Project 5: Mainstream Consumer Magazine

Redesign

In this project you are challenged to redesign a magazine following the specifications provided in this project sheet. Final design needs to reflect good and sophisticated use of typography and image as it is applied to editorial design. Final product will consist of a printed magazine which is also uploaded as a digital file on issuu.com.establishing a new visual voice for a magazine is a serious undertaking: the design solution represents the magazine’s identity and values in public consciousness. In a masthead design, typography forms the basis of such an identity. The hallmarks of successful typographic branding are simplicity, easy recognition, and memorable form, and, in the case of overall systems such as a magazine, flexibility and ease of use.

APEX PREDATORS ARETAKING IT TO THE TOP

The Case For summer Bird Feeding

CaTering To BuTTerFly royalTy

Inspiring Americans to protect wildlife for our children’s future

NATIONAL WILDLIFE NATIONAL WILDLIFE FEDERATION APRIL/MAY 2013 WWW.NWF.ORG WORLD EDITION

NWF VIEWCan You Image That?

NWF in Action: Protecting Apex Consumers

Healing the Wounded

Confronting the Climate Crisis

Protecting the Nation’s Grasslands

create a haven for beneficial insects

ADVENTURES AFIELD

YOUR HEALTH Fishing Away Stress

CONSERVATIONReturn of the Mighty PygmyACTION REPORTHow national Wildlife Federation is making a differenceFINAL FRAME SPECIAL SECTION

DEPARTMENTS

FEATURE

Columns

CONTENTS

URBAN RENEWAL

April/May/ 2013National

WILDLIFE

WORLD EDITION

SPECIAL SELECTIONTAKING IT TO THE TOP6

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45Published by the National Wildlife Federation Volume 51 Number 3www.nwf.org

CATERING TO BUTTERFLY ROYALTY

THE CASE FOR SUMMER FEEDING

Biologists have long though that ecosystems are shaped fro the bottom of the food web up, but new research suggests big animals at the apex are just as important

By Roger Di Silverstro

By Doreen Cubie

By Laura Tangley

Climate change may disrupt the chemistry of milkweeds that monarchs depend on; gardeners can help the insects.

Along with the food native plants provide, feeders help nurture our feathered friends in warm months.

FRONT COVER: Photograph by Mark Smith BACK COVER: Image by Reuters

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Creating Bird-Friendly Urban Landscapes

Apex Predators are Taking It to the TopLarge animals at the top of food webs may have as much in-fluence shaping ecosystems as those at the bottom

IN THE 1990s, biologist James Estes noticed that something was going wrong with the sea otters he had been studying for the past 20 years along Alaska’s Aleutian

archipelago. After decades of recovery from near extinction brought on by the fur trade, the otters were dwindling again under what proved to be a more natural force. “By 1997, it became clear to me that

orcas were driving the otters down,” Estes says. “They really hammered them.” In some areas, 98 percent of the otters disappeared. Numbers in the Aleutian area fell from more than 100,000 before 1990 to perhaps 3,000 to 5,000 today.

After another 15 years of study Estes, an evolutionary biologist at the University of California–Santa Cruz, believes the sea otter decline is only one link in a series of ecological changes in the archipelago. The starting point was industrial whaling, which in the early 1900s decimated the large whales on which orcas fed in the waters off Alaska’s coast. The killer whales turned to preying on Steller sea lions, which can grow to 2,500 pounds, and caused the sea lion population, perhaps already stressed by climate change and by an intensive commercial fishing industry, to collapse. The orcas then turned to feeding on sea otters, which also may have been debilitated by pollution.

As the sea otters declined, other ecological effects arose: The sea urchins on which the otters fed expanded in number and began eating coastal

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kelp, destroying habitat that supports fish and other animals.

Bald eagles, which fed on fish and sea otter pups, turned to preying on seabirds. Thus the loss of a large species at the top of the food web—whales—disrupted an entire ecosystem. “It’s probably more complicated than that, but that’s probably

what’s at the base of it all,” Estes says.

