1. Laurentian Mixed Forest
2. Eastern Broadleaf Forest (Continental)
3. Prairie Parkland (Temperate)
4. Great Plains Steppe (west of Minnesota)

Climate.--Winters are moderately long and somewhat severe, but more than 120 days have temperatures above 50F (10C). Average annual temperatures range from 35 to 50F (2 to 10C). A short growing season imposes severe restrictions on agriculture; the frost-free season lasts from 100 to 140 days. Snow usually stays on the ground all winter. During winter, the province lies north of the main cyclonic belt; but during summer it lies within this belt, and the weather is changeable. Average annual precipitation is moderate, ranging from 24 to 45 in (610 to 1,150 mm); maximum precipitation comes in summer.

Vegetation.--This province lies between the boreal forest and the broadleaf deciduous forest zones and is therefore transitional. Part of it consists of mixed stands of a few coniferous species (mainly pine) and a few deciduous species (mainly yellow birch, sugar maple, and American beech); the rest is a macromosaic of pure deciduous forest in favorable habitats with good soils and pure coniferous forest in less favorable habitats with poor soils. Mixed stands have several species of conifer, mainly northern white pine in the Great Lakes region, with an admixture of eastern hemlock. Eastern redcedar is found in the southeast. Pine trees are often the pioneer woody species that flourish in burned-over areas or on abandoned arable land. Because they grow more rapidly than deciduous species where soils are poor, they quickly form a forest canopy; but where deciduous undergrowth is dense, they have trouble regenerating, and remain successful only where fire recurs. Fires started by lightning are common in this province, particularly where soils are sandy and there is a layer of dry litter in summer.

Soils.--The greatly varying soils include peat, muck, marl, clay, silt, sand, gravel, and boulders, in various combinations. Spodosols are dominant in New England and along the Great Lakes coast; Inceptisols and Alfisols dominate farther inland. The Alfisols are medium to high in bases and have gray to brown surface horizons and subsurface horizons of clay accumulation.

Fauna.--In winter, the shorttail weasel (ermine) and snowshoe hare turn white, as they do in polar provinces. The black bear, striped skunk, marmot, chipmunk, and two genera of jumping mice all pass the winter in hibernation. So do badger and the striped ground squirrel that live in the western parts of the province. Beaver and muskrat remain active all winter, working beneath the ice that covers the lakes and streams. Ptarmigan also turn white in winter. Many other birds, especially insectivorous species, migrate south. Common summer resident birds include the white-throated sparrow, northern junco, and yellow-bellied sapsucker.

Plant Communities (Minnesota).--Cold winters and cool summers caused by Arctic air masses result in extreme temperature variations and a low energy budget for the plant communities found here. Most of the precipitation occurs during warm months, and the air and soils are moist in comparison to the non-forested landscapes of western Minnesota. Soils that have developed from glacial till and loess now thinly overlay the Canadian shield.

Species that succeed in this environment have adaptations that economize on energy-both temperature and sunlight-and on nutrient requirements. For example, coniferous trees hold their needles from 2 to 15 years, depending on the species. This adaptation avoids the necessity for producing a full crop of new leaves every spring, and it also allows photosynthesis for extended periods of the year. Species that occur in the boreal hardwoods, such as trembling aspen, balsam poplar and paper birch, have special adaptations to withstand temperatures below -30° Fahrenheit.

Forest Canopy (Minnesota).--The canopy layer of a forest community may be seen as being the primary buffer between atmospheric conditions and the communities below; it bears the brunt of wind and temperature extremes, and is the first beneficiary of sunlight.

Coniferous Forest canopies may be dominated by coniferous, deciduous, or mixed coniferous-hardwood species.

Six forest communities are characteristic of Minnesota's Coniferous Forest area: white pine, red pine, jack pine, black spruce-feathermoss, spruce-fir, and upland white cedar. While all pines regenerate after fire, the fire regime differs for each species.

After a disturbance in the coniferous forest, such as logging or burning, the canopy opening favors deciduous species, with their higher rates of photosynthesis. Aspen and paper birch pioneer such areas, and they may in turn be followed by mixed hardwood and coniferous trees in a zone of intergrading communities. Northern hardwood stands of sugar maple, basswood, yellow birch, and associated species develop on mesic uplands. On drier sites in the south and west portions of the Coniferous Forest, oak communities are more common.

