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Phenology Report: Migrators or winter residents? How to spot the difference

An American Robin sits on a patch of bare ground near a spruce tree. Snow covers the ground nearby.
An American Robin sits on a patch of bare ground near a spruce tree.

This week, John covers the return of Great Blue Herons, how robins are finding bare ground despite the snow, and a litmus test for distinguishing newly arrived migrators from hardy winter residents.

Do you have observations to share? We’d love to hear from you! Get in touch with me (, John Latimer (, or text "phenology" to 218-326-1234.

Short maple syrup season

As anyone who’s waiting for the maple sap to run knows, it’s been a slow spring.

In Northern Minnesota, the sap isn’t flowing yet. The lack of warm, above-40-degree days paired with below-freezing nights has prevented the trees from sending sap to their branches, meaning the syruping season is going to be short (and sweet, of course)!

Migrating birds delay their return

 A Killdeer ponders its reflection in a puddle. It is a small shorebird with strongly-contrasting white, black, and brown markings. It stands on a gravel surface and looks into a brown puddle. The image is captioned "Killdeer".
A Killdeer ponders its reflection in a puddle.

In a typical year, John would see American Robins, Red-winged Blackbirds, Killdeers, Northern Harriers and many other migrating birds around this time. This year, however, the birds have taken one look at the conditions and decided to linger in the south a bit longer.

“If you were a robin and you were expecting to find some angle worms to eat, you’d have to bring a shovel in order to get down to the ground to find those angle worms,” John points out. (I think that'd make them Northern Shovelers! Ba-dum-tshhhhh.)

During the heavy, wet snow last week, a large pine in the Wabana Township Cemetery shielded a portion of the ground from snow, creating a bare “snow shadow.” John saw 25 robins on this small patch of bare ground! The robins also flocked to any bare areas left by wayward cars.

Despite these small congregations of robins, there still hasn’t been a large influx of migrators. John is getting reports of robins and Red-winged Blackbirds in the area, but he has a litmus test to determine if they’re migrators or year-round residents:

  • Are people from multiple areas seeing them? 
  • Are you seeing more than one? 
  • Are you seeing them over multiple consecutive days? 
  • Are they singing or showing territorial behavior? 

For instance, John notes each time he sees a robin in the spring. If he sees one each day for a week, and sees it singing, he’ll go back and mark the first sighting as the “first migrating robin.” This litmus test is particularly useful for species like American Robins, Red-winged Blackbirds and Killdeer.

For birds like the Red-tailed Hawk or Great Blue Heron, singing and territorial behavior can be harder to determine. However, winter residents are much less common — the sighting alone is a sign of migration, without the additional litmus test.

A Great Blue Heron heron stands on ice. Wind ruffles its feathers. Its neck is pulled close to the body., and it appears chilly. The image is captioned "Great Blue Heron".
A chilly, windy day for a Great Blue Heron.

Are you hearing herons?

Speaking of Great Blue Herons, John wants to know if you’ve seen one! (I saw my first one last week in West St. Paul.) Because their migration depends on day length (or photoperiod), not temperature, their arrival is quite consistent across years.

They return to the Grand Rapids area during the last week of March and first week of April. If you live in Northern Minnesota and see one, please let John know. You can email him at

A look through John's records

As part of his phenology assessment, John looks at the amount of open ground along Blue Heron Drive. (Generally, south-facing slopes and dark-colored surfaces will melt first, due to the respective effects of aspect and albedo.) Right now, everything is covered in snow, and the snowbanks are piled so high along the roadsides that John can’t see over them to view the fields. Here’s how things compare to previous years:

Two images are shown side-by-side. On the left is a treed hillside next to a road. The snow is partially melted off of the side of the hill. There is an annotation saying "South-facing slope" with an arrow pointing to the bare patch. The image is captioned "Aspect: The angle of a slope in relationship to the sun". The right-hand image shows a small tree trunk standing in deep snow. The snow has melted around the trunk of the tree. There are annotations showing "dark bark" and "White snow". It is captioned "Albedo: A surface's propensity to absorb heat energy from the sun."
Sarah Mitchell
A comparison of aspect and albedo

  • 1984: Tulips were up on March 30. 
  • 1991: Tulips were up on March 10. 
  • 1994: Ground was open on March 4, 6 inches of snowfall on March 24. 
  • 1995: 14 inches of snow on March 1, some bare ground in open areas on March 13. 
  • 2000: Columbine was growing in John’s driveway and yard on March 26. 
  • 2011: 18 inches of snow fell on March 15. 
  • 2013: 13 inches of snow on the ground on March 13, and 11 more inches fell over the next 10 days, leaving 24 inches of snow on the ground by March 23. 
  • 2015: 70% snow cover in the woods on March 11. 
  • 2022: Ground was visible along Blue Heron Drive on March 17. 

