Indian Elephant - Ecology and Behaviour

Ecology and Behaviour

The movement and habitat utilization patterns of an elephant population were studied in southern India during 1981–83 within a 1,130 km2 (440 sq mi) study area. The area encompasses a diversity of vegetation types — from dry thorn forest at 250 to 400 m (820 to 1,300 ft) of altitude through deciduous forest (400 to 1,400 m (1,300 to 4,600 ft)) to stunted evergreen shola forest and grassland (1,400 to 1,800 m (4,600 to 5,900 ft)). Five different elephant clans, each consisting of between 50 and 200 individuals had home ranges of between 105 km2 (41 sq mi) and 320 km2 (120 sq mi), which overlapped. Seasonal habitat preferences were related to the availability of water and the palatability of food plants. During the dry months of January to April, elephants congregated at high densities of up to five individuals per km2 in river valleys where browse plants had a much higher protein content than the coarse tall grasses on hill slopes. With the onset of rains in May, they dispersed over a wider area at lower densities, largely into the tall grass forests, to feed on the fresh grasses, which then had a high protein value. During the second wet season from September to December, when the tall grasses became fibrous, they moved into lower elevation short grass open forests. The normal movement pattern could be upset during years of adverse environmental conditions. However, the movement pattern of elephants in this region has not basically changed for over a century, as inferred from descriptions recorded during the 19th century.

In the Nilgiri Biosphere Reserve three elephant clans had overall home ranges of 562 km2 (217 sq mi), 670 km2 (260 sq mi) and 799 km2 (308 sq mi) in the beginning of the 1990s. During three years of survey, their annual home ranges overlapped to a large extent with only minor shifts in the home ranges between years.

Elephants are classified as megaherbivores and consume up to 150 kg (330 lb) of plant matter per day. They are generalist feeders, and both grazers and browsers. In a study area of 1,130 km2 (440 sq mi) in southern India, elephants were recorded to feed on 112 different plant species, most commonly of the order Malvales, and the legume, palm, sedge and true grass families. They graze on the tall grasses, but the portion consumed varies with season. When the new flush appears in April, they remove the tender blades in small clumps. Later, when grasses are higher than 0.5 m (1.6 ft), they uproot entire clumps, dust them skilfully and consume the fresh leave tops, but discard the roots. When grasses are mature in autumn, they clean and consume the succulent basal portions with the roots, and discard the fibrous blades. From the bamboos, they eat seedlings, culms and lateral shoots. During the dry season from January to April, browse constitutes a major food resource. They take both leaves and twigs preferring the fresh foliage, and consume thorn bearing shoots of acacia species without any obvious discomfort. They feed on the bark of white thorn and other flowering plants, and consume the fruits of wood apple, tamarind, kumbhi and date palm.

In Nepal’s Bardia National Park, elephants consume large amounts of the floodplain grass, particularly during the monsoon season. They browse more in the dry season with bark constituting a major part of their diet in the cool part of that season. During a study in a tropical moist mixed deciduous forested area of 160 km2 (62 sq mi) in Assam, elephants were observed to feed on about 20 species of grasses, plants and trees. Grasses such as Imperata cylindrica and Leersia hexandra constituted by far the most predominant component of their diet.