Afton State Park phenology, April 14 to 20

Excitement is growing as energy increases.




4 minute read

White-throated sparrow. (Greg Seitz/St. Croix 360)


On Thursday the 20th look in the western sky after sunset for the crescent Moon. Above the Moon you may be able to spot the planet Mercury!


White-throated Sparrows are passing through our area heading north. Some people say their whistling call sounds like “O Sweet Canada Canada”, others think it sounds like “Old Sam Peabody Peabody”. Song Sparrows have returned and some will stay here the whole summer. American Robins are starting to build nests. This time of year, before the trees leaf out, is a good time to look for last year’s nests.

And don’t forget to look UP for birds. Flocks of Pelicans overhead are easy to identify – they are very large white birds with black on the ends of their wings. The black color comes from the pigment melanin, which makes the wingtips stronger than the rest of the feather. This is important because the wingtips experience more wear during flight. Whooping cranes have black wingtips, too!

Turkey Vultures are another large bird you might see overhead. About this time of year Turkey Vultures have returned to our part of Minnesota. Their wing feathers are darker toward the leading edge of the wing and lighter at the back. They hold their wings in a “V” shape as they glide and they wobble a lot (in contrast to Eagles and Hawks, which hold their wings straight out and glide smoothly). Sandhill Cranes pass by high overhead; you may hear their rattling call before you see them. They hold their necks out ahead of them as they fly, with their legs trailing out behind them. This distinguishes them from Herons, which fly with their necks curled back toward their bodies. And Canada Geese and Ducks fly near the river.

Amphibians and Reptiles

By mid-April there are FOUR species of frogs calling in the evening hours: Spring Peepers, with their high-pitched peeping, Chorus Frogs, with their trilling call that sounds like running your finger along a comb, the chuckling call of the Wood Frogs, and now the low snoring call of the Northern Leopard Frogs, ending in a croak or cluck.


The Monarchs are coming! The butterflies that overwintered in Mexico have left the Oyamel Pine forests of Mexico and begun their journey north. These individuals won’t be the ones to return to Minnesota – the butterflies that spent the winter in Mexico mated and laid eggs in Texas or Oklahoma, and first reports are coming in that those eggs have hatched and the caterpillars are busy eating milkweed plants. This new generation of Monarchs will make another stop to mate and lay eggs farther north, and those eggs will lead to the generation of butterflies that will return to Minnesota in May or June. Here in Minnesota the seed pods of last year’s milkweed plants have opened, and the seeds are blowing in the wind, dispersing over the landscape. Some of them will land in hospitable places and grow into milkweed plants, just in time for the return of the Monarch butterflies.

While we’re waiting for the Monarchs to return, keep a lookout for Spring Azures. Spring Azures are one of many kinds of butterflies that overwinter as pupae. Last fall the larvae finished eating and made their cocoons, where they rested until the spring sunshine and longer days signaled that it was time to complete metamorphosis and emerge as butterflies. As the name suggests, Spring Azures are a vibrant blue on the top side of their wings. But they are rather pale on the underside of their wings, and when they land they almost always hold their wings closed. Sometimes people are reluctant to believe that the pale colored butterflies they see perched are the blue butterflies they just saw on the wing, but they are!


Spring ephemerals season continues! Hepatica, Bloodroot, Dutchman’s Breeches, Yellow Trout Lily, Large-flowered Bellwort, Wild Ginger, and Wild Violets are still in bloom, and joining them about mid-month are Spring Beauties and Jacks-in-the-Pulpit.

Jacks-in-the-Pulpit have a reddish-green or green club-like flower that is shaded by a sort of hood. The flower is called a “spadix”, while the hood is called a “spathe”. There are both male and female plants and both have flowers. The only difference is that the males have small holes at the base of the spathe, while the females do not. The hole makes it easy for pollinators that ventured in to visit the flower to escape and perhaps go on to visit a female flower. Since there is no hole at the bottom of the spathe in the female plants, the pollinators have to move around more to get out and are more likely to brush up against the flower and drop some of the pollen they collected at a male flower.

They’re called “ephemerals” for a reason – they won’t be around long! Once the trees leaf out and block the sunshine from reaching the forest floor these beautiful little flowers die back for another year. So take the opportunity to hike through the woods and enjoy the ephemerals soon!

Weather observations

Here are some weather observations from the Afton State Park area from past years.

Friday, April 142022: gusty wind and blowing snow through day; 2003: record high of 89°
Saturday, April 152018: record snowfall of 3.5”; 2014: record low of 18°; 2002: record high of 91°
Sunday, April 162019: temperature in 60s; 2017: 3/8” rain
Monday, April 172019: rain with thunder and lightning; 2016: high in 70s
Tuesday, April 182021: flurried and rain in the morning, in the 20s; 2020: sunny and mild, in the 50s; 2013: record snowfall of 6.4”
Wednesday, April 192020: partly sunny with a cold wind, temperature in the 50s; 2013: 6” heavy wet snow overnight
Thursday, April 202022: rain the afternoon, temperature in the 40s; 2019: sunny and in the low 70s; 2013: record low of 21°

Photo/Image credits

All photos/images copyright Nina Manzi, except:

  • Dean Lokken: American Robin, Canada Geese, Northern Leopard Frog, Turkey Vulture
  • Gary Sater: Song Sparrow, Sandhill Cranes
  • Allen Blake Sheldon, MN Conservation Volunteer: Boreal Chorus Frog, Spring Peeper


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Afton State Park phenology, April 14 to 20