Shrub Layers (Minnesota).--Beneath the canopy layer, shrubs vary locally in density. Seedlings and saplings of canopy trees bide their time in the shade; when a canopy tree falls, these young trees inherit the sunlight they need to succeed to canopy status themselves. Shrub-level species include beaked hazel, mountain maple, honeysuckle, and dogwood, along with others associated with specific soils and canopies. Variation of shrub density within the forest significantly affects the habitat and diversity of animal species.

Groundlayer (Minnesota).--The groundlayer in coniferous plant communities often includes feathermosses as well as forest herbs. The acid needle litter on the forest floor supports herbs such as clintonia and rose twisted-stalk, while feathermoss communities support such herbs as wintergreen and pyrola.

Landscape Areas (Minnesota).--The Coniferous Forest biome ranges from relatively flat lake plains and outwash plains in the west, to hillier moraines in the mid-section, with rugged, rocky outcrops abutting Lake Superior. Peatlands occur in huge areas across the western and central glacial lake plains. As elevation rises eastward, soils become thinner and bedrock outcrops more prominent. Here passing glaciers caught on rugged bedrock; ice blocks broke off and were abandoned to melt slowly beneath glacial till, forming many of our "10,000 lakes."
 

Land-surface form.--Most of the area is rolling, but some parts are nearly flat and in the Ozark Highlands the relief is moderate (up to 1,000 ft [300 m]). Low rolling hills, dissected plateaus, and basins are found in Tennessee and Kentucky. The northern parts of the province have been glaciated, but not the southern. Elevations range from 80 to 1,650 ft (24 to 500 m).

Climate.--The climate has many characteristics in common with the oceanic broadleaf forest to the east, but precipitation decreases in quantity and effectiveness as one moves inland. Average annual temperatures range from 40F (4C) in the north to 65F (18C) in the south. Summers are hot, with frequent tornadoes. Precipitation varies from 20 in (510 mm) near the 95th meridian to 40 in (1,020 mm) in Ohio, and to 50 in (1,280 mm) in Tennessee. Most precipitation takes place during the growing season.

Vegetation.--Like its counterpart to the east, this province is dominated by broadleaf deciduous forest, but the smaller amounts of precipitation found here favor the drought-resistant oak-hickory association. Although other forests have oak and hickory, only this particular forest association has both species in abundance.

The oak-hickory forest is medium-tall to tall, becoming savannalike in its northern reaches from eastern Oklahoma to Minnesota, where it gradually turns into prairie (described below for the Prairie Parkland [Temperate] Province). From eastern Kansas to Indiana, it forms a mosaic pattern with prairie. Widespread dominants are white oak, red oak, black oak, bitternut hickory, and shagbark hickory. The understory is usually well developed, often with flowering dogwood. Other understory species include sassafras and hophornbeam. The shrub layer is distinct, with some evergreens. Many wildflower species occur. Wetter sites typically feature an abundance of American elm, tuliptree, and sweet gum.

Northern reaches of the oak-hickory forest contain increasing numbers of maple, beech, and basswood. The maple-basswood forest, dominated by sugar maple and American basswood, occurs from central Minnesota south through Wisconsin and northeastern Iowa. Glaciated areas of Ohio and Indiana feature a beech-maple forest defined by American beech and sugar maple. In these latter associations, oak and hickory occur on poor sites.

Soils.--As in the oceanic broadleaf forest, the soils change from Alfisols in the north to Ultisols in southerly latitudes. Toward the continental interior, calcification sets in as forest soils give way to the darker soils of the grasslands (Mollisols).

Fauna.--In the oak-hickory forest, acorns and hickory nuts provide abundant food for the ubiquitous gray squirrel. Fox squirrels are often found, as are eastern chipmunks. Roving flocks of blue jays also feed on forest nuts. In summer, scarlet and/or summer tanagers, rose-breasted grosbeaks, and ovenbirds are common. The wild turkey is also found here. The cerulean warbler is common in the beech-maple forest, and occurs elsewhere as well.

The Big Woods (Minnesota).--is an area of dense forest characterized by maple-basswood forests-represent the peak of deciduous forest development. Minnesota had extensive stands of this woodland community at the time of European settlement. Today only a tiny fraction remains. Common tree species in Deciduous Woods include sugar maple, basswood, various oak types, ironwood, elm, hickory, butternut, birch, and aspen.

The driftless area in southeastern Minnesota features caves, ravines, and sinkholes, with clear, spring-fed trout streams coursing through the steep and hilly countryside.

