Afton State Park Phenology, week of June 12, 2020

Details about what’s growing, flying, blooming, nesting, and otherwise alive right now at the popular park on the lower river.




5 minute read

Afton State Park swimming beach on the St. Croix River. (Photo by McGhiever via Wikipedia)

Thank you to long-time Afton State Park volunteer Nina Manzi for sharing her observations!

Note: Additional facilities at the park have recently been reopened, including camping. Visit the park website for detailed information about visiting.


Look for Venus in the east before sunrise.


On the prairie, look for bluebirds, tree swallows, meadowlarks, bobolinks, and for turkey vultures circling overhead.

Near the water look for herons, egrets, ducks, and geese. Geese are losing their flight feathers and will be grounded for the next few weeks until they grow new flight feathers for this fall’s migration.

American goldfinches will be nesting soon. They use the fluffy seeds of thistles to build their nests. And here’s a photo taken last week at Afton of a rufous-sided towhee, courtesy of John Schultz. Thanks, John!


Animals active primarily in the daytime, like squirrels, are called “diurnal”. Those active mostly at night, like bats, are “nocturnal”. And those active at dawn and dusk, like skunks, are called “crepuscular”.

Amphibians and reptiles

The evening chorus of frogs and toads will continue for a few more weeks. Western chorus frogs sound like running your finger over a comb; they are not as vocal as they were a few weeks ago. Tree frogs make a very loud short trill that many people mistake for a bird, and American toads make a long high-pitched trill. Look for tadpoles in still water along Trout Brook and the St. Croix River.

Turtles and snakes bask in the sunshine. Turtles have started laying eggs; watch out for them crossing roads and trails near the water.


Monarchs have returned, and you may see their larva on milkweed plants.

Another species to look for is the red-spotted purple. The red-spotted purple and the white admiral are the same species of butterfly. At Afton we often see the intergrade between the two forms. Fifty miles or so north of us it takes on the color pattern of the white admiral.

And it’s a good time to look for dragonfiles and damselflies. Here are some species you might see in June.


Look for early-blooming flowers on the prairie.

Milkweed is the host plant for Monarch butterflies. Both common milkweed and swamp milkweed live at Afton and will bloom soon. Common milkweed has rounded leaves while the leaves of swamp milkweed are more pointed.

Weather observations

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

Friday, June 122013: Thunderstorms and heavy rain
Saturday, June 132001: record rainfall of 2.37”
Sunday, June 142012: 3⁄4” of rain through day
Monday, June 152018: record high of 95°
Tuesday, June 162013: sunny and 80s, with thunderstorm in afternoon
Wednesday, June 172014: muggy with high in 80s
Thursday, June 182013: sunny with a high in the 70s


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 June 12, 2020