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Nature

Phenology Report: March 8 2022

Saw-whet owl
https://www.inaturalist.org/observations/18811512
Northern Saw-Whet Owl in Edina, MN. Photo by iNaturalist user gonodactylus.

We start off the show with the very validating news that this February was the fourth coldest February on record! Only 1989, 2013, and 2014 were colder or slightly colder than this year. March has continued the trend with few really warm days and still deep snow. There are some signs of thaw- on a recent snowshoe excursion, John found the snow was wet and sticky, showing evidence that there was enough heat to begin melting the snow.

On top of the snow is a thin glaze of ice, due to the light mist over the last week. John found out about it the hard way with a big slip (but not a fall) on his front porch! It’s not just John who’s struggling with the snow and ice- any critter heavier than a cottontail rabbit breaks through the crust and has to dig their way through the snow. While mice are leaving tiny tracks on top of the crust, the coyotes, wolves, and deer have to hack their way through- strenuous work after a cold, hungry winter! The deer, with their long legs, are at an advantage during this time: the wolves aren’t able to chase them down through the deep snow.

While the wolves struggle through the snow, John’s been struggling with a mystery involving two aspens at the end of his driveway. Aspens can reproduce by producing new shoots from their spreading root system, and entire stands of trees can be formed from one individual (in Utah, there is a stand named “Pando” with 40,000 individual trees that are all clones! It covers 106 acres, and is the largest organism ever found). Because his two trees bud out simultaneously, John had assumed that they were clones (genetic identicals). On reflection, however, John remembered that one tree is male and one is female, which should be impossible if they are genetically identical. He turned to Dr. Andy David, a professor at the University of Minnesota who studies aspens, to solve the mystery. Dr. David confirmed John’s suspicion that the aspens are not clones (they likely bud out simultaneously because they share a similar environment, instead of identical DNA).

Dr. David also shared some fascinating discoveries from his research; while studying bud development in male aspens, he and his assistant found that one of their study branches had produced a new shoot. As the branch was male, they expected the shoot to be male as well. Surprise! It was female! While hermaphrodism (having both male and female reproductive organs) has been well documented in other trees, such as silver maples, it is much less common in aspens. They had just happened to come across one when they were collecting specimens!

Both male and female aspens produce flowers, but the timing of their development differs. Male flowers, called catkins, will come out at the end of March. As they develop, they swell and elongate to three or four inches long, and start to give off pollen. The female flowers are very short at this time, only three quarters of an inch long. If they are ready, they will accept the pollen and begin the process of developing seeds. Their job done, the male flowers fall off the tree, while the female flowers develop into green pods that contain the seeds. This green color is visible in late April, just before the aspens leaf out. If you see that green color, you know the tree is female!This time of year, both male and female aspens will have their buds out. They are small and furry (similar to pussy willows), though you may need binoculars to see them clearly!

It’s not just the aspens that are worth watching this time of year. Tamaracks are beginning to show some color, as well as the birches, willows, dogwoods, mountain maples, and more. Look at the tops of the trees to see the show, as well as to identify the species! If the tree has a white trunk and the tips of the branches are bright or deep red, that’s a birch. A tree with a white trunk and greenish-white tipped branches will be an aspen. The colors will continue to brighten until the trees leaf out in early May.

Bare ground is beginning to show through the snow, at least on south facing hillsides, despite average snow depth of about 22 inches. As things warm up in the near future, those patches of bare ground will become more common.

A report came in to the station about a rough grouse snacking on a hazel. The grouse are eating the catkins (male flowers) off the hazels right now, although their preferred diet is aspens. The aspens stave off the grouse by producing compounds that make their buds less palatable. Discouraged, the grouse will turn to hazels and birches to supplement their diet.

Though we’re all looking forward to spring, the wonderful thing about snow is that it provides such a wonderful, clean canvas for nature to paint a picture! With the new snow last week, John had the chance to walk around and observe woodchips from a woodpecker working on an Aspen, seeds and bracts from birches, seeds from the speckled alder, and red squirrel middens. Middens are spots where squirrels have accessed underground caches of cones; the squirrels tunnel down to get the cones, then bring them up to on top of the snow to eat. In this case, the squirrel chose to have its snack in a little aspen barely thicker than a thumb: the base of the tree was littered with bracts (scales) from norway pine cones. In other spots, John found remnants of the seeds from the cones, which look like little wings. The squirrels are definitely finishing off their winter stores!

The winds also deposit a lot of debris from the trees- bits of balsams, norways, white pines, and white spruces were laying on top of the snow. Those darker objects absorb sunlight more quickly, melting the snow faster- John found a pine cone that had melted four inches into the snowpack! The oaks are also helping out the melting effort, dropping their old dry leaves in preparation for new spring ones. While the snow melts quickly under those warming dark leaves, sometimes debris can work in the opposite direction! John has observed objects sitting on top of the snowpack that actually prevent the sunlight from melting the snow, forming an island of snow where everything around it has melted away. (An aside: climate scientists have studied this phenomenon on a much larger scale! An unfortunate side effect of melting polar ice is that it exposes large amounts of dark open water. This water more efficiently absorbs sunlight, warming the ocean further, and reinforcing the melting cycle. While not great news for our planet, it’s cool to be able to see that same process happening on a small scale in your neighborhood snowbank!)

For now, the snow is still here, and John observed the track of a ruffed grouse that was almost two inches deep. Grouse grow small projections on the side of their toes in winter, which act as tiny snowshoes to help them stay on top of the snowpack. Whether this grouse was a particularly hefty specimen, or if the snow was extra fluffy when the grouse went by, John wasn’t able to tell!

This time of year, it pays to keep an eye out for pileated woodpeckers. They can be seen at the base of trees, where they feast on ants that are beginning to get active! The bases of trees, warmed up by sunlight, melt the snow around them and form a small, warmer microclimate that allows ants to become active. The pileated woodpeckers will hear the activity and stop on by for a snack!

Also in evidence are Bohemian wax wings, which move in big flocks and are often found in town. In Grand Rapids, John saw a flock of almost 200 birds moving between the fruit trees in town! On the Season Watch page on Facebook, there is a photo of a northern saw-whet owl. Their call sounds like a truck backing up, and they are tiny, about the size of a robin! (They eat half a mouse at a time, which is absolutely adorable if you can ignore the carnivory aspect). They’re moving back to the area, so keep an eye (and ear) out for them later in March and in the beginning of April.

Northern saw-whet owl call

That does it for this week! For more phenology, tune in to Northern Community Radio at 91.7 KAXE in Grand Rapids, 90.5 KBXE in Bagley, or come to one of our phenology training workshops in Duluth (March 12), Tamarac Wildlife Refuge (March 15th) or Northfield (March 19th).