Elephas maximus
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There are two species of elephants, the African savannah elephant ( Loxodonta africana) and the Asian elephant ( Elephas maximus). The differences between the two can be characterized by the differences in there appearance. The Asian elephant is characterized by smaller ears (McDonald, 2001). Also, unlike in the African elephant, the male Asian elephants are the only ones that have tusks. The trunks of the two species are different as well, the Asian elephant has one "finger like" projection at the base of its trunk, while the African elephant has two (Arkive, 2005).
The average adult Asian elephant can range from 18 to 21 feet long, 8.2 to 9.8 feet tall, and it can weigh up to 11,000 pounds. Asian elephants can live from 60-70 years (Chaffezoo, 2005). Humans are the main threat to the Asian elephant. The natural habitat of the Asian elephant is decreasing, due to the increase in the population of humans. Also, since the males are the only ones with tusks, ivory hunting causes an over population of females, disrupting the breeding ratio (McDonald, 2001).
The Asian elephant normally inhabits open, grassy fields adjacent to jungles. These areas are preferred because it combines grassy fields, low wood shrubs and trees. They are also always close to a water supply . The Asian elephants once existed throughout most of the Asian continent, south of the Himalayas continuing into China. Today in the wild, they reside in parts of India and Southeast Asia, mainly in Sumatra and Borneo (Animal Diversity Web, 2005).
The Asian elephant consumes a large variety of plant species. Well over 100 different species to be exact. They typically prefer to eat grasses, but also like roots, leaves, vines, shrubs, stems, and bark (Sukumar, 1990). They eat in the mornings, late afternoons, and night. They take breaks from feeding during the hottest parts of the day. On average an adult elephant consumes 330 pounds of vegetation and drinks 140 liters of water a day. However, 55% of what they consume is not digested (Animal Diversity Web, 2005).
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 (Animal Diversity Web, 2005).
Availability of food and water determines how much elephants move 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, 1989).
Since the Asian elephants consume large amounts of food they are constantly moving around looking for new resources. This causes the need for elephants to have home ranges. Asian elephants can have home ranges that vary from 58 to 124 square miles. Typically their home ranges will overlap with those of other elephants. This is possible because elephants do not defend their home ranges, like territories. It would not be energy efficient and almost impossible to defend an entire area that would satisfy the animals’ food intake (Sukumar, 1989).
Communication (Payne, 1986)
Asian elephants use infrasonic calls to communicate with each other. Since family units often overlap each others large home ranges, this system of communication is perfectly adapted to communicate over great distances. The frequency of these calls typically ranges from 14 to 24 Hz, while having 10 to 15 second durations between them.
In 1985, Payne, Langbauer, and Thomas did a study on two groups of captured Asian elephants’ infrasonic calling. They concluded infrasonic calls consistently coincided with the arrival of elephant keepers at the start of daylight hours, their departure at the end of the day, the relocations of elephants among their display and resting areas, vocalizations of other elephants in the same room, and vocalization of elephants in other areas. Thus giving solid evidence that elephants not only communicate within their own groups. They also communicate about their specific locations and the presence of other species.
The social structure of female Asian elephants consists of related adults and their offspring. These groups are led by the eldest female, called the matriarch. A dominant hierarchical system determines the social status of each individual in the group. This system is based on age and physiological status (Shulte, 2000).
Females provide sole care of the offspring during the 10 to 15 year development. When sexual maturity is reached females typically remain with their natal unit throughout their lives, although it is not uncommon to leave if the family unit becomes too large. Teenaged males leave the group and travel with males of similar age until they reach physiological and behavior sexual maturity. Adult males are solitary except during breeding seasons, when they visit female groups and compete for mates (Shulte, 2000).
The size of the basic family unit can range from four to twelve individuals. Though rare in the Asian elephant, family units have been reported to meet and greet other units. Sometimes units come together to form clans (Shulte, 2000). A clan can consist anywhere from twenty to two-hundred individuals (Sukumar, 1989). However, inside these clans, each family unit is still held together very closely by the matriarch (Shulte, 2000).
