Afton State Park phenology, May 17 to 23

Birds at Afton right now spent their winters all over the Western Hemisphere.

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Afton State Park Visitor Center (Greg Seitz/St. Croix 360)

Astronomy

Thursday, May 23rd is the Full Moon. This Moon is called the Flower Moon, because many kinds of flowers are blooming about now. It’s also called the Leafing-Out Moon.

Birds

Anywhere you are at Afton look up to see Turkey Vultures soaring overhead. Look in the woods for Indigo Buntings, and on the prairie for Eastern Bluebirds, Eastern Kingbirds, Eastern Meadowlarks, and Bobolinks. Turkey Vultures in our part of the country don’t go very far away in the winter, only to the southeastern U.S., which is part of the reason we see them return so early in the spring. Eastern Bluebirds spend the winter in the southeastern U.S. or Mexico. Eastern Meadowlarks go to the same areas as bluebirds, though some go farther south into the Caribbean, Central America, and northern South America. Bobolinks go all the way the grasslands east of the Andes Mountains in Brazil, Paraguay, northern Argentina and Bolivia.

You also may see Kildeer, Spotted Sandpipers, and Pied-Bill Grebes along Trout Brook or the edges of the St. Croix. Kildeer build their nests on their ground, and the parent birds will pretend to have a broken wing and flutter away from the nest to trick predators into following them. Spotted sandpipers practice sexual role reversal. The females have large territories and mate with several males, each of whom has a smaller territory within the female’s territory. The males care for the eggs and young birds. And Pied-bill Grebes get their name from an old meaning of the world “Pied”, which is “having two or more colors”. You can see in the photo that the grebe clearly has two colors on its bill!

Keep watching for colorful warblers — you’re most likely to see them in the woods, busy catching insects. Some may stay in our area all summer while others go farther north into Canada to breed (and eat insects that hatch in the summer). Common Yellowthroats spent the winter in the southeastern U.S., the Caribbean, and Central America, Chestnut-sided Warblers in Central America, Yellow-rumped Warblers in Mexico and Central America, and some American Redstarts went as far as northern South America.

Insects

Other than the migratory green darners, dragonflies overwinter as aquatic larvae called “nymphs” and undergo what is called “incomplete metamorphosis”. Unlike butterflies and moths, dragonflies do not go through a pupal stage. Instead the larvae molt their exoskeletons several times, each time getting bigger. Some species remain in the larval form for only a few weeks, while other species are larva for years!

When the nymphs are ready to become adults, they rest in what’s called “diapause” for a couple of days. Very early in the morning they crawl out of the water and hold onto some kind of surface – a rock, a tree trunk, or a plant stem. After a short time the skin at the back of the head cracks open, spreads down the back of the larva, and before long a full-sized dragonfly emerges. Dragonflies emerge in the early morning, and must let their wings harden for an hour or so before taking flight. They are especially vulnerable to predators, mainly birds, at this time. That’s why dragonflies emerge very early in the morning!

Reptiles

Two large snakes you might see at Afton are the Bullsnake, sometimes called the Gopher Snake, and the Western Fox Snake. The Bullsnake and Fox Snake look very much alike. Both have black or brown blotches across the length of their bodies. The Bullsnake has a more yellowish background color, while the Fox Snake has a more reddish background color. And the Fox Snake has a solid brown or reddish-brown colored head with a rounded nose, while the Bullsnake’s head is yellow with dark markings and a pointed nose. Bullsnakes can reach six feet in length, making them the longest snake in Minnesota, while Fox Snakes are typically a little shorter, up to around five feet. Both Fox Snakes and Bullsnakes are constrictors, killing their prey by wrapping around it and squeezing. If threatened, both species may shake their tails and pretend to be rattlesnakes. And both species may on occasion climb trees!

Two smaller snakes you might see at Afton are Garter Snakes and Smooth Green Snakes are much smaller than Fox and Bullsnakes. Garter snakes are generally about three feet long or less, and they have longitudinal yellow stripes, not blotches. Garter Snakes are not constrictors, but instead can use a mild venom to immobilize their prey (small mammals, insects, frogs and earthworms). Smooth Green Snakes are the only snakes in Minnesota that are completely green. They are smaller than garter snakes, usually one to two feet long, and they are the only Minnesota snake that feeds almost exclusively on insects. They are sometimes called Grass Snakes, because they like grassy areas.

Watch out for snakes when you are hiking or biking at Afton; none of them are dangerous to humans and they play an important role in the ecosystem.

Plants

In the woods look for Wild Columbine, Wild Geranium, Virginia Waterleaf, and Wild Blue Phlox.

You may still see Yellow Trout Lily, Jack-in-the-Pulpit, and both Downy Yellow and purple Wild Violets.

On the prairie you might see Prairie Phlox, Golden Alexanders, Blue-eyed Grass, and Puccoons. Blue- eyed grass is not really a grass, but is a member of the Iris family.

Weather observations

Here are some weather observations from past years.

Friday, May 172023: haze from Canadian wildfires; 2020: rain through the day, for a record of 2.47 inches
Saturday, May 182013: rain and thunder in the morning; 2012: record high of 93°
Sunday, May 192022: Hailstorm in late afternoon; 2015: 30s in the morning, rising into the 50s; 2014: record rainfall of 2.25 inches; 2009: record high of 97°
Monday, May 202023: beautiful sunny day in the 70s; 2021: rain off and on through day; 2017: record rainfall of 1.47 inches; 2009: record high of 94°
Tuesday, May 212021: one inch of rain; 2013: rain and temperatures in the 50s
Wednesday, May 222014: high in the 70s
Thursday, May 23 2023: Temperature in the 80s, and smoke advisory due to Canadian wildfires; 2015: sunny and high near 70°; 2012: record high of 89°

Photo credits

All photos copyright Nina Manzi, except:

  • Bob Dunlap, MN Conservation Volunteer: Common Yellowthroat
  • Dudley Edmondson, MN Conservation Volunteer: Chestnut-sided Warbler
  • Mike Lentz, MN Conservation Volunteer: Bobolink
  • Dean Lokken: Eastern Kingbird, Kildeer, Turkey Vulture
  • Bill Marchel: Meadowlark
  • Gary Sater: American Redstart, Eastern Bluebird, Indigo Bunting
  • Greg Seitz, St. Croix 360: Darner Nymph, Rapids Clubtail Dragonfly in diapauses, Rapid Clubtail Dragonfly emerging, and recently-emerged Rapids Clubtail Dragonfly

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Afton State Park phenology, May 17 to 23