REVIEW: ASIAN ELEPHANT: STATUS, DISTRIBUTION, BIOLOGY AND THREATS 1 Int. Zoo Yb. (2006) 40: 1–8 © The Zoological Society of London A brief review of the status, distribution and biology of wild Asian elephants Elephas maximus R. SUKUMAR Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India E-mail: [email protected] The Asian elephant Elephas maximus is distributed Elephas maximus indicus from the Asian discontinuously across the Asian continent. The mainland and Elephas maximus suma- total wild population is 38 500–52 500, with a further c. 16 000 in captivity, the majority of which are in tranus from Sumatra (Indonesia). Recent range countries. India has 60% of the global popu- evidence from molecular genetic studies lation of wild Asian elephants. The species has a does not support the differentiation of the multi-tiered social system with 88 living in matriar- Sri Lankan elephant population from chal groups of five to 20 individuals that interact with other family units in the area. Adult 77 live those on the Asian mainland (Fernando alone or in small, temporary groups with weak social & Lande, 2000; Sukumar, 2003). Ele- bonds. Asian elephants are megaherbivores that phants in Sri Lanka share mitochondrial spend 12–18 hours per day feeding, and they eat DNA haplotypes with matrilines found on browse and plants depending on availability and the mainland and, therefore, should not season. Home-range size is dependant on the avail- ability of food, water and shelter in the region. Loss be considered as distinct subspecies. DNA and fragmentation of habitat, human–elephant con- analysis (Fernando et al., 2003) indicates flicts and poaching are the greatest threats to the that elephants in Borneo, on the basis of species. Asian elephants are managed using tradi- genetic distinctiveness and evolutionary tional and modern methods but progress still needs to be made to improve welfare, training and history, may constitute a separate subspe- breeding for these animals. cies Elephas maximus borneensis, which has been isolated for over 300 000 years. Key-words: animal care, Asian elephant, biology, These studies on elephant genetics add to captive management, conservation, diet, our understanding of the evolutionary his- human–elephant conflict, social system, status in wild, threats tory and population genetic structure of the species across its range, which pro- vides a firmer basis for evaluating conser- The Asian elephant Elephas maximus is vation priorities and management the only living species of the genus Ele- decisions (Fernando & Lande, 2000; Fer- phas (Elephantidae) that evolved in Africa nando et al., 2003; Vidya et al., 2005a,b). c. 5–6 million years ago and migrated into Eurasia. The natural range of the Asian elephant is today confined to the Asian STATUS AND DISTRIBUTION continent. Elephas maximus is believed to About 6000 years ago the range of the have descended during the later Pleisto- Asian elephant extended from Mesopo- cene from Elephas hysudricus, the fossil tamia in the west across the Indian sub- remains of which are found in the Siwaliks continent to South-east Asia and China in the Indian sub-continent (Maglio, and as far north as the Yangtze River 1973). (Olivier, 1978). At time of writing the Historically, zoologists have recognized Asian elephant has disappeared from three subspecies of Asian elephant: Ele- c. 95% of its historical range. It is now dis- phas maximus maximus from Sri Lanka, tributed discontinuously in India, Nepal, 2 ELEPHANTS AND RHINOCEROS Bhutan, Bangladesh, Myanmar, Thailand, India has by far the largest numbers of Peninsular Malaysia, Sabah, Kalimantan, wild elephants, comprising c. 60% of the Cambodia, Laos, Vietnam, China and the global population. The major populations islands of Sumatra (Indonesia) and Sri are in southern and north-eastern India, Lanka (Santiapillai & Jackson, 1990; Suk- with fewer in the east-central and north- umar, 2003). A small feral population western regions. Myanmar, Sri Lanka, occurs in the Andaman Islands in India. Malaysia, Thailand and Indonesia also The Asian elephant is listed as Endan- have significant numbers. Owing to the gered by IUCN (2004) and appears on uncertainties of counting elephants in Appendix 1 of CITES (Convention on dense tropical forests, it is difficult to International Trade of Endangered quantify accurately changes in animal Species of Wild Fauna and Flora). numbers over time. However, the avail- The total population of Asian elephant able figures suggest a substantial reduc- in the wild is estimated at 38 500–52 500 tion in elephant populations in many individuals (Table 1). Estimates by range states from Myanmar to Vietnam country vary from Q100 in Vietnam to and Sumatra (Sukumar & Santiapillai, q25 000 in India. There are an additional 1996; Heffernan & Trinh Viet Cuong, 16 000 elephants in captivity, mainly in 2004). Increases in several regional ele- range states, and c. 1000 maintained in phant populations in India have helped to zoos in western countries. offset declines occurring elsewhere, with country elephant range (km2) wild population captive population (min–max) (min–max) Bangladesh 1800 196–227 c. 100 Bhutan 1500 250–500 * Cambodia c. 40 000 400–600 q500 China 2500 200–250 * India 110 000 23 900–32 900 c. 3500 South (39 500) (10 300–17 400) Central (23 500) (2400–2700) North-east (41 000) (10 300–11 300) North-west (5500) (900–1500) Indonesia 105 000 1180–1557 c. 350 Kalimantan (c. 5000) ?