Welcome to Subirdia by John M. Marzluff, Yale University Press, 303 pages
Bird lovers may need a lift after reading the National Audubon Society’s recent report that climate change could drive 50 species from New Mexico by 2050. A new book written by ornithologist John M. Marzluff and beautifully illustrated by his University of Washington colleague Jack Delap offers a small measure of comfort.
While rising temperatures and the associated consequences threaten the most fragile avian populations, other birds are evolving physically and socially in response to the stresses of industrialization, disease, urbanization, harassment, noise, light, traffic, and pollution. This is especially true in “subirdia,” the suburban greenbelts that Marzluff, a professor of wildlife science, calls “compact microcosms of the plant world.” Where different habitats meet, as they do in the wildlife-urban interface, birds enjoy more diversity in their diets and housing, and their populations are larger and healthier. But this is true only where the human touch is more creative than destructive.
The lawns, gardens, trees, and variable landscapes of subirdia attract a mélange of the hardiest birds — adapters and exploiters, as they’re known to scientists. The “fab five” of the latter group — Canada geese, rock pigeons, house sparrows, European starlings, and mallards — occupy most of the world’s large cities and need no assistance to survive, Marzluff writes. Adapters benefit when we modify the environment — homes, neighborhoods, parks, and cities — to nurture birds, amphibians, and other creatures that are symbiotic with our species. Avoiders, though, exist only in specific habitats, many of which are disappearing. The sage grouse needs vast tracts of its namesake shrubbery, just as the wood thrush thrives only in mature deciduous forests with leafy understories. These birds, among many others, are ill-equipped by biology or habit to find workable alternatives or develop complex coping behaviors. Saving these birds from extinction requires that people act with deliberation.
Marzluff proposes 10 ways in which people can enrich communities for birds and other wildlife. He frames them as commandments. Two of them, “Do not covet your neighbor’s lawn” and “Do not light the night sky,” dovetail with local efforts to reduce water use on non-native lawns and with New Mexico’s Night Sky Protection Act. Admonishments to “keep your cat indoors” and “make your windows more visible to birds that fly near them” address two of the most significant ways to avoid bird mortality. Marzluff encourages people to provide food and nest boxes and design variability in lawns and landscapes. We can coexist with native predators, such as bears and mountain lions, by building barriers around homes and outbuildings and doing less to lead large carnivores into temptation, such as not leaving food and garbage outside.
Other guidelines require collective political action, with communities building bridges or underpasses for animals where highways intersect with migration paths and reserving undisturbed corridors that link land and water. By following these commandments, urban and suburban dwellers can recover from “environmental amnesia” — an alienation from the natural world that encourages apathy about its neglect, mismanagement, and devaluation.
The rewards of reconnection are enormous — and measurable. According to an economic analysis by the U.S. Fish and Wildlife Service released in 2009, birds are the foundation of a multibillion-dollar tourism industry in the United States alone. Besides enticing people outdoors to admire them, birds scavenge roadkill, disperse seeds, aid in pollination, and help us monitor the planet’s health. They feed on insects that spread disease, destroy buildings, and devastate crops. Any many of them sing like opera divas.
“As the birds of a forest adjust to human settlement, the entire community is reshuffled,” Marzluff writes. “The changing abundance of one species may ripple through the full web of life. The web is refashioned, as new strings are added and old ones are diminished or reconnected into a new architecture.” The pace of evolution is explosive among birds and other animals that live close to human settlements. Birds are morphing into new species within a few generations, and the evolution is cultural, not just physical. City birds, for example, raise their voices to be heard over traffic and other urban and suburban noise and lower their pitch on weekends and holidays. They rise earlier than their country cousins and stay up later to accommodate rush-hour racket.
The measured optimism of this book is based on exhaustive research and fieldwork, including the banding and monitoring of thousands of birds. “The life we create does not replace what we have destroyed,” Marzluff writes, “but … all destructive forces in nature have a creative side; fires create unique ecosystems and diversify forest structure, earthquakes create lakes, volcanic eruptions enrich the soil. Urbanization too has the ability to create biological diversity.
“Nature is fragile, but it does not always break when bent: sometimes it evolves. Evolution is not something that happens only in the abstract eons of geological time. It is happening right now, in your own backyards. You are a force, as potent as the glaciers of the last ice age, shaping your feathered neighbors.”
— Sandy Nelson