I’m sitting in my backyard one August morning. Glinting in the summer sun, tiny flies in colors of sapphire, emerald, topaz, and onyx are buzzing around a clump of white-frosted mountain mint; they swoop onto each tiny lavender wreath-like blossom and crawl in a circle over the flowers, extracting nectar as they go. In an adjacent St-Johnswort shrub, a bumblebee buzzes purposefully among the yellow-crowned flowers, vivid orange pollen baskets on its legs indicating it has spent the first hours of the day foraging. A spicebush swallowtail butterfly, having warmed its wings in a nearby patch of sun, rises, and drifts languidly over the scene, surveying the fare du jour. Near my feet, small white blobs like rice grains parade rapidly across the red brick patio – not on their own, but each carried gently within the jaws of an ant: one colony is raiding another for its larvae, to be raised as slave workers for the raiders. A young toad, startled by a sudden movement nearby, hops under the shelter of a ground-hugging barren strawberry plant.

A screen of shrubs divides my seating area from the pole-mounted birdfeeders. Purple finches, titmice, cardinals, chickadees, nuthatches and cardinals take turns launching themselves from within one of two nearby hollies to the feeder perch. Among surrounding stands of purple ironweed, pink swamp milkweed and red cardinal flower, a ruby-throated hummingbird hovers at a blossom, its beating wings a blur; it stabs its long bill into the nectar-rich heart of the flower, sips, and darts to the next. A tiger swallowtail butterfly follows the same route, but compared with the high energy of the hummingbird it seems to be standing still. Farther back in the yard, two Carolina wrens call loudly to each other, hopping in and out of a stone wall covered with Virginia creeper vines; the wrens seem to call “cheeseburger, cheeseburger, chips!” but they are hunting for insects, not patties. A woodpecker drums on a dead tree. Catbirds flit between shadows in the thickets of arrowwood and spicebushes. In a pocket of low grasses, jumpseed, and enchanter’s nightshade, crickets sing in choruses of tinkling bells and stuttering chirps, while meadow katydids click and buzz. A wasp flies by trailing a leaf blade that she will chew up for the makings of her chambered nest.

Everywhere, there are spiders. There are the spined micrathenas and green orb-weavers that sit all day at the hub of a web suspended between plant stems; huge striped argiopes, which wait till sunset to construct their webs; funnel weavers that spin webs along the wall. On plants there are the long-legged harvestmen tucked into leaf shadows, and crab spiders with open pincers poised to strike. On the ground, wolf spiders hide under leaf litter, while dwarf spiders hurry every which way on every square foot of soil.

The sun is moving inexorably across the sky, and as it passes between trees, shadows drift and re-form. Suddenly, a shaft of light pierces the woods. A spider web appears out the darkness, a spiral of spun silk that glimmers like silver. It lasts but a moment, then the light winks out and the web disappears. That shining moment is like a sudden insight: this abundance of life is good… and I helped.

Recently I had my backyard certified as an official “Backyard Wildlife Habitat” by the National Wildlife Federation. The NWF is the “nation’s largest and oldest protector of wildlife,” with over four million members. Founded in 1936 as a sportsmen’s organization devoted to protecting and promoting conservation of habitats for fish and wild game, the NWF’s mission has broadened to conservation of wildlife generally. Ultimately the NWF realized, along with many other similar organizations, that it is not enough to set aside special places like parks, refuges and sanctuaries for wildlife. These places are critical, and their establishment must continue. But so much land has been, and will continue to be, developed for human uses, that only individual land stewardship will save most of the world’s species from extinction.

Wildlife is in crisis. There is mounting evidence that loss of habitat, along with global warming, is sending most of the world’s plants and animals hurtling toward oblivion. “The biological world is approaching the sixth major extinction event in history,” as a recent report in the prestigious journal Science put it. The last great extinction, 65 million years ago – probably caused by one or more asteroid strikes – wiped out the dinosaurs along with 85% of all the other creatures on Earth.

Why care about other species? Does biodiversity really matter? Well, there are scientific reasons why it ought to matter. First, we depend on other life forms for our own existence. We humans are a relatively new species. We evolved within a complex environment of innumerable plants, microorganisms, and animals. These species, simply by going through the daily business of living, support all kinds of natural processes on which our lives depend: producing oxygen that we can breathe, creating food for us to eat, cleaning our air and water, protecting us from harmful cosmic rays … the list of free services goes on. Our knowledge of how all these species and processes work together is getting better all the time, but is far from comprehensive – there are just too many other forms of life for us to understand it all. Once you start removing large numbers of species, all bets are off. It’s like one of those games in which you build a tower out of sticks or blocks, then remove one at a time: at some point the tower will collapse completely and catastrophically. Second, taking the Earth and its systems as a whole, a diverse population of different life forms is much more resilient, that is, can adapt more easily to unexpected events such as the introduction of a new disease or changes in climate. The more variety, the more likely that there will be one or more species that can adapt and survive.

But for me the most important reason is the ceaseless wonder of being alive in the midst of variety. Our society values diversity of opinion, diversity of culture, diversity of religion: diversity of species is just as important for enriching our lives as members of a community of Earth-dwellers. Biodiversity is the Earth’s way of expressing the variety of ways in which life can exist. Would you want to live in a world where there’s one kind of flower? One tree? Or worse, a world where the only insects are mosquitoes? Would you want to listen to an orchestra of one kind of instrument, a choir of one voice singing one note?

Each new backyard wildlife habitat adds another riser on which a section of the Earth’s choir can stand and sing. It’s easy to create a backyard habitat, no matter how small your yard, and no matter where you live. In Bucks County there are 191 certified habitats, according to Catherine Fox of the NWF. My own habitat is within earshot of one of the busiest roads in the county. There are backyard habitats in cities, towns, suburbs and rural areas. You don’t even need a backyard…a front yard will do. You just need to plan a habitat that makes sense for the kinds of wildlife that inhabit your area. The NWF has reams of guidance for anyone wanting to create a backyard wildlife habitat.

