Afton State Park Phenology August 11 to August 17

The first migrants are beginning to gather for their journeys south.




3 minute read

Afton State Park (Chris/Flickr)


The Perseid meteor shower peaks on Friday the 11th and Saturday the 12th,and a favorable moon should make the view premiere. Look to the northeast after midnight for maybe up to 50 shooting stars per hour.


Tree Swallows and Barn Swallows are all done raising young and are about to migrate south. Looks for groups of them gathering on utility wires. Bobolinks, Meadowlarks, and Eastern Bluebirds will be with us on the prairie a while longer. In the woods look for marauding bands of Cedar Waxwings feeding on berries. They make a short whistling call.


Squirrels begin to prepare for winter by gathering acorns and black walnut seed pods. Gray Squirrels bury acorns and nuts in shallow holes in the ground, one nut per hole. They don’t have very good memories, but do have a good sense of smell, so all the nuts and acorns that are buried may later be eaten by the squirrel that buried them, or by some other squirrel. And some are never eaten and become new trees!

Amphibians and reptiles

In the early morning hours you may see young tree frogs climbing windows in search of insects. Frogs climb up glass using sticky pads on their toes. Or you may see them hanging out in the shade of milkweed plants or just about anywhere – keep your eyes peeled! They can change color from gray to green.


Monarch butterflies will soon begin roosting in groups in anticipation of their southward migration; look for groups of them on cool mornings before the air has warmed up enough for them to be active. Also look for common sulphur butterflies on the prairie and mourning cloaks in the woods. And have you ever seen lots of butterflies gathered at a mud puddle or on a pile of horse manure? That’s where I recently saw about a dozen Eastern Tailed-Blue Butterflies! Male butterflies gather at mud puddles or on manure to absorb salts. They transfer the salts to females during mating, which provides nutrients for the resulting butterfly eggs.

Some insects are very small, like the colorful Sharpshooter Leafhopper, the Leaf-footed Bug, and the Twice-Stabbed Stink Bug. These are all members of the group called “true bugs”, which have sucking mouthparts. Like grasshoppers, true bugs undergo only an incomplete metamorphosis and do not have a larval form. Instead a “nymph” hatches directly from an egg, and is simply a miniature version of the adult. As the insect grows, it molts its exoskeleton and a new soft one underneath hardens. These in- between forms are called “instars”; the insect is an adult after its final molt.


Look for Joe-Pye Weed and Ironweed in wet areas, White Snakeroot and Boneset along the edges of the woods, and Blue Vervain and Prairie Onions on the prairie. And Thistles are blooming; late-nesting American Goldfinches use thistledown in their nests and feed the seeds to their young.

Weather observations

Here are some weather observations from past years.

Friday, August 112007: Record rainfall of 1.73 inches; 1968, 2004: Record low of 47°
Saturday, August 122022: 1.4” rain overnight; 2019: Sunny and high 50s to start the day; 2011: cloudy through day, in the 70s
Sunday, August 132014: Low 60s in the morning, rising into the 80s; 2007: record rainfall of 2.05 inches
Monday, August 142022: fog and low 60s to start day; 2015: Severe storms with hail around 8 pm, 1⁄2 inch of rain
Tuesday, August 152022: clouds early, with sunshine and 70s in the afternoon; 2011: 60s in the morning and overcast, rising into the 80s by late afternoon
Wednesday, August 162022: 60s in the morning, rising into the 80s; 2020: high near 80°; 2002: record rainfall of 1.92 inches
Thursday, August 172022: Muggy with a thunderstorm around 3 pm bringing almost an inch of rain; 2015: 1 inch of rain overnight, in the 70s.

Photo/Image credits

All photos copyright Nina Manzi, except:

  • Keith Henjum: Cedar Waxwing
  • Gary Sater: Easter Bluebird
  • Allen Blake Sheldon, MN Conservation Volunteer: Bobolink


2 responses to “Afton State Park Phenology August 11 to August 17”

  1. Matt Smith Avatar
    Matt Smith

    Nina I so enjoy your writings.
    Thanks for doing them!
    Matt Smith

  2. Bonnie Avatar

    Thank you very much for all the information. I really enjoy it.



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Afton State Park Phenology August 11 to August 17