Afton State Park phenology, September 16th to 22nd, 2022

Much is on the move as autumns falls fast.




5 minute read

American white pelicans migrating south along the St. Croix River (Greg Seitz/St. Croix 360)

From park naturalist Linda Radimecky: Nina is keeping track of the phenology events happening in the park while access is limited this week and next week (Thank you Nina!). We are happy to send this to you and look forward to seeing you again once the park’s bridge is repaired. In the meantime, see if you can spot some of these phenology events around your neighborhood.


On the 16th if you’re up late, after 10:30 or so, look for Mars next to the waning gibbous Moon. And summer draws to a close and we say hello to autumn on Thursday the 22nd, which is the day of the autumnal equinox. The word “equinox” means “equal night” and on the equinoxes there are 12 hours of daylight, and 12 hours of darkness.


American Goldfinches feed on the seed heads of coneflowers and bee balm plants. This is a good time of year to look for Green Herons and Black-Crowned Night Herons along the edges of waterways. And Pelicans are moving through, migrating south. When they are in flight you can recognize them by their white bodies and the black on their wings. White Pelicans have the second biggest wingspan of any bird in North America, behind the California Condor. The pelicans passing through our area will probably spend the winter along the coast of the Gulf of Mexico.


Deer have almost fully changed to their winter gray coats, as you can see on the individual in the first photo. And bucks have grown antlers and rubbed the velvet off of them; antler growth in deer and related species is one of the few examples of regeneration among mammals. Gray Squirrels continue to gather acorns and black walnuts and to store them up for the coming winter.

Amphibians and reptiles

You may still see frogs and toads out and about, but they are not the only amphibians at Afton. On cool fall mornings after it rains, watch for tiger salamanders moving south of the park to spend the winter in abandoned tunnels and burrows below the frostline. If you see them on 70th street, try not to run them over!


Look for Monarch butterflies passing through, going south. The Monarchs that emerged from their pupae or chrysalises in August were in “reproductive diapause”, which means that they weren’t fully developed and won’t be able to mate and lay eggs until next spring when they are on their way north from their overwintering sites in Mexico. This adaptation allows them to conserve energy for their long journey south. How did they know to emerge in reproductive diapause? Scientists think that the developing butterfly inside the pupa is aware of the length of day, and the age of the milkweed plant to which the pupa is attached. The butterflies that emerge in August will travel thousands of miles to Mexico and spend the winter in large colonies clustered on oyamel fir trees. After they leave Mexico to head north these individuals will develop the ability to mate and lay eggs, and it will be their grandchildren or great-grandchildren who will arrive back in Minnesota next spring.

Some of the dragonflies still on the wing in late September are the Lake Darner, and the twelve-spotted skimmer. The twelve-spotted skimmer takes its name from the number of black spots on its wings. The males also have white spots, while the females do not.


Sky-blue Asters and Canada goldenrod continue to bloom. Milkweed and butterflyweed seed pods are just starting to open. Both have fluffy seeds that drift in the wind.

Weather observations

Here are some weather observations for this week from past years.

Friday, September 162013: temperature in the 60s with an inch of rain; 2021: 60s early, rising into the 80s
Saturday, September 172015: Record rainfall of 2.37”; 2021: morning thunderstorm with many downed trees
Sunday, September 182016: sunny and high near 80°
Monday, September 192011: foggy morning, with clearing skies and high in the low 70s
Tuesday, September 202018: record rainfall of 3.28”
Wednesday, September 212019: quarter inch of rain, high in low 70s
Thursday, September 222020: high in low 80s, sky hazy with smoke from wildfires

Photo/Image credits

All photos copyright Nina Manzi, except:

  • Bill Marchel: MN Conservation Volunteer: Buck Deer
  • Gary Sater: American Goldfinch, Green Heron, Whitetail Deer


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Afton State Park phenology, September 16th to 22nd, 2022