The understanding of death in cetaceans

Mother supporting the corpse of her calf (Image: Joan Gonzalvo/Tethys Research Institute)

It is from about a couple of month ago the news of the recovery of a dead spinner dolphin’s calf in Samadai, Marsa Alam, a few months old female whose body was being carried by an adult of the pod, presumably the mother. Now, what are your first thoughts? The event would activate different mental paths according to your mindset  and you would come out with several interpretations and speculations: a population scientist would immediately desire to assess the impact on the reproductive potential of a population whose trends are still poorly known; a conservationist would start investigating potential causes and think about ways to strengthen protection initiatives; an eco-ethologist would wonder how the animals would have behaved; a sea lover would feel sorrow for the disgraceful event. Whatever force drives us, whether simple curiosity, scientific approach or emotions, a questions will go through our minds at some point: how would a mother feel when losing her calf? Would she understand it, suffer, react, act, actually feel soreness? Our (human) tendency to attach human emotions and attributes to animals (known as anthropomorphism) is an interesting cultural and psychological topic indeed, however we, as scientists, tend to criticize this approach. This doesn’t diminish the value of the above questions which, on the contrary, has been brought to the public attention by the renowned journal New Scientist lately. It is really worth reading!

Despite the fact that death is an event unlikely to be witnessed in the wild often enough to be properly and systematically described, a few accounts of dolphins interacting with dead companions have provided noteworthy insights into behavioural reactions to losses.

Social animals have proven to show behaviours comparable to mourning and this seems to be supported by strict observations rather than emotional transport that would fatally compromise our interpretations. Studies on dolphins, in particular, have benefitted from reports coming from our fellow researcher Joan Gonzalvo who, within his work with the Tethys Research Institute, had the chance to witness two events involving common bottlenose dolphin (Tursiops truncatus) mother and calf pairs in Greek waters: in one of them the calf appeared to have suddenly died a traumatic death, in the other the corpse of the calf showed signs of a chronic lethal intoxication.  Reactions of mothers and pods differed in the two situations –hectically carrying the calf to keep it on the surface for two days in the first case, stressed but somewhat resigned in the second- suggesting that sudden and slow progressive deaths could be differently elaborated by the members of the pod. Those are only speculations for the moment, more reports and observations would help understand the issue, but first supportive elements seem to come from neurophysiology studies concerning the presence of specialized neurons which are associated to empathy, intuition and grief in humans. Can they really prepare themselves to the death of a sick companion and keep company to him until the end? Do they actually take longer to accept a sudden departure? Questions still looking for answers.

What happened in Marsa Alam then? We don’t know exactly, if you were there or have access to images of the recovery please contact us. You would also possibly help us understand the cause of death which, from the poor material and information provided to us, is still undetermined. We know only that, according to the few witnesses met, the behavior displayed by the group is very similar to the one Gonzalvo observed in Greece, with the mother frantically lifting the calf above the surface and the whole group emitting loud sounds and whistles. We have inspected the photographic material sent to HEPCA showing that the dolphin’s corpse present a large bruise on the upper jaw, this suggesting the occurrence of a violent trauma, perhaps from external objects or due to aggressive behaviours from other members of the group (infanticide is known to occur in other species). Unfortunately HEPCA Team was not promptly contacted and couldn’t carry out a necropsy that would have helped investigating other potential causes (infections, diseases, malformation, etc), therefore, in the lack of further evidences, we are not able to describe more in details what might have happened.  We call upon the community: your contribution is fundamental, do not hesitate to contact us if you have more information!

If interested in this topic, search the web and you will find several documents telling or showing similar stories about various mammalian species, including dolphins, cats, elephants, lions and chimps. Although no final conclusions can be reached, all the reports seem to indicate that social, large brain, long-lived animals could share some particular cognitive abilities or social behaviors.  Nowadays, this is the maximum science can affirm, the matter is debated and open to hypothesis and interpretation. What is sure is that, while observing these complex and fascinating behaviours, we realize that those animals definitely earn all our respect.

HEPCA team

Advertisements
This entry was posted in Cetacean. Bookmark the permalink.