The 2024 Wisconsin spring waterfowl breeding survey showed a continued decline in mallards, the state's most abundant duck species, and a year-over-year drop in total ducks as well as Canada geese.
However the number of total ducks was higher than the 50-year average and waterfowl numbers are still in good shape compared to most other bird groups.
Wetland basins in all regions of the state were above the long-term averages.
The latest duck and goose numbers are listed in a Department of Natural Resources report titled "Waterfowl Breeding Population Survey for Wisconsin, 1973-2024."
Data for the annual survey are collected by trained observers in aircraft and on land. This year the work was completed between April 15 and 26 and included eight days of flights and nine of ground surveys.
The work was performed by DNR and U.S. Fish and Wildlife Service employees.
The information is incorporated in a federal survey of breeding waterfowl in North America as well used to help make state-level waterfowl management decisions. The Wisconsin work has been conducted annually since 1973 (except for 2020 due to the COVID-19 pandemic).
The annual estimates allow direct comparisons to previous years but biologists often say its best to look at trends over several years.
The 2024 survey produced a statewide estimate of 502,058 breeding ducks, a 4% decline from 2023 but 13% above the long-term (1973 to 2023) average.
Among species, the survey estimated 146,561 mallards, 8% lower than 2023 and was 18% lower than the long-term mean.
Blue-winged teal, the second-most abundant duck in the survey, was estimated at 103,717, a 2% year-over-year increase but 1% below the long-term mean.
The survey estimated 96,711 wood ducks in Wisconsin, 0.5% lower than 2023 and 13% higher than the long-term mean.
Other ducks, mostly ring-necked ducks and common and red-breasted mergansers in this year's survey, were estimated at 151,845, essentially equal to 2023 and 126% higher than the long-term mean.
Among Canada geese, arguably the state's most visible breeding waterfowl species, the work produced an estimate of 153,402, a 3.5% decrease from 2023 but 42% higher than the long-term mean.
Although the annual survey is focused on ducks and geese, it also collects information on non-game species. This year, for example, it cited a continued increase in trumpeter swans and sandhill cranes in the state.
As significant declines have been documented in recent decades in most bird groups, waterfowl have generally fared much better.
A 2019 report in Science magazine found since the 1970s North America has lost 3 billion birds, or nearly 30% of the total. Shore birds and grassland birds are among the most affected with many species showing long-term declines of 50% or more.
Yet thanks to programs such as the Federal Duck Stamp, birds that rely on wetlands have generally fared better. Hunting regulations, based largely on results of the breeding bird surveys, also have helped protect ducks and geese.
The decline in mallards has concerned many wildlife biologists and hunters, though.
Wisconsin's 2024 data are similar to recent results in the continental waterfowl survey. In the traditional North American survey area the total duck population estimate was 32.3 million birds, a 7% year-over-year decline and 9% below the long-term average of 35.5 million, according to the 2023 U.S. Fish and Wildlife Service Waterfowl Population Status Report.
Estimated mallard abundance across the continent was 6.1 million, 18% below the 2022 estimate of 7.4 million and 23% below the long-term average of 7.9 million.
To further highlight the mallard decline, in 2023 the California and Oregon mallard estimates were 39% and 23%, respectively, below their long-term averages and Michigan was down 41% year-over-year and 75% below the long-term average (1991–2022), according to the USFWS.
Due to higher levels of precipitation and improved breeding conditions this spring across much of North America, mallards and other species could experience increased recruitment in 2024.
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