During their study, the team captured 71 mallards, fitting the “backpack” transmitters to each one.
From mid-October until mid-January, DeVito and Kleist would leave the field station in search of mallards. They used radio antennas – which can be held by hand or attached to trucks or airplanes, receiver boxes and electronic compasses to locate the “tracer” ducks – those already wearing the backpacks.
Most of the time, the team worked out of the truck, which is fitted with ecological software that helps locate the mallards. When not searching for new ducks to tag, DeVito and Kleist listen to a receiver box that tells them if a tracer duck is nearby. When the team is close enough to a mallard, they will hear a beep every 30 seconds, “We listen to a fabulous static all day long,” DeVito jokes. “When we’re doing this, and these are each emitting the signal, we’ll hear a beep. That gives us the idea that we need to stop and figure out where the bird is.”
The team used hand-held tracking when investigating a mortality, she says. If a duck has not moved for more than eight hours, its tracking device will emit an urgent “mortality” beep at twice the original speed.
“A lot of the time, it’s not as simple as it sounds,” DeVito says.
She recalls a recent tracking experience where she and her team could not seem to find the transmitter after receiving the mortality signal. After listening more closely, she thought it seemed to be coming from underground.
“It makes you feel like you’re losing your mind for a little bit,” she says.
As DeVito started to dig beneath the frozen ground, she came to a den, likely belonging to an otter or mink, she says. Finally, her team found the remains of two wings.
“It was pretty cool,” she says. “After we recovered the transmitter, we found there was a big chomp mark in it.”
Some of the mallards have been discovered far out of the transmitter’s range. Of the 71 ducks, 20 died during the study. Three were mortalities (meaning they died from natural predators, such as the one found underground) and 17 were shot by hunters.
Two ducks were shot by a man in northern Tennessee, DeVito says. Each backpack comes with the field station’s telephone number on it, so hunters can call to return the transmitter.
The backpacks are about $200 each, Stafford says. The batteries are designed to run out in about 200 days, at which time researchers will have completed their observation.
Observing the mallards is like a full-time job, Kleist says. Both he and DeVito are originally from Minnesota, and have worked on numerous waterfowl projects for universities and conservation groups.
“I definitely enjoy it,” he says. “We’re out from sunrise to sunset, catching ducks and tracking them.”
He adds that the backpack transmitters are much easier than other kinds, which can involve surgical implants.
“I just did a project out in Louisiana
continued on page 14