Plant Communities (Minnesota).--Natural plant communities in this area are mostly influenced by climate, topography, soils, and fire. Gulf air masses bring warm summer temperatures and humid, sunny days that provide an ample growing season. This rich energy budget allows deciduous trees to drop their leaves each fall, then grow an entirely new crop each spring and still produce luxuriant growth each year.

The landscape includes a mosaic of prairie, forest, and wetland communities. Prairie grasslands have historically occupied the flat lands that today are agricultural fields. Today most prairies are found on steep slopes with thin soils, or on sandy or wet areas unsuitable for agricultural production. Forests developed around lakes and wetlands along winding rivers, where the effects of fire were limited. Forests also developed on the north sides of hills, ravines, and other areas where temperatures were cooler and moisture more available. Wetlands allowed wet prairie and specialized forest communities to develop.

Deciduous forest communities themselves are distinguished by degree of soil moisture:

• Xeric forests, found on dry sites, feature drought-tolerant species, typically dominated by white, red, and black oak canopies.
• Mesic forests, found on sites with moderate soil moisture, are the stable maple-basswood forests we know as Big Woods.
• Lowland forests, found along floodplains and swamps, are adapted to the greatest extremes in moisture, ranging from spring flooding to summer drought. Cooler air settles or drains through these areas. Canopy species vary widely. Floodplain forests include silver maple, cottonwoods, black willow, American elm, green ash, and bur oak. Hardwood swamp forests include black ash, paper birch, yellow birch, red maple, American elm, slippery elm, and green ash.

Plant species associated with these communities are adapted to the stress of drought, excessive moisture, and shade in a variety of ways. Consider these examples:

• Rich, mesic forests support a variety of spring ephemerals that avoid the stress of deep shade by emerging, flowering, and fruiting before the forest canopy leafs out. Other herbaceous plants tolerate the shady environment, beginning their growth flush upon closure of the leaf canopy, and fruiting during the summer months.
• In the extremes of the floodplain forest, tree species tolerate inundation as well as abrasion by debris-ice, fallen trees, or manmade objects-in floodwater currents. Frequent treefall in these conditions create canopy openings that optimize individual tree growth, resulting in individual trees that are large in diameter and height. Trees often develop multiple stems. Floodplain understory is highly variable from year to year, depending on the duration and depth of flooding: vines and short-lived opportunists are most successful in these communities.

Xeric Forest Communities (Minnesota).--Sandy, porous, nutrient-poor soils on southern and western slopes or on hilltops and ridges support xeric forest communities typically of oak and aspen. Oak leaves are low in nutrients, high in acid, and can take from three to five years to decay, further affecting soil development. After a fire, oaks "stump-sprout," while aspen produce profuse suckers, both rapidly perpetuating their species as an adaptation to fire. The irregular oak-aspen canopy of southern forests creates openings for sunlight to penetrate to the forest floor, where a variety of saplings develop, opening the way for succession.

Shrub diversity is highly variable throughout this extensive landscape area, providing varied food and habitat for animal species. The ground layer under this relatively sunny canopy tends to bloom in mid-summer: orchids, rattlesnake plantain, pink shinleaf, smooth bedstraw, wild geranium, and false Solomon's seal are just some of the native flowers in this community.

Mesic Forest Communities (Minnesota).--Mesic forest communities have developed on cool north slopes whose rich soils formed from glacial till and loess, with the fertile leaf litter of the maple-basswood forest. Adequate soil moisture and protection from fire by wetlands, rivers, and topography have promoted development of this fire-sensitive community.

The closed maple-basswood canopy intercepts most of the sunlight, impoverishing the understory's supply of light. Spring ephemerals have evolved to capitalize on the early spring sun before the tree canopy emerges. It is within the "Big Woods" mesic forest remnants that spring ephemerals are at their best. Trout lilies, Dutchman's breaches, spring beauty, toothwort, and false rue anemone are among this group of forest wildflowers. Shade tolerant wildflowers, however, retain their leaves after the canopy emergence, and ripen their fruit in mid-summer: mayapples, bloodroot, Jack in the pulpit, wild ginger, hepatica, and trilliums constitute this group. Groundcover in the mesic forest community is typically patchy in distribution.

