An Overview on Elephants
The significance of the Asian elephants is now unequivocally established. Notwithstanding the significance, this valuable mammal, the largest living land animal on the planet has dwindled dramatically in the recent years primarily due to anthropogenic disturbances. They are found in 13 different countries in Asia.
Asian elephants are forest dwelling species, often illustrated as key stone species (Shoshani et al., 2004), flagship species (Perera, 2009), umbrella species (Whyte, 2004) and as well as the engineers of the forest, as they play a significant role in maintaining the ecosystem they inhabit and can modify it both in positive and negative ways by their actions (Perera, 2009).
The word ‘Elephant’ comes from the Greek word “elephas” meaning ivory. This refers to their tusks. In scientific nomenclature, elephants belong to the order Proboscidae. This word is also Greek referring to other distinctive elephant anatomy, the trunk (Elephant Evolution, 2002-11; Rahman, 2008).
Under the order Proboscidae, there are two species of elephants, the Asian elephant (Elephas maximus) and the African elephant (Loxodonta africana). They belong to the family Elephantidae. There are four subspecies of Asian elephant, Indian elephant (Elephas maximus indicus), Sumatran elephant (E. m. sumatrensis), Sri Lankan elephant (E. m. maximus) and Borneo pygmy elephant (E. m. borneensis) (WWF, 2011).
The Asian elephant is smaller than its African cousin. It can be distinguished by its much smaller ears and rounded back, as compared with the saddle back of the African species (Santiapillai & Jackson, 1990). There are many other differences, including the tip of lip of the trunk is single ‘finger’ in Asian species, compared with two lips in the African species (Khan, 1985), and a double domed forehead instead of a single dome (Santiapillai & Jackson, 1990). There are some anatomical differences between the two species distinguished by the number of ribs and vertebrae, and in the morphology of the cheek teeth (Seidensticker, 1984).
Present Status of Asian Elephants in the WorldAsian elephants inhabit a variety of tropical forest habitats from moist, evergreen lowland forest to dry semi-deciduous teak forests to cooler mountain forests up to 10000 feet. They also frequent adjacent to grassland and farm areas. Their varied diet enables them to live in disturbed forests as soon as they have plenty of space to move around and exploit different foods without coming in to conflict with people. Thus, the Asian elephant is as ‘umbrella’ species, whose conservation will ensure the maintenance of biological diversity and ecological integrity on a large scale, across its range. The Asian elephant has become a critically endangered animal in Bangladesh (Khan, 2015) due to habitat destruction and loss of corridors (IUCN Bangladesh, 2004).
Populations of both elephant species continue to decline in the wild as they live under the constant threat of habitat destruction and deforestation, as well as illegal slaughter for ivory and bushmeat. Being the largest terrestrial mammal, elephants do not have any natural predators except for the human. In terms of life history, elephants require larger areas for foraging and therefore survival. It has also a longer calving interval comparing to other mega mammals. These two attributes put this umbrella species at a risk of rapid population decline in addition to the abovementioned threats. For example, the population of African elephants plummeted in the late 1970’s to early 1980’s due to ivory poaching; estimates showed that the population declined from 1,341,000 animals to a little over 700,000 in less than 10 years (Douglas-Hamilton, 1989). Unfortunately, the illegal killing of elephants for ivory still remains a grave threat all species (Douglas-Hamilton, 2009).
Loss of habitat is another major threat to the survival of elephants in the wild. As the human population continues to grow at an alarming rate, all wild animals are forced to survive in the smaller habitats compare to their former home range. The corridors and routes that once offered a passage way for wildlife to travel from one area to another are now subjected to human habitation. Forests are being cut down and wild areas are turned into human settlements and crop land to ensure greater benefits only for human in terms of food and space. Therefore, it should come to no surprise that human-elephant conflicts are on the rise. In Sri Lanka alone, human-elephant conflicts claim the lives of 150 elephants and 100 people per annum. Similarly, a number of countries in Africa are experiencing similar human-elephant conflicts resulting in deaths of both human and elephants. In most cases, elephant victims are monetarily compensated for their loss; however, there is no price that can ever make up for the ultimate loss of a life, be it human or elephant (Stephenson, 2007). The Asian elephant is currently listed as an endangered species (IUCN, 2008) and classified under Appendix I in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES/WWF, 2004). This species once occurred from the Tigris-Euphrates in western Asia, east through Iran and south of the Himalayas; throughout south and southeast Asia including the islands of Sri Lanka, Sumatra and Borneo, and into mainland China northwards at least as far as the Changkiang (Yangtze river) (CITES/WWF, 2004; IUCN/SSC, 2008). At present, elephants have disappeared entirely from western Asia, Iran, and most of China. The present populations of Asian elephants are thought to be restricted to primarily mountainous areas in the following countries: a) Indian sub-continent: India, Nepal, Bhutan and Bangladesh, b) Continental southeast Asia: China, Myanmar, Thailand, Cambodia, Laos, Vietnam, and Malaysia, c) Island Asia: Andaman Islands (India), Sri Lanka, Sumatra (Indonesia), and Borneo (Malaysia & Indonesia) (Sukumar, 2003)..
