Wild elephants captured and put to work in Myanmar’s logging industry don’t live as long as their captive-bred counterparts.
For more than a century, local government officials have kept accurate stud books of Asian elephants (Elaphas maximus) used as beasts of burden in timber camps in Myanmar, which used to be known as Burma. The age at capture and method of capture is recorded for wild-caught individuals, as well as the age of death. Life history data of elephants born in captivity is also noted.
The dataset represents a unique opportunity to assess the longevity of individuals in a population of animals that are subject to the same diet, living conditions, work load and presumably stress levels – the only difference being whether they were wild-caught, or captive-born.
Mirkka Lahdenperä, from the University of Turku, Finland, and colleagues used these exceptional demographic records to study the life spans of 5150 elephants in the timber camps. Of these, 2072 elephants were wild-captured between 1951 and 2000, and 3078 were captive-born during 1925 and 1999.
The findings, published in the journal Nature Communications, reveal that elephants captured from the wild had higher mortality rates than captive-born elephants of all ages. And wild-capture results in a reduction of the median lifespan of elephants by several years, compared to captive-born elephants.
The detrimental effects of capture are similar for both sexes, but younger animals fare better; the older the elephant is at the time of capture and taming, the higher the increase in mortality.
And although the capture of elephants for use in the logging industry in Myanmar was banned in the 1990s, wild-capture of them and other long-lived mammals is still used to supplement breeding programs in zoos, research facilities and conservation programs worldwide.
Lahdenperä cautions that “the use of wild-captured animals in research alongside captive animals may lead to erroneous conclusions, and that both immediate … and long-term effects of capture should be taken into account in further studies”.
The researchers also suggest that alternative methods should be sought to boost captive populations in order to avoid further pressure on endangered wild populations.
Tanya Loos is an ecologist and science writer based in regional Victoria, Australia.
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