The sparse shrub layer in the mesic forest is dominated by shade tolerant specialists, particularly saplings of the canopy species, awaiting their day in the sun when a mature tree falls, leaving its legacy of sunlight to the younger sibling. This homogeneity accounts for the long-term stability and continuity of an established maple-basswood forest. Shade-tolerant shrubs such as leatherwood, American hornbeam, ironwood, bitternut hickory, and pagoda dogwood complete the understory.

Lowland Forest Communities (Minnesota).--Lowland forest communities occur throughout the length of this landscape wherever conditions of abundant soil moisture are found. In the southern portion, high summer temperatures, long frost-free periods, and high humidity create optimum growing conditions for lowland forests. Most extensive examples occur along floodplains where the extremes of flooding and drawdown, along with abrasion by floodwater debris, are annual events. Ice scars on trees, along with windrows of debris on the forest floor and abandoned channels of stagnant water, provide evidence of the floodplain dynamics. Hardwood swamps, though not subject to these extremes, occupy areas of poor drainage on peaty soils. In both cases, soil improvement is limited, and the communities are stable.

Floodplain communities of northwestern Minnesota include American elm, slippery elm, green ash, cottonwood, and bur oak. In southern Minnesota, silver maple, black willow, and cottonwood are more common, with scattered patches of river birch, American elm, slippery elm, green ash, and swamp white oak. Tree and shrub seedlings are limited by flooding, resulting in an open understory. Vines such as wild grape and Virginia creeper seek out light gaps and open areas, where they escape the ground layer and join the canopy. The groundlayer is low in diversity, and comprised of short-lived opportunists such as cleavers, sedges, and wood nettle.

Wet sites with muck and shallow peat substrates support hardwood swamp forests dominated by mixed hardwoods, black ash, American elm, slippery elm, green ash, quaking aspen, or balsam poplar. In the north, tamarack is common, with occasional white pine or white cedar. Canopy density varies considerably, and communities occur in isolated pockets, reflecting highly localized variations.

The Deciduous Woods biome is made up of lake and outwash plains, moraines, and drumlin fields. Topography ranges from relatively level plains, to very steep gradients in southeastern Minnesota along the edge of the Paleozoic Plateau. Containing a mixture of grassland and deciduous woodlands, it forms a transition between the Prairie Grasslands and Coniferous Forest.
 

Land-surface form.--The Prairie Parkland (Temperate) Province covers an extensive area from Canada to Oklahoma, with alternating prairie and deciduous forest. The topography is mostly gently rolling plains, but steep bluffs border a number of valleys. Some areas are nearly flat; others have high rounded hills. Elevations range from 300 to 2,000 ft (90 to 600 m). The far northern portion of the province has been glaciated.

Climate.--Summers are usually hot, and winters are cold, especially in the northern part of the province. Average annual temperatures may reach 40F (4C) in the north and 60F (16C) in the south. Winters are short and relatively mild in southerly areas. The frost-free season ranges from 120 days along the northern fringe to 235 days in the south. Average annual precipitation ranges from 20 to 40 in (510 to 1,020 mm), falling mainly during the growing season.

Vegetation.--Vegetation in this province is forest-steppe, characterized by intermingled prairie, groves, and strips of deciduous trees. The alternation of forest and prairie in the western part of the province results chiefly from local soil conditions and slope exposure; trees are commonly found near streams and on northfacing slopes. The thin soils atop this area's limestone hills support very few trees. In the eastern part of the province, however, trees often cover the highest hills. The prairies seem to be areas that have not yet become forested, either because of frequent fires or because the last glaciation was too recent for final successional stages to have been reached.

Grasses are the dominant prairie vegetation. Most are moderately tall and usually grow in bunches. The most prevalent type of grassland is bluestem prairie, dominated by such plants as big bluestem, little bluestem, switchgrass, and Indian grass, along with many species of wildflowers and legumes. In many places where grazing and fire are controlled, deciduous forest is encroaching on the prairies. Due to generally favorable conditions of climate and soil, most of the area is cultivated, and little of the original vegetation remains.

The upland forest in this province is dominated by oak and hickory, forming part of the oak-hickory forest described above for the Eastern Broadleaf Forest (Continental) Province. On floodplains and moist hillsides, the deciduous forest is richer. In the western part of the province, it includes eastern cottonwood, black willow, and American elm.

Soils.--Mollisols dominate throughout the province. Alfisols are found in the Mississippi Valley.

