Afton State Park phenology, week of September 25

With autumn’s arrival, changes have started happening faster at the seasons change.




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Chickweed Geometer Moth (Haematopis grataria) observed at Afton State Park on Sept. 10, 2020 (rgsullivan7 via iNaturalist)

Note: Afton State Park volunteer Nina Manzi has been updating the phenology calendar in the visitor center with events and pictures for years. Since the visitor center has been closed due to coronavirus, and visitors haven’t been able to check the phenology calendar to see what signs of the season to look for, Nina is sending it online.

Phenology is the study of recurring events in the life cycle of plants and animals, many of which are closely tied to patterns of climate and seasonality. Learn more at the Minnesota Phenology Network.


Harvest moon (Photo by Kolforn via Wikimedia)

On Friday, the 25th, look for Jupiter and Saturn near the waxing moon in the evening. And Venus is bright in the pre-dawn eastern sky. The moon is full on Thursday the 1st – this full moon is called the Harvest Moon.


Look for northern flickers pausing at Afton on their way south. Flickers are a type of woodpecker, but instead of pecking into trees flickers peck into the ground in search of ants. Watch for Canada geese flying south in V-formation. This flight formation helps the geese conserve energy on their journey – the lead birds encounter more wind resistance, and the birds behind them have an easier time flying. When the birds in front get tired they drop back and let other members of the flock move up and do the hard work. Other birds you may see moving south along the St. Croix flyway include hooded and red-breasted mergansers.


With the arrival of cooler weather squirrels are working even harder to gather food for winter. Gray squirrels gather nuts and fruits, while red squirrels concentrate on the seeds of conifers. Raccoons do no store food for winter; instead they bulk up in fall and store an insulating layer of fat under a thick winter coat. And when it gets very cold they curl up in their dens and can sleep for weeks in a state called “torpor”. This is not true hibernation as raccoons will come out and forage on mild winter days.

Amphibians and reptiles

Look for snakes and turtles basking in the sun. Soon snakes will travel to their hibernating places and turtles will burrow into the mud of riverbanks and lake bottoms. Snakes hibernate in large groups sheltered by rocks or in caves. The hibernating place is called a “hibernaculum”, which is Latin for “tent for winter quarters.”


A few late Monarchs move through going south to Mexico. Green darner dragonflies migrate, too – look up in the evening to see swarms of them on the move. And look for Goldenrod soldier beetles . . . on still-blooming goldenrod plants!


The last of the wildflowers are blooming now: Canada and showy goldenrod, sky blue asters, and maybe some vervains.

Weather Observations

Friday, September 252018: rain off and on throughout the day
Saturday, September 262016: gusty winds with high in the 60s
Sunday, September 272019: temperature falling through the day from 66° at sunrise to the 50s at sunset
Monday, September 282019: sunny and 65°
Tuesday, September 292016: sunny and 60s
Wednesday, September 302007: record rainfall of 1.06”
Thursday, October 12009: record rainfall of 1.29”

Photo credits

All photos copyright Nina Manzi, except:

  • Keith Henjum, Hooded mergansers, Raccoon
  • Dean Lokken, Canada geese, Painted turtles, Red squirrel
  • Gary Sater, Red-breasted mergansers


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Afton State Park phenology, week of September 25