Members of an elephant family may be out of sight but they are always in the minds of the herd's matriarchs  , researchers have found. Tests have found that female elephants are able to remember the whereabouts of at least 17 family members simultaneously and perhaps as many as 30. They watch which of their relations are ahead of them when the herd searches for food, which of them are lagging behind and which are traveling in separate groups. Professor Richard Byrne, of the prefix = st1 /UniversityofSt Andrews, said that the elephants performed a good memory by being able to recall where each of their  s was in a changing environment. "It's hard enough for us to watch two or three children in a busy shopping centre. Imagine trying to do it with 30 or so," he said. Researchers tested the ability of African elephants to remember where each family member had got to. Elephants have poor eyesight but an excellent sense of smell and are able to identify   one another from traces of urine   on the ground. To test the memories of the elephants, samples of urine-soaked earth were collected by researchers and placed in positions where a herd was about to pass. Observations showed that the animals exhibited surprise when they could detect the odor of a family member they knew was behind them. Interest was shown when the urine was that of a close   traveling in the same group or in a separate herd, but samples left by unknown individuals were ignored. The researchers, who reported their findings in the journal Biology Letters, concluded: " It seems that female elephants have a general interest in monitoring family members with whom they are traveling. Elephants' order of traveling often changes and overtaking is common, suggesting that elephants must frequently update their expectation of where others are in relation to themselves." Elephants identify their family members mainly by using their_.
eyes nose ears mouth