Fauna.--In addition to prairie animals that do not need woody vegetation, many forest animals are found in this province. They inhabit the wooded valleys that extend westward across the region. Few forms are peculiar to the region, but certain mammals are indicative of its riverine forests, including mink and river otter. On the prairies, thirteen-lined ground squirrels and blacktail prairie dogs are commonly seen. Birds of the riverine forests include the belted kingfisher, bank swallow, spotted sandpiper, and green-backed heron. Upland birds include the horned lark, eastern meadowlark, and mourning dove.

Minnesota Prairie.--This is the prairie palette that marked the seasons for native peoples of long ago, when vast grasslands spread from the northwestern to the southeastern tips of the state. These grasslands ranged from sparsely vegetated sand dunes to vast fields of big bluestem up to eight feet tall, from low, wet sedge meadows to short-grass prairies high on the bluffs of the Mississippi River. Bison and elk roamed the plains, and prairie birds such as the upland sandpiper and sandhill crane were plentiful.

With the advent of European settlement, much of the flat and fertile prairie land fell to the settler's plow. Now, just a century and a half later, only one percent of the original 18 million acres of prairie remains. Urban sprawl, agricultural expansion, and gravel mining continue to threaten this rich resource and the mammal, bird, and insect species it supports. Protection is critical if this complex ecosystem, with its shifting array of color and form, is to survive into the future.

Plant Communities (Minnesota).--Prairie communities are as varied as the landforms on which they occur-beach ridges formed by ancient glacial lakes; gravelly hills left by retreating glaciers; sandy plains deposited by ancient rivers; steep bluffs; and rolling plains. Moisture levels vary throughout, determining the types of plant communities that develop. Since fire tends to eliminate trees and shrubs while enhancing the growth of prairie grasses, wildfire frequency also affects the types and persistence of prairie communities.

Dry Prairies (Minnesota).--At the lowest end of the moisture spectrum, dry prairies are dominated by short- to mid-height (up to 2 feet tall) grasses and forbs (flowering plants) adapted to dry conditions. Little bluestem, side-oats grama, and porcupine grasses typically dominate; dotted blazing star, pasque flower, and puccoons are characteristic forbs. Biologists identify four subtypes of dry prairie.

• The sparsely vegetated barrens subtype occurs on deep deposits of sand left primarily by glacial meltwater rivers. Winds have often reworked these deposits into dunes during subsequent periods of severe drought.

• The sand-gravel subtype occurs on nearly level to steeply sloping gravel-rich deposits left by melting glaciers or deposited along the shores of large glacial lakes.

• The hill subtype, richest in species, climbs steep slopes of loamy till also deposited by glaciers.

• Along steep Mississippi River bluffs in southeastern Minnesota, the bedrock bluff subtype, often called goat prairie, sprouts from a thin layer of soil over bedrock.

In all four cases, frequent fires as well as low moisture levels help to prevent the encroachment of trees.

Dry Oak Savannas (Minnesota).--Where the frequency and intensity of fire in the dry prairie is lower, species such as bur oak and northern pin oak may invade successfully to create a community called dry oak savanna. Here small to large, single to clumped, gnarled and spreading bur oaks dot typical dry prairie vegetation. Dry oak savannas were once much more common, occurring in the transition zone between prairie and forest on the same landforms as dry prairies (except bedrock). Today they are very rare; most have been plowed under for cropland or, with the suppression of fire, have succeeded to woodlands.

Mesic Prairies (Minnesota).--In mesic prairies, moderate soil moisture levels support grasses up to six feet tall. Big bluestem, Indian grass, and prairie dropseed generally dominate; heart-leaved alexander, maximilian sunflower, and wood lily are typical forbs. These rich prairies occur mainly in southern and western Minnesota on level or gently rolling land. Their black, nutrient-rich soils range from sandy to silty and support more than 300 plant species.

Where mesic prairies occur in cooler climates, as in the Aspen Parklands of northwestern Minnesota, less frequent burning allows the invasion of stunted trees such as young aspen and scrub oak, and shrub species such as slender willow, bog birch, and hazel. These communities, in which brush comprises 30 to 50 percent of the total vegetation cover, are called mesic brush prairies.

Wet Prairies (Minnesota).--In flat or low-lying areas with poorly-draining, mineral (inorganic) soils, snow melt or rainwater may accumulate and stand for short periods, or the water table may remain close to the surface for much of the growing season. Here grasses such as prairie cordgrass, blue-joint, bog reed-grass, big bluestem, and mat muhly dominate the wet prairie, along with several sedge species. Wet prairies occur throughout the prairie zone, but are especially common on the broad, poorly drained flats of the Glacial Lake Agassiz Interbeach Area in Minnesota's far northwestern corner.