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Mating System and Parental Care
In the Asian elephant hierarchical promiscuity occurs because there are dominant hierarchies among males and females, food resources on the home ranges are hard to defend, predation is low, males can randomly mate, and males do not give parental care. Using contest competition, males will compete for rank. Females will then choose males based on their rank, hoping they will pass on high quality genes to her offspring. However, the choosing of males is determined by the hierarchical rank of the females. Subordinate females wait until more dominant females have chosen their mates (Shulte, 2000).
Typically a female will give birth every 3 to 4 years. They will bare a calf after a gestation period of 18 to 22 months. Their estrus cycle lasts about 22 days. The first day of their estrus cycle is the only day when they are receptive to copulate. Calves will nurse for 18 months, but have the ability to eat grass after a few months. Mothers, along with the entire family unit will raise the young until they reach sexual maturity (typically 14 years of age) (Animal Diversity Web, 2005).
Musth (Shulte, 2000)
Once a year adult male elephants will experience a period of highly elevated testosterone, greater interest in females, and increased aggressiveness. During musthing, the male elephant expends a great deal of energy, this is why males in good condition are more likely to enter musth and remain in musth longer. Even though musth is observed throughout the entire year, individual males seem to experience musth at the same time each year. During musth, males dribble urine and secrete a thick fluid from the temporal gland.
Allomothering (Shulte, 2000)
In elephants, reproductively inactive females play an important role in the care giving of the young. This behavior is called allomothering. There are four possible benefits to allomothers that may increase direct or indirect fitness of the young elephants. Allomothers may improve their accesses to resources; by assisting in the care giving of a more dominant female’s young. Allomothers may gain experience and/or receive assistance when caring for their own young. As a form of kin selection, assisting related young may increase their indirect fitness.
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Photo Courtesy of Classroomclipart
(2004). "Asian elephant (Elephas maximus)." Retrieved April 26, 2005, from http://www.arkive.org/species/GES/mammals/Elephas_maximus/more_info.html.
(2005). "Asian Elephant." Retrieved April 14, 2005, from http://www.chaffeezoo.org/animals/elephant.html.
(2005). "FAQS ABOUT THE ASIAN ELEPHANT (ELEPHAS MAXIMUS)." Retrieved April 14, 2005, from http://www.ringling.com/cec/ponder.aspx#9.
(2005). "Elephas maximus." Retrieved April 7, 2005, from http://animaldiversity.ummz.umich.edu/site/accounts/information/Elephas_maximus.html.
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Lincoln, G. A. R., W.D. (1996). "Testosterone secretion, musth behaviour and social dominance in captive male Asian elephants living near the equator." Journal of Reproduction & Fertility 108(1): 107-113.
Macdonald, D. (2001). The New Encyclopedia of Mammals. Oxford, Oxford University Press.
Marak, T. T. C. (2002). "Satus, distribution and conservation of the Asian elephant (Elephas maximus) in Maghalaya." Indian Forester 128(2): 155-160.
Payne, K. B. L., William R.; and Thomas, Elizabeth M. (1986). "Infrasonic calls of the Asian elephant." Behavioral Ecology & Sociobiology 18(4): 297-302.
Rasmussen, L. E. L. (1998). "Chemical communication: An integral part of functional Asian elephant (Elephas maximus) society." Ecoscience 5(3): 410-426.
Rasmussen, L. E. L. S., B.A. (1998). "Chemical signals in the reproduction of Asian (Elephas maximus) and African (Loxodonta africana) elephants." Animal Reproduction Science 53(1-4): 19-34.
Rees, P. A. (2002). "Asian Elephants (Elephas maximus) dust bathe in response to an increase in environmental temperature." Journal of Thermal Biology 27(5): 353-358.
Schulte, B. A. (2000). "Social structure and helping behavior in captive elephants." Zoo Biology 19(5): 447-459.
Sukumar, R. (1989). "Ecology of the Asian Elephant in Southern India. I. Movement and Habitat Utilization Patterns." Journal of Tropical Ecology 5(1): 1-18.
Sukumar, R. (1990). "Ecology of the Asian Elephant in Southern India. II. Feeding Habits and Crop Raiding Patterns." Journal of Tropical Ecology 6(1): 33-53.
| General Information | Habitat and Food | Social Spacing |
|---|---|---|
| Social Organization | ||
| Animal Behavior |