Follow that Bird! How Drones Are Helping Scientists Track Wildlife

The sun hasn’t yet risen over Montana’s Blackfoot Valley, but Laura Dykstra has already hiked miles in the dark—through lumpy, ankle-breaking fields, over creeks, fences, and barbed wire. She arrives in a cattle pasture, holds an antenna above her head, and listens until she hears the telltale beeps that tell her a radio-tagged Sharp-tailed Grouse is nesting, invisibly, a few meters away. 

A few hours later, back at the pasture entrance, her collaborator takes a turn at finding nesting grouse, but he’s got a much easier job. Montana Fish, Wildlife and Parks (MFWP) biologist Ty Smucker has spent the summer learning to fly an aerial drone equipped with radio-tag detecting software. He’s now testing whether it could save researchers time and energy as they work to restore this vulnerable population. He launches the device, and within a few minutes of it buzzing into the sky, the controller shows the signal from nearly a dozen tagged birds—more than Dykstra could find in hours of hiking.

Radio-tracking has been a staple of bird research since the 1950s. Today, radio telemetry is only one of many ways that wildlife researchers track animals, which range from implanted tags that can be scanned from a handheld device to satellite and GPS tags that can be tracked from anywhere by computer. Radio tags have remained popular, however, due to the comparably low cost, ease of use, and potential to be small and lightweight.  

But finding a radio-tagged bird can be difficult. It’s essentially like the childhood game “hot and cold”: the tag transmits a very high frequency signal to a person holding a receiver, and the beeps get louder the closer they get. That means a researcher like Dykstra, a PhD student at Montana State University, must physically track down a grouse and follow it as it moves. The task gets harder when thick forests or mountainous terrain block the signal.

For more than a decade, drones have helped scientists conduct aerial surveys of large, relatively stationary bird colonies. But more recently, as drone technology has improved, these airborne devices are starting to offer researchers an alternative for tracking down individual birds over large areas and difficult terrain—though their use can be challenging, expensive, and isn't widespread. “The elusive creation of a cheaper, off-the-shelf drone to track birds and other wildlife is still a bit of a holy grail to achieve, in my opinion,” says ornithologist David Bird (yes, he’s noticed the aptronym), an emeritus professor of wildlife biology at McGill University and founding editor of the journal Drone Systems and Applications.

Smucker began using drones as part of an effort to reintroduce Sharp-tailed Grouse into two valleys in western Montana, where development and agriculture had decimated the population. To do so, researchers translocated grouse from healthy populations in eastern Montana, tagging some with VHF transmitters to help study how the new transplants were faring. The tags could help the scientists know if the wide-ranging birds roamed away from the reintroduction site, if they set up a nest, or if they were eaten by a predator. Such data, Dykstra says, can indicate if the reintroductions are successful or, if they aren’t, why.

Drones entered the picture during the project’s first season. Nesting grouse are so well-camouflaged that even after locating a tagged hen, researchers may struggle to spot her, or may risk accidentally flushing her off her nest while searching. So Smucker began using a small quadcopter with an infrared camera to check on nesting grouse and count hard-to-see hatched chicks.

But that didn’t help the problem of finding the hens to begin with. In 2023, MFWP approved the purchase of a radio telemetry drone to help. The system, from the Australian company Wildlife Drones, can track up to 40 tags simultaneously and triangulate a bird’s location down to a few meters, increasing the odds of finding grouse that, say, move to another valley or nest in a deep gully. While Smucker doesn’t think drones will ever replace painstaking field research entirely, he imagines a day where field visits—both finding nesting birds and counting their brood—can be done entirely from a property entrance.

Yet the technology has its downsides. Its bulk and weight make it hard to lug around in the field, and it's expensive. Wildlife Drones’ radio-receiver system with the recommended drone package costs on the order of $50,000, plus an annual $3,000 software subscription. (Company founder Debbie Saunders notes the system reduces staffing expenses). And because only two companies currently sell radio telemetry drone systems, researchers have limited leeway to choose between options.

In search of a smaller, cheaper drone-tracking system, Erica Fleishman, director of the Oregon State University’s Oregon Climate Change Research Institute, partnered with Colorado State University (CSU) to develop one from scratch. CSU Drone Center director Christopher Robertson and avian ecologist Luke George created a tracking system that can be mounted on any drone capable of carrying 100 grams. Robertson estimates it cost about $5,000 to build (not including the drone’s price).

While it can fit in a backpack, keeping their system small and light also creates limitations: a 25-minute battery life, difficulty flying in strong winds, and only room for a single antenna, which means it can’t as precisely triangulate a tagged bird’s exact location. Still, Fleishman says the drone “works great, and it doesn’t seem to disturb the birds.” She’s been using it to track individual Green-tailed Towhees and Lazuli Buntings in the arid Great Basin region, hoping to learn how the breeding birds react to environmental changes and human activity. While the team doesn’t yet have enough data to draw conclusions, the system has afforded insight that would otherwise be impossible to get: “The terrain that we are working in is pretty rugged, and it’s not easy to get eyes on birds,” she says.

Such a small and cheap drone system sold commercially could be a tremendous boon to avian research, says Bird. It could be particularly handy for studying breeding songbirds, which stay within a relatively small territory. Given limited battery life and common regulations that require pilots fly in their line of sight, drones are likely less useful over long distances or timeframes. (The growing MOTUS tower network, which uses strategically-located towers to detect lightweight radio tags as wildlife pass, is showing particular promise for avian migrations.)

More broadly, Bird would like to see more types of aerial vehicles—such as fixed-wing aircraft and unpowered crafts like gliders or even balloons—employed for tracking terrestrial wildlife. This diversity of vehicles already exists in ocean research, offering scientists choice in the size, power requirements, range, and price of the technology they use.

As the field grows, researchers will also need to take care not to disrupt the animals they’re studying. Scientists generally follow established regulations and guidelines to minimize disturbance, but there’s very little data about how drones impact animal health and behavior.  “There is no standard—and there needs to be more research on determining the safe and best practice use of drones for wildlife,” Bird says. On the other hand, drones can also significantly minimize intrusions caused by scientists in the field.

These benefits are on Dykstra’s mind. The 2024 breeding season ended with 30 of the 44 recorded nests successfully hatching, and 15 broods reaching to adulthood—a high survival rate. After running test flights for the drone system, she’s excited to use them in earnest in 2025. “It could potentially be a big time-saver instead of sending an observer, but it also might reduce disturbance to the birds, which is really valuable in reintroduction,” Dykstra says. “The birds born here will be more likely to survive and then, one day, have babies of their own.”

This story was made possible in part by a grant from the Institute for Journalism and Natural Resources.