African elephants (Loxodonta africana) can detect TNT using olfaction: Implications for biosensor application

•African elephants were trained to detect TNT using olfaction.•Elephants can detect TNT reliably and with high accuracy.•Elephants have greater sensitivity accuracy compared to TNT-detection dogs.•As biosensors, elephants may require less training maintenance than dogs do.•African elephants show great potential as biosensors going forward. The impact of war on local wildlife can be devastating, the effects of which are often felt well beyond the terminus of the initial threat. In areas where wildlife experiences unrestricted movement through previously affected zones, residual, unexploded landmines present a significant and potentially lethal problem. Anecdotal reports of African elephants (Loxodonta africana), in a once war-torn Angola, avoiding minefields together with telemetry data suggest that the species may be able to detect concealed landmines using olfaction. Before any in-field experiments can be conducted, an elephant's olfactory capacity for the detection of the most commonly used component in landmines, trinitrotoluene (TNT), needed to be established. Using three African elephants under controlled conditions, we used operant conditioning to test whether elephants are able to detect and reliably indicate the presence of TNT using olfaction. Elephants detected and indicated TNT using olfaction at levels greater than chance, with high sensitivity and selectivity, even when in the presence of highly volatile distractor odors. Additionally, the sensitivity of detection surpasses that of TNT-detection dogs working under similar conditions, suggesting that the potential application of African elephants within the biosensor-field should not be underestimated.