Habitat fragmentation and loss continues to be the primary reason for the decline of Asian elephants. About 20% of the world’s human population lives in or near the present range of the Asian elephant. With human numbers increasing at a rate of approximately three percent per annum in most countries, theoretically there could be a doubling of the human population in 23 years (ERI, 2008). The elephant’s forest home has been reduced to a fraction of its former range. The World Wildlife Fund (WWF) estimates that there may be only 10 Asian elephant populations of more than 1,000 animals in the 13 countries (Stephenson, 2007). The extensive forests in India, where elephants roamed widely, now cover less than 20% of the country and barely half of that remain as suitable habitats for elephants. In central India, elephant population has been seriously fragmented (ERI, 2008). Thailand has cleared almost all its lowland forest, creating a huge void of wildlife habitat in the heart of the country. On the Indonesian island of Sumatra, vast areas of forest are being cleared to accommodate millions of people resettled from the crowded islands of Java, Bali, and Madura. Indo-China’s forests were seriously damaged during 30 years of constant warfare. In Sri Lanka, the vast Mahaweli River Valley Project for settlement, crops, and irrigation cuts a wide swath through the heart of elephant country. Myanmar, Cambodia, and Laos still have considerable forest cover, but this is suffering from unmanaged and unsustainable logging (Hedges, 2006).
Home Range and Core Habitat Areas
The Asian elephant lives in a wide variety of habitats, including savanna, scrub forest, and closed-canopy forest. Asian elephants also inhabit grasslands, tropical evergreen forest, semi-evergreen forest, moist deciduous forest, dry deciduous forest and dry thorn forest, in addition to cultivated and secondary forests and scrublands. Previous studies have found that elephants prefer lowland forest habitats (Hedges et al., 2005), where nutritious foliage is Abundant. Elephants have a strong preference for forests with a high productivity located within valleys (Rood et al., 2010). The fact is that landscape depressions are also natural waterways providing a main source of water and natural routes crossing through rugged terrain (Pan et al., 2009; Shannon et al., 2009). This forest dwelling elephants are seen from sea level to over 3,000 m or even 4,875 m (Grimshaw et al., 1995; Choudhuri, 1999). According to the USFWS (2002), grassland forest-mosaics are considered optimal habitat and in such areas, concentrations as high as five elephants per 0.38 square mile (1 km2) have been recorded.
The home ranges of Asian elephant vary. For female it is between 34-800 km2 and for male 200-235 km2 (Sukumar, 2003). Sometimes home ranges of elephant appear to cover thousands of square kilometers (Sukumar, 2003). Variation in home ranges can be determined through habitat type, individual preference, tradition, inter family relationships and sex ratio. Grasslands are the preferred feeding habitat of elephants. For movement, resting, shade, breeding and other purposes Asian elephants need some other habitats. The use of grasslands by elephants is determined by different factors such as, grassland composition, densities of other herbivores, distance of grazing locations from the forest boarder and proximity of grazing locations to drinking sites (Ishwaran, 2001).
Routes and Corridor
Asian elephants are migratory species. It can move more considerable distances even with a short period (Sukumar, 1989b). In the wild, elephant herds follow well-defined seasonal migration routes. The survival of this species largely depends on corridors and routes because it allow elephants to safely migrate, access food sources and establish crucial genetic links between herds (Joshi & Singh, 2009). It is the chore of the eldest elephant to remember and follow the traditional migration routes (Wikipedia, 2011). The presence of traffic on the road, construction of steep retaining walls and the presence of human population along the entire corridor and routes can limit the migration of elephants (Johnsingh & Williams, 1999).
Food and Feeding Behavior
Elephants are classified as mega herbivores and consume up to 150 kg of plant matter per day (McKay, 1973; Vancuylenberg, 1977) and drinks 140 liters of water a day (Ciszek, 1999). The Asian elephant consumes a large variety of plant species as their diet. They typically prefer to eat grasses, but also like roots, leaves, vines, shrubs, stems, and bark (Sukumar, 1990). According to USFWS (2002), grasses typically account for more than 50% of the Asian elephant’s diet. From a study of Joshi & Singh (2008), it was found that consumption of tree species (74%) is highest as compared to grasses (14%) and shrubs (8%) but their diet is mainly dependent on availability of seasonal food round the year and on their migration.
