Agricultural Practices Influence Waterfowl Distribution
Dr. Rick Kaminski is a professor of wildlife ecology and holder of the James C. Kennedy Endowed Chair in Waterfowl and Wetlands Conservation at Mississippi State University.
Kaminski has 30 years of experience in waterfowl habitat research
, mainly in the Mississippi Alluvial Valley (MAV). In recent years, he has overseen extensive studies in the MAV on food availability for wintering ducks. Specifically, Kaminski and his colleagues have focused on the abundance of rice, corn, soybeans, and grain sorghum (milo), as well as on agricultural practices that affect the availability of waste grain for wintering waterfowl.
"Food energy is crucial for sustaining waterfowl populations
. We've learned that if food availability on the wintering grounds decreases, it may impact the birds' survival and subsequent reproduction," Kaminski says. "This is the main premise behind habitat conservation on the wintering grounds. Waterfowl must obtain adequate nutrition to endure winter and to return to the breeding grounds in spring and have a strong reproductive effort."
Kaminski's research has revealed that changing modern farming practices have reduced the availability of agricultural foods for wintering waterfowl in many areas. "Most row crops nowadays are being planted earlier in spring and harvested earlier in fall, and much of the waste grain left in the field rots or sprouts during September and October, before the ducks arrive on their wintering grounds," Kaminski explains. "Other birds and rodents also get their share. Thus we should mitigate this loss, and we have evaluated several ways to do so.
"We've learned that in harvested rice fields, more waste grain remains if the stubble is left standing or burned instead of being rolled or disked after harvest. We've observed that mallard use is greatest in fields that are burned and then flooded. When flames meander randomly through a field, they remove stubble in patches and leave it intact elsewhere. Ducks are attracted to this mix of patchy stubble and water. Plus, burning can prevent waste grain from sprouting, but the seeds are still edible and nourishing to the birds." (Kaminski notes that burning is not allowed in certain areas because of air quality and aviation regulations, but is allowed in most of the MAV.)
Another management practice that provides more food for ducks is growing what Kaminski calls "grassy corn." In this practice, the rows are planted farther apart (about three feet) than standard corn crops, which allows more sunlight to stimulate growth of natural grasses and sedges between the rows. This grassy understory, in turn, produces moist-soil seeds, and after the field is flooded, aquatic invertebrates flourish in the flooded grass, providing wintering ducks
with protein and other nutrients.
As Petrie discovered in the Pacific Northwest, Kaminski's research has also documented that the highest densities of mallards and other dabbling ducks in the MAV occur in areas with a combination of natural wetlands, where the birds can rest and find natural foods, and agricultural crops, which provide reliable foraging habitat. In the Mississippi Delta, Kaminski found that the ideal mix of habitat for wintering ducks consists of approximately 50 percent flooded cropland, 20 percent forested wetlands, 20 percent moist-soil wetlands, and 10 percent permanent wetlands (beaver ponds, rivers, sloughs, etc.). "The exact percentages are not known, but these results emphasize that a complex of multiple habitats attracts a greater abundance and diversity of ducks than single habitat types," he says.