Conservation: Making a Difference for Mottled Ducks

By Jennifer Boudart

Waterfowl are highly mobile, and as a rule most species make long seasonal migrations—often spanning hundreds or thousands of miles—between their breeding and wintering grounds. As with any rule, however, there are exceptions. Perhaps the most notable in this case is the mottled duck. This nonmigratory relative of the mallard, American black duck, and Mexican duck occurs in several distinct populations. The largest population is found along the western Gulf Coast, mostly in Texas and Louisiana, where mottled ducks rely on coastal marshes and associated inland habitats to meet their biological needs. Smaller populations are found in Florida, South Carolina, and Georgia.

Given their nonmigratory lifestyle, mottled ducks are highly vulnerable to habitat loss, notably along the western Gulf Coast. Mottled duck numbers in Louisiana have dropped 65 percent since 2009. In Texas, the population has recently stabilized but remains well below long-term levels.

The mottled duck has been designated a high-priority species by the Gulf Coast Joint Venture (GCJV), a conservation partnership involving Ducks Unlimited, the Louisiana Department of Wildlife and Fisheries (LDWF), the US Fish and Wildlife Service, and many other partners. DU’s Dr. Joe Lancaster is the biological team leader for the GCJV and was a member of the working group responsible for updating the joint venture’s Mottled Duck Conservation Plan in 2023. That update gathered the most recent research and survey data for mottled ducks in Texas and Louisiana to clarify factors limiting the population and to develop guidance for delivering conservation work that will help mottled duck numbers rebound.

The primary limiting factor for mottled duck populations, according to Lancaster, is recruitment, the process by which new individuals are added to the population. “The main components of recruitment are breeding propensity, nest success, and brood survival,” he explains. “These drivers limit population growth when quality breeding and post-breeding habitats are scarce.”

Mottled ducks breed in isolated wetlands that are adjacent to grasslands. Lancaster notes that having abundant wetlands during January and February is important for stimulating breeding and nesting activity. Wetlands are also critical during the brood-rearing period, from March through July.

“One key to improving recruitment in mottled ducks is increasing the availability of spring and summer wetlands in close proximity to large tracts of upland nesting cover,” Lancaster adds. “We have found that we can make the biggest net gains for mottled ducks by improving breeding habitats on private lands.” 

Efforts like the Louisiana Mottled Duck Project are doing just that. Through this species-specific habitat conservation program, which is funded by LDWF, landowners sign contracts for up to three years to manage wetlands that provide brood-rearing habitat for mottled ducks. DU and LDWF assist participating landowners by providing financial and technical assistance. Beneficial practices include holding shallow water in restored seasonal wetlands, which are managed to contain approximately 50 percent emergent vegetation. Preferred plant species are managed through practices such as herbicide application, disking, roller chopping, and prescribed burning. Landowners are paid on a per-acre basis according to the practices they employ.

DU biologist David Hicks oversees the Louisiana Mottled Duck Project and is currently working with five landowners on projects ranging from 50 to 565 acres. One landowner runs a waterfowl hunting operation. Another produces rice, crawfish, and cattle. The program fits well with these land uses, and Hicks expects more landowners to sign up this year.

DU and its partners rely on several sources of information to select project sites, including a Mottled Duck Decision Support Tool (DST), which identifies where nesting and brood-rearing habitat already exists or could be improved. “For example, we can say that based on the DST, an area where we want to increase brood-rearing habitat also has suitable nesting habitat, so it’s a good place to look for a site,” Hicks says. He also taps local knowledge. “I work with our rice stewardship coordinator quite a bit because he’s on the landscape meeting with landowners and knows which ones are interested in waterfowl conservation.”

In addition, Hicks targets properties that are already enrolled in other conservation programs, such as the GCJV’s Coastal Grasslands Restoration Incentive Program, which provides incentives to landowners to manage grassland habitat benefiting mottled ducks and other bird species. Another is DU’s Louisiana Waterfowl Project, which provides landowners with cost-sharing assistance to install infrastructure needed to manage wetlands for wintering waterfowl. The same habitats can often be managed to hold water through the spring breeding period for mottled ducks.

Hicks is encouraged by the positive feedback he has received from participating landowners. He has also seen a strong response from the birds, which are monitored using aerial drones. In 2024, he observed 340 adult mottled ducks and seven broods totaling 52 ducklings on project sites. An impressive number of other waterfowl species were also documented, including fulvous and black-bellied whistling ducks, wood ducks, and blue-winged teal, as well as waterbirds such as gallinules, king rails, little blue herons, and roseate spoonbills.

While the three-year funding period for the mottled duck project concludes this year, Hicks is optimistic that LDWF will renew funding for another three years. DU has also secured a grant from the National Fish and Wildlife Foundation for this work through 2026. Hicks looks forward to expanding the mottled duck project and hopes other conservation and research efforts that benefit mottled ducks will expand as well.

“Mottled ducks are a home-grown species, and we have the unique opportunity to influence their entire annual cycle,” Hicks says. “They’re iconic to waterfowl hunters in south Louisiana and Texas. Although we can’t control everything that impacts mottled ducks along the Gulf Coast, we can work within the parameters that are available to us to help keep this species at a viable population level.”

Refining Mottled Duck Research

Mottled ducks are highly secretive birds that nest in isolated areas, making them difficult to study and monitor. Ducks Unlimited is working on a proposal to test the effectiveness of implantable transmitters to collect better data about mottled duck movements and habitat selection throughout their annual cycle. The transmitters use satellites and mobile communications networks to track the birds’ movements. Twenty mottled ducks will be marked with transmitters each year for three years. Capture sites will be located on private and public land across two distinct coastal landscapes in Louisiana: the Chenier and Deltaic Plains. 

Transmitter data will be analyzed to determine how the birds’ behavior contributes to survival and nest success; to better understand local and fine-scale habitat characteristics at nesting sites; to assess season-specific survival and causes of mortality; and to compare habitat selection and reproductive success. The transmitters’ operational efficacy will also be tested. Partners in this work include Rockefeller Wildlife Refuge, the Louisiana Department of Wildlife and Fisheries, the Louisiana Waterfowl Working Group, and Tennessee Tech University. Additional financial and logistical support is being provided through DU’s partnership with ConocoPhillips.