Reproductive behavior of the Asiatic elephant (Elephas maximus maximus L.).

Abstract

A description of sexual behavior was formulated based upon observations of both captive and wild Asiatic elephants. Communication mechanisms, including visual, acoustic, tactile, and chemical signals, are reviewed. The importance of chemical signals in the integration of elephant sexual behavior is emphasized. Secretions from the temporal glands of the male may possibly function as identifiers and indicators of age and sex. Vaginal secretions from the female appear to be involved in indicating her state of receptivity to the male. It is suggested that the seasonal aggressiveness shown by male elephants, termed musth, is comparable to rutting behavior in other ungulates, such as deer. Estrus in the female was determined by behavioral criteria and through vaginal smears. The interval between estrous periods in females is approximately 3 weeks, with a mean of 22 days and a range of 18 to 26. The mean duration of estrous periods for 6 females was 4 days. Sexual behavior patterns were broken down into three categories: Contact promoting behaviors include the exchange of chemical information employing the trunks. Various areas of the body have different valences depending on the reproductive condition of the interacting animals. Females tend to investigate the male's temporal gland most frequently and males investigate the urogenital sinus of the female. Precopulatory behavior involves wrestling with intertwined trunks, reaching over by the male, driving, neck biting, and attempted mounts. Copulation requires the complete cooperation of the female who remains passive and standing or kneeling. The male mounts and through independent movements of the penis achieves intromission. Intromission is brief, being less than 8 seconds in duration and the total duration of a mount is often less than 30 seconds. The number of mounts per ejaculation by the male varies between 4 and 2. The number of intromissions per ejaculation varies from 1.4 to 3.5. Typically the females are organized into cohesive matriarchal herds which travel about in a rather large home range which overlaps the home ranges of individual males. Adult males are typically solitary in their movements unless they join a cow herd. If a cow is in estrus, a male will remain with the cow herd actively courting her. Competition. between males can arise when more than one male comes into contact with the same cow herd. The sexual behavior of African elephants is contrasted with the behavior patterns described for the Asiatic elephant. The two elephant species show broad similarities in behavior and temporal patterning. The function of the temporal gland in the Asiatic elephant male appears to be quite different from the functions implied from the African elephant studies. The courtship and copulation behaviors shown by the elephant are interpreted with respect to its evolutionary history. It is concluded that the major modifications in elephant behavior involve no departures from homologous behavior patterns in other mammals but rather involve adaptations to major structural differences that the elephant has evolved including its graviportal support system and its prehensile trunk. No major departures in social structure and behavior can be discerned for the elephant when it is compared with other ungulate species.