Center for Conservation Biology

Tracking poached ivory

Research overview

Please click the following links to obtain the DNA Assignment Software or full reprint of our recent article on ivory tracking, published in Science 2015!

DNA ASSIGNMENT SOFTWARE: Click here to download.

JOURNAL ARTICLE: Genetic assignment of large ivory seizures of elephant ivory reveals Africa’s major poaching hotspots. SK Wasser, L Brown, C Mailand, S Mondo, W Clark, C Laurie, BS Weir.

Poaching decimated African elephant populations from ~ 1.3 million to 500,000 individuals in the eight years between 1979 and 1987. This prompted the Convention on International Trade in Endangered Species (CITES) to list the African elephant as an Appendix I (endangered) species in 1989. Despite these protections, a higher percentage of Africa’s remaining elephants are now being killed than ever before.

We estimate that as many as 50,000 elephants are currently being killed annually based on the 46.5 tons of African elephant ivory seized in 2011. (Read our calculations in a PDF.) Assuming approximately 400,000 elephants remaining in Africa, African elephants could be virtually extinct in the next decade.

Dead, bloody elephant lies on the ground amongst reeds and small trees

Elephant poaching.Photo by Karl Ammann

In 2004, the Center for Conservation Biology began collaborating with INTERPOL and other law enforcement authorities, applying DNA-based methods pioneered by our laboratory to identify the sources of seized African elephant ivory. Our investigations uncovered important features of transnational organized wildlife crime that could be used to unravel the criminal networks that feed this illegal trade. We found that individual large seizures (> 0.5 tons) tend to be composed of ivory from a localized source that is hit repeatedly over time, generally within a single country. The same sources tend to recur and appear to be limited in number. Apparently, not many places still have enough elephants to supply numerous multi-ton shipments of ivory over time where poachers also have low risk of being apprehended. Our current program aims to rapidly identify most of Africa’s major ivory poaching hot spots by genetically determining the origin of a representative portion of major ivory seizures.

Decision 16.83 at the last CITES COP (COP16, Bangkok, March 2013) set the stage to put this plan into action. The decision urged countries to promptly submit ivory sub-samples from all large seizures (> 0.5 tons), made immediately and over the past two years, for origin assignment by an appropriate forensic laboratory. The UN office on Drugs and Crime (UNODC) was asked to cooperate with the CITES Secretariat in these investigations (Decision 16.81) and UNODC asked our Center to lead these DNA-based analyses in collaboration with them, INTERPOL and the World Bank. The information obtained from these analyses is helping to focus law enforcement efforts on Africa’s major poaching hot spots and the newsworthiness and excitement that this actionable science brings to the problem is helping to facilitate these objectives.


Our goal is to identify the major elephant poaching hot spots across Africa by determining the geographic origin of large volumes of contraband ivory seized by wildlife authorities. These large volume seizures bear the stamp of organized crime, based on the value of the contraband and all that is required to ship it internationally. Identifying the origins of these large seizures helps reveal where to most efficiently focus law enforcement as well as key strategies used by ivory poachers and dealers.


DNA is successfully isolated from small amounts of ivory, sampled anywhere along the length of the tusk and used to create a unique genetic “fingerprint” of each elephant based on 16 microsatellite DNA loci (Figure 1).

Image of tusk samples and the DNA sequences extracted from them.

Figure 1. DNA is purified from pulverized ivory and used to create genetic fingerprints. Click image to enlarge.

We also extract the same genetic information from elephant feces. Ease of collection to use DNA from feces enabled us to assemble a geographic-based map of elephant gene frequencies across Africa (Figure 2).

We applied a novel statistical smoothing method to these gene frequencies to create a continuous distribution of elephant gene frequencies across the continent. This allows us to estimate each poached ivory sample’s position across Africa (see below), including areas with no reference samples, and provides a confidence estimate for each assignment. Click here for the DNA Assignment Software.

