2016 - where ten early career researchers (each nominated by their school) present their research in 3 minutes. It was a fantastic evening - showcasing the breadth of research across the faculty - and I was very happy to be representing the School of Animal Biology.
The team returned to the field on the 1st August, this time they are based at Monkey Mia Dolphin Resort where the Dolphin Alliance Project has been running for nearly 35 years!
We were lucky to start the month with a week of glorious weather and lots of time on the water with some of the Red Cliff Bay alliances – including the 8 member second-order alliance the ‘Kroker Spaniels’. We are already documenting consortships, with males using a low frequency pulsed sound, termed ‘pops’, as a threat vocalisation towards females. These are fascinating sounds and we are collecting a lot more information on how these males are using them to coerce females. We are also recording lots of other vocalisations, including likely signature whistles, and a diverse array of burst-pulsed sounds. The overhead video collection is going well and will enable us to better assess the location of vocalising animals with respect to the towed hydrophone array. These stills were taken during an exciting follow on the Kroker Spaniels, who were consorting two females, and also giving a young alliance, the Spark Plugs, a good telling off.
Fieldwork here in MM will continue until the end of September so keep checking for more updates!
We've had a great first two months of the 2016 field season - although things were slow to start with all the wind, the weather soon turned in our favour and we managed to rack up a lot of time on the water with our focal male alliances.
In June we saw quite a few newborn calves, and given that the gestation period for bottlenose dolphins is 12 months, these new mothers would have conceived in June last year. This certainly makes sense given that we saw a lot of alliance action in June; trios of males consorting females, allied males attempting to steal females from competing alliances, and big fights between males over females. Needless to say we recorded a lot of interesting sounds; stereotyped whistles and pops, and a diverse array of burst-pulsed calls. The hydrophone array and overhead video will help us interpret signal function and identify which sounds play a key role in both consortships and fights. The aim of this study is also to understand how male alliances encode identity and how they negotiate these complex relationships with one another.
The team are taking July off but will be heading up to Monkey Mia on the 1st August for the second stint of fieldwork...
The 2016 field season got off to a windy start this year ... low-pressure system after low-pressure system in the aptly named roaring 40s to the south of Australia have meant the infamous ‘sausage highs’ over Shark Bay and the associated howling sou-easters. So much for the magnificent ‘May in the Bay’!
However, the team was well and truly ready to roll when the first lull appeared. We scored four days, or part there-of, in a row, and made data collection happen while the sun shone.
It's been a great opportunity to trial new kit, including the Allsopp Helikite with GoPro that is attached to the boat with flying line, and flown at 30m elevation. This will really help our focal follows of male alliances, giving us a much better idea of what's going on spatially between the animals, and helping with the acoustic localisation from our hydrophone array.
With more good weather on the horizon the team are looking forward to getting back out on the water....
See www.sharkbaydolphins.org for the latest blog on the Dolphin Innovation Project's and The Dolphin Alliance Project's kick off in the western gulf of Shark Bay.
Photo Credit: Simon J Allen
We have a new paper out in the journal Bioacoustics that shows Welsh bottlenose dolphins produce high frequency signature whistles, the highest frequency recorded for the species so far.
Authors; Helen M. Hiley, Sarah Perry, Steve Hartley & Stephanie L. King
Abstract: Animal communication signals are diverse. The types of sounds that animals produce, and the way that information is encoded in those sounds, not only varies between species but can also vary geographically within a species. Therefore, an understanding of the vocal repertoire at the population level is important for providing insight into regional differences in vocal communication signals. One species whose vocal repertoire has received considerable attention is the bottlenose dolphin. This species is well known for its use of individually distinctive identity signals, known as signature whistles. Bottlenose dolphins use their signature whistles to broadcast their identity and to maintain contact with social companions. Signature whistles are not innate, but are learnt signals that develop within the first few months of an animal’s life. It is therefore unsurprising that studies which have characterized signature whistles in wild populations of bottlenose dolphins have provided evidence of geographic variation in signature whistle structure. Here, we describe the occurrence of signature whistles in a previously unexplored wild population of bottlenose dolphins in Cardigan Bay, Wales. We present the first occurrence of a signature whistle with an ultrasonic fundamental frequency component (>30 kHz), a frequency band that was not thought to be utilized by this species for whistle communication. We also describe the occurrence of an ultrasonic non-signature whistle. Our findings highlight the importance of conducting regional studies in order to fully quantify a species’ vocal repertoire, and call into question the efficacy of those studies that use restricted sampling rates.
The article can be found here: http://www.tandfonline.com/doi/full/10.1080/09524622.2016.1174885
Photo Credit: Donald McMullen/Dolphin Research Center
We are very pleased to announce the publication of our recent study on postpartum signature whistle production in bottlenose dolphins, published in the journal Marine Mammal Science.
Authors; Stephanie L. King, Emily Guarino, Katy Donegan, Jane Hecksher and Kelly Jaakkola.
Summary: Individual vocal signatures play an important role in facilitating maternal care in many animals. In those species where neonates are precocial immediately following parturition, the need for individual recognition between mother and offspring is paramount. In bottlenose dolphins such acoustic recognition signals, termed signature whistles, have been shown to be pivotal in mother-offspring recognition. Here we explored how female bottlenose dolphins used their signature whistle in the weeks leading up to and following the birth of their calves. We show that females significantly increased signature whistle production immediately after the birth of their female calves (LMER, P < 0.0001). Average signature whistle rate increased from 0.14 whistles/min to 0.78 whistles/min, representing a > five-fold increase in postpartum signature whistle production, with rates remaining high for four weeks after birth. Our findings complement those of Fripp and Tyack (2008), and offer further support to the imprinting hypothesis, where calves imprint on their mothers’ signature whistles immediately after parturition. The increase in maternal signature whistle use facilitates the calf’s recognition of its mother’s call before mother-calf separations occur. These results highlight the importance of postpartum signature whistle use in aiding mother-calf recognition in bottlenose dolphins and provide insight into one of the underlying mechanisms that aids mother-offspring recognition in species with precocial young.
You can access the paper here: http://onlinelibrary.wiley.com/doi/10.1111/mms.12317/full
We are pleased to announce the publication of our recent study on the importance of maternal signature whistle use in aiding mother-calf reunions in bottlenose dolphins, published in the journal Behavioural Processes.
Authors; Stephanie L. King, Emily Guarino, Loriel Keaton, Linda Erb, and Kelly Jaakkola.
Abstract: Individual vocal signatures play an important role in parent-offspring recognition in many animals. One species that uses signature calls to accurately facilitate individual recognition is the bottlenose dolphin. Female dolphins and their calves will use their highly individualised signature whistles to identify and maintain contact with one another. Previous studies have shown high signature whistle rates of both mothers and calves during forced separations. In more natural settings, it appears that the calf vocalises more frequently to initiate reunions with its mother. However, little is known about the mechanisms a female dolphin may employ when there is strong motivation for her to reunite with her calf. In this study, we conducted a series of experimental trials in which we asked a female dolphin to retrieve either her wandering calf or a series of inanimate objects (control). Our results show that she used her vocal signature to actively recruit her calf, and produced no such signal when asked to retrieve the objects. This is the first study to clearly manipulate a dolphin's motivation to retrieve her calf with experimental controls. The results highlight that signature whistles are not only used in broadcasting individual identity, but that maternal signature whistle use is important in facilitating mother-calf reunions.
You can access the article at: http://www.sciencedirect.com/science/article/pii/S0376635716300535