During their first lab, I used to take the students in my vertebrate zoology class at the University of Puget Sound on a walk in the urban wilds. After we had walked a few blocks, I asked them to tell me why we weren't seeing any wildlife. When someone pointed out that we just saw a squirrel, I tell them that, sadly enough, this most obvious “wild” mammal isn’t native, nor are some of the “wild” birds we had seen.
But the answer is so obvious that eventually I always got the response I wanted: “The habitat is so different from what it was.” They didn’t know the half of it! Not only do we cut down the trees, leaving a few token conifers, but we also wipe out the shrubs and herbs that make up the diverse understory of our forests. Each of those plant species has insects living on it, and all those insects disappear with their host plants. Guess the most important prey for our small wildlife species (amphibians, lizards, many birds and small mammals). That’s right, insects.
Don’t the cultivated plants we plant in the place of those we eliminate attract their own insects? Some of them do, but most aren’t native, and the insects that eat their leaves or pollinate their flowers may not occur here. And if they do appear, the typical response to them is a liberal application of pesticides. But it’s worse—most people favor evergreen plants such as rhododendrons and junipers that produce insect-deterring chemicals in their leaves and are thus relatively pest-free. Most evergreens fall in this category. And yes, I know honey bees aren't native, but they seem important in the pollination of many flowers, as our native bees have declined.
And the final habitat constraint most of us apply is instead of letting a great variety of (admittedly weedy) herbaceous plants become established in our yards, we literally mow ‘em down. If you watch your yard, you’ll see that the rare dandelions that go to seed are immediately attractive to any seed-eating birds in the neighborhood. But how many of us sanction this sacrilegious seed set? However we view them, seeds are the primary diet for many small birds and mammals.
So my answer is “Don’t do as your neighbors do.” If you’re like most of us and don’t live on a ten-acre lot with real habitat, do your best to simulate it. Remember two important food groups, seeds and insects. Plant native trees and shrubs, especially deciduous ones, which are more attractive to insects. Plant native flowers attractive to pollinating butterflies, bees and hummingbirds. Fruits are also important foods for many birds and mammals; plant plenty of fruiting trees and shrubs.
Don’t put any kind of biocides in your yard; save the aphids!
Leave a swatch of lawn unmown. Don’t rake up all the leaves and throw them away each fall; let them stay on at least part of your yard. Several of our wintering birds forage by turning over dead leaves, which shelter seeds from the summer before as well as a multitude of small arthropods and worms. Make a brush pile in one corner of the yard; songbirds love to shelter in it. Add a pond or fountain. You’ll be amazed at the wildlife habitat you’ve made.