We strive to improve the accuracy of predictions by collecting scat samples to fill the remaining gaps in the gene frequency map used to determine elephant origin. DNA extracted from feces provides a non-invasive method of rapidly acquiring these reference samples from across Africa.

Map of Africa with indicators showing where dung samples for both forest and savanna elephants were collected

Locations of forests (green) and savanna (red) elephant reference samples collected across Africa. Each location includes 10 -50 dung samples, each collected from separate family groups.

What we learned

Our investigations uncovered important features of transnational organized wildlife crime in ivory that could be used to unravel their criminal networks. We found that individual large seizures (>0.5 tons) tend to be composed of ivory from a localized source that is hit repeatedly over time, generally within a single country. This disproved widely held beliefs that single large shipments were generally derived from ivory collected from multiple sources, spanning multiple countries across Africa. More importantly, the source countries we identified have tended to recur and be relatively small in number.

Our first investigation identified the geographic origin of the largest ivory seizure since the 1989 ivory trade ban—6,500 kg of ivory seized in Singapore, June 2002, en route from Malawi. This shipment contained 531 tusks, many of which were atypically large (mean = 11 kg), suggesting it was targeting wealthy buyers. Small tusks were conspicuously absent. The shipment also contained 42,000 hankos (small solid ivory cylinders used to make individual seals for letters), representing 20% of Japan’s annual hanko sales.

We also examined ivory scraps seized in a raid of an ivory carving factory in Malawi, two months prior. Confiscated records suggested these scraps might be from the same ivory that was cut into hankos.

All the ivory was from savanna elephants native to a narrow E-W band of southern Africa, centered on Zambia (Figure 2A). Then, in 2006, a controlled delivery that appeared to originate from Zambia was seized in Singapore by authorities. This was a significant seizure as ballistics showed that the elephants were shot from above, implicating machine guns shot from helicopters. This seizure was also determined to have originated in Zambia. (Figure 3).

Visual representation of data from Singapore and Malawi ivory seizures in 2002.

Figure 3. Geographic origin assignments of (a) tusks, (b) hankos, and (c) hanko shells (leftover scraps from which the hankos were cut) from the Singapore and Malawi ivory seizures in 2002, as well as ivory assigned from a subsequent seizure in 2006.

We examined other seizures in 2006 that told a similar story. Nearly 4,000 kg of ivory were seized in Hong Kong, shipped from Cameroon. Hong Kong authorities using x-ray discovered the ivory in a false compartment of a container containing sawn timber.

They subsequently seized two more containers returning to Cameroon from Hong Kong, registered to the same shipper. False compartments were also found in these two containers. The compartments were empty, but a few ivory chips were found on the floor.

Our analyses showed that the tusks and ivory chips were from forest elephants of a common origin, centered on SE Gabon near the Congo-Brazzaville border. (Figure 4).

Visual representation of ivory origin data from a Hong Kong seizure and a Cameroon to Hong Kong seizure

Geographic origin assignments of ivory from (a) tusks from the Hong Kong Seizure and (b) chips remaining from a single tusk seized in an analogous container on its return to Cameroon from Hong Kong. Click image to enlarge.

Then, in July 2006, four seizures totaling 11 tons were shipped from Tanzania. Two seizures were made in Taiwan, one in Hong Kong and one in Japan. The Taiwan and Hong Kong seizures all originated from the Selous Game Reserve in Tanzania, spilling over into Nyasa Game Reserve in northern Mozambique. Japan would not allow their seizure to be examined. However, the ivory seized in Japan had Swahili writing on it, also supporting a similar origin.

Collectively, these seizure assignments led to the hypothesis that there may currently be fewer major poaching hotspots across Africa than suspected. These hotspots are likely limited because not many places still have enough elephants to supply numerous multi-ton shipments worth of ivory over time where poachers also have low risk of apprehension. If this hypothesis is correct, we should be able to identify most of Africa’s major poaching hotspots in a short time-frame by genetically determining the origin of a representative portion of major ivory seizures. This information would, in turn, allow law enforcement to be effectively focused on these areas, potentially choking the trade at its source.


