Fall migration presents one of the best opportunities to observe warblers in Minnesota.
There are 31 warbler species that occur regularly in the state, and the Minnesota Ornithologists’ Union has recorded sightings for 10 additional casual and accidental species. While the occasional rarity, such as 2020’s second-ever sighting of a Painted Redstart in Minnesota, generates the most buzz, even the regular harder-to-spot species offer a satisfying birding challenge.
Migration is also a last chance to see even the most common of these diminutive little birds until the following spring.
But fall warblers can be notoriously tricky — not just to find, but to properly identify when they do briefly flicker across your binoculars’ sights. To help you in your fall warbler adventures, here are five tips from experienced MOU members.
1. Knowing where to look
A lot of warbler species can be found in areas where forest meets water, whether a lake, stream, pond or river. Major flyways — such as wooded spaces right off the Mississippi and St. Croix Rivers — are usually good, as are east/west creek corridors. And look for “urban oases” areas that tend to concentrate birds into one spot: forested parks that are surrounded by urban or suburban “desert.”
Some warbler species (particularly Nashville, Palm, and Orange-crowned) will actively forage in prairie grasses and flowers, especially in late September.
2. Fog and drizzle can be a boon
You don’t need that picture-perfect, sunny fall day to look for warblers. A dense morning fog might not seem like great birding weather, but it can actually cause migrating birds to feed closer to the ground and move through the trees at eye level, making them a bit easier to spot. Drizzly days can do the same.
3. Chickadees can be a giveaway
Where there are chickadees, there may be warblers too.
Migrating warblers will often mix in with flocks of feeding Black-capped Chickadees. Listen for chip notes amid the typical chickadee songs, while keeping an eye out for movement.
4. Don’t overlook the underside
Some warblers are completely unique from others based on their underside and undertail.
Those areas of a warbler may be enough to properly ID a warbler — which is particularly helpful since those are sometimes the only parts of the bird you get to see in fall. Make sure to note characteristics such as:
- Tail feather color
- Tail length
- Vent coloring
“The Warbler Guide” offers some free quick finders, including for warbler undersides, that are a great resource.
5. One at a time
Searching for warblers can be both exhilarating and frantic, especially when waves of birds show up in one location.
Bouncing from bird to bird can be dizzying, and create frustration when you are not able to make a complete identification. So don’t feel like you have to ID everything at once.
Instead, try to focus on a single bird at a time. Stay on it as long as you can to observe key features (eye ring, wing bars, facial pattern, behavior, etc. etc.). Don’t hesitate to bring a field guide or phone app to help with the ID once the observation time is complete.
Getting one hard fall plumage warbler this way will pay off much more than identifying three or four you already know well.