A New View of Ecosystem Dynamics

His work may be among the harbingers of a shift in how biologists view ecosystems and how conservationists protect

habitat. “In the past, the default paradigm among biologists was that of bottom-up regulation of ecosystems, where the base of vegetation affected everything above,” says Sterling Miller, a bear biologist and NWF senior wildlife biologist. “But within recent decades scientists have increasingly recognized how important top-down effects are in keeping grazers and browsers from damaging the vegetative base of the pyramid and the cascade of smaller species dependent on this base.” Research by Estes and others underscores the need for strong protection of large consumers atop the ecological pyramid to ensure ecosystem health.

Many apex consumers are dwindling, part of a process that began more than 10,000 years ago with the extinction of such megafauna as the mastodon, giant ground sloth and saber-toothed cats and continued through the extirpation or drastic reduction of such species as Steller sea cows, elephant birds, dodos, brown bears, bison, gray wolves, tigers, rhinos and many more. A recent paper published in the journal Science cites this wave of destruction, caused largely by human activity, as “arguably humankind’s most pervasive influence on the natural world. This is true in part because it has occurred globally and in part because extinctions are by their very nature perpetual, whereas most other environmental impacts

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A drastic drop in sea otters around Alaska’s Aleutian islands may have started with the decline of whales cause by commercial whaling. (above)

are potentially reversible on decadal to millennial timescales.”

The Science paper, “Trophic Downgrading of Planet Earth,” was the brainchild of both Estes and John Terborgh of Duke University, who has spent decades studying tropical rainforest ecology. Their research, which suggested that profound changes in ecosystems could come from the top down, led to the formation of a two-and-a-half-day conference about four years ago that produced the paper, a review of ecological research on large apex consumers written by Estes, Terborgh and 21 other scientists. “What’s important to me is the impact of the paper and its ideas,” Estes says. “Can we use it to influence people’s conceptions about ecosystems and what we do about them?”

The Wolf ConnectionLike Estes’ sea otter studies,

wolf research in Yellowstone National Park underscores the importance of apex consumers to ecological integrity. After control efforts wiped out park wolves in the 1920s, elk numbers rose, and the elk browsed areas they would have avoided if threatened by wolves. The result: reduced new growth of aspens on some mountainsides and of willows along streams.

When wolves were reintroduced to Yellowstone in 1995 and 1996, a reduction

in elk numbers began to show positive effects on tree and shrub growth, says William Ripple, director of Oregon State University’s Trophic Cascades Program and a coauthor of the Science report who has studied wolf, elk and plant dynamics in Yellowstone since the 1990s. In some areas, aspen and willow are growing taller and filling in the plant community, though not at all sites Ripple has studied. “Restoration takes time,” he says. “We’re only 17 years after wolf reintroduction, and we were 70 years without wolves. We need more time to see how Yellowstone unfolds.” Regrowth of willows along streams will shade and cool the water, reduce bank erosion and benefit many species that use such habitat, including

songbirds and even beavers, which function as ecological engineers by reconfiguring

streams.The role of wolves in

Yellowstone is not unique. In a paper published in 2011 in Geomorphology, Ripple and his Oregon State University colleague Robert Beschta point out that loss of mountain lions in Utah’s Zion National Park led to an overabundance of deer and that destruction of wolves in Washington’s Olympic National Park allowed elk to explode, in both cases affecting the growth of trees along streams and increasing factors such as erosion.

Apex Consumer Ripple EffectsLoss of apex consumers

can even affect the occurrence of some diseases. The spread of Lyme disease, which can be

deadly to humans, requires the presence of ticks, deer and deer mice, but, according to

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The monkeys favor sources of human food, increasing contact with people and leading to higher rates of intestinal aliments among both primate species. (above)

research published last year by Taal Levi of the Cary Institute of Ecosystem Studies and his colleagues, the ailment also is strongly linked with the extirpation of wolves in the East, which allowed coyotes to move in. Unlike wolves, coyotes kill mouse-eating foxes, which helps deer mouse populations to increase and the disease to spread.

Predators are not the only apex consumers driving changes in ecosystems. In one of the stranger tales from this field of research, a population of deer drove a population of black bears to extinction on 3,000-square-mile Anticosti Island at the mouth of the St. Lawrence River. At one time the forested island, punctuated with peat bogs, probably was home to only half a dozen species of land mammal, including the river otter, pine marten and two bat species. Only two, the deer mouse and black bear, ate plants.

