Seasons of Wildlife
Located in the center of North America, far from the influences of marine environments, the climate of Minnesota is highly variable. We enjoy four distinct seasons here that are marked by extremes in moisture and temperature. Within the eastern Great Plains, peak periods of precipitation occurs in the spring with rain showers and thunderstorms, fall includes rain showers, and winter comes with snow and blizzards. Annual summer droughts are typical in the prairie environment, with the occasional thunderstorm, locally referred to as a prairie roller thunderstorm. Hot and humid summer days in the 90s contrast with dry, cold winter nights that can go down to -30 degrees F, not including wind chill.
As the seasons progress, the wild animals you see and hear on the district must adapt to these extreme variations to survive and reproduce or perish - without the benefit of a heating or cooling system. They are outside 24 hours per day, seven days per week, 365 days per year. Some migrate, some hibernate, some become temporarily dormant, and others stay here and remain active, resisting the weather. Their presence or absence and specific behaviors help mark the changing seasons and is called phenology.
"I wonder if the snow loves the trees and fields, that it kisses them so gently? And then it covers them up snug, you know, with a white quilt; and perhaps it says, ‘Go to sleep, darlings, till the summer comes again.'"– Lewis Carroll, Through the Looking-Glass, and What Alice Found There
Winter is all about food availability and balancing energy expenditure with energy consumption. District animals survive winter in three possible ways. Migrators travel great distances to find food in warmer climates and spend the winter actively searching out food, returning in the spring. Hibernators stay here and sleep deeply through the winter living off body fat built up from consuming extra food in summer and fall. Resistors stay here and remain active, consuming food that is still available to them.
Let’s Look At a Few Examples
There are two kinds of migratory birds: those that leave here for the winter and those that arrive here for the winter. Once our ponds, lakes and rivers freeze over, waterfowl move on from the area and spend the winter in the southern United States. A few hardy souls may stay behind in the city of Fergus Falls at the Riverside Waterfowl Sanctuary. Many duck, goose and swan species join some of our songbirds there that already departed, like tree swallows, eastern phoebes, yellow-rumped warblers, house wrens, gray catbirds and brown thrashers. Other songbird species continue on to Mexico and Central America, like wood thrushes and ruby-throated hummingbirds. The longest distant travelers include our scarlet tanagers, eastern kingbirds, bobolinks, chimney swifts, purple martins and certain shorebirds. We must also remember the Caribbean destination for some indigo buntings and American redstarts, most black-throated blue warblers and some palm warblers and prairie warblers. Horned larks live here almost year round, heading south only for the deepest, coldest winter months. They are our last species to leave and the first to return as the distance travelled is so short.
Therefore, winter bird life here is quieter but also graced with a few surprises landing from further north, like the occasional snowy owl, plenty of slate-colored juncos, American tree sparrows and sometimes - common redpolls. Watch the roadsides and listen overhead for flocks of snow buntings, as well. For these species, the prairie of Minnesota is like Florida for us!
Chubby 13-lined ground squirrels hibernate in their burrows beneath the prairie. They live off the fat built up through a busy summer of eating. Painted turtles head under water into the mud to hibernate, or brumate, as it is sometimes called for reptiles and amphibians. Their metabolism slows so much that they get the little dissolved oxygen they need from the water through their skin. However, you can possibly see them moving around ever so slowly under the ice. Frogs, on the other hand, still need a good oxygen supply and spend much of the winter lying on top of the mud or only partially beneath it. Some toads will dig deep burrows to get below the frost line in the prairie, taking advantage of pocket gopher mounds and tunnels. Tiger salamanders also use gopher burrows but stay active below the frost line all winter long as do gophers. The land frogs, like the spring peeper, are particularly interesting. They crawl deep into crevices, where it gets well below freezing. However, they do not freeze to death. Even though ice crystals may form in the body or under the skin, high concentrations of glucose in the vital organs prevent them from freezing. These frozen frogs stop breathing, and their hearts stop beating. Nevertheless, when the weather warms, the frozen portions thaw, and the frog’s heart and lungs start again.
Shrews, voles and mice survive winter in the subnivean world, that narrow air space between the bottom of the snowpack and the top of the ground. Converting plant material into protein, they form the basis of the prairie food pyramid, providing nutrition for other resistors, like weasels, mink, fox, coyote, northern shrikes and great horned owls. Muskrats and eastern cottontails, also resistors, help round out the carnivore menu.
Year round resident birds must actively seek out food during winter days and build up enough fat to survive each nightly fast. It is as if each winter day is one summer, and they hibernate each night. The tiny black-capped chickadee is a marvel at this survival pattern. They reach an energy edge at 32 degrees F, and yet our winter nights get much colder than that and may be extended by blizzards. Chickadees stretch their fat reserves overnight by lowering their body temperature and by shivering vigorously, maintaining a state of hypothermia. In addition, they must also succeed in avoiding windy places and finding effective shelter at night with warmer air temperatures inside. Their greatest heat loss is from the eyes and beak, so they sleep with their heads tucked beneath their shoulder feathers. They fluff out their feather coat to trap warm air near their skin and ball up to sleep. Chickadees have many other amazing adaptations which help them survive winter, including like seed caching, an increased memory and denser plumage. Other winter bird residents include white-breasted nuthatches, pileated woodpeckers, American goldfinches and American crows.
