Winter Waterfowl Counts

Hooded Merganser Pair (Male(right) and Female (left)) by Bruce Szczechowski

Detroit Audubon has been partnering with Birds Canada on the Lower Detroit River Important Bird and Biodiversity Area (IBA) Waterbird Surveys (Or what we call our Winter Waterfowl Counts) since 2016.

The goal of this survey is to take a snapshot of the number of birds found within the IBA during the peak season. The Lower Detroit River is recognized as a globally significant IBA because it regularly supports more than 1% of the world population of Canvasbacks most winters. Monitoring populations of the “trigger species” each year helps us quantify the importance of the site for the species, and monitor for changes which could indicate imminent threats to the health of the species or biodiversity in general.
The IBA Program is an international initiative to identify, monitor, and conserve the world’s most important sites for birds and biodiversity. To date, there are about 12,000 of IBAs around the world. To find out more about the Canadian IBA Program, which began in 1996, please visit

Michigan Winter Waterfowl

Here in Michigan and the Great Lakes Region, we are lucky enough to be overwintering habitat to a variety of waterfowl you normally wouldn’t see in the summer. For a lot of these arctic and boreal-breeding ducks (Winter Waterfowl), they depend on the Great Lakes and other large rivers such as the Detroit River for food when other water bodies further north are frozen over. While here, they depend on fish, plant matter and shellfish found in open water where you’ll commonly find them in large, concentrated groups of anywhere from the dozens to hundreds or even thousands if you’re lucky enough.

To learn more about our Winter Waterfowl and how to identify them, check out the webinar link below.

Conducting a Winter Waterfowl Count

We conduct 3 different counts on Saturdays between January and March starting at 9am and ending between 12 and 2pm depending on bird activity. During the count, we cover as much of our designated locations along the Detroit River as possible by either stopping at every vantage point or walking the length of the section.

When there is only one possible vantage point, we look as far up and down the river (a scope is handy here) as possible. When counting at multiple locations, we divide the sections into logical survey points and do a separate tally for each one. This helps make data more precise, and helps us map important areas for species on the river. Remember that the focus is on waterbirds, but feel free to watch and add others to your checklist! Please do your best to avoid double-counting birds! If you think you have already counted a flock from another vantage point, leave those birds out from your next count.

The designated sites along the Detroit River can be found on the map here.

Estimating Numbers

Estimating large numbers of birds can be challenging and the most accurate way is to count each bird. However that is not possible with the large flocks we will be surveying! A good estimating technique is to count in blocks. First count out a block of 10, and using its size, count how many blocks of 10 are in the flock (adjusting for how dense they are in certain spots). If it is a very large flock you can measure out 10 blocks of 10, and then use a larger block of 100. This way, you can easily count thousands of birds in a few minutes. If you are surveying with a partner or a group in our case, you can both count a flock, and compare numbers. Here is an excellent eBird article to help you strategize your counting:


For the Winter Waterfowl Counts, we depend on volunteers to assist with counting the birds along the Detroit River during 3 scheduled dates between January and March. If you are interested in learning more about becoming a Winter Waterfowl Volunteer, click here. If you want to know what to bring and expect before volunteering, click here.