In the wild, a mature elephant will spend as many as 18 hours per day for feeding. Asian elephants eat in the mornings, late afternoons, and night. They take breaks from feeding during the hottest parts of the day. Obviously the food consumed in the wild is low in nutrients and high in fiber (John & Subramanian, 1991).
Asian elephant has special digestive system for rapid throughput of coarse vegetation and are adapted to a lifetime of foraging. Effective foraging is attained through continuous movement including, seasonal migrations and daily movement through a variety of habitats. Foraging activity is accomplished with the coordinated movement of feet, tusks and dexterous trunk to select individual items of fruit (Poole & Granli, 2009). Asian elephants use many creative methods to retrieve their food. To eat long grasses they pluck a bundle and stick it inside their mouths using their trunks. Short grasses are eaten by stomping and kicking up the ground, and then grabbing the grass using their trunks. To eat shrubs they break off twigs with their trunks (Ciszek, 1999; Poole & Granli, 2009). According to McKay (1973), elephant grazing in the dry season is negatively impacted by the presence of other herbivores. Elephants feeding preferences and behavior are also known to change over time due to changes in its habitat (Ishwaran, 2001).
Movement patterns of wild elephants may vary according to the age, sex, reproductive state and population of an individual. Free-living Asian elephants are moving almost all day long and even at night (20 out of every 24 hours) and actively engaged in foraging, exploring, socializing and searching for con-specifics (Poole & Granli, 2009). Generally elephants become active well before dawn and start their morning activities in the surrounding area of the area where they spent night (Joshi & Singh, 2008). In case of elephant, the energetic cost of walking is recorded as the lowest among other land animals (Langman et al., 1995) and it seems that it still behaves in ways to conserve energy (Wall et al., 2006).
Being an enormous animal the movement of Asian elephant is slow but they are vigorous animals and continuously active in mind and body. In nature, elephants are rarely found still; some portion of their body, legs, ears, eyes, trunk, or tail, is always in motion. Even sometimes a motionless wild elephant is found continuously moving its trunk and scenting; positioning its ears and head to monitor the movements, locations and behavior of other elephants and activities in their complex social and ecological environment. These types of motions are good predictors and indicators of an active thinking in case of elephants (Poole & Granli, 2009).
Asian elephants always stay close to a water supply and for movement and other activity prefer the secondary forest, which grows on abandoned villages and plantations, and avoid roads and villages (Barnes et al., 1991). Predictor variables such as human presence and proximity to elephants resulted in reduced feeding and increased display in elephants while distance of settlements to elephants did not influence behaviour of elephants. Protection and non-conversion of canopy habitats and maintaining minimum threshold distance of humans from elephants would foster normal movement activities of elephants and help promote human-elephant coexistence in such landscapes (Mavatur & Singh, 2010).
During the monsoon period, the moving and resting activity generally fluctuate because of slight restriction in movements. At the onset of monsoon, elephants show their long-term migration towards upper slopes in some of the areas (Joshi & Singh, 2008). Availability of food and water determines extent of elephant’s movement throughout their home ranges. Typically during the dry months (January-April) Asian elephants reside in river valleys. During the first wet season (May-August) they reside in tall grass forests. The second wet season (September-December) they move to short grass open forests (Sukumar, 1989a). In summer, percentage of movement is higher, due to lack of fodder species and shrinkage of natural water sources, as elephants have to travel more in search of food and water (Joshi & Singh, 2008). Sometimes when habitat patches that contain the fodder plants of Asian elephant are small and scattered, elephants have to extend their range to satisfy their dietary requirements. This would invariably bring them into conflict with man, which is the main constraint in conserving these elephants (Samansiri & Weerakoon, 2007). A study pointed out that most of the incidents of crop raiding were found to be in late evening hours or during night period (Nair, 1990), whereas, another study indicated that raids by elephants were the results of either solitary individual (adult males) or small groups (Santiapillai & Suprahman, 1986).
Asian elephants use infrasonic calls to communicate with each other (Payne et al., 1986). The ability of elephants to distinguish genuine strangers from a wide range of more regular associates through recognition of voices (McComb et al., 2000) and scents (Bates et al., 2007) may in part explain the extremely large and convoluted temporal lobes of the elephant’s brain (Shoshani, 1992). Communication can be as follows.
