100 Years Ago…
For a blast from the past, check out this document from a survey for waterfowl in the Potomac from the 1920’s.
Thank you to everyone who volunteers to keep this tradition alive!
2026 Winter Waterfowl Count Summary
Larry Cartwright, Compiler
The 2026 Winter Waterfowl Survey, sponsored by NVBA, was conducted on February 14 and 15. Nearly 70 participants monitored areas along the Potomac River from western Loudoun County to Quantico Marine Base in Prince William County. They also surveyed many inland water bodies for the presence of waterfowl. Here’s a link to the raw data.
Icy conditions likely impacted the number of some waterfowl species recorded during the 2026 count. With some notable exceptions, duck totals, especially dabblers, were incredibly low. Of the seven most common dabbling ducks seen in our area (Northern Shoveler, Gadwall, American Wigeon, Mallard, American Black Duck, Northern Pintail, and Green-winged Teal), five were tallied with fewer than 50 individuals apiece. Granted, the dabbling duck wintering population has been low for some time, but the numbers for these five species were at basement level.
Northern Shoveler: 28 in 2025 and 30 in 2026
Gadwall: 616 in 2025 and 46 in 2026
American Wigeon: 33 in 2025 and 1 in 2026
Northern Pintail: 134 in 2025 and 13 in 2026
Green-winged Teal: 16 in 2025 and 5 in 2026
Green-winged Teal prefer shallow water and love to forage along the shoreline, so the low numbers for 2026 might be explained by ice-covered shorelines, but conditions for the 2026 count do not explain low figures for previous years.
The Mallard and American Black Duck numbers were the exceptions to the low dabbling duck figures for 2026. The wintering Mallard population remained practically unchanged, and the American Black Duck count showed a dramatic increase. The count of Mallards was 1,240 in 2025 and 1,233 in 2026, while the count of American Black Ducks increased from 716 in 2025 to 1,044 in 2026.
Mallards are the most common of the dabbling ducks and can be found almost everywhere, including small inland lakes and ponds. American Black Ducks have been most abundant at Pohick Bay, Ft. Belvoir, and the Great Marsh at Mason Neck, but I am noticing a slight change in distribution that may be independent of the ice cover in 2026. One-third of the American Black Ducks in 2025 were tallied at Chopawamsic Creek at Quantico Marine Base. In 2026, over one-fourth of American Black Ducks were at Chopawamsic Creek.
There were dramatic declines in some diving ducks in the genus Aythya (Canvasback, Redhead, Ring-necked Duck, and Greater and Lesser Scaup) while the Common Merganser numbers doubled between 2025 and 2026. Canvasbacks declined from 6,176 in 2025 to 180 in 2026, and Redheads from 776 in 2025 to 468 in 2026. Common Mergansers increased from 755 in 2025 to 1,461 in 2026.
It’s hard to know how much the ice cover impacted these numbers, but it seems not to have deterred Common Mergansers. Canvasbacks and Redheads generally congregate around Pohick Bay, Occoquan Bay National Wildlife Refuge, and Mason Neck Refuge and State Park. This was partially true in 2026. Half the Redheads were tallied in the northern half of Belmont Bay, but over half of the small number of Canvasbacks were found at Leesylvania State Park. Common Mergansers were well represented in the Potomac River as seen from Ft. Belvoir and in Belmont Bay (over 800 birds).
There was little fluctuation in Ring-necked Duck and Lesser Scaup numbers between 2025 and 2026. The count for Ring-necked Ducks was 601 in 2025 and 562 in 2026, and for Lesser Scaup was 6,565 in 2025 and 7,275 in 2026. Distribution was unchanged as well. Well over half the Ring-necked Ducks were found in the Potomac River west of Great Falls or in lakes and ponds in western Fairfax and Loudoun Counties. Lesser Scaup were present in large rafts in the Potomac River at Mason Neck and in Occoquan and Belmont Bays.
As for the small diving ducks, Buffleheads and Ruddy Ducks witnessed the most significant declines while Hooded Mergansers had no fluctuation.
Bufflehead: 583 in 2025 and 282 in 2026
Hooded Merganser: 357 in 2025 and 351 in 2026
Ruddy Duck: 424 in 2025 in 184 in 2026
These smaller divers are often more at home in inland bodies of water than the Potomac River, so perhaps iced-over lakes and ponds did not provide suitable conditions for them.
