Introduction
Human-induced rapid environmental change often alters nonhuman species’ reproductive, nutritional, and physiological behaviour (Cosmides and Tooby 2000; Chartier et al. 2011; Sih et al. 2011). Both Asian (Elephas maximus ) and African (Loxodonta africana ) elephants face land-use challenges more than other species due to their substantial dietary requirement and extensive home range (Young et al. 2007; Kshettry et al. 2020; Roy et al. 2022). Known for their strategic planning and cooperation, these social animals also become victims of environmental modifications, and the resultant low fertility and high calf mortality rates emerge as noted unforeseen consequences (Mar et al. 2012). Realizing the slow reproductive rate in elephants (Macdonald et al. 2013), calf deaths directly influence their population dynamics. While these sentient megaherbivores constantly adapt to land-use and environmental change to increase survival rates, they demonstrate various novel behaviours. Conversely, in order to survive many such behaviour, of their affection for their offspring, comes to the limelight when they frequently use the human domain than before. One such behaviour is how they farewell their deceased calves and the herd behaviour thereafter.
The manner in which nonhumans address the dying and the dead reflects their cognition and emotional side (Hawley et al. 2016; Watson and Matsuzawa 2018; Carter et al. 2020; Fernández-fueyo et al. 2021). Animal behaviour and thanatology, therefore, remain a central part of understanding the overall fitness of nonhuman species in a changing landscape (Gill et al. 2020). Most animal species, unlike humans, pay less interest to their dead conspecifics. Different species’ ’weak’ cognitive abilities and disease avoidance theories support this ’leaving alone’ behaviour (Goldenberg & Wittemyer, 2019). However, cetaceans, primates, and elephants show contrasting examples of strong behavioural reactions to their deceased young ones. While most of such caring behaviour between mother and the offspring among different species are observed (Bercovitch, 2012), notably, the entire herd projects an affectionate behaviour among elephants (Sikes 1971, McComb et al. 2006). With up to 22 months of gestation, these K-strategist species invest a lot of emotional energy in their young ones, even after their demise.
For instance, a behaviour where the elephant carcass parts were carried across a distance, covering the carcass with vegetation (”weak” burial), or observing the carcass over several hours has been covered in various scholarships concerning African elephants (Douglas-Hamilton and Douglas-Hamilton 1975; Goldenberg & Wittemyer, 2019). Apart from elephants, burial behaviour has been observed in termites (Reticulitermes fukienensis ) (Fernández-fueyo et al. 2021) but in no other large mammals. Calf burials by elephants are among the less-studied topics of thanatology, especially in Asia (Sharma et al. 2019), even though this practice is known to the conservation gatekeepers. Elephants show a variety of behaviour ranging from investigative, stationary, self-directed, social, and mourning behaviour around their dead conspecific (Hawley et al. 2016; Goldenberg and Wittemyer 2019; Watts 2019; Stephan et al. 2020).
Even though such sensory behaviours have been vastly studied, most of these scholarships fail to report the exact cause of calf deaths and weakly contribute to animal thanatology. The cause of death remains a salient mediator to individual responsivity (Bercovitch 2020). We deem it urgent as the herd’s behaviour (especially the mother) would vary in deaths due to natural illness and accidents (injury and wounding). Calves up to five years of age experience mortality risks due to various factors such as maternal age, sex of the calf, inter-birth intervals, and whether firstborn or later-born (Mar et al. 2012; Rutherford and Murray 2020). Controlled studies have reported 43.3% of deaths due to accidents among young calves (Mar et al. 2012), and therefore, the resultant behaviour remains critical and dependent on the cause of death.
From an evolutionary biology standpoint, natural illness and the consequent death ultimately increase the fitness of the surviving population (Fernández-fueyo et al. 2021). Thus, such an incident of calf death wouldn’t escalate the conflict against humans. However, in case of accidental deaths (attributed to humans), revenge behaviour has been observed across many species, such as elephants (Chalcraft, 2015), primates (Watts 2019), and more recently among orcas (Orcinus orca ) (Anderson et al. 2016). Retaliation and revenge by elephants escalate the human-elephant conflict (HEC) and pose a severe challenge to wildlife managers and anthropologists. However, various socio-ecological and political factors still determine the magnitude of HEC, but such factors aren’t included in this article. This study rather contributes to the ecological behaviour of elephants, both peri and postmortem, while investigating into death cause through postmortem reports of carcasses and attempting to bridge the two different elephant species and draw commonalities and contrasts between the two as far as thanatology is concerned.
While the elephants occupy only 5% of their historic home range globally, India hosts more than sixty percent of the global Asian elephant population despite being one of the most populated countries in the world (Leimgruber et al. 2003; Sukumar 2006). As much as 78% percent of their current habitat lies outside protected areas (PAs) in heterogenous landscapes (Naha et al. 2020). With ever-increasing human population alongside livestock heads and agricultural land on one hand and conservation efforts to increase the large mammal population on the other hand increases the human-nonhuman overlap (Sukumar 1989; Goswami et al. 2015). The Asian elephant is listed as Endangered on the International Union for Conservation of Nature (IUCN) Red List of threatened species and is regarded as a sentient being for its intelligence. Many novel behaviours come to the limelight when elephants use non-forested areas more frequently. The study’s novelty lies in the unique style of ceremonial burial of elephant calves inside tea gardens (TGs) of north Bengal.
Along with a green cover and comparatively undisturbed passage for the pachyderms, the tea gardens also provide ample stretch to trenches for the burial of their deceased conspecifics. The trenches move out excess water during the monsoon season to protect the tea bushes. However, elephants reportedly use these depressions to bury their deceased offspring. This study also presents the first photographic report of dead calf burial by elephants in the tea gardens.
We aimed to (1) study the cause of death for the elephant calves, (2) understand the rationale behind the unique carcass burial strategy, and (3) observe the postmoretem behaviour among elephants near the burial sites. We report the underlying reasons, from postmortem examination reports for the calf deaths, anecdotal evidence of herd members during peri and postmortem phases. This study contributes to the existing literature on elephant behaviour and thanatology through a combination of observation, analysis, and interpretation methods.