Afton State Park phenology, March 15 to 21

The equinox arrives as red-winged blackbirds sing in marshes.




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Tuesday the 19th is the Vernal Equinox. In Latin “vernal” means “of or relating to Spring”, and “Equinox” means “equal night”. On this day every place on earth will experience twelve hours of daylight, and twelve hours of darkness. Following the equinox the daylight hours will get longer and longer here in the Northern Hemisphere as we approach summer, and shorter and shorter in the Southern Hemisphere as our friends on the other side of the equator move toward winter. And early in the morning on Thursday, the 21st, use binoculars to look for the planet Saturn very close to Venus low in the eastern sky.


Male Red-winged Blackbirds have returned and are singing their “Ko-Ka-Ree” song to claim nesting territories in marshy areas. The female Red-winged Blackbirds will be here in another few weeks. Red-winged Blackbirds spend the winter in the southern part of the U.S. Eastern Bluebirds return about now, too, after wintering in the southeast or Mexico. Great Blue Herons seem to magically appear as soon as there is open water. They have a longer migration than Blackbirds and Bluebirds, with some Herons wintering in the Caribbean or northern South America. Waterfowl are beginning to be present in greater numbers as they follow open water north – look for Mallard Ducks, Wood Ducks, Buffleheads, Canada Geese, and Mergansers on the St. Croix River.

In a typical year juncos that went farther south for the winter would now be passing through on the way farther north for the summer. Juncos have seemed scarce this winter, however; let us know if you see any passing through Afton. Robins that went south are back and singing loudly at sunrise, along with Cardinals and Chickadees.

Great-horned owls are one of the first birds to nest each year in Minnesota. They laid eggs in February or even January, and the eggs are hatching about now. In a little over a month the young owls, called “owlets” will leave the nest, but they will remain with their parents until fall.

Amphibians and Reptiles

After a long winter’s rest the amphibians and reptiles are back! The first ones we are likely to encounter are two species of frogs, the spring peepers and the boreal chorus frogs, formerly called the western chorus frogs. And we’re more likely to hear them than to see them. Spring peepers make a “peeping” sound, and boreal chorus frogs sound like someone running their finger over a comb. Both species will begin calling as soon as there is a little open water and warm weather. Take a walk at around sunset and keep your ears open for frogs! If you happen to see one, the peepers have a dark “X” on their backs, while the chorus frogs have stripes, including a prominent stripe on their skin that looks like it runs through their eyes. Both species are about one inch in length.


Some oaks hold their leaves through the winter, and only drop them as the new leaves begin to grow. Some people say it’s only the white oaks that hold their leaves, while others say it’s the red and black oaks. I’ve seen many kinds of oaks still holding onto their leaves in mid-March. When you hike at Afton see what oaks YOU can find that are still holding their leaves.

Weather observations

Here are some weather observations from the Afton State Park area from past years.

Friday, March 152023: 40s and cloudy; 2021: three inches of wet snow; 2015: record high of 70°
Saturday, March 162021: high in the upper 30s, and the wet snow quickly melted; 2012: record high of 79°;
Sunday, March 172013: near 10° in the morning; 2012: record high of
Monday, March 182023: teens to start the day and windy; 2020: 30s in the morning; 2012: record high of 79°; 2001: St. Croix River frozen over
Tuesday, March 192014: ½ inch of snow; 2012: record high of 79°
Wednesday, March 202023: sunny and in the 40s, with lots of snowmelt; 2021: high in 50s
Thursday, March 212020: sunny and 20s in the morning; 2008: record snowfall of 3.9 inches

Photo/Image credits

All photos/images copyright Nina Manzi, except:

  • Michael Furtman, MN Conservation Volunteer: Black-capped Chickadee
  • Keith Henjum: Hooded Mergansers
  • Sherri Holliday-Sklar: Great Blue Heron
  • Dean Lokken: American Robin, Dark-eyed Junco
  • Bill Marchel, MN Conservation Volunteer: Red-winged blackbird
  • Nathan Pasch, University of Minnesota College of Veterinary Science: Great horned owl nest and egg
  • illustration
  • Gary Sater: Eastern Bluebird, Juvenile Great-horned Owl, Northern Cardinal, Wood Ducks
  • Allen Blake Sheldon, MN Conservation Volunteer: Spring Peeper, second Boreal Chorus Frog
  • Stan Tekiela, MN Conservation Volunteer: first Boreal Chorus Frog
  • Tammy Wolfe, MN Conservation Volunteer: Great-horned Owl and Owlet




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Afton State Park phenology, March 15 to 21