Tundra Swans maintained a nice presence between 2025 and 2026 with birds primarily distributed around Occoquan and Belmont Bays and the Great Marsh at Mason Neck. Volunteers also reported small flocks at Leesylvania State Park and Chopawamsic Creek. The count was 396 in 2025 and 357 in 2026.
The top bird of the 2026 Winter Waterfowl Count was not even a waterfowl (ducks, geese, swans), but an occasional winter waterbird not seen every year. This was a Red-necked Grebe, the star of the show seen at Pohick Bay Regional Park.
Trends? It’s hard to identify them with the amazing fluctuations seen in some species. We can say that certain species prefer to winter in certain locations, so we have an idea of the distribution of some waterfowl, whether it’s Lesser Scaup at Occoquan and Mason Neck or Ring-necked Ducks hanging out west of Great Falls.
Thanks to everyone that participated in the 2026 count. Come back and join us in February 2027 and see what surprises that wintering waterfowl in northern Virginia present for us.
2025 Winter Waterfowl Count Summary
Larry Cartwright, Compiler
The 2025 Winter Waterfowl Survey was conducted on February 1 and 2. Volunteers monitored areas along the Potomac River from western Loudoun County to Quantico Marine Base in Prince William County. They also surveyed many inland water bodies for waterfowl presence.
The fluctuation in some waterfowl numbers is now making it difficult to see trends. Generally, dabbling duck numbers (Northern Shoveler, Gadwall, American Wigeon, Mallard, American Black Duck, Northern Pintail, and Green-winged Teal) remain low, with shovelers, pintails, and teal having noticeably low tallies.
Northern Shoveler: 17 in 2024 and 28 in 2025
Northern Pintail: 185 in 2024 and 134 in 2025
Green-winged Teal: 63 in 2024 and 16 in 2025
Mallards and American Black Ducks numbers are perhaps 10 to 15 percent lower than their historic winter population levels but were stable when compared to 2024. The count produced 1,106 Mallards in 2024 and 1,240 in 2025, and 821 American Black Ducks in 2024 to 716 in 2025.
The biggest surprise was the dramatic increase in Gadwalls and the incredible decline in American Wigeons between 2024 and 2025, making me think that the wintering waterfowl numbers are influenced heavily by external factors. Gadwall increased from 337 in 2024 to 616 in 2025, and American Wigeons declined from 816 in 2024 to only 33 in 2025!
I see the same trend, if you can call it that (a phenomenon might be a better choice of words), with diving ducks: Canvasback, Redhead, Ring-necked Duck, Lesser Scaup, Bufflehead, Hooded Merganser, Common Merganser, and Ruddy Duck. Look at the wintering population increase in Canvasbacks, Redheads, and Common Mergansers between 2024 and 2025.
Canvasback: 3,578 in 2024 and 6,176 in 2025
Redhead: 791 in 2024 and 1,776 in 2025
Common Merganser: 311 in 2024 and 755 in 2025
Now let’s contrast these numbers with the decline of Ring-necked Ducks, Lesser Scaup, and Ruddy Ducks in the same two years.
Ring-necked Duck: 1,111 in 2024 and 601 in 2025
Lesser Scaup: 9,672 in 2024 and 6,565 in 2025
Ruddy Duck: 1,895 in 2024 and 424 in 2025
There was insignificant fluctuation in the remaining smaller diving ducks, Hooded Mergansers and Buffleheads, with 535 Bufflehead in 2024 and 583 in 2025, and 303 Hooded Merganser in 2024 and 357 in 2025.
Tundra Swans are big and majestic and generate much interest. The number of birds doubled between 2024 and 2025 from 191 in 2024 to 396 in 2025.
Waterfowl can be located anywhere along the river and in inland lakes and ponds, but there are several concentrations worth mentioning. Canvasbacks and Redheads, both large divers, generally congregate in Pohick Bay, Occoquan Bay, and Belmont Bay, and it was no different in 2025. Gadwalls and American Wigeons are usually found in the same area, but in 2025 Wigeons were hardly present and half of the 616 Gadwalls tallied in 2025 were observed at Leesylvania State Park and Quantico Creek.
The large rafts of Lesser Scaup historically are heavily concentrated around Pohick Bay, the Potomac River off the southern shoreline of Mason Neck, and Occoquan Bay, and although dramatically reduced in number of individual birds, it was true again in 2025.
Of all the diving ducks, Ring-billed Ducks always have a good representation in the Potomac River above Great Falls but are also content in inland water bodies with Hooded Mergansers and some Ruddy Ducks.