There are four elements to habitat: water, food, cover and a place to raise young. If you don’t have a natural water source on your property, or a garden pond, a birdbath is fine. Water is particularly important during the winter, because so many of the natural sources are frozen. I use a simple birdbath heater, a flat coil covered with aluminum; when there’s snow on the ground the birds fall all over themselves to get to the oasis. During the rest of the year, birds frequent my birdbath to drink and also to bathe; they wet their feathers and then sit in the sun: this enables them to cool off and also to rid their feathers of mites and parasites. My birdbath attracts not only birds but also pollinating insects like bees, wasps and flies, all of whom need water as much as the birds. The birdbath is set among low shrubs and trees. This is the all-important “cover” that birds need to feel safe from predators. Other than water, cover is probably the most important thing to add to your habitat, and when you add it, you are also going to be adding food and a place to raise young, if you do it right. For what is called “watchable wildlife” – like most birds and butterflies – the way to add food, cover and a place to raise young is primarily by planting. For birds, plant shrubs and small trees; for butterflies and bees, plant native flowers (trees, shrubs and plants). Another key to your habitat is to minimize or eliminate pesticides. Pesticides are designed to kill insects, and typically they kill many more kinds of insects than you actually think of as “pests.” Insects are indispensable to your habitat. Most crucially, flowering plants need pollinating insects or they will not reproduce. Insects are also a requirement for birds; during the breeding season most birds feed insects to their young. Without caterpillars, spiders, grasshoppers and beetles, the young birds will starve.

The classic four-factor definition of habitat that NWF uses to guide habitat creation is one way to approach creating backyard habitat. But I think an easier way to think about it is as creating a middle. Every backyard site has a bottom: the ground. If you have trees, you have a top. On the other hand, if you live in a brand-new house in the middle of a former cornfield, you may not have a top, so you need to plant trees. Even if they’re small to begin with, they count. Once you have a top layer, what’s in between is the middle. If it’s empty, fill it in: add shrubs and understory trees. Most people who create a backyard habitat want birds there. Birds add constant activity and interest, and even if you’re not a birdwatcher, birds are an easily seen and understood indicator of the health of your habitat. The middle layer is where most birds spend most of their time: feeding on insects, berries and seeds; nesting; hiding from predators; taking shelter from inclement weather. A habitat of trees and lawn has no middle and therefore, will support very few kinds of birds, not to mention other wildlife. Birds are one of the most important creators of habitat, too. They eat berries and other fruits, then drop the seeds, dispersing the fruit-bearing shrubs and trees all around. So once you have a middle layer, it becomes self-perpetuating.

There’s another way to look at creating a middle. From where we humans stand, the ground is the bottom. But to a vole, the ground is the top layer. The soil layers below the top are the middle, and the bottom is the subsoil and bedrock. Those middle layers are where dead things become live: detritus is broken down into smaller and smaller bits by tiny arthropods like millipedes and springtails, as well as by bacteria and fungi; here also, voles, moles and burrowing animals aerate the soil, providing vital oxygen for the roots of plants. These animals also provide another essential service: they disperse spores of fungi (Mycorrhizae) that plant’s roots depend on to enable them to take up nutrients from the soil. Without the middle soil layers the trees, shrubs and flowers will not survive. So creating a backyard habitat means creating healthy soil. Soil is built from the top down. Leave the leaves, remove grass (except where you want a lawn), and lay off the pesticides. And in my habitat, this has meant learning to live with, and appreciate, the voles. Sure, they’ve knocked off a shrub or two by eating or nesting against its roots. But there are many more that they haven’t eaten, while also performing their critical soil conservation service. I love being surprised to see the earth move as they tunnel just beneath the surface; in the winter their tunnels appear as networks of dark lines in the snow, like “Kilroy was here” graffiti. And the voles attract great horned owls to my habitat – too bad for the voles, but the owls keep the population in check while adding their own shadowy nighttime presence to the backyard.

Though the NWF awarded the certification to me, I really shouldn’t take credit for the habitat. I did the planning and the planting, and keeping the habitat healthy requires some maintenance to make sure that invasive plants aren’t taking over. But all the real work is done by nature itself. Habitat is what nature does when we’re not around.

The key word in that certification is not habitat, but backyard habitat. Our backyards are typically havens from the outside world, where we create private outdoors space for playing and relaxing or just enjoying looking out at green space. Creating a backyard habitat enables us to share our havens without giving them up. When I sit in my backyard, I know I’m in the middle of something. There’s a difference between being in the center and being in the middle. A difference between thinking of the world as if humans are in the center, and all revolves around us, and thinking of being in it as being in the middle. It’s like the ubiquitous spiders. Their webs are always in the middle of something. They weave strands between parts of the world and sit suspended in a place of their own creation, yet still connected to the world. The webs are solid enough to support the spiders, yet also open enough the let most of the world pass right through. By creating a backyard wildlife habitat, not just a backyard human habitat, your backyard can be a place to connect your home to the natural world, let wildlife into your life, and ensure that wildlife, as well as humans, will continue to have a home on our planet.
For more information:

Backyard wildlife habitats:
National Wildlife Federation Backyard Habitat Program

The global extinction crisis:
J.A. Thomas, et al, “Comparative losses of British butterflies, birds, and plants and the Global Extinction Crisis,” Science, 19 March 2004, p. 1879-1881.
F.S. Chapin III et al, “Consequences of changing biodiversity,” Nature, 11 May 2000, p. p. 234-242.