Elephant acoustic communication includes a broad variety of sounds (with components ranging from 5 Hertz to over 9,000 Hertz (Poole et al., in press). Calls include very low frequency rumbles and higher frequency trumpets, snorts, roars, screams, barks, cries, chirps, croaking and other idiosyncratic sounds (Stoeger-Horwath et al., 2007). Elephants use acoustic signals to communicate complex messages of agonistic, defensive, affiliative, parental care, mating, and social natures. They are able to combine different call types to utter more complex calls and they are capable of imitating or learning new vocalizations (Poole et al., 2005).Acoustic Communication
Via acoustic signals elephants can recognize the individual voices of other elephants at distances of up to 2 km (McComb et al., 2003). Detection of the calls of conspecifics has been estimated to vary from 2.2 km during daytime to 9.9 km at night (or over an area of 15-300 km2) depending upon atmospheric condition (Garstang, 1994). Extensive studies have confirmed that elephants produce low frequency sounds to interact in thick vegetation and among separated groups, and to coordinate their movements (McComb et al., 2000). Elephants are the first terrestrial mammals reported to produce infrasonic sound (Payne, 1998). Infrasonic calls produced by elephants can travel 1-5 km or even more (ANCF, 2007).
Chemical communication relates to signaling between opposite sexes for mating. Olfactory communication is achieved by pheromones (ANCF, 2007). Chemical signals including saliva, mucus secretions from the eyes, fluids from the ano-genital tracts, temporal glands, ears and inter-digital glands, also play an essential role in elephant social and reproductive communication (Rasmussen & Krishnamurthy, 2000; Rasmussen & Wittemyer, 2002).
Tactile communication happens through sight and touch. It is mainly found during breeding period. When elephants meet, they vocalise, rub their bodies, press each other’s foreheads, intertwine trunks or put trunks in each other’s mouths (ANCF, 2007).
Asian elephants can be categorized into families, bond groups and clans (Sukumar, 2003; Vidya & Sukumar, 2005).
Within this social arena, the lives of adult female and male elephants differ radically (Poole, 1994). Female elephants remain with their families for life, while male elephants leave their natal families around puberty, at which point they enter the socio-sexual world of adult males. Members of a family and bond group may be distinguished by long-term association patterns, greeting behavior, coordinated movement, strong affiliative and protective behavior toward one another and cooperative anti-predator behavior, resource acquisition, offspring care, and decision-making (Payne, 2003). In areas where water, minerals or high quality food are limited, or unevenly distributed, agonistic behavior in elephants is more common (Poole, 1994). The close and lasting social relationships formed by female elephants are remarkable in the context of their fluid social system (Archie et al., 2005).
Social learning and behavioral innovation are essential elements of individual development and are the very fabric of elephant society, tradition and culture (Poole & Moss, 2008). Many of the techniques used by wild elephants to locate, select and extract food must be learned, either through experience or by watching others (McComb et al., 2003), and social learning plays a critical role in calves’ acquisition of foraging knowledge and techniques of manipulating food items (Hart et al., 2001). Successful mounting and intromission requires considerable skill and experience which may, in part, be gained by watching the behavior of older, more experienced males. Interaction with other elephants and the transmission of social and ecological knowledge is a key to an elephant’s survival (McComb et al., 2003), and the motivation it demands is necessary for an elephant to thrive.
Asian elephants often physically transform the forest as they move through it, contributing to the ecological functioning of the forest. They create light gaps by knocking down trees; they keep the undergrowth clear by trampling vegetation and speed decomposition by shattering rotting logs. Elephants can provide water for other species by digging water holes in dry riverbeds. The depressions (created by their footprints and their bodies) trap rainfall. Their paths also act as firebreaks and rain water channel (RAIN, 2010). Elephants act as seed dispersers by their fecal matter (Chapman et al., 1992). They disperse seeds and fertilize the soil with their dung, compact it with their feet and cultivate it with their tusks. By digging for essential minerals they change stream flow, creating wet forest clearings (RAIN, 2010). Dispersing rice seeds through defecation elephants sometimes introduce new types of rice far from the villages (Alexandre, 1978). An elephants’ journey through the high grass provides food for birds by disturbing small reptiles, amphibians or insects (RAIN, 2010; IUCN Bangladesh, 2004).
This page is based upon:
Motaleb, M.A., Rahman, S.M., Rahman, S. and Sultana, M. (2011). The Asian elephants and associated human-elephant conflict in south-eastern Bangladesh. IUCN, International Union for Conservation of Nature, Bangladesh Country Office, Dhaka, Bangladesh, pp. x+104.