BEIJING, Aug. 12 (Xinhuanet) -- Patterns of calf mortality revealed elephant matriarchs to remember life-sustaining sources that could be key to the survival of their family groups, according to a study by the Wildlife Conservation Society (WCS) and the Zoological Society of London as quoted by media reports Tuesday.

    The study was carried out during a 1993 drought in Tanzania's Tarangire National Park. 

    "Understanding how elephants and other animal populations react to droughts will be a central component of wildlife management and conservation," said lead author of the study, Charles Foley, of the WCS.

    During the nine-month drought period, 16 out of 81 elephant calves in the three groups studied died, a mortality rate of 20 percent. The normal mortality rate of calves during non-drought years is only 2 percent.

    Researchers studied correlations between calf survivorship, the movements of the groups and the ages of the female members of the groups. They found two groups that left the park during the drought suffered lower mortality rates than the one group that stayed behind. 

    This suggested, the researcher said, the groups that left may have benefited from the experience of their oldest matriarchs, who could perhaps have drawn upon memories of earlier drought periods.

    Some of these matriarchs are known to have been at least 5 years old during a drought from 1958 to 1961, whereas the group that stayed behind had no elephants old enough to remember that event.

    (Agencies)