Gardening for wildlife

Image credit: Bruce Leander, Wildflower Center

As wilderness disappears and the human-dominated landscape expands, butterflies, songbirds, and other creatures are left without places to live. Douglas Tallamy, University of Delaware entomologist and author of Bringing Nature Home, has pointed out that we have already turned 54 percent of the lower 48 states into cities and suburbs and 41 percent more into various forms of agriculture. In other words, we humans have already taken 95 percent of the original native habitat.  New development continue to eat up 2 million acres of quality wildlife habitat each year—an amount equal to the size of Yellowstone National Park.  Natural habitats are damaged further by invasive plants that commonly spread from our residential gardens and by the overuse of fertilizers and pesticides that pollute streams and water sources.

The good news is that residential landscapes can be home for both humans and wildlife.  We can share our landscapes with the plants and animals with which we humans have co-evolved.  The first step when gardening for wildlife is to determine the priority species.  Then identify the food, water, shelter, and other resources each animal requires.  Here are the essentials:

Food

The best food source is often a diverse selection of native plants.  For the vast majority of native wildlife, most of the non-native plants we’ve favored in our landscapes for more than a century do not provide sufficient food.  That includes the insects on which 96 percent of all terrestrial birds depend. But when you plant native trees, shrubs, and herbaceous plants, you provide wildlife with the nectar, pollen, fruits, leaves, seeds, and nuts—and associated insects—that have nourished them for millennia. Space is limited in the typical home garden, so it makes sense to plant the natives that are the champions at providing food and shelter for birds and other wildlife.

bird bath surrounded by Echinacea and Gregg's mist flower. Image credit: Bruce Leander.

Water

Like all living things, wildlife needs water for drinking as well as bathing and cooling off.  Water can be a scarce commodity in arid areas and in cities. Nature provides water to wildlife in a multitude of ways that the homeowner can replicate such as a shallow in-ground pool or pond, water barrel, or birdbath.

Places to hide, rest and nest

Native trees, shrubs, thickets, grasses, brush piles, and man-made wildlife houses serve as home and shelter.  For birds, all trees and shrubs provide cover, but none are better than evergreens, especially conifers. And the seeds in their cones are an important source of food for some species. As with other plants for wildlife, regionally native pines and other conifers are best, since they are more likely to host the native insects upon which birds depend.

Homeowners should avoid the use of pesticides, which can harm birds and other wildlife directly or contaminate the flowers or vegetation that are their food source.  To provide maximum habitat for the widest array of wildlife, it helps to recreate the vertical layers of vegetation – trees, shrubs, flowers, and grasses – found in nearby natural areas.

All native plant communities consist of vertical layers, which are most obvious in forested regions. The tallest layer of a forest is called the canopy and is composed of mature trees. The highest canopy trees may be 100 feet or more, while the lowest grow to about 30 feet. The next layer down is called the understory. It is composed of saplings of canopy tree species as well as smaller flowering trees such as dogwoods and redbud. The understory layer rises from about 12 to 30 feet above the ground. The shrub layer is the lowest layer of woody vegetation. It occupies the area between 3 and 12 feet. The lowest aboveground layer of a forest, below 3 feet, is called the ground layer. Here, wildflowers, ferns, grasses, and sedges grow in often spectacular combinations. Plants in the ground layer also partition their environment vertically. Spring ephemeral wildflowers bloom first, typically raising their foliage only a few inches above the leaf litter. As they go dormant, taller ferns and wildflowers overtop them.

Vertical layers of a woodland and prairie. Image credit: Landscape for Life

Prairies and other communities dominated by herbaceous plants also have distinct vertical layers. The earliest plants to emerge in spring are low to the ground. Each successive emerging plant overtops the next, culminating with the tallest grasses and late-blooming asters and other composites that end the growing season. The layers also extend below the ground, from fibrous-rooted grasses to wildflowers with deep taproots.

In general, the more vertical layers there are, the more complex the vegetative structure and therefore the more habitat created for a wider array of animal life.