For elephants roaming the savanna in Kenya, drought can be a matter of life and death. Prolonged periods with little to no rainfall can cause vegetation to wither, leading the colossal animals to starve to death.
About one-third of Kenya’s elephants can be found in the Tsavo Conservation Area in the southern part of the country. As of 2011, the area supported 12,000 elephants. That population was once a lot larger; in 1974, you would have found about 35,000 elephants. Previous research attributed much of the decline to drought. But Yussuf Wato, a wildlife ecologist at Wageningen University (Netherlands), wanted to know more.
To investigate the relationship between drought and elephant mortality, Wato and colleagues collected information on deaths, rainfall, locations of water sources, elephant population density, and a space-based measure of vegetation health or “greenness.” These data, collected between 2004 and 2012, became part of a model to determine the probability of death during the wet and dry seasons.
“Our results suggest that elephant populations in arid and semi-arid savannas appear to be regulated by drought-induced mortalities,” the authors wrote, “which may be the best way of controlling elephant numbers without having to cull.”