In the 1890s a landowner

introduced about 200 white-tailed deer to Anticosti as part of a plan to turn the island into a paradise for hunters. In the absence of efficient predators, the deer rocketed to 50,000 individuals within a few decades, noshing away shrubs that produced a key bear food: berries. Because the island’s forests lacked nuts and seeds and its waters offered few salmon, local bears had to pack away about a third of their body weight daily in berries to make it through winter. As the deer wiped out the shrubs, the berries disappeared, and so did the bears. Researcher Steeve Côté of the Department of Biology at Quebec’s Laval University reported the extinction in the journal Conservation Biology in 2005, crediting his paper as “the only documentation of a large herbivore extirpating a successful and abundant carnivore from a large ecosystem.”

In the Science paper, Estes

and his colleagues proposed that “many of the ecological surprises that have confronted society over past centuries—pandemics, population collapses of species we value and eruptions of those we do not, major shifts in ecosystem states, and losses of diverse ecosystem services—were caused or facilitated by [changes in apex consumers].” Examples:

• Destruction of sharks in recent years along the U.S. Atlantic coast allowed cow-nosed rays to stage a population explosion; heavy feeding by the rays later caused a collapse in bay scallop fisheries.

• In East Africa, the introduction in the 1800s of rinderpest, a viral disease that infects a variety of hoofed animals, decimated populations of such browsers as wildebeest and buffalo, resulting in more woody vegetation, which in turn increased the extent and frequency of wildfires. In the 1960s, game and livestock managers eradicated rinderpest. As large ungulates recovered in the early 1980s, woody vegetation declined, grasslands returned and the frequency of wildfire fell off across the region.

• Industrial whaling in the 20th century resulted in the loss of large numbers of plankton-consuming great whales, which are now known to sequester carbon in the deep sea when

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Deposing the King of beasts , declines in lions and leopards have allowed populations of the olive baboon to grow. (below)

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they die and sink, rotting at the ocean bottom. The decline in whales resulted in the transfer of approximately 105 million tons of carbon into the atmosphere, contributing to climate change.

• The reduction of lions and leopards in parts of Africa has led to population outbreaks of olive baboons, which are drawn into increased contact with people by the monkeys’ attraction to sources of human food. The interaction is causing higher rates of intestinal parasites in both people and baboons.

The authors of the Science article reasoned that the critical role of apex consumers in ecosystem integrity must be included in conservation plans “if there is to be any real hope of understanding and managing the workings of nature.” This conclusion bears profound implications for conservation. “The science is showing that the large predators at the top of the food web are important to the function of ecosystems,” Ripple says. “In short, conserve the large predators so the natural interactions can take place.”

Deposing the King of BeastsA study released last

December reported that lions are rapidly declining across Africa because human population growth and land development have reduced the cats’ habitat by 75 percent. Published in Biodiversity and Conservation, the paper indicated that only 67 regions remain in Africa where significant lion populations can survive, but only about 15 of the sites are home to at least 500 of the big cats. Lions may number fewer than 32,000 animals continent wide.

How this decline will affect African ecology is hinted at in the effect that lion and leopard reductions have had on olive baboons. But, says Luke Hunter, president of Panthera, an organization devoted to wild feline protection, evidence suggests more far-reaching effects. In South Africa, for example, where wildlife is restricted mostly to parks and other protected areas, herds of large ungulates can destroy grassland habitat if lions are absent. The big predators keep zebras, wildebeest and other prey on the move, helping to foster more biologically diverse grassland-woodland mosaics.

“Without lions and other top carnivores preventing ungulate populations from localizing, you end up with a golf course that easily collapses ecologically,” Hunter says.

Removing lions from native habitat sets in motion a cascade of ecological changes. “The interactions are so complex, but once you pull the string, it starts unraveling,” Hunter says. For example, he speculates that vultures, already dwindling across Africa from eating the carcasses of livestock treated with an antibiotic toxic to the scavengers, are likely to face even worse inroads as the loss of lions cuts into their primary source of food, the remains of large prey killed by the cats.

