Extremes of temperature and rainfall are affecting the survival of elephants working in timber camps in Myanmar and can double the risk of death in calves aged up to five, new research from the University of Sheffield has found.
With climate change models predicting higher temperatures and months without rainfall; this could decrease the populations of already endangered Asian elephants.
The researchers matched monthly climate records with data on birth and deaths, to track how climate variation affects the chances of elephant survival.
It is hoped this research -- which was published in the journal Ecology -- will make a difference by highlighting the importance of protecting vulnerable calves in captivity from the effects of climate change
Experts at the University of Sheffield accessed unique recordings of the life and deaths of more than 8,000 elephants from Myanmar spanning three generations throughout almost a century.
The elephants in the database are semi-captive animals working in the timber industry by pushing and dragging logs.
Lead author and PhD student Hannah Mumby, from the University of Sheffield, said: "Our results show that the optimal conditions for elephant survival correspond to high rainfall and a moderate temperature of 23ēC, but that further from those optimal conditions, elephant survival was lower.
"Overall, switching from good to bad climatic conditions within an average year significantly increases mortality rates of elephants of all ages. The most dramatic example comes from baby elephants, whose risk of death before the age of five approximately doubles in the hottest weather in comparison to the optimal moderate temperature for elephant survival."
The researchers found that increases in deaths from heat stroke and infectious diseases accounted for the larger number of deaths during the hot months. Elephants are vulnerable to heat stress because their large size and because they don't sweat like humans or pant like dogs to cool down.
"These results could have important implications for Asian elephant populations both in western zoos, where they may experience unfamiliar climate," added Hannah, "and in range countries where climate may be changing faster than elephants can adapt to it. It also highlights the importance of protecting vulnerable calves from extremes of temperature because more calves will be needed to maintain the dwindling population of endangered Asian elephants."
The project is funded by the Natural Environment Research Council (NERC) and was carried out at the University of Sheffield and Wissenschaftskolleg zu Berlin and the Leibniz Institute for Zoo and Wildlife Research in Germany.
- Hannah S. Mumby, Alexandre Courtiol, Khyne U. Mar, Virpi Lummaa. Climatic variation and age-specific survival in Asian elephants from Myanmar. Ecology, 2013; 130201021245002 DOI: 10.1890/12-0834.1
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