[en] The use of UASs (Unmanned Aerial Systems) in wildlife survey is still recent but the fast development of this technology shows great possibilities and it could soon become an inevitable tool in wildlife management.
The purpose of this study was to test the feasibility of inventories by UAS to survey large mammals in the Nazinga Game Ranch in the south of Burkina Faso. The Gatewing X100TM equipped with a Ricoh GR III camera was used to test the animal reaction as it passed, and their visibility on the images. A set of more than 7000 images was collected and observations revealed that only elephants (Loxodonta africana) were easily visible while medium and small sized mammals were not. At a height of 100 m the easy observation of elephant allows experts to enumerate them on images and no reaction was recorded as the UAS passed. We therefore implemented an aerial strip sample count along transects used for the annual wildlife foot count. A total of 34 elephants has been recorded on 4 transects, each overflown twice. The elephant density was estimated at 2.47 elephants/km2 with a coefficient of variation (CV%) of 36.10 %.
UAS inventory of elephants is promising but improvements need to be done. The main drawback of our UAS was its autonomy. If we wish to replace manned aircraft survey of large areas (about 1000 km of transect per day vs 40 km for our UAS), increased endurance of small UAS is a requirement and the monitoring strategy should be adapted according to the sampling plan. Also, the UAS is as expensive as a second-hand light aircraft. However the logistic and flight implementation are easier, the running costs are lower and its use is safer. With technological evolution making civil UASs more efficient, they will be able to compete with light aircrafts for aerial wildlife surveys.
