Spring Moisture Rejuvenates Duck Rearing Areas

Aside from the physical appearance of prairie pothole sloughs filled to the brim with runoff from spring snow melt and rain, the ability of these engines of America's duck factory to support broods of waterfowl has been supercharged. The ducklings now emerging from nests alongside these refilled lowlands and onto their heightened waters stand a better chance of survival, thanks in part to the increased nutrients and food provided by those areas along their shores, which last year were left high and dry. Mike Szymanski, Migratory Game Bird Supervisor for the North Dakota Game & Fish Department (NDG&F), suggests that while ephemeral wetlands such as those found in ditches are now starting to drain and disappear, larger sloughs and semi-permanent potholes are regenerating those things all ducks – young and old – need in summer.

"As new habitats become flooded, and soil is rewetted there is a bump in productivity. That's certainly important for ducks that are using the habitats all across the board: migrating in the spring, or hens requiring nutrients or even food availability for ducklings in the summertime, and then of course in the fall with birds getting up and starting to migrate through our landscape. That boost of productivity is super important to see on an annual basis," Szymanski explains.

More water and more area covered by it allows shallow wetlands to produce a greater amount of vegetation which is not only a source of food for ducks, but also habitat for other prey items ducks feed on. Invertebrates such as aquatic insects, mollusks and arthropods are available as their living space and habitat expands as well in the wetter conditions. These items of both plant and animal forage sustain adult ducks, and help ducklings survive and grow throughout the brooding process, and the aquatic insect life present in these sloughs provides a large portion of a young duck's diet in the first few weeks of life.

With the drought of 2021, there was a great deal of exposed dirt and shoreline in many of North Dakota's semi-permanent and larger wetlands, which decreased their ability to provide nutrients to would-be ducklings. These lower water levels coupled with higher temperatures and lack of rainfall – both environmental stressors – placed greater disincentive on waterfowl to breed as normal. NDG&F agents noted in last season's surveys of ducks on the landscape that a number of species had limited breeding activity, and even exhibited outward behaviors showing they would not be nesting.

"The wetter it is, the more effort the ducks will put into breeding. They'll have a higher probability of breeding in the first place, which was a big problem we had last year, where it just seemed like ducks showed up and they just weren't going to breed. They were already figuring out what they were going to do for the rest of their spring and summer," Szymanski recalls, adding, "this year ducks were really getting after it, getting that strong initial breeding effort out onto the ground. And then, as it stays wet and if we continue to get moisture and wetland conditions continue to be pretty good, ducks will continue renesting for a pretty long time period, even getting through July and hatching broods into late July and August."

While increased water levels in many sloughs are a positive note coming after a long dry stretch, some concerns remain on the landscape, particularly for ducks like mallards which nest in the uplands surrounding those waters. Limited carry-over grasses resulting from haying and simply from lack of last season's growth mean many nests will have heightened exposure to predators, and this spring's regrowth, while good, may not be enough to limit predation as in a normal stretch of consecutive good years.

"I'm a little concerned about how things will play out, it's kind of a tough year when you change from being so dry to so wet. Stuff gets hammered pretty hard in drought and we've got a lot of areas in the state where it's really just dirt and water right now," Szymanski cautions, noting that ducks are adaptable and can re-nest if conditions early on don't result in a hatch, concluding, "those oddball areas will start to revegetate and we'll probably have some late nesting birds actually get in there."

Last year's spring breeding duck survey was the fifth driest on record, with the largest percentage decrease in wetlands year-to-year between 2020 and 2021 in the program's 75-year history. This year's survey showed an increase of 616 percent (the single highest year-to-year change) in wetlands during the survey period in late May, and an estimated total number of ducks at around 3.4 million in the state, up 16 percent from the survey estimates in 2021.