Yes, Minnesota winters are harsh, but wildlife are well adapted. This ensures a spring filled with new life once again.
“Is the spring coming?” he said. “What is it like?” ...“It is the sun shining on the rain and the rain falling on the sunshine and things pushing up and working under the earth...” – Frances Hodgson Burnett, The Secret Garden
The melting of winter into spring brings with it a rush of life. Waterfowl, wading birds and songbirds arriving from the south for another nesting season along thousands of miles of shoreline. Melting ponds and warming waters release turtles and frogs from their winter retreats. Thawing ground and receding snow unleash the insect life that overwintered in cocoons or beneath leaf litter or simply froze in place. In late spring, ducklings follow hens in neat lines, and the first tree swallow nestlings have fledged, filling their crops with airborne insects.
Water not constrained by wetland shorelines also fuels an explosion of life. Snowmelt and heavy rains bring forth floral swatches of pasque flowers, golden alexanders and prairie roses, contrasting colors to last year's brown grasses gradually giving way to this season's greens. Western chorus frogs stake out breeding sites in the swollen sloughs, filling the spring night air with sometimes deafening trills.
Everywhere - spring water, in all its forms, means life.
“Early summer days are a jubilee time for birds. In the fields, around the house, in the barn, in the woods, in the swamp—everywhere love and songs and nests and eggs.” – E.B. White, Charlotte’s Web
After the frantic movement, mating and nest building of spring, life settles into a different rhythm for summer. Songbirds flit between nests and hunting grounds with dozens, hundreds, thousands of insects to sate hungry young. Ducklings and goslings dutifully follow their parents from hiding place to hiding place, growing in their first flight feathers as their flightless parents molt their own. White-tailed deer and their fawns trek from secret locations to forest edges and fields each and every dusk and dawn to feed. Muskrats maintain their huts with to and fro trips to cattail plants. Bumblebee queens are doing the same, visiting flowers for nectar and pollen upon which they feed and lay their eggs. Once their eggs hatch, they use those plant resources to feed larval worker bees in underground burrows or abandoned mouse nests. Life is a busy routine of foraging, feeding and growing
But while school kids may be out for the summer, in the waters and prairies of Minnesota, school is well underway for wildlife. The muskrat is teaching its own young how to watch and warn of dangerous predators like weasels and mink who are likewise bringing meaty meals to their young. Birds are learning to fly, northern harriers and purple martins learning to navigate the tight twists and turns of flight over the prairie. Everything is pointing towards preparation for survival.
“I’m so glad I live in a world where there are Octobers.” – L.M. Montgomery, Anne of Green Gables
Fall is a time of plenty for Minnesota’s wildlife. Where prairies intersect with wetlands, bursting insect populations, ripening seeds and thickening roots mean protein, fats and carbohydrates to chunk up for cold winters and long migrations. The nutritious greens of summer are still around, at least for a while. Predators have an abundance of prey available, in the large brood and litter sizes of inexperienced, younger herbivores.
It is also a time of restlessness. Red-winged blackbirds are flocking together, getting ready for mass migrations south; their long, dark, chattering ribbons coursing overhead. Ducks and geese, too, are dispersing, starting to turn their unconscious thoughts in all directions then ultimately southward. White-tailed deer does are coming into heat, bucks into the frenzy of the rut, starting the next generation of the following spring. As the days fade into late fall, reptiles and amphibians burrow into the mud or enter group hibernacula that stretches below the deepening frost line. Prairie grasses and forbs, while not knowing any urgency, turn red and orange and purple and yellow. Soon fading to brown and supporting the first snowflakes. Western Minnesota is emptying out and hunkering down for the short bright days and long dark nights of winter.
Natural History of the Prairie Pothole Region
Fergus Falls Wetland Management District is situated in western Minnesota on the eastern edge of North America’s prairie pothole region, also known as the duck factory. About 118 million acres in size, the prairie pothole region produces more than 50 percent of the continent’s waterfowl due to its historically highest density of wetlands and associated upland prairie on the continent. These wetlands of varying sizes and depths skirted by short, mixed and tallgrass prairies are places unlike any other. They still provide nesting habitat for a rich variety of dabbling and diving ducks despite a massive conversion of the landscape to agriculture. Here, trumpeter swans glide gracefully across the water as their haunting calls echo under an expansive sky and the earthy smell of wetland reeds and clean water drift through the air.
