A Snapshot From Above

Getting the chance to venture out of the office on a sunny Wisconsin spring day?! Count me in!

In late March 2022, I was lucky enough to tag along with fellow DNR colleagues into the field as they collected aerial images of trout streams for a scientific study. With an interest in general aviation, I am usually the first to jump into the right-seat of a small plane. However, this time, I wouldn’t even make it off the ground!

So, how do you capture streams from above? By unmanned aerial vehicles (UAVs)!

More commonly known as drones, these aerial vehicles are frequently used by researchers throughout the world to capture aerial imagery and data. You can find drones being used in a variety of scientific disciplines ranging from the energy industry to wildlife research to climate physics.

As we traveled almost 1.5 hours west of Madison, we found ourselves in the driftless region of Wisconsin. The target streams had been pre-selected by the DNR’s Office of Applied Science (OAS) researchers. This particular scientific study will provide quantitative data on the effects beaver have on cold-water stream habitats and trout populations. You can learn more about the study here.

Arriving at the first stream, we took a few minutes to get out of the truck and stretch. Ryan Bemowski (OAS Unmanned Aerial Systems Coordinator) set up the drone and programmed the device to follow a preferred trajectory. Nick Hoffman (DNR fisheries technician) verified the set trajectory, and once the drone was programmed, Ryan started it up. He had programmed the drone to fly at about 300 feet off the ground and up it went!

Bemowski setting up the drone for the first flight of the day.

When the programmed altitude was reached, the drone began moving in the direction of the stream we aimed to capture. My role was to follow the drone on foot and help make sure that we could keep an eye on the device at all times- being weary of trees, power lines, manned aircraft, etc. To get the full image, the drone followed the targeted section of the stream twice.

Aerial image of a trout steam taken from the drone.

While following the drone, I got a first-hand glimpse of the cold, clean waters of the driftless area- so clear, you could see large trout swimming. The goal of the study is to monitor recolonization of beaver and measure their impacts on water temperature, stream structure, and trout movement and population dynamics. The occasional beaver dam would pop up during our survey, showing us where beaver are returning to the stream.

A beaver dam located on one of the target streams.

These collected images, among other habitat data, will be used to better understand the effects of beaver activity and beaver control on salmonids in streams. The image data not only identifies the location of beaver activity, but allows us to directly measure the size of beaver structures and area of beaver impoundments. Infrared temperature sensors mounted on the UAV even let us directly measure surface water temperatures along the length of the stream, identifying cold water springs and possible temperature changes above and below beaver dams.

It was interesting to see the perspective from above, which as you all know, looks a little different than the typical snapshot our project cameras capture! Imagery data, whether captured by UAV or Snapshot Wisconsin trail cameras, plays a critical role in scientific research.

With my interest in general aviation and planes, it was really exciting and a great experience to add this to my belt. I am grateful for this opportunity and especially grateful to my colleagues, Ryan Bemowski and Nick Hoffman for letting me tag along.

The author with the drone and drone controls.