Historic environmental issues of cropland habitat differ from those related to other habitat types. Cropland is the only habitat that occupies more acreage in Illinois today than it did 150 years ago. In fact, outside of small agricultural fields and plots developed by Illinois' Native Americans, cropland was non-existent 250 years ago. While loss of habitat creage isn't a problem for wildlife using cropland like it is for species dependent on wetlands, woodlands, and Grasslands changes have occurred in cropping systems since the 1960s that have negatively affected wildlife. These changes are significant because they have occurred over a very large land base. Three changes are especially important:

Table 6.1  "Selected Wildlife That Use Cropland Environments"

Types of Crops Grown

From the early days of Illinois agriculture until the middle part of the 20th century, a broad mixture of crops was grown. Fields were frequently rotated, from hay, to corn, to small grains such as wheat and oats, and back to hay again. Both temporary and permanent pastures also formed part of the cropland mosaic. These early agricultural practices actually increased numbers of some species, such as prairie chickens, loggerhead shrikes, and Bobwhite quail.

This crop rotation and mixture of uses created habitat diversity on the landscape. The increased habitat variety in turn resulted in a diverse food chain base-insects, spiders and other invertebrates, rodents, reptiles, and amphibians-and ultimately provided for a variety of other wildlife, such as birds and larger mammals. The seasonal changes in the crops also provided cover that was disturbed at varying intervals, giving many wildlife species a better chance of nesting, raising young, and finding undisturbed habitat nearby when a particular site was tilled or harvested.

Today, two-thirds of our croplands grow only corn and soybeans. Neither crop can offer the diversity of wildlife cover provided by hay, pasture, and small grains. Hay and pasture, in particular, once provided a partial substitute for the millions of acres of native prairie that were lost. Corn and soybeans simply can't furnish the same type of habitat.

The hay-field crops grown in Illinois today also differ from those of the late 1800s and early to mid-1900s. Much of the hay produced now is alfalfa rather than the clover-grass mixtures of earlier days. Like corn and soybeans, alfalfa as a single plant provides for a less-diverse insect community. Crops grown as monocultures also provide less variety of post-harvest waste grain and seeds for wildlife consumption. In addition, many permanent pastures have been converted to monotypic tall fescue that is too dense for most wildlife to use.

Intensity of Cropping

Though cultivated acreage increased steadily in Illinois after the invention of the steel moldboard plow in 1837, it has been only since the 1960s that the intensity and scope of agricultural land use-for example, "fencerow-to-fencerow" farming-have increased dramatically. This change has occurred as a result of several interrelated factors.

Machinery has gotten much larger, faster, and more efficient in recent decades. As a result, farmers can plant, harvest, and till more acres of row crops in less time. Another important factor has been federal agricultural policies. which have encouraged farmers to increase feed-grain output. As a result, more acres of pasture, hay, and small grains have been converted to row crops along with shrubby fencerows, odd grassy areas, and hedgerows, making field sizes much larger, with little or no edge or interspersed habitat.

These changes have reduced the overall amount and quality of habitat for wildlife that once thrived along the edges of crop fields or traveled between the croplands, Grasslands woodlands, and wetlands. Also, "wet spots," the ephemeral wetlands, continue to be drained in agricultural fields, further reducing the potential value of cropland to wildlife.

Management of Agricultural Lands

The primary management practices that can influence cropland's value to wildlife are tillage, pesticide application, and mowing. Conservation tillage is now widely used on Illinois croplands. The residue from previous years' crops remains on the surface and provides significant habitat to many wildlife species throughout the year. And a food source is provided for many animals when the postharvest waste grain is not turned under in the fall. Crop stubble also distributes snow more evenly in the winter, preventing heavy accumulation of snow in protective wildlife cover such as fencerows, grassed waterways, drainage-ditch banks, and terraces.

However, millions of acres of Illinois cropland continue to be tilled more extensively than is needed for optimum crop production. Besides eliminating valuable food and cover for wildlife, extensive tillage often causes off-site damage to wildlife habitat. It promotes soil erosion and causes sedimentation and pollution in aquatic habitats.

Integrated pest management strategies are being used over more acres, which may help reduce pesticide use over the long term. However, many pesticides are much more potent, and the use of pesticides still warrants concern. Rodenticides and insecticides have caused the most significant negative impacts to wildlife, and as a result they are now highly regulated. Many cases of poisoning have occurred in a variety of species, from eagles, songbirds, and game birds to various mammals, as an indirect result of pesticide application. Eggshell thinning in raptors, caused by the now-banned DDT, is a classic example.

As predators higher in the food chain consume dead or dying invertebrates or vertebrates targeted in a pesticide application, the pesticide may be passed on to the animal eating the poisoned bug or rodent. Immediate toxic effects may result, or there may be a delayed result from the cumulative effect of eating numerous poisoned prey.

Insecticide application also reduces the overall number of insects, reducing the food base for many wildlife species. A general insecticide application can also negatively impact crop fields themselves, because many insects that are beneficial (because they consume harmful insects or act as pollinators) are destroyed in the process. While some of the most persistent insecticides, like DDT, have been banned in the U.S. inappropriate use of approved products still impacts wildlife.

Herbicides used to control grasses or broadleaf weeds are not targeted to destroy insects, spiders, or vertebrate animals, but they may injure or eliminate some species. And eliminating all weeds destroys host plants for many beneficial insects. Destroying all weeds also removes potential food sources (seeds) and possible nesting sites for some wildlife species.

Mowing in waterways, terraces, odd areas, field borders, roadsides, or crop fields reduces wildlife abundance, especially if done during nesting season. Keeping these areas visually tidy requires early and frequent mowing. Nesting cover, foraging cover, and often incubating adults, nests, and young themselves are destroyed when mowing is done during prime nesting and brooding season (April 1 to August 1). Conversely, late-season mowing (after September 15) destroys important winter cover and food for many species. Too much unnecessary mowing has hurt wildlife.

Some species have actually increased in the last 40 years in response to the growth in Illinois' row-crop acreage. Apparently they are less affected by cropping systems, pesticide use, mowing, and tillage practices. Among these are red-winged blackbirds, killdeers, and horned larks. But the great majority of Illinois native wildlife species have decreased as a result of agriculture's intensification and mechanization.

While most agricultural land in Illinois will never return to prairie, forest, or wetland, moderating some of the more recent changes in agricultural land management to address wildlife and other environmental considerations is essential to our wildlife's future. Even small changes, when adopted on large cropland acreages, can have a positive impact on the future of Illinois wildlife and can provide improved environmental health for humans.