Our objectives include developing and managing habitat for waterfowl production, including habitat for native plants and animals, especially prairie songbirds. Staff also assist private landowners with restoration of wetlands and grasslands. More than 293 species of birds have been observed in the district, with about 170 of those species nesting here, including approximately 57 pairs of bald eagles and nearly a dozen osprey. This avian diversity compliments at least 40 species of mammals and 25 species of reptiles and amphibians.
Many visitors particularly enjoy viewing waterfowl like ducks, geese and swans, as well as other migratory birds. Some of our characteristic species include: trumpeter swans, Canada geese, wood ducks, mallards, blue-winged teal, ring-necked ducks, scaup, northern harriers, killdeer, yellowlegs, ring-billed and Franklin’s gulls, horned larks, purple martins, sedge and marsh wrens, yellow warblers, clay-colored and swamp sparrows, bobolinks, western meadowlarks, red-winged blackbirds, yellow-headed blackbirds and American goldfinches. Remnant native grasslands in the western part of the district are ideal places for more adventurous explorers to see greater prairie chickens, marbled godwits and short-eared owls.
Prior to colonization, this portion of Minnesota was part of a broad, sweeping grassland known as the Northern Tallgrass Prairie which remains the wettest portion of the North American Great Plains. This vast prairie offered nesting habitat for many species of ground nesting birds including waterfowl, songbirds and prairie grouse. With the easterly progression of increasing amounts of rainfall and the absence of expansive wildfires, drought and nomadic bison grazing, the lanky grasses and picturesque wildflowers yielded to oak savannah and eventually to the dense forested regions of the eastern United States. It was on the eastern edge of the Northern Tallgrass Prairie that the competition between grassland and forests took place, and the Fergus Falls Wetland Management District is located today in that transition zone.
Interspersed throughout this open landscape was an abundance of small ponds in every shape, size and depth imaginable. This area, known as pothole country, was formed 12,000 ago when retreating glaciers melted and filled the erratic depressions left in their path. With its abundance of grasslands and wetlands, this prairie pothole country was a virtual duck factory – producing mallards, blue‐winged teal, redheads, geese, swans, canvasbacks and other water birds by the millions.
The various sizes and depths of wetlands provided the required habitats of waterfowl and many other wetland‐dependent species of wildlife. Dabbling ducks like mallards and teal thrive in the invertebrate rich shallow water of temporary and seasonal wetlands where they can tip up to feed. Diving ducks like canvasbacks, redheads and scaup, also known as bluebills, prefer deep clear marshes with abundant submerged aquatic plants. Whether temporary half‐acre ponds or large, open water marshes, all wetlands are important and necessary for waterfowl to thrive.
When the organic material from decomposing prairie vegetation blended with the mineral rich soil left behind by the glaciers, some of the most fertile soil in the world gradually formed in this region of Minnesota. Colonization did not blend well at first with wetlands and the thick prairie sod. Once settlers could access , this fertile soil beneath the sod, colonization and settlement of the prairie accelerated and would eventually be its own demise. In the past century, 90 percent of the historic wetlands in prairie portions of Minnesota have been drained for agriculture and development, and less than one percent of the original prairie remains. Nesting waterfowl populations have declined significantly, and other wildlife species have suffered.
The following excerpt is from Ducks Unlimited Cattails magazine, originally published in Forest and Stream, circa 1880. Reprinted with permission.
"This land is covered by a carpet of the richest verdure, interspersed with flowers of every shade. Everywhere there is the same waving prairie surrounded by groves of majestic oaks... The lakes and waters of the most perfect purity swarm with wildfowls, ducks, geese and swans. For surely in no place have I ever seen game more abundant."
A Diversity of Wildlife
Fergus Falls Wetland Management District is in an area where freshwater prairie wetlands and the associated northern tallgrass prairie join to form a zone of transition with the northern hardwood forest. This blend of habitats provides for an impressive diversity of bird species. The bobolink, northern shoveler and sora rail are a few interesting examples to enjoy.
You can see bobolinks in many of the restored prairies in the Fergus Falls Wetland Management District. The males are black below with a white rump and shoulders and a buff-colored neck. Males have a bubbly song that sounds like their name. Since they like to nest in grassy areas, singing males have a rather unusual way to get their song heard. They take off from a grass singing and rising high into the sky. This highflying method is called skylarking.
Beauty and unusual features combine in the northern shoveler. They are a medium sized dabbling duck. Found in shallow wetlands throughout the Fergus Falls Wetland Management District, the spoon shaped bill of this unique duck sets it apart, earning it the nickname of spoonbill. Their long bill has more than one hundred hair like projections that strain wetland water and retain its diet of mostly wetland invertebrates. The iridescent and glossy green head, rich chestnut sides and white feathers of the chest make this duck a feast for the eyes.
This small migratory bird is worth the search. The secretive sora rail is just nine inches long from beak to tail. With its large feet, soras can almost walk on water. Look for a small brownish chicken-like bird close to the heart of a cattail wetland.