Afton State Park phenology, July 16 to 22

What to look for this week in the natural world.




5 minute read

Afton State Park. (Drew Geraets/Flickr)

“Phenology is nature’s calendar—when cherry trees bloom, when a robin builds its nest and when leaves turn color in the fall.

“Phenology is a key component of life on earth. Many birds time their nesting so that eggs hatch when insects are available to feed nestlings. Likewise, insect emergence is often synchronized with leaf out in host plants.”

Why Phenology? USA National Phenology Network

Note: Nina Manzi is a long-time volunteer at Afton State Park who has long recorded and shared seasonal observations at the visitor’s center. Due to COVID closures, St. Croix 360 is publishing her updates when possible. Thank you, Nina!

Astronomy: July is a good time to look for what’s called the Summer Triangle, which is made up  of the three brightest stars in the summer sky. In the early evening look for a bright star fairly  high up in the eastern sky. That’s Vega, the brightest star in the constellation Lyra the Harp.  Once you’ve found Vega, look below it and to the right for Altair, the second brightest star in  the summer sky. It’s in the constellation Aquila the Eagle. And then look to the left of Altair and  up from the horizon for Deneb, the third brightest star in the summer sky. Deneb is in the  constellation Cygnus the Swan. 

Birds: Look for turkey vultures soaring overhead. You can tell them apart from eagles and  hawks because: turkey vultures wobble from side to side as they glide, the feathers at the ends  of their wings look ragged, and their wings are dark at the leading edge and lighter at the  trailing edge. American goldfinches are one of the last birds to nest in our area. They use the  fluff of field thistles in their nests, and also like to eat thistle seeds. And watch for great blue  herons hear the water. In flight they have their heads tucked in near their bodies with their legs  trailing behind. 

Mammals: Look for bats flying after sunset. Bats in our area have been affected by a disease  called “white nose fungus”. Infested colonies wake up from hibernation in the winter, which  often causes their death. Help protect bats from this deadly disease by staying out of caves  where bats hibernate, and making your yard bat-friendly by retaining large trees or putting up  bat houses. And enjoy the aerial acrobatics of any bats you see at Afton– they eat lots of  mosquitoes! Also watch for red squirrels, and deer moving quietly through the forest.

Insects: The Painted Lady,  Monarch, and Tiger Swallowtail are three of the many species of butterflies you may see sipping nectar from flowers at Afton this week.  

Many dragonfiles and damselflies are on the wing. Dragonflies rest with their wings held open.  Damselflies rest with their wings together. Look for soldier beetles climbing on leadplant  flowers on the prairie, and along the river look for great clouds of mayflies flying upstream to  mate and lay eggs. They only live for about a day as adults, and don’t even have any mouths  because they don’t live long enough to need to eat anything.

Plants: Look for Butterflyweed,  Yellow Coneflowers, Blue Giant Hyssop, Bee Balm (also called wild bergamot or mondarda),  Leadplant, and Rough Blazing Stars blooming on the prairie.  

You may still find ripe wild black raspberries – a tasty treat for hikers! Look for Monarch  caterpillars on milkweed leaves. And you may see magpie inkcap mushrooms under pine trees –  but don’t eat them, since they’re poisonous!

Weather observation

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

Friday, July 16, 2019:1/4 inch of rain
Saturday, July 17, 2015:very humid, with high in the 80s
Sunday, July 18, 2015:thunderstorm after midnight brings ¾” rain
Monday, July 19, 2011:steamy and 80s in the morning, with a powerful mid-morning thunderstorm
Tuesday, July 20, 2013:60s in the morning, rising into the 70s
Wednesday, July 21, 2015:sunny and pleasant, high near 80°
Thursday, July 22, 2020:high of 69°

Photo/Image credits

All photos copyright Nina  Manzi, except: 

  • Dean Lokken: Turkey Vulture 
  • Deborah Rose, MN Conservation Volunteer: Bat 
  • Gary Sater: American Goldfinch 
  • Jane Williams-Petersen: Magpie Inkcap Mushroom, Wild Black Raspberries