We now appear well on our way to acquiring the required representative portion of seizures necessary to reliably determine the total number of major elephant poaching hotspots across Africa. Locating the sources of the major poaching hotspots across Africa is part of a larger collective effort to get the illegal ivory trade under control. The plan includes programs aimed at reducing short and long-term demand for ivory, acquisition and DNA-based assignment of a representative number of all recent seizures, and successful implementation of law enforcement operations in response to this information. Our laboratory is well-positioned to conduct the source identification portion of this plan. Our experience suggests that the newsworthiness and excitement that this actionable science brings to the problem will also facilitate the law enforcement component of this program and hopefully the success of the program as whole.


Our approach provides reliable information on where ivory poaching is most concentrated in Africa. Such information tells authorities where greater enforcement efforts are needed and helps to identify trade routes used to move ivory inside and outside Africa. Results also create accountability by forcing nations to be more responsive to poaching in their country.

Local ranger crouches to the ground and collects elephant dung samples for research

Ecoguard dung samples from Nduzo Bokomo-Bolungi for our DNA reference map. Participation of local rangers in sample collections is pivotal to the success of our project. It also serves to educate local people that something is being done to combat poaching on a broader scale.Photo by Gay Reinartz

Information gathered from these analyses, and associated increases in seizure rates, should enable international authorities to more effectively evaluate the consequences of future trade decisions.

Traffic in forest elephant ivory can also be used to indicate hotspots in the burgeoning bushmeat trade across central Africa . These methods may be among the only reliable means to monitor trade in forest ivory and bushmeat because poached carcasses are difficult to detect in dense forests.

Additional uses include:

  • Detecting whether declared government ivory stockpiles are being sold off and illegally replenished.
  • Detection of illegally traded tusks from other countries in sanctioned ivory sales.

Similar methods could be readily applied to other wildlife crimes as diverse as the illegal trade in timber or tiger parts.


  • Wasser, SK, J Poole, P Lee, K Lindsay, A Dobson, J Hart, I Douglas-Hamilton, G Wittemeyer, P Granli, B Morgan, J Gunn, S Alberts, R Beyers, P Chiyo, H Croze, R Estes, K Gobush, P Joram, A Kikoti, J Kingdon, L King, D Macdonald, C Moss, B Mutayoba, S Njumbi, P Omondi, K Nowak. 2010. Elephants, Ivory, and Trade. Science 327: 1331-1332.
  • Wasser, SK, B Clark, C Laurie. 2009. The Ivory Trail. Scientific American: 68-76.
  • Wasser, SK, WJ Clark, O Drori, ES Kisamo, C Mailand, B Mutayoba, M Stephens. 2008. Combating the illegal trade in African elephant ivory with DNA forensics. Conservation Biology 22: 1065-1071.
  • Mailand, C., SK. Wasser. 2007. Isolation of DNA from small amounts of elephant ivory. Nature Protocols 2: 2228-2232.
  • Wasser, S, C Mailand, R Booth, B Mutayoba, E Kisamo, B Clark, M Stevens. 2007. Using DNA to track the origin of the largest ivory seizure since the 1989 trade ban. Proceedings National Academy of Sciences 104: 4228-4233.
  • Wasser SK, A. Shedlock, K. Comstock, E. Ostrander, B. Mutayoba, M. Stephens. 2004. Assigning African elephant DNA to geographic region of origin. Applications to the ivory trade. Proceedings National Academy of Sciences 101: 14847-14852.


This research is funded by grants from the UN Office of Drug and Crime, U.S. Fish and Wildlife Service Elephant Conservation Act, the International Fund for Animal Welfare, the Bosack Kruger Charitable Foundation and the Woodtiger Fund. This study is being conducted in collaboration with several government agencies and NGO’s, including: UN Office of Drug and Crime, Worldbank, Interpol, Lusaka Agreement Task Force, CITIES, WCS and WWF.