Habitat determines where wildlife live, or if they will live at all. Wildlife require some very basic elements for survival, most notably food, water, shelter, and space. These elements are provided by the habitat that is present. Some species have very specific habitat needs, such as cerulean and hooded warblers that require large tracts of mature forest for nesting and protection. Other species, known as generalist species, can make do with a wide range of habitats. Red-winged blackbirds are a prime example: they seem to do quite well in a variety of grasslands, roadsides, and edges of wetlands. As a result, this species is one of the most common birds seen along Illinois highways.

How we humans use and alter the landscape largely influences what and where various species of wildlife live. The changes in Illinois land cover over the last 100 years are shown in this figure prepared by Jeffrey Walk and referenced on page 12 in this issue of The Illinois Steward. As you can see, there have been dramatic drops in the acreages of hay, pasture, and small grains, especially during the last 50 years. Thus, it is no surprise that populations of grassland birds, such as bobolinks and grasshopper sparrows, have taken a precipitous drop.

Traditionally, the early spring planting of oats initiated a crop rotation sequence on a field that provided some grassland habitat for several years (see The Illinois Steward, Fall 2001, page 9). In Illinois, oats were planted in late February and March, then harvested in July. Legumes, such as red clover and alfalfa, and perennial grasses, such as brome and timothy, were planted along with the oats. The rapidly growing oats served as a nurse crop by creating a favorable environment for the slower growing legumes.

These perennial legumes and grasses remained after the oat harvest, grew the following year, and were cut for hay. The field often remained as a hayfield for more than 1 year, with two or three cuttings of hay taken each year. These fields of mixed legumes and grasses were also pastured. The legumes and grasses were then plowed under and served as a “green manure” crop to fertilize the row crops of corn and soybeans that followed. In the 1950s, on most Illinois farms, different fields on each farm were in some stage of this crop rotation. Thus, each farm was providing some continuous grassland habitat as individual fields progressed through various stages of a crop rotation.

While the cutting of oats in July and the first cutting of hay in June of the following year(s) disrupted some nesting of grassland birds, overall, this crop rotation of oats, hay/pasture, corn/soybeans, and back to oats again, provided valuable grassland habitat. And this habitat attracted more than grassland bird species. A variety of insects; small mammals; bird-nest predators, such as snakes, skunks, raccoons, and opossums; and bird predators, such as red foxes and red-tailed hawks, were attracted to these agricultural grasslands.

All of this has changed with the move to growing monocultures of corn and soybeans; with little or no planting of small grains, legumes, and perennial grasses; and with the drastic reduction of raising livestock as an integrated part of livestock–grain farms.

Over the last century, agricultural practices have had far-reaching effects on the landscape. In our quest to provide plentiful food at a reasonable cost to consumers, sometimes unintended consequences have occurred that have affected the nature of Illinois wildlife.

As a Master Naturalist, take stock of the changing landscape in your community, and think about how these changes are influencing wildlife populations.