–? Sumatra (c. 100 000) (1180–1557) Laos c. 20 000 781–1202 1100–1350 Malaysia c. 45 000 2351–3066 * Peninsular (c. 20 000) (1251–1466) Sabah (c. 25 000) (1100–1600) Myanmar 115 000 4000–5300 q5000 Nepal c. 2500 100–170 c. 170 Sri Lanka c. 15 000 2100–3000 200–250 Thailand 25 000 3000–3700 3500–4000 Vietnam c. 3000 76–94 c. 165 total 486 800 38 534–52 566 14 535–15 300 Table 1. Estimated minimum and maximum number of Asian elephants Elephas maximus in the wild and in captivity in Asia. Information from Santiapillai & Jackson (1990), Lair (1997), Sukumar (2003) and updated by the IUCN/SSC Asian Elephant Specialist Group in 2004: * there are few elephants in captivity in these countries; bold font indicates the totals for the country; numbers in brackets are regional. In addition to the numbers presented c. 1000 Asian elephants are found in zoos outside the range states. REVIEW: ASIAN ELEPHANT: STATUS, DISTRIBUTION, BIOLOGY AND THREATS 3 the result that the overall population tats and thus ensuring better survival of across Asia has probably not changed young. ‘Allomothering’ is also important much or has only declined slightly during in the protection and rearing of calves the past 25 years. (Gadgil & Nair, 1984). Females become sexually mature at BIOLOGY 10–14 years of age, cycle every The Asian elephant is one of the few 14–16 weeks and, if they conceive, extant megaherbivores (Owen-Smith, undergo a gestation of 20–21 months. 1988). Neonates of both sexes are c. 90 cm They produce a calf every c. 4–5 years. in height and 100 kg in mass. Males grow Males attain maturity around the same faster than 88 from the age of 2 years age or slightly later and disperse from onwards (Sukumar et al., 1988). Adult their natal herds, which avoids inbreeding bulls are typically 240–300 cm in height (Sukumar, 1989). Adult bulls live alone or and 3500–6000 kg in body mass compared in small, temporary groups (‘bull herds’) to 195–240 cm and 2000–3500 kg for with weak social bonds. It is possible that adult cows, although there is considerable social constraints result in 77 mating suc- regional variation with the largest ele- cessfully only a few years after they are phants possibly in north-eastern India and sexually mature. A bull elephant attains the smallest in Borneo. dominance in the 7 hierarchy when it Elephants are highly intelligent comes into musth, a physiological and (Rensch, 1957) and have superior cogni- behavioural phenomenon that usually tive abilities. The basic social unit is the occurs once a year (Eisenberg et al., 1971). family consisting of an adult cow and her When a bull is in musth the testosterone immature offspring. Elephant society is in the blood increases to high levels, the multi-tiered, starting from the mother–calf temporal glands secrete a pungent fluid, (or several offspring) unit and moving on the animal shows heightened aggression to larger joint-family units with several towards other bulls and it has a better adult cows, the ‘kin’ or bond group (two chance of successful mating with an oes- to four family units that associate fre- trous 8. quently), the clan (a number of family The mechanisms of chemical and audi- units and bond groups in an area that co- tory communication are highly developed ordinate their movements), the sub- in elephants. The trunk and the vomeron- population (a number of clans using a asal organ, located on the roof of the particular part of the range) and the mouth, are the main detectors of chemical whole population (McKay, 1973; Kurt, signals. Various chemical compounds 1974; Sukumar, 1989; Baskaran et al., secreted by the temporal gland, urine, 1995) faeces and exhaled breath act as specific Females remain in the cow herd of their biological signals for communication birth, which is essentially a matriarchy led within the family group, with other ele- by the oldest 8 who is also probably the phants and between 77 and 88 for repro- mother, aunt or grandmother to most of duction (Rasmussen, 1998). Elephants are the herd members. Studies of genetic extraordinarily vocal and have a rich rep- relatedness have confirmed that adult ertoire of calls; their auditory communi- cows within a family unit are closely cation extends to the infrasound range related to one another (Vidya & Sukumar, that is not audible to humans (Payne 2005).