Spying on Ducks

In fall, migrating ducks are conspicuous. Masses of ducks darken lakes and wetlands; large noisy flocks fly overhead.

But during nesting season, ducks can be hard to see. Ducks are water birds, but their nests may be far from water, scattered and hidden in surrounding grasslands, making them hard for predators to find. That also makes them hard for biologists to find and researchers have had to develop tools for locating nesting ducks.

Grasslands at Davis Ranch are a Haven for Nesting Ducks

The Nature Conservancy’s Davis Ranch in North Dakota is a perfect location for studying nesting ducks and developing duck-finding tools. The 7,017-acre preserve sits in the heart of America’s duck factory—the Prairie Pothole Region. The region’s numerous lakes, ponds and wetlands interspersed among extensive grasslands create ideal duck nesting habitat.

In 2015, researchers from Ducks Unlimited and the University of North Dakota started using interns to study the behavior of nesting ducks at Ducks Unlimited’s adjacent Coteau Ranch before expanding their work the next year to include Davis Ranch.

Ducks are found by the chain drag method: a 50-meter chain stretched between two ATVs dragged through the grass, flushing nesting birds. The chain does not damage nests, and once a nest is found, ATV drivers stop and record its location. However, this method may stress nesting birds, and ATVs cannot traverse all available habitat (some spots are too wet or rocky).

Using Drones and Nest Cams to Study Ducks

Those drawbacks can be addressed by another method being tested at Davis Ranch and Coteau Ranch: drones. Drones can fly anywhere, and if high enough (more than 150 feet above ground), are less apt to frighten birds. Susan Felege, UND Associate Professor of Wildlife Ecology, calls drones a “camera delivery device,” but not all cameras are created equal. A duck hidden in the grass might be visible only to a heat-sensing camera. The camera doesn’t detect the actual temperature of a duck but does detect the difference in the heat signature of a brooding duck and the surrounding grass. Confirming that a hot spot is indeed a duck requires some calibration. Researchers can fly a drone first over a lake of known temperature, then over the prairie. That way, it is easier to later distinguish between a duck and a sun-warmed rock.

Once nests have been found, researchers then begin watching them closely using video surveillance cameras. Ducks tend to ignore these small cameras, which are mounted on a low post close to their eggs. Their day and night-time activities are captured by a digital video recorder in a waterproof box linked to the camera by a 25-meter cable. That’s far enough away that researchers can change the recorder’s SD card about every four days without disturbing a nesting hen. In 2019, 151 nests were located at just a fraction of Davis Ranch, and of these, several blue-winged teal, mallard and gadwall nests were equipped with cameras.