Autumn: Time for Change on the St. Louis RiverCliff Langley
Fall is beginning to set in and it’s still a great time to come whitewater rafting on the St. Louis River. Last night we had our first frost warning of the year. The days are getting shorter, the nights are getting cooler. Soon the leaves will be changing while other subtle changes are happening along the banks of the St. Louis.
The migration of birds is a telltale sign that summer is giving way to fall. Minnesota’s state bird, the common loon, gathers in numbers to fly south to places such as the Gulf of Mexico. Once wintering in the south, loons shed their brilliant plumage and over winter as greyish black birds—we are lucky they give us their best showing in the north woods!
We all know that birds such as Canadian Geese, song birds and raptors all fly south but birds aren’t the only ones that head for warmer destinations. So do some insects! The Green Darner dragon fly (those that emerge in the summer) migrate south in masse. Their off spring migrate north in the spring. It is hypothesized that the American Kestrel migrates at the same time, feeding on darners as they migrate south. What about those without wings?
Our north woods ungulates, whitetail deer and moose, are in rut seeking a mate. The bulls are charged up on testosterone and are extremely aggressive. A bull moose in rut is one of the most dangerous animals a human can encounter, no bull! Regardless of their demeanor a bull in fall is a magnificent creature to witness. Sure the big guys are impressive but what about the smaller critters like frogs? What changes do they make to adapt to the cooling weather?
Amphibians, such as, the wood frog and grey tree frog have special adaptations to survive the winter. The wood frog hibernates in leaf litter over the winter. These frogs survive the freezing temperatures of winter by producing large amounts of glucose acting as antifreeze protecting their vital organs from freezing.
Of course, the coup de grace, the grand finale, the blast of color from autumn forests. This in and of itself is a great reason to come whitewater rafting on the St. Louis River if you are in the Duluth, MN area.
Fun Fact: Why Leaves Change Color
As autumn settles in, cooler nights and shorter days prompts trees to shut down their production of plant materials. Trees stop producing chlorophyll, a green pigment in the chloroplasts of the leaf that absorbs incoming sunlight and gives leaves their color.
As Chlorophyll trapped in the leaves begins to breakdown, other pigments that are present in the leaf begin to show their true colors: From the carotenoids we get brilliant yellows and blazing oranges seen in poplars, birches and maples, from the anthocyanins we see fiery reds in certain maples and oaks. And from the tannins we see rich browns. The varying amounts of chlorophyll and other pigments mixing in the leaf determine the leaf’s autumnal display.
For whitewater rafting near Duluth, Minnesota the Louis and her colors are a must see!