John’s heard the spring song of the White-breasted Nuthatch, which he thinks sounds like an American Robin. Since he’s listening so eagerly for territorial migrating robins to arrive and start singing, he’s been fooled a few times by White-breasted Nuthatches unintentionally masquerading as robins.

A tableau of trumpeter tracks

Snow shows the tracks from a Trumpeter Swan. A ruler shows the tracks are over 6 inches in length and width. On the top edge of the image, the snow gives way to dark ice with white crystalline structures embedded within it. The image is captioned "Trumpeter Swan tracks".
iNaturalist user etvehe
Snow shows the tracks from a Trumpeter Swan.

On nearby Crooked Lake, John found the huge tracks of Trumpeter Swans. They were sitting out on the ice calling over the last few days, waiting for open water. At the moment, the lake is fully covered in ice. There are a few patches of darkly stained snow, but no areas for the swans to hop in and get something to eat.

John carefully ventured onto the ice (not too far, since he was wearing snowshoes, and that’s a recipe for disaster) to take a look at the tracks. He found two wing prints on the snow as the swan came in and slowed down for a landing, followed by the impact and slide of its feet as they hit the lake ice. There followed a few long steps and a pause, presumably as the swan shook, collected itself and adjusted its feathers.

The swans wandered about for a bit, leaving huge hand-sized prints in the snow. John even found the tracks from where they departed.

“The swan starts going across the lake at what I can only describe as a gallop,” John explains. “There are two tracks, and then a 2-foot gap, and then two more tracks (and the tracks are about 12 inches apart), and then a 2-foot gap, and two more tracks. It goes like this for several hundred feet as it crosses the lake to get out away from the shoreline. ... It was quite the tableau out there on the snow, pretty interesting to look at!”

Flying squirrels and woodpeckers active at feeders

A flying squirrel perches face-down on the side of a brick building. It has large black eyes, a strongly contrasting white belly, grey back and head, and a flattened tail. The image is captioned "Southern Flying Squirrel".
iNaturalist user MaureenClare
A flying squirrel perches face-down on the side of a building.

John, the lucky ol’ dude, had a flying squirrel at his feeder the other night. (Yes, I am bitter that everyone else is seeing flying squirrels and I, their No. 1 fan, am left alone and bereft of their adorable presence.) As he was quietly sitting in his living room reading, he heard a thump, looked outside and saw his niger seed bird feeder swinging back and forth. There was no wind and no sign of anything on the feeder itself, so he went outside with a flashlight to investigate. To his delight, he found a flying squirrel hanging on the outside of the house!

John’s buddy Sam saw Canada Geese and Sandhill Cranes. Five Canada Geese flew over his lake, presumably checking for open water near the lake’s ingress or egress. Moving water thaws quickest, opening up patches where waterfowl can land and forage for food.

For the first time in 37 years, John lacks the company of Bald Eagles during his wait for spring. He does, however, have a Red-bellied Woodpecker who is active at his feeders and actively searching out a female. He is calling and drumming quite a bit! (The woodpecker, not John.) In contrast, the Downy, Hairy, and Pileated Woodpeckers have mostly established their mating bonds and aren’t doing much calling or drumming.

Catkins finally soften up a bit

Flowering speckled alder catkins hang down from a bare branch. They are long and maroon with yellow flecks. The background shows a bare deciduous forest and blue sky.
iNaturalist user joebartok
Flowering speckled alder catkins hang down from a bare branch.

Every season, it seems, John has a phenology practice that I find inexplicably hilarious. This time of year, he’s out pinching the catkins on the speckled alder. He’s waiting to determine when they soften up, elongate, and start to release pollen. At the moment, most of them are still quite stiff, but he found one in a sunny patch that was beginning to loosen up and elongate. He wrote “an optimist’s sign of spring” in his notes for the day.

John asked for it, and he got it! During his report, texts flowed in about bird sightings in the area. One reported no robins or herons, but geese had returned to Grand Rapids on Sunday. Chad from Bass Brook saw a Great Blue Heron, and another was seen in the backwaters of the upper Gull River near Brainerd. At the same location, six Wood Duck pairs arrived on Tuesday morning.

John’s happy to hear the Wood Ducks are returning. Hopefully, the other puddle ducks won’t be far behind. We’ve got a long way to go, though. Last week, John predicted that 2023 would be one of the top-five latest springs on record, and he’s found no reasons to renege on that prediction so far.

For more phenology, subscribe to our Season Watch Newsletter or visit the Season Watch Facebook page.

Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).

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Charlie Mitchell (she/they) joined the KAXE team in February of 2022. Charlie creates the Season Watch Newsletter, writes segment summaries for the website, and coordinates our Engaging Minnesotans with Phenology project. With a background in wildlife biology, she enjoys learning a little bit about everything, whether it's plants, mushrooms, aquatic invertebrates, or the short-tailed shrew (did you know they can echolocate?).