n order to effectively manage and conserve natural ecosystems, 
wildlife must be monitored on a regular basis. In Africa, this involves 
counting the animals that inhabit different parts of the continent; having 

an accurate wildlife population count facilitates conservation efforts. 
Typically these counts involve the use of light aircraft, but this approach 
is virtually impossible in some remote areas; as a result, the time between 
successive surveys can often reach a decade or more, during which time 
some species may have disappeared entirely.

A recent study—conducted in the Nazinga Game Ranch in southern 
Burkina Faso, an area mainly covered with clear shrub and woody savannah—
investigated the use of an Unmanned Aircraft System (UAS) to count 
elephants, whose population is dramatically decreasing due to hunting, 
poaching and other human pressure on the ecosystem. Conservationists 
are seeking to quantify the elephant populations over time to support 
the implementation of effective solutions. Comparing population density 
over time brings insight to whether the population is endangered or 
not. A Gatewing X100 (wingspan: 100 cm, weight: 2 kg, cruise speed: 80 
km/h, flight height: 100–750 m, maximum flight duration: 40 minutes) 
equipped with a Ricoh GR3 still camera was used to test animal reaction 
as the UAS passed, assess the visibility of the images, and capture images 
from which the final count could be made. 

The Gatewing X100 UAS was chosen for its silent electrical propulsion. It 
was equipped with GPS and an inertial measurement unit (IMU). These 
sensors determined the position as well as the altitude of the X100 in 
flight. The GPS accuracy was a few meters, and the orientation angle 
(pitch, roll, twist) accuracy was 2 degrees. In order to prepare the flight 
plan, flight characteristics (working area size and location, image overlap, 
height, take-off and landing point locations, wind and landing directions) 
were recorded from a Trimble Yuma® rugged tablet computer used as a 
ground control station.

No reaction—e.g., flight or warning behavior—was recorded as the X100 
passed at a height of 100 m. Observations based on a set of more than 
7000 images revealed that elephants were easily visible at an altitude of 
100 m, while medium- and small-sized mammals were not. A total of 34 
elephants were recorded on four transects, each overflown twice. The 
elephant density was estimated at 2.47 elephants per km


The use of UAS such as the X100 opens interesting possibilities for moni-
toring elephants and other mammals. The technology is ideal to count 
African elephants in savannahs: Flight implementation is easier (very short 
airfield) and safer (no operators on board) than using manned aircraft, 
and the UAS is reliable in very rough conditions. Results of this study show 
that small UAS are useful for an aerial sampling count. Technological evo-
lution will make civil UAS even more efficient, allowing them to compete 
with light aircraft for aerial wildlife surveys.

Counting Elephants

Unmanned Aerial Surveys Used in Monitoring Wildlife to Help Conserve Natural Ecosystems.




See research article at www.plosone.org