Harrisburg – While mallard ducks have long been one of the most recognizable, and seemingly abundant, waterfowl species, today’s numbers are trending in a different direction.
For the last 20 years, mallards have been declining in Pennsylvania and across the Atlantic Flyway. As recently as the 2017-18 waterfowl season, the mallard harvest in the Atlantic Flyway was 286,400, a 30% decrease from the long-term average (1999-2016). No other duck species in Pennsylvania showed a decrease as significant. In Pennsylvania, the mallard harvest in 2017-18 was 19,400, a 54 percent drop from the long-term average.
While the mallard decline has been occurring for some time, Nate Huck, waterfowl biologist with the Pennsylvania Game Commission, said the population appears to have stabilized in Pennsylvania, but that doesn’t mean the species has recovered.
As a result of the drop in mallard numbers, the PGC implemented a change beginning with the 2019-20 waterfowl season, reducing the bag limit from four to two. The two-bird limit, including one hen, remains in place for the upcoming waterfowl season and Huck said the provision will likely remain in place for the near future.
“Unfortunately, our hunters will have some reduced opportunities, but the reduced bag limit is what’s best for the resource right now,” he said.
But the PGC isn’t just reducing the mallard bag limit in response to the population decline – they will soon be looking for a cause as well.
In partnership with multiple states in the Atlantic Flyway, along with Ontario and Quebec, a mallard study will be launched next winter to examine survivability, nest success and other factors. From January 2022 to March, mallard ducks will be captured and outfitted with GPS devices that will provide key data into movement and nest success. Also, the devices will produce data revealing just how much an individual bird is moving. If a hen is immobile for 28 days, for example, it’s a good indication the bird was successful in hatching a brood.
Huck said highs and lows aren’t uncommon in duck populations, and the initial hope with mallards was the species would eventually reverse the decline.
“We all kind of thought they’d pull out of it and recover, but they’re not,” Huck said. “We’re at a point where we need to focus on this, and I think we’ll get some answers with the study.”
One of the questions that Huck hopes will be addressed has to do with habitat. When other populations of duck species experienced declines, it was usually associated with habitat, he said. That might not be the case with mallards, which Huck described as being a generalist when it comes to habitat preferences. The study could shed light on what mallards prefer for nesting cover, specifically, and Huck said it’s possible that work can be done on game lands to manipulate habitat favorably for mallards.
In addition to the upcoming GPS study, Huck said there is research occurring on the impact of hybridization with domestic mallards and genetic issues. If hybridization is a contributing cause to the decline, mallard wasn’t sure what could be done to address the issue.
“The best thing we can do right now is reduce harvest pressure and improve habitat,” he said.
While the mallards’ place as the most numerous duck in the waterfowl world is in jeopardy, wood duck numbers are increasing to the point where they may overtake mallards. Huck attributed the rise in wood ducks to the fact that much of the forested land in Pennsylvania is maturing.
“Wood ducks are a cavity nester, and these older forests present more natural cavities on the landscape. Wood ducks are taking advantage of that,” he said.
