Weather, Drought Impact Waterfowl Migration

ROBERT NATHAN GREGORY

STARKVILLE, MISSISSIPPI

“Where are all the ducks?” It’s a question James Callicutt fields with more frequency and urgency from hunters and birders in Mississippi by the year.

Callicutt, a Mississippi State University Extension Service instructor specializing in waterfowl and wetlands ecology, said aerial waterfowl survey data show duck abundance in the southeastern U.S. is well below average.

“Earlier this year, forecasts for an El Nino year producing a cold and wet winter had waterfowl hunters and watchers optimistic for the coming season,” he said. “Up to early January, this has been a heartbreaking year to be a duck hunter in Mississippi. Milder winter weather or dry conditions have been experienced from time to time over the years, but in the 2023-24 season we have experienced both at great extremes.”

Wetlands are popular stopping points for early- and late-migrating birds alike, but drought conditions along the flyway have left those sources of habitat drier than normal. Houston Havens, waterfowl program coordinator with the Mississippi Department of Wildlife, Fisheries and Parks (MDWFP), said the complete drying of many wetlands has already taken place.

“Drought conditions have prevented many seasonal wetlands from filling due to rainfall or from groundwater well pumping,” Havens said. “Winter rains have not yet been sufficient to rebound moisture levels in many low-lying areas that would typically be flooded during winter across the state. However, some larger wetlands like lakes, cypress brakes and sloughs were able to maintain enough water through the summer and fall.”

Weather patterns and habitat availability play pivotal roles in determining whether ducks arrive in big numbers, Callicutt said.

“The drought-like conditions may have stalled early migrant ducks at northern latitudes as well,” he said. “If it appears dry to ducks to the north of us, then it might be drier south, making an energetically costly migration a risky endeavor.”

In Mississippi, waterfowl numbers typically peak in mid- to late January, but some ducks and geese begin arriving here as early as late October and early November. For those populations, the resources found in wetlands – particularly forage – are sometimes in shorter supply, unless sufficient rainfall or water-pumping efforts occur to make these resources available to foraging waterfowl.

“Many early migrants move south in the absence of severe winter weather,” Callicutt said. “Early fall is typically one of the driest times of the year, so this makes managed flooded and naturally flooded wetlands very important for these birds.”

Colder weather events in the northern U.S. had also been lacking until mid-January, he said, which drove waterfowl abundance down more.

“Research suggests that in addition to colder temperatures, factors such as snow cover are highly influential in pushing birds south, particularly mallards,” Callicutt said. “Snow cover and depth at this time of year in northern latitudes are much less than in recent years. Additionally, waterfowl surveys conducted at mid-latitudes in the Mississippi Flyway report much greater than average waterfowl abundance compared to recent years.”

A single, large-scale weather event like the winter storm that brought ice to Mississippi in mid-January can push more southbound waterfowl into the state. Havens said MDWFP is conducting an aerial waterfall survey in late January, and biologists expect to observe increased numbers during the flights.

“Many of Mississippi’s quality-managed, shallow wetlands, which produce a lot of waterfowl forage sources, froze during the extreme cold temperatures,” he noted, “so ducks will likely become concentrated on large, deep, or flowing water bodies until shallow wetlands thaw.” ∆

ROBERT NATHAN GREGORY: Mississippi State University