Afton State Park phenology, week of October 16, 2020

A meteor shower, late migrators, hibernating butterflies, fall color, and… “coprophagy.”




4 minute read

Via the Minnesota Department of Natural Resources:

Blooming little bluestem grass at Afton State Park, October 4, 2018 (Photo by aossanna via Flickr)

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.


Overnight on both Wednesday the 21st and Thursday the 22nd look in the south
for the Orionid meteor shower, which will be at its best in the darkness before sunrise.


Migration continues. Late-flying warblers trickle through heading south, including
yellow-rumped warblers and American redstarts. Mallard ducks and Canada geese follow the
St. Croix flyway, and many will linger in this area as long as there is open water. Robins have
formed flocks – some will travel farther south, while others will stay in this area through the
winter. Watch for them moving through the trees like ghosts when you hike.


Rabbits are plentiful at Afton, and they remain active all winter long. They are
most active at dawn and dusk, when the temperatures tend to be milder and when they can
move about without attracting too much attention from predators. For much of the day and
night they shelter in brush piles, under evergreen trees or in hollow stumps. In the winter
their diet switches from grasses, which are often buried by snow, to tree bark, twigs, and . . .
their own poop! Rabbits have inefficient digestive tracts so they can extract calories from
their droppings by eating them. The practice of eating poop is called “coprophagy” .


Mourning Cloak and Eastern Comma butterflies both overwinter as adults, hiding
under leaves or tree bark and becoming active on mild days. What about Red Admirals? Red
Admirals to the north of our area migrate south for the winter. Red Admirals to our south
overwinter locally as adults. It’s likely that some of the Red Admirals at Afton overwinter
here, while others go south.


October is the perfect time to enjoy the fall colors at Afton State Park. The leaves of
most quaking aspens turn yellow, but some turn red! The yellow color is from carotenoids in
the leaves that become visible once the chlorophyll dies in the fall, while the red is
anthocyanins. Only some aspens have the genetic trait that allows them to produce
anthocyanins, and those trees only produce anthocyanins and have red leaves when the
weather conditions are just right: warm sunny days followed by cool nights – just the kind of
weather we had here in early October. This might be a year to see red aspen leaves at Afton!

Weather observations

Here are some weather observations for this week from past years

Friday, October 16 2014Sunny with a high of 72°
Saturday, October 17 2002Trace of snow
Sunday, October 18 2011Temperature in the 40s through the day
Monday, October 19 2000Record high of 84°
Tuesday, October 20 2014Sunny, with the high in the low 60s
Wednesday, October 21 20020.4” snow
Thursday, October 22 2013Frosty, with temperature in the 20s in the

Photo credits:

All photos copyright Nina Manzi, except:
Keith Henjum, first Rabbit
Jamie Kinne: Eastern comma
Gary Sater, American Redstart, Mallard Duck, Yellow-rumped Warbler
Allyn Uniacke: Fall colors on St. Croix River


You may republish this article online or in print under our Creative Commons license. You may not edit or shorten the text, you must attribute the article to St. Croix 360 and you must include the author’s name in your republication.

If you have any questions, please email


Creative Commons License Attribution-ShareAlikeCreative Commons Attribution-ShareAlike
Afton State Park phenology, week of October 16, 2020