Studies on the development of behaviour in the asiatic elephant

Abstract

The present study focuses on the development of behaviour during the first year of age in the calf of the Asiatic elephant. The elephant calf can be classified as a defended follower. It is completely dependent until the age of three months, begins to explore and attempts to feed between the ages of three to six months, and becomes partially independent with some feeding on its own after the age of six months. It continues suckling well beyond one year, the age at which the observations reported here cease.

The Asiatic elephant is a highly social animal. The primary function of the social group appears to be the care of the young by a group of related females. Suckling by allomothers is a notable feature of elephant society.

The present investigation was largely carried out on captive elephants at forest camps. The elephants are left free for grazing in the forest, where they appear to display normal behaviour. Although not genetically related, their behaviour toward other elephants in the herd resembles that in a natural social group.

The present study involved observations on six such groups of captive elephants located at three different places in South India. The observation period totalled 644 hours and 32 minutes. Limited observations were also carried out on wild elephants.

The observations pertain to defining the basic behavioural repertoire, activity time budgets, development of various behavioural elements, communication, and social behaviour. Careful quantitative observations were maintained using the complete record technique. These were analysed employing modern statistical techniques such as cluster analysis.

Gange, Radhika, and Parimala, three adult females, constituted one of the study groups. Gange gave birth to a calf at the beginning of the study. Radhika cared more for this calf than did Parimala. When the calf was removed, the adult elephants started drifting much further apart. Radhika gave birth to a calf after Gange’s calf was weaned. Parimala showed much attachment to this calf. While this calf was still present, Gange gave birth to another calf. This calf was little cared for by Radhika or Parimala until the weaning of Radhika’s calf.

Another group consisted of three mothers with their calves, a few other females, and a few juveniles. Only females without calves permitted suckling by other calves. A mother with a calf suckled only her own calf and protected it from bullying by other calves. The allomothers showed distinct preferences toward certain other females and their calves. Attempts at suckling by weaned juveniles were violently repelled. Similar observations were repeated in other larger groups. Juveniles repelled calves when the latter tried to play with them.

A female elephant, Gaury, gave birth to an undersized calf that was unable to suckle. When the calf died at the age of one week, the mother showed no hesitation in leaving the corpse. Forced separation of the calf from the mother at the age of around one year produced violent reactions in the calf, the mother, as well as allomothers. The separation required the use of force, and one of the mothers died in the process.

In all the groups, the calves tended to stay between the mother, other adults, and juveniles. The animals rushed to each other whenever there was an alarm. The calves stayed closest to their mothers. The distance of the calves from the mothers and other adults gradually increased with age.

The activity time budgets of elephants show that they spend most of their time feeding or resting. The mothers and allomothers stand guard near the resting calves. The time spent by a calf resting decreases with age, as it spends more time feeding. Consequently, the mothers and allomothers also spend more time feeding as the calf becomes older.

The development of various behavioural elements was studied in detail. Essential activities like suckling, locomotion, and lying down for rest appear soon after birth, whereas elements of feeding, grooming, and play appear only at a later age.

The initiative for suckling in the elephant lies with the calf. It also terminates suckling. Grooming during suckling is limited in elephants because of their body form. Elephants nurse calves at one of the highest reported rates, roughly every 30 minutes during the day. Initially, each suckling lasts about two minutes; this drops to about one minute by the age of one year. The intensity of nursing by allomothers is variable and depends upon a number of factors.

Elephant calves begin walking soon after birth but acquire the adult gait of placing the hind foot exactly over the forefoot only by the age of one year. The calf stays close to at least one of the adults at any time, contacting the mother at short intervals and the allomothers at longer intervals. The adults tend to remain within 20 metres of each other, although occasionally some of them may drift away. The mother’s movements appear to be influenced by those of the calf. The calf tends to drift further away as it grows older but rushes back to the adults after exceeding a threshold distance. The pattern of transition between different distance categories shows interesting changes with age.

Elephant calves drink directly through their mouths until the age of six months, when the steps of sucking water into the trunk and emptying it into the mouth develop.

The first elements of feeding behaviour appear at about one week of age in the form of attempts to pick up and hold objects with the trunk. Coordination of the movements of limbs, trunk, and mouth is achieved by about one month of age. The calf begins regular feeding on plants by six months, at which age feeding becomes established. An elephant calf can break an overhead branch only by the age of four to five years. Important aspects of feeding on grass—such as holding, pulling out, and beating on the legs to remove soil—have several intermediate stages before full development by about six months of age. The transitions and associations between different elements show interesting patterns of differences with age. During the initial stages, more time is spent smelling, trying to pull, and trying to hold, with a high incidence of transitions from holding to dropping and picking up again after dropping.

Full ability to throw soil on the body is attained only by about one year. Until this period, the most frequently repeated steps are scraping and heaping soil, collecting it in the trunk, and attempting to throw it on the body.

The play of elephant calves consists of pushing, butting, hitting, and climbing over each other. The duration of time spent in different elements of play changes significantly with age.

Elephants depend on olfactory, visual, tactile, and auditory modes of communication, in decreasing order of importance. The behavioural modifications accompanying communication largely seem to benefit the calves, at some cost to the adults or are neutral. The number of signals and responses increases with the age of the calf, resulting in improved transfer of information. Acts of communication are predominantly between calves and adults, with little communication between two adults.

The observed pattern of social behaviour corresponds well with the expectations of kinship theory. In nature, groups of related females constitute the core of elephant society. The females therefore show considerable alloparental care. This, however, is never at the expense of their own calves. There are indications of allomaternal care being employed to establish bonds of reciprocal altruism. Male elephants, which are expected to possess little information as to paternity, do not take part in the care of calves. Overall, the herd of tame elephants and their calves provides a rich opportunity for analysing the development of behaviour in this highly social animal.