While companies like Amazon, Flirtey, and Zipline continue to use drones for deliveries, a group of ornithologists at Gettysburg College in Pennsylvania have studied a different way to use unmanned aerial vehicles (UAVs).

By suspending a “simple, lightweight recorder” below a DJI Phantom 2 quadcopter drone, Gettysburg College environmental studies professor Andrew Wilson and two undergraduate students studied songbirds and published their results in The Auk: Ornithological Advances. The study, called “The feasibility of counting songbirds using unmanned aerial vehicles,” found that data on songbirds compiled with a drone was comparable to that of “standard counts for most species.”

Noise from the drones caused issues

Why would you bother using a drone to study birds in the first place? “Because audio bird recordings are generally from ground-based or close-to-ground recorders, they may still be limited by site accessibility and the logistical constraints of traversing difficult terrain,” the study reads. “However, aerial recordings have greater range and mobility and can be used to access sites normally not surveyed by terrestrial methods.”

In other words, you can cover a lot more ground with a drone, and get microphones into hard-to-reach areas. Of course, using drones to study bird songs has an obvious drawback. “Excessive UAV noise is a major hurdle to using UAVs for bioacoustic monitoring, but we are optimistic that technological innovations to reduce motor and rotor noise will significantly reduce this issue,” the study reads. “We conclude that UAV-based bioacoustic monitoring holds great promise, and we urge other researchers to consider further experimentation to refine techniques.”

Studying songbirds serves an important purpose. As the study states, “Bird surveys provide crucial data for monitoring bird populations, conducting ecological studies, and determining effective environmental management strategies.” The purpose of the experiment was “to test the initial feasibility of collecting data on songbird abundance using a UAV and, importantly, to highlight potential problems and pitfalls associated with aerial monitoring.”

Because of “masking by drone noise” and the application of “high-pass filters to the recordings,” the researchers underestimated counts of birds with low-frequency songs, such as the mourning dove. Additionally, birds such as the gray catbird that live in very high densities were underestimated in counts. Wilson told TechCrunch that while “research-grade drones used by the likes of large agricultural business would have been nice,” they “aren’t particularly affordable for academic purposes.”

Researchers have also been using drones to gather images

“Our approach was to build a low-cost and relatively low-tech aerial system, which we consider important if UAV-based bioacoustic monitoring is to become accessible to ornithologists with limited funding opportunities,” the study reads.

Additionally, the study states that aerial surveys, such as ones conducted via drone, “offer a solution to coverage biases and have already proved a valuable tool in wildlife monitoring.” By using drones to study songbirds, Wilson and his colleagues join the growing practice of using drones for ecological studies. So far, they have mainly been used to gather images.