Unmanned aerial vehicles, also known as drones, are more precise than traditional ground counts at determining the size of colonies of nesting birds in tropical and polar environments, according to research published in Scientific Reports this week. The study suggests that the precision afforded by drones, along with the ability to survey hard-to-reach populations, may mean that wildlife monitoring projects move from traditional methods to drone technology.

Drones have already been used to monitor the breeding success of canopy-nesting birds and to survey elephants. However, when monitoring the size of populations of wildlife, it is unclear how accurate this technology may be.

Jarrod Hodgson and colleagues compared the precision of drone-derived image counts with those made at the same time by human counters on the ground for colonies of three types of seabird: frigates, terns and penguins. Counters also monitored the colonies during the drone flights for signs that the birds may be startled by the presence of the drone. The authors found that counts using drones did not startle the birds, were consistently similar in size to those taken from the ground and, in some instances, were significantly larger. The authors suggest that the down-facing perspective of drone imagery reduces the likelihood of missing seabirds owing to the terrain and birds obscuring the counters’ line of sight.