Afton State Park phenology, Dec. 10 to Dec. 23

Notes on the seasonal rhythms along the Lower St. Croix.




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Afton State Park (aossanna/Flickr)

Note: Afton State Park volunteer Nina Manzi has been updating the phenology calendar in the visitor center with events and pictures for years. When the pandemic began in March 2020, Nina adapted by providing the information online, including sharing it with St. Croix 360.

Phenology is the study of recurring events in the life cycle of plants and animals, many of which are closely tied to patterns of climate and seasonality. Learn more at the Minnesota Phenology Network.

Astronomy: Look for the Geminid Meteor Shower all night long on the nights of December 13  and 14th; the Geminids average 75 shooting stars per hour. December 21st is the Winter  Solstice, the shortest day of the year. At our latitude there will be only 8 hours and 51  minutes of daylight from sunrise to sunset on the Solstice. If you watch the point on the  horizon where the sun rises and sets each day, from the Summer Solstice to the Winter  Solstice it moves from north to south, and then after the Winter Solstice reverses course and  moves back northward. The world “Solstice” means “Sun Stands Still,” since it is on the  solstice that the sun reaches its southernmost (or northernmost) point on the horizon.  

Birds: As long as there is open water on the St. Croix River, look for flocks of geese overhead  in the morning and late afternoon, and mallard ducks, mergansers, grebes and other  waterbirds on and near the water. In 2014 there were reports of over 500 mergansers on the  St. Croix in late December. That’s a lot of mergansers! 

Mammals: People used to think that when coyotes moved into an area they would kill any  resident foxes in order to reduce competition for food. But recent studies have shown that to  be true in rural areas, but not in urban areas. That’s because urban areas generally have an  overabundance of prey – large populations of rabbits, mice, and the like due in part to  humans providing a landscape with lots of forage. Urban areas also have lots of scavenging  opportunities provided by roadkill, human garbage, and compost piles – more than enough  food for both coyotes and foxes. So with regard to coyotes and foxes, is Afton more rural or  more urban? Which of the two species have YOU seen?

Plants: Aspens are relatively easy to identify by their bark in the winter, and you can also look  for their heart-shaped leaves on the ground around them. They usually grow in a group, and  that’s because their main form of propagation is to send out runners underground. The runners send up shoots and the shoots become new aspen trees . . . except they’re really all  part of the same organism. One of the world’s largest organisms is a grove of 47,000  genetically identical aspen trees in Utah called “Pando”. Reddish-colored aspen buds are the  most important winter food of ruffed grouse, so keep an eye out for grouse wherever you  see aspen trees at Afton.  

Weather observations:

Here are some weather observations from past years 

Friday, December 102013: record snowfall of 1.8”
Saturday, December 112010: record snowfall of 16.3 inches
Sunday, December 122012: mild and sunny, with the high in the 40s
Monday, December 132014: high of 51°
Tuesday, December 142010: single digits below zero
Wednesday, December 152014: record high of 51°
Thursday, December 162000: record snowfall of 7.0 inches
Friday, December 172011: cloudy, high in 30s
Saturday, December 182000: record snowfall of 6.5 inches
Sunday, December 19 1983: record low of 29 below zero
Monday, December 202010: record snowfall of 4.6 inches
Tuesday, December 211996: record low of 24 below zero
Wednesday, December 221983: record low of 20 below zero
Thursday, December 232020: record snowfall of 8.7 inches

Photo/Image credits:

All photos copyright Nina Manzi, except: 

  • Keith Henjum: Hooded Mergansers 
  • Dean Lokken: Rabbit 
  • Bill Marchel, MN Conservation Volunteer: Coyotes 
  • Gary Sater: Mallard Duck, Pie-billed Grebe 


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Afton State Park phenology, Dec. 10 to Dec. 23