A new study published on July 7 in Nature Communications, a scientific journal, examined the effects of long-term captivity on wild timber elephants in Myanmar (1). The study, performed by researchers from the University of Turku, Finland, and the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany, compiled data from the detailed records held by the Myanmar government on the life-history of over 5 000 captive timber elephants between 1951–2000. Based on this data, predictive modelling was used to demonstrate age-specific, adverse effects of capture on the mortality of wild Asian elephants.
Timber elephants work during the day and are released into the forest at night, where they can interact with other captive timber elephants as well as wild elephants. Captive-born and wild-caught elephants are tamed and trained in the same way and fall under the same governmental regulations ― including holidays, maternity leave, and a retirement age ― however, wild-captured elephants are often treated more harshly.
The analysis shows that captured elephants have an increased mortality rate compared to captive-born elephants regardless of how they were captured. Moreover, their average life expectancy is several years shorter than captive-born elephants. No differences between male and female elephants were observed but age was shown to be an important factor. Elephants captured at an older age are at a higher risk of mortality compared to those tamed from a young age.
Elephants are most at risk of dying during the first year immediately following capture. This risk declines in subsequent years, but the negative effects can last an entire decade. What makes this study even more alarming is that according to Dr Mirkka Lahdenperä, lead author of the study, “60 percent of elephants in zoos are captured from the wild and about a third of all remaining Asian elephants now live in captivity.”
Wild animals are placed in captivity for a variety of sanctioned purposes including conservation, veterinary, and research, as well as population management. However, the stress of capture is known to result in changes in behaviour, physiology, and immunity. Furthermore, interactions with humans, taming, interspecies competition, and social isolation can lead to reductions in survival rates and other adverse effects, and disrupting early development by altering the environment is also known to cause health, reproductive, and survival issues later in life.
Elephants are frequently captured despite being known to perform badly in captivity. Wild or semi-captive elephants, of both African (Loxodonta africana) and Asian (Elephas maximus) origin, kept in zoos are at a much higher risk of dying (2). However, the reasons are poorly understood. The 3000-year long history of capturing Asian elephants continues today despite declining elephant populations. These striking long-term differences between captive-born and wild-captured elephants should be considered in future research and conservation programs, to prevent further decline of wild elephant populations.
(1) Lahdenperä, L. et al. Differences in age-specific mortality between wild-caught and captive-born Asian elephants. Nature Communications (2018) DOI: 10.1038/s41467-018-05515-8
(2) Clubb R. et al. Compromised survivorship in zoo elephants. Science (2008). DOI: 10.1126/science.1164298