American Black Ducks usually have high numbers at Pohick Bay, Ft. Belvoir, and the Great Marsh at Mason Neck, but in 2025 about a third of the 716 birds counted were present at Quantico Creek. Paradoxically, the same is true for Tundra Swans. The Great Marsh is still the best place to look for these white giants, but Quantico Creek seems to be becoming a great secondary location.
2024 Winter Waterfowl Count Summary
Larry Cartwright, Compiler
The 2024 Winter Waterfowl Count sponsored by the Northern Virginia Bird Alliance was conducted on February 3 and 4. The survey tract covers the Potomac River from Loudoun County to Quantico Marine Base in Prince William County, as well as many inland bodies of water in Loudoun, Fairfax, and western Prince Williams Counties. The survey is composed of 15 sectors and in 2024 had over 50 volunteers in the field. We tallied both traditional waterfowl (ducks, geese, and swans) and water-associated birds (grebes, cormorants, waders, etc.).
Volunteer data shows that, with one exception, dabbling ducks (Northern Shovelers, Gadwalls, American Wigeons, Mallards, American Black Ducks, Northern Pintails, and Green-winged Teal) remain in low numbers. The traditionally ubiquitous Mallard that boasted a population of almost 2,400 individuals in 2017 and up to 3,000 birds in the early teens barely broke 1,100 in 2024. The highlight was the impressive increase in the numbers of Gadwall and American Wigeon between 2023 and 2024. Gadwall increased from 103 to 337 and American Wigeon went up from a mere 19 to an amazing 816 in 2024. The Gadwall figure is on average about half the number we got in the early teens, but the American Wigeon number is above average for this survey.
Diving ducks (Canvasbacks, Redheads, Ring-necked Ducks, Lesser Scaup, Bufflehead, Common Goldeneye, Hooded and Common Mergansers, and Ruddy Ducks) are seemingly better off than their dabbling counterparts. Note that we are still below the 14,000 Lesser Scaup we used to tally in the mid-teens, but an increase from 7,000 birds in 2023 to over 9,500 in 2024 is a hopeful sign. Canvasbacks came in at an impressive 3,578 individuals, a new record for the survey. Ruddy Ducks and Ring-neck Ducks also had good tallies, with just under 1,900 birds for the former and over 1,100 birds for the latter.
Note that the waterfowl found in our waterways in 2024 were not evenly distributed. The vast majority of American Wigeons, Gadwall, Lesser Scaup, Canvasbacks, and Ruddy Ducks were concentrated in an area from Pohick Bay Regional Park and Ft. Belvoir to Occoquan and Belmont Bays. Ring-neck Ducks preferred the Potomac River and inland waterways above the fall line in Loudoun County.
A final word on the large and majestic Tundra Swans that in past years could be found in the Great Marsh at Mason Neck during the winter in numbers up to nearly 500. This may no longer be the case. In 2024 volunteers counted 191 birds and most of them (150) were identified in Quantico Creek between Possum Point Road and Hospital Point at Quantico Marine Base. This is the third consecutive year that Tundra Swans have been concentrated at Quantico Creek.
You can view summary charts showing trends from 2009 to 2024 here and the 2024 raw data file here.
2023 Winter Waterfowl Count Summary
Larry Cartwright, Compiler
The Winter Waterfowl Count, which ASNV sponsors, covers the Potomac River from Algonkian Regional Park in Loudoun County to Quantico Marine Base in Prince William County, as well as many inland bodies of water. The 2023 count was conducted on February 11 and 12 by teams in 15 sectors composed of 61 volunteers. They documented 34,797 individuals of 42 species. We tallied both traditional waterfowl (ducks, geese, and swans) and water-associated birds (grebes, cormorants, and waders).
Volunteer data shows that dabbling ducks were present only in low numbers. Even the normally ubiquitous dabblers had a poor showing. American Mallards, which five years ago would boast numbers well over 1,500, barely broke 1,000, and American Black Ducks that formerly had 800 to 900 individuals, had only 450 individuals in 2023. The other dabblers, including Northern Shovelers, Gadwalls, American Wigeons, and Northern Pintails, were in low numbers. The most numerous after Mallards and Black Ducks were Northern Pintails, with only 129 individuals.
