Increasing Biodiversity with Native Plant Wildlife Habitat Gardens
More Habitat Gardening
Of all the many reasons to plant California natives in our gardens - for creating a sense of place, for their beauty and adaptability, for their drought tolerant qualities, and certainly for increasing biodiversity - their ability to help save our ecosystems and the bird and insect species that depend on them is, for me, the single most important reason to grow native plants. Our suburban, urban, and rural gardens are fast becoming a last refuge for many wildlife species, such as songbirds, butterflies, bees, toads, frogs and other beneficial creatures, that have lost habitat due to human development. In some cases, cultivated gardens that offer a rich diversity of native plants may offer more resources, such as foraging opportunities for birds and other wildlife, than surrounding degraded wild lands.
We can no longer rely solely on protected wilderness areas in this country; they are a very small percentage of all available land (not modified for agriculture or converted to urban and suburban development), and they have become isolated islands of habitat that no longer contain enough native plants to sustain wildlife. In his highly regarded book, Bringing Nature Home, Douglas Tallamy gives notice: "Habitat islands can only protect a tiny fraction of the species that once thrived in North America. If we are to succeed in recreating enough biodiversity to sustain at least some of our wildlife species, it will be the widespread planting of native plants." Our native plants, which co-evolved with our local wildlife, provide shelter, nest sites, food and nectar through the seasons. Rufus and Allen’s hummingbirds, for example, time their migration to the bloom periods of native monkey flower as they head north and the California fuchsia as they head south in late summer. Over 300 species of wildlife use our native oak woodlands for food, shelter, and nest sites; over 5,000 insects are part of this web of life, including 7 species of butterflies. Our native milkweeds are not only caterpillar food plants for the Monarch butterfly, they also serve as a nectar source for butterflies and other large insects. They provide seeds for small mammals and birds, seed silk for nesting materials. Ladybird beetles and the larvae of lacewings and other beneficial insects hunt the orange oleander aphids associated with milkweeds. Two species of beetles and two species of true bugs are milkweed specialists.
Tallamy discovered in his own garden and through extensive research that many of our native insects "cannot or will not use alien plants." Why do we need insects? They are the very foundation of all other life. They pollinate our plants, they clean up excess plant debris, they are food for insect predators - other insects, garden spiders, lizards, and other beneficial creatures. They are essential food for our number one insect predator, birds! Many bird species feed primarily on insects, and virtually all bird species need insects to feed their young. "So many animals depend partially or entirely on insect protein for food," Tallamy points out, "that a land without insects is a land without most forms of higher life."
Our individual gardens do make a difference, and if we make the effort collectively throughout neighborhoods and communities, we can achieve even more. Networks of habitat gardens help to recreate corridors between open spaces. Using the closest natural habitat as our guide, whether living on the edge of development or the inner spaces of an urban community, it is possible to support biodiversity. We are blessed with stunning terrain and plant life in this state - from mountain meadows and streams, coastal bluffs and beaches to oak-studded canyons, redwood groves and evergreen forests. Gardening with an eye to this larger landscape, but specifically to the plant communities of our own area (or what were historically present) is where we start.
Restoring neighborhood creeks and other riparian areas, woods and meadows by planting natives is important work. We can make a difference in smaller ways, too. Plant a native tree or shrub in the fall. Look for sunny places to grow drifts of nectar flowers that bloom in different seasons. Grow butterfly host plants that will sustain the next generation of local butterfly species. Plant a native vine, such as California wild grape, that provides fruit. Birds need food: the more trees, shrubs and other native plants you grow that provide berries or other fruit, seeds, nectar - and of course, insects, the more bird species you’ll attract to your garden. A living soil with lots of organic material, mulched with leaves and other plant trimmings from the garden, provides a home for all of the tiny bugs and beetles, crickets, caterpillars, and salamanders that many local birds, and migrants, depend on for food.
My wildlife garden offers me a daily invitation to have a more intimate connection with Nature, whether it is the discovery of butterfly eggs on a host plant or watching the nest-building activities of my resident bird species or the amusing behavior of their fledglings as they learn how to fly and find food. Each year as more native plants are added, the bird and insect life increases. "The plants we grow in our gardens", says Tallamy, "have the critical role of sustaining, directly or indirectly, all of the animals with which we share our living spaces." How well we succeed, he points out, will directly affect the diversity of wildlife that will be able to survive in our cultivated landscapes. Offering food, cover, and water, with an emphasis on native plants, is how we turn our gardens from outdoor decoration into beautiful, healthy mini-ecosystems that support local wildlife and, ultimately, ourselves.
Nancy Bauer is a wildlife habitat gardener and author of The California Wildlife Habitat Garden (UC Press, 2012) and The Habitat Garden Book: Wildlife Landscaping for the San Francisco Bay Region (2001, 2008).She has been teaching and writing about wildlife habitat gardens for over 10 years.