The African elephant is perhaps one of the world’s most iconic species, and yet in the near future, it may become extinct. Elephants’ tusks are made of ivory, which is highly sought after by Asian consumers for use in ornaments and jewelry1. Though international ivory trading has been banned since 1989, it has not stopped poachers from killing elephants2. In fact, from 2007-2014, savanna elephant populations decreased by almost 30%3. Officials are working to protect elephants, but how effective are these measures?
Efforts to protect elephants and stop the ivory trade can be evaluated by many different methods; one of these is by studying ivory shipments. Recently, a team of researchers studied large ivory shipments that were seized by officials from 2002-2014. They were interested in determining the length of time between death of the elephant and seizure of the ivory4.
To do this, they used a technique called radiocarbon dating4. Radiocarbon dating can determine the age of organic material by measuring the amount of carbon-14 left in the sample. Carbon-14 is an unstable isotope of carbon that is radioactive and decays over time5. Although carbon-14 is formed in the atmosphere, it is taken up by plants through photosynthesis. Herbivores ingest carbon-14 through eating plants6.
In living organisms, any carbon-14 that decays is replaced through eating or photosynthesis. Thus, they maintain a stable amount of carbon-14 in their tissues; the same as the amount of carbon-14 in the atmosphere. However, after an organism dies, carbon-14 is no longer replenished and decreases steadily. By measuring the amount of carbon-14 left in the sample, researchers can determine when the organism died5.
When researchers dated the seized ivory, they found that all but four of the 231 specimens was “new”–that is, the elephant had been killed less than five years before seizure of the ivory. In addition, the mean time between death of the elephant and seizure of the ivory ranged from 7-13 months. From 2011 onward, however, this length of time increased to 13-32 months4.
With regards to the location of origin of the ivory, ivory originating from East Africa had a rapid transit time. This ivory was typically seized less than 12 months after the death of the animal. Other regions had slower transit times, or were unable to be characterized due to lack of specimens4.
The results of this study show that old ivory from stockpiles doesn’t contribute significant amounts of ivory to the illegal ivory trade. The results also indicate that poached ivory is rapidly moved into the illegal trade, and ivory from East Africa has an especially fast transit time. Though the time between death of the elephant and seizure of the ivory has increased since 2011, the reason for this is unknown. However, researchers speculated that declining elephant populations make it more difficult for poachers to gather enough ivory to make a large shipment profitable4.
These results, along with the evidence of declining elephant populations, means not enough is being done to stop the poaching of elephants. If we wish for future generations to see elephants in the wild, a greater effort must be made.
This blog post is based off an original research article. You can read the original research article for free here.
1: Threats to African elephants [Internet]. 2016. Gland, Switzerland: World Wildlife Fund International; [cited 2016 Nov 22]. Available from http://wwf.panda.org/what_we_do/endangered_species/elephants/african_elephants/afelephants_threats/
2: Perlez J. 1989. Ivory trade is banned to save the elephant [Internet]. New York City: The New York Times; [cited 2016 Nov 22]. Available from http://www.nytimes.com/1989/10/17/science/ivory-trade-is-banned-to-save-the-elephant.html
3: Hersher R. 2016. African elephant population declines by 30 percent [Internet]. Washington, D.C.: National Public Radio; [cited 2016 Nov 22]. Available from http://www.npr.org/sections/thetwo-way/2016/08/31/492124724/african-elephant-population-declines-by-30-percent
4: Cerling TE, Barnette JE, Chesson LA, Douglas-HamiltonI, Gobush KS, Uno KT, Wasser SK, Xu X. 2016. Radiocarbon dating of seized ivory confirms rapid decline in African elephant populations and provides insight into illegal trade. PNAS 113(47):13330-5.
5: Carbon-14 dating [Internet]. n.d. Eau Claire (WI): University of Wisconsin-Eau Claire; [cited 2016 Nov 22]. Available from http://www.chem.uwec.edu/Chem115_F00/nelsolar/chem.htm
6: Nave CR. 2016. Nuclear: Carbon dating [Internet]. Atlanta (GA): Georgia State University; [cited 2016 Nov 22]. Available from http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/cardat.html