Where fire is either less frequent or less intense, wet prairies may succeed into wet brush prairies, in which willow species and other shrubs cover 30 to 50 percent of the ground. The shrubs form thickets that dot a continuous cover of typical wet prairie grasses and forbs. Web brush prairies occur primarily in the northwestern part of the state.

Calcareous Seepage Fens (Minnesota).--A rare and different kind of prairie wetland, the calcareous seepage fen, is dominated by sedges such as prairie sedge, sterile sedge, and tussock sedge adapted to soils continuously saturated with cold groundwater. Typically, groundwater that has been percolating through a permeable layer of porous material (overlying a less permeable layer) surfaces where the porous layer is exposed at a slope. Where the cold, oxygen-poor groundwater emerges, organic matter decomposes very slowly, and eventually a layer of peat accumulates, typically more than a half meter deep. Certain very rare plant species, such as hair-like beak rush and beaked spike rush, specifically adapted to the water's cold temperature, high pH, and uniquely high calcium and magnesium bicarbonate content, occur only in calcareous fens.

The prairie subtype of the calcareous seepage fen contains prairie grasses and forbs intermixed with sedges and rushes. These unique fens occur sporadically throughout much of the prairie zone.
 

Land-surface form.--This region is characterized by flat and rolling plains with relief of less than 300 ft (90 m). Elevations range from 2,500 ft (760 m) near the western edge of the province to 1,000 ft (300 m) at the eastern edge. Except south of the Missouri River, most of the lands are young glacial drifts and dissected till plains. Water covers much of the surface. Loess and sand deposits cover the area south of the Missouri River. This flat-to-rolling hill land has well-developed drainage systems. Mixed-grass steppe in the sandhills of central Nebraska.

Climate.--Average annual temperatures in this province range from 40F (4C) in the north to 55F (13C) in the east, 60F (15C) in the west, and 65F (18C) in the south. Along its eastern boundary from Oklahoma to Nebraska, annual precipitation approaches 30 in (770 mm), dropping to about 20 in (510 mm) in North Dakota. Along the western limit of the region, precipitation ranges from 20 in (510 mm) in Oklahoma to 25 in (640 mm) in Nebraska, dropping to 15 in (380 mm) in the extreme northwest. Drought periods are less frequent and severe near the prairie parkland than in the more westerly areas.

Vegetation.--This region, called mixed-grass steppe, reaches from the tallgrass prairie parkland to the shortgrass steppe at about long. 104 W. As its name suggests, it contains a mixture of shortgrass and tallgrass species. The tall grasses grow to a height of about 48 in (1,230 mm); the shorter grasses reach 18 in (460 mm). Shorter dominants include blue grama, hairy grama, and buffalo grass. Taller grasses include little bluestem and needle-and-thread grass. Woody vegetation is rare, except on the cottonwood floodplains.

In mixed-grass steppe, additional species include green needlegrass, sand dropseed, slender wheatgrass, galleta, and purple three-awn. There are numerous species of forbs throughout the region. Match weed or broomweed, scurf-pea, sunflowers, goldenrods, and ragweed occur from Oklahoma into Canada.

The eastern and western boundaries of this region continually shift with changes in precipitation. A series of dry years results in an increased dominance of short grasses (better adapted to a dry climate), moving the region's boundaries to the east. Westward shifts occur after periods of relatively high precipitation, which favor the taller grasses.

Soils.--The soils of the mixed-grass steppe are primarily Mollisols. There are smaller areas of Entisols, such as the sandhills of Nebraska, and one small area of Vertisols. Most soils have dark upper horizons.

Fauna.--Bison once grazed the western margin of the mixed-grass steppe. Pronghorn antelope and coyotes are still present. Jackrabbits are numerous on the steppe, and cottontails are present where there are streams and cover. Burrowing rodents include ground squirrels, prairie dogs, pocket gophers, and many smaller species. Burrowing predators include the badger and the blackfooted ferret, now classified as an endangered species. The northern portion of this region is an important breeding area for migrating waterfowl. Mourning doves have become abundant in shelterbelt plantings. The sharp-tailed grouse, greater prairie chicken, and bobwhite are present in fair numbers; but the northern greater prairie chicken is classified as threatened.