Counts of Lesser Scaup, our most numerous diving duck, have fluctuated over the last five years, and at first blush give the impression of stability. That would seem to be justified by the large flocks of Lesser Scaup observed in the Potomac River, Occoquan Bay, and Belmont Bay in 2023. However, if we compare the 2018 numbers with 2023, we see a drop of 50 per cent in the winter population, from over 14,000 birds in 2018 to over 7,000 birds in 2023. Could the 2018 numbers be artificially high? Not likely. The 2015 survey tallied over 15,000 Lesser Scaup while the 2012 number was above 18,000. My analysis can change depending on how I view the figures, but it looks as if, despite the up and down fluctuations, that the Lesser Scaup trend is downward.
Other diving ducks are holding their own and seem to be a bright spot. Many of these birds prefer certain spots for where they spend the winter. Ring-necked Ducks seem to enjoy the area around Riverbend Park and Great Falls and inland bodies of water in western Fairfax County and Loudoun County. Volunteers observed 515 of the count’s 730 Ring-necked Ducks at these locations. A small flock of two dozen Common Goldeneye have occupied the area downriver of the American Legion Bridge over Interstate 495 for several years now. Want to see Canvasbacks or Redheads? Ft. Belvoir and Pohick Bay may provide your best opportunity.
As far as other waterfowl go, we only tallied 204 Tundra Swans during the 2023 survey. Generally, we get several hundred at the Great Marsh at Mason Neck alone. Now the birds seem to be more spread out between Mason Neck and Quantico, and perhaps some are moving further downriver beyond the scope of our survey.
Thanks to everyone who participated in the 2023 survey. It is amazing that over 60 people volunteered to go out on a winter’s day to count birds. We hope to see all of you back for the 2024 survey on February 3 and 4.
2021 Winter Waterfowl Count Summary
The Winter Waterfowl Count is sponsored by the Audubon Society of Northern Virginia. When begun in 2008, ASNV volunteers covered the Potomac River from Algonkian Regional Park in Loudoun County to Quantico Marine Base in Prince William County, as well as many inland bodies of water. In 2020 we expanded the survey by adding areas along the Potomac River in King George and Westmoreland County down to the mouth of the Potomac River where it empties into the Chesapeake Bay.
The 2021 Waterfowl Survey was conducted on February 6 and 7. The survey logged 33,364 birds, which is only 75% of the average for the previous five years. It also is the lowest count since at least 2016 despite adding the lower reaches of the Potomac River to the survey area in 2021. The 38 species found is also the lowest since at least 2016.
Common dabbling ducks had modest increases overall. Northern Pintails increased from 16 to 258, which is a big improvement, but still below historical averages, and Mallards increased from 1,140 to 1,685. However, Gadwalls declined from 204 in 2020 to 165, American Wigeons declined from 37 to only 14, and American Black Ducks decreased from 987 to 815.
Diving duck numbers generally increased. Canvasbacks increased from 291 in 2020 to 646 in 2021; Redheads increased from 47 to 155; and Ring-necked Ducks increased from 207 to 695, the highest number since 2018. Hooded Mergansers and Common Mergansers increased from 203 and 147 birds, respectively, in 2020 to 360 and 378 birds in 2021. Lesser Scaup were a particularly bright spot, increasing from 8,443 to 10,254, the highest count since 2018. However, Buffleheads declined from 1,931 to 512 and Ruddy Ducks declined from 4,930 to 2,688.
Among the large waterfowl, Tundra Swans increased from 397 to 422, but the 9,078 Canada Geese surveyed in 2021 is less than half of the number found in 2020 and only 2/3 of the average of 13,500 birds for the previous five years. The decline in Canada Geese accounts for about half of the total decline in birds surveyed in 2021.
The low numbers of waterfowl we have experienced in northern Virginia during the past three years might be attributed to the rapid decline of submerged aquatic vegetation (SAV) after large amounts of rain in the spring of 2018. The high water levels and sedimentation caused much of the SAV to die off, and it has taken time for it to return to the levels sufficient to support the normal population of wintering waterfowl in our area. Hopefully, the 2022 survey will reflect better overall numbers.
We owe special thanks to the 40 intrepid surveyors who participated in this year’s count and particularly to Larry Cartwright, who recruited and organized the surveyors, served on three survey teams, and compiled the results of all fourteen teams. The Winter Waterfowl Survey depends on our citizen scientists.
Raw Data Tallies from Previous Counts
2020 Winter Waterfowl Count
2019 Winter Waterfowl Count
2018 Winter Waterfowl Count
2017 Winter Waterfowl Count
2016 Winter Waterfowl Count
For older data, please contact us.