New research led by Colorado State University has revealed that an estimated 100,000 elephants in Africa were killed for their ivory between 2010 and 2012. The study shows these losses are driving population declines of the world's wild African elephants on the order of 2 percent to 3 percent a year.

This study provides the first verifiable estimation of the impacts of the ongoing ivory crisis on Africa's elephant populations to date, solidifying speculation about the scale of the ivory crisis. An average of 33,630 elephants per annum are calculated to have been lost over those three years, with preliminary data indicating unsustainable levels continued in 2013.

To quantify the poaching death toll, researchers drew on data and experience from a continent-wide intensive monitoring program. The most thoroughly studied site was Samburu in northern Kenya where every elephant birth and death over the past 16 years has been recorded. The intensive population study was conducted in a project founded by George Wittemyer of Colorado State University with Save the Elephants, and in association with the Kenya Wildlife Service.

Wittemyer is lead author of the new report and a professor in the Department of Fish, Wildlife and Conservation Biology at CSU's Warner College of Natural Resources. He has dedicated his scientific career to understanding and conserving one of Earth's most intelligent and charismatic species.

"Witnessing the killing of known elephants, some that we have followed since they were born, has been terrible," said Wittemyer. "Our data has become the most sensitive barometer of change during this poaching epidemic. We needed to quantify the scale of killing and figure out how to derive rigorous interpretation of poaching rates."

The researchers determined illegal killing in Samburu began to surge in 2009. This surge was directly correlated to a more than quadrupling of local black-market ivory prices paid to poachers and tripling in the volume and number of illegal ivory seizures through Kenyan ports of transit. The data also show that the destination of the illegally trafficked ivory increasingly shifted to China.

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The team used the intensive study of the Samburu elephants as a Rosetta stone to translate less detailed information from 45 elephant populations across Africa to estimate natural mortality and illegal killing rates to model population trends for the species. The UN-mandated continental Monitoring of Illegal Killing of Elephants (MIKE) programme establishes cause of death for each elephant carcass found in these sites, and this has provided the best measure of poaching pressure.

Over the last decade, the proportion of illegally killed elephants has climbed from 25 percent to between 60 percent and 70 percent. Such figures cause conservationists alarm, as the study shows over 54 percent is a level of poaching that elephant birth rates are unable to overcome and will lead to population decline.

"This study helps make sense of the challenge faced by thousands of rangers working on the frontlines to protect elephants and other species across Africa," said co-author Julian Blanc of the Convention on the International Trade in Endangered Species (CITES) secretariat. "It also highlights the importance of the accurate collection of data as part of their day-to-day patrol work, which is essential to understand and communicate the true proportions of the threat that elephants face."

To establish figures rather than proportions, two types of model were used. One focused on the elephant populations with the best information and used them as an indicator for the conditions in their region of Africa. The other used proxy variables such as Chinese consumption rates and a corruption index to estimate illegal killing in 300 sites. Both came to similar conclusions.

While the timing and magnitude of declines differed by region in Africa, with central Africa experiencing the worst levels, all regions of Africa are facing unsustainable levels of ivory poaching with the killing peak in 2011 equating to more than 40,000 elephant deaths.

"It's a complex situation for elephants across Africa, with some populations -- such as in Botswana -- still increasing. History has taught us that numbers alone are no defense against attrition from the ivory trade, and this new work confirms that elephant numbers are decreasing in East, Central and Southern Africa," said co-author Iain Douglas-Hamilton, founder of Save the Elephants.

The research paper, "Illegal killing for ivory drives global decline in African elephants," is published in the Proceedings of the National Academy of Sciences.