This mottled duck hen is being fitted with a GPS/GSM telemetry unit. (Submitted Photo/Courtesy of John K. Flores)
Researcher hopes to find mottled duck nests with telemetry study
When it comes to mottled ducks, a lot has been written scientifically. But, according to Elizabeth Bonczek, a Louisiana State University graduate student working on her PhD. much of what has been published about this Gulf of Mexico puddle duck was low hanging fruit, so to speak.
There’s still much to learn about this species.
With the recent decline in mottled duck population along much of the upper Texas coastline — where it appears to be mainly due to habitat loss — biologists are looking closer at nesting success, which according to Bonczek, very little has been written about. Bonczek is determined to change some of that.
In a cooperative effort between several agencies that include the Louisiana Department of Wildlife and Fisheries, Ducks Unlimited, Gulf Coast Joint Venture and the LSU School of Renewable Resources, Bonczek hopes to gain critical knowledge, while working towards her dissertation, which will help to understand this species more.
“What I’m looking at is the basic breeding ecology,” Bonczek said. “There were some mottled duck studies back in the early ’80s published by Allen and Baker. Originally, they focused on the coastal marsh of Rockefeller Wildlife Refuge. They looked at both pasture and marsh habitats. They wanted to find and locate nests and learn about nesting success. But, it’s hard to find mottled duck nests out in the vast marshes of southwest Louisiana. So, they didn’t get a lot of quality data.
“The whole goal of my project is to find nests,” Bonczek added. “I’m going to be looking at nesting success, adult survival, female breeding propensity and nest site selection and how all that relates to landscape characteristics.”
How Bonczek plans to be more successful than some of her predecessors is by attaching Global Positioning System / Global System for Mobile Communications (GPS/GSM) transmitters on female mottled ducks to locate them during the spring nesting period.
Biologists previously used Very High Frequency (VHF) radio telemetry antennas to track the ducks. Unfortunately, VHF antennas only were accurate to within one kilometer.
By contrast, GPS/GSM tracking devices are accurate to within 30 meters. That kind of accuracy is significant because of the mottled duck’s reclusive nature in an effort to avoid predators like alligators, raccoons and other mammals.
Locating a nest in the extensive marshes of coastal Louisiana can be compared to finding a needle in a haystack. The GPS/GSM transmitters will help Bonczek dial in a mottled duck’s position to a more finite geographic location.
The advantage to GPS/GSM transmitters is the device operates off the cellular network. They also are programmable, where biologists can choose recording intervals that log where mottled ducks have been at specific times. Moreover, they are solar charged and have an estimated life of just beyond three years.
In late August while Hurricane Harvey was bearing down in the western gulf, Louisiana Department of Wildlife and Fisheries staff on Rockefeller Wildlife Refuge assisted Bonczek extensively by coordinating capture efforts. With inclement weather pending and a goal of placing transmitters on 65 mottled ducks during peak molting, her window of opportunity was narrowing as the department also had to make preparations for the storm the following day.
Mottled ducks molt annually at this time of year, causing them to be flightless.
Using airboats and seal beam hand-held lights under the cover of darkness, the ducks were spotted, grabbed and placed in crates by biologists and technicians working in teams. All birds captured were banded and only the healthiest adult females received transmitters.
“The U.S. Geological Survey Bird Banding Laboratory doesn’t like any auxiliary devices like transmitters used that are more than 3 percent of the bird’s body weight,” Bonczek said. “Transmitters are 16 to 18 grams, so the lowest body weight we could attach them to was 670 grams. But, all of the birds we placed transmitters on have been between 700 and 800 grams. If there is any inkling of a scratch, the bird is banged up or looks suspicious, you don’t want to put a unit on them.”
Bonczek’s three-year research project began during the winter of 2016-2017, where she was hoping to capture ducks prior to the nesting season. Unfortunately, she had very little success, capturing only three birds. What’s more, those mottled ducks were fixed with VHF antenna.
By contrast, taking advantage of the summer molting period, Bonczek fastened GPS/GSM transmitters on 30 ducks one night and reached her goal of 65 total by the second night.
Transmitters come with a price tag of approximately $1,700 each, not including the cost of data collecting. Additionally, capture operations require a large commitment of equipment and manpower.
The cooperative efforts between the Louisiana Department of Wildlife and Fisheries, Ducks Unlimited, Gulf Coast Joint Venture and the LSU School of Renewable Resources, collectively, with funding and logistical support, make important research projects like Bonczek’s possible.
Come spring, Bonczek’s research should begin to pay dividends that will help biologists understand quite a bit more about mottled ducks, when she locates the first nests.