ice out

 'Ice Stars' adorned the melting ice on the pond last week, since winter was long and more snowy than usual.  

Warmer this week, and ice was all melted by today.

mallards arriving

Even though Spring is here and the birds have been moving to their nesting areas in Minnesota, the ice  is thick on the middle of ponds.  The Mallard pair is finding food in the open water near the shore.  They act like ice-breakers with their beaks and legs to get to the plant material beneath the water. 

ice stars

'Ice stars' or 'Lake stars' develop under very specific early winter conditions. 

First, a cold snap that freezes the pond ice an inch or two thick, followed by warmer days that bump the ice temperature above 32F. Pores form in the ice sheet where there are any imperfections in the water surface (plant matter, logs). Then, some snow falls with a cold front blowing in.  Warm water wells up from beneath the thin layer of ice, covered with a coating of snow and slush.  Temperature and precipitation have to be perfect for this to happen. 

stars on ice

Another interesting feature of winter on the pond is the 'ice star'  or 'lake star'.  In my search for information about these patterns, I found many theories -- all related to the physics of temperature, moisture, pressure, and ice formation.  One of these theories is that patterns are formed in early winter when a hole allows water to swell up from beneath and spread over the surface, leaving dark fingers of melted ice radiating from the hole.

ice holes on pond

Cold, grey, blustery weather on the pond.

The water is covered by a thick layer of ice and snow drifts. Where the ice is visible between the drifts, a few holes break the smooth solid sheet. These seem to form where plant matter floating close to the surface or a submerged rock interrupted the process of liquid freezing to solid.

log in snow drift

We call the log near the shore of the pond  'turtle log'.  

Now it is buried in a snow drift.  It is curved, and usually emerges above the water or ice at least 18 inches.

Twenty inches of snow fell on the pond in this one early-winter storm. 

tracks, cracks, marks, mysteries

Snow overnight.  A thin sheet of ice on the pond beneath the slush.  Wonderous tracks and marks this morning.  Maybe the muskrats, or the mallards, or other birds, or the mice or voles?  Maybe all of them, cavorting at dawn!  Tracks in a row, wandering.  Slide marks in the slush like a runway with bunched snow at the end.  Cracks expanding in the ice, icy fingers spreading both black and white!

 

surviving below freezing - turtles

Since we had several cold days and nights already, Painted Turtles Chrysemys picta who live in the pond are getting ready for winter.  Lacking summer heat, this one was wandering very very slowly for a food item or a place to settle. Turtles will spend the next several months in frigid pond water below the frozen ice, with their metabolism and their heart rate slowed way down. They can absorb oxygen from the water through vascularized areas in their mouth, throat, and anus (cloacal respiration).  But using oxygen produces lactic acid in their body, which the turtle counteracts with minerals released from its shell and bones.  Painted Turtles do not eat during this time, but they do remain alert, especially to light from above.  In Spring, when the hours of daylight increase, they will respond.

Chickadees at feeder over the pond

Black-capped Chickadees stay in Minnesota all winter.  They eat seeds and insects or larvae when they can find any.  They come to feeders where I offer sunflower seeds, safflower seeds, and peanut chips.  This feeder hangs over the pond with an extra branch for the birds to perch on.

From November to April I watch, count, and report the birds I see as a citizen scientist.  Cornell Lab of Ornithology is replete with data and information about birds.  https://www.birds.cornell.edu/home

This pond is covered with snow, and a layer of ice under that.  The turtles are hibernating below in the mud.  The muskrats are snug in their burrows.  It looks quiet and peaceful on the pond, but there is a lot going on in all seasons.

snowy pond February

How different the same view looks in winter! Still, we see evidence of critters who live at the pond by their tracks in the snow.

feeding birds on the pond

Chickadees, house finches, juncos, and even downy woodpeckers venture out of the trees nearby to take seed at the feeder next to the pond.

winter water

 
A heated water bowl at the edge of the woods has been our bird oasis through several cold winters.  It keeps water available for the birds, even when the rim accumulates a crust of snow and long icicles around the perimeter.  It is close to the "woody tree" where many roosting holes provide avian accommodations on cold nights.

Northern Flicker