But, Hunter says, the relationship of a large predator to other species “is so complicated that the lion decline isn’t universally detrimental.” Lions and spotted hyenas can suppress cheetah populations that share their habitat. In some African nations lions survive only within protected areas like parks, so cheetahs are increasing outside parks. As lions decline, cheetahs have an edge in rebounding.

NWF in Action: Protecting Apex ConsumersNWF has worked for decades to protect large species such as the grizzly bear, bighorn sheep and Florida panther. The Federation played a lead role in returning wolves to Yellowstone National Park in the 1990s, and last year, working with the Assiniboine and Sioux tribes, helped obtain more than 60 purebred Yellowstone bison for release on the Fort Peck Reservation in eastern Montana. During the past decade, NWF has used a market-based approach to retire more than 500,000 acres of livestock grazing rights on federally administered lands in the Greater Yellowstone Ecosystem to safeguard habitat for native wildlife. See nwf.org/restoringbison.

Catering to Butterfly RoyaltyClimate change may disrupt the chemistry of milkweeds; gardeners can help monarchs by planting more of these critical host plants03-11-2013 // Doreen Cubie

LIKE MANY COLORFUL SONGBIRDS that have wintered in the Tropics, monarch butterflies are returning to backyards across much of the country after migrating hundreds or thousands of miles from coastal California (monarchs that spend summer west of the Rocky Mountains) or central Mexico (those that summer east of the Rockies). One key to the success of

these widespread and beloved butterflies is the species’ special relationship with milkweed plants.

As most wildlife gardeners know, monarchs lay their eggs only on milkweeds. The caterpillars hatch, eat the leaves and, in the process, ingest cardenolides, powerful toxins found in milkweed sap. The poison does not harm

caterpillars but makes them and later adult butterflies unpalatable to potential predators, a critical defense mechanism. Several studies have shown that monarchs with high levels of cardenolides are less likely to be preyed upon by birds.

A few years ago, Stanford University ecologist Rachel Vannette began investigating

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monarch butterflies are returning to backyards across much of the country. (above)

whether climate change might disrupt the age-old association between milkweed and monarch. Then a graduate student at the University of Michigan, Vannette and her advisor, Mark Hunter, studied five different genetic families of common milkweed. (Milkweed plants, even those of the same species, vary genetically and can be grouped into families, or genotypes.) They grew the plants in open-air chambers, exposing them to elevated amounts of carbon dioxide designed to mimic Earth’s atmosphere in the future. Although most of the plants grew slightly larger, the composition of plant leaves changed dramatically. “Most of the milkweed families decreased their production of toxins,” Vannette says, some by as much as 50 percent. Milkweed leaves also became tougher when exposed to extra carbon dioxide. “Caterpillars would have a harder time chewing the leaves,” she says.

Milkweeds for MonarchsThough Vannette and other

scientists remain uncertain what these findings might mean for monarchs in the future, “we speculate that it won’t be good,” she says. And while there isn’t much an individual can do about the potential problem, there is a simple way to help today’s monarchs: You can grow more milkweeds in your garden.

“There is a milkweed for

every situation,” says John Schneider, who owns Wildtype Design, Native Plants and Seed, Ltd., a nursery in Mason, Michigan. Of the slightly more than 100 species native to North America, here are five that are commercially available and easy to grow. All are perennials indigenous to the eastern two-thirds of North America, except for showy milkweed, found from the central states west to California and Oregon. All five are also deer and rabbit resistant and support a variety of other insects, including several species that, like monarchs, depend on milkweed for survival.

• Whorled milkweed usually tops out at 2 feet tall. “It prefers really dry and sandy soils,” says Schneider. The white flowers, which appear between July and September, also entice native bees.

• Butterflyweed has orange flat-topped flowers that attract many other butterflies in addition to monarchs, including tiger, spicebush and pipevine swallowtails. “This is a much-beloved ornamental plant, and it grows well either in the garden or a naturalized area,” says Schneider.

• Common milkweed has purplish flowers that bloom from early to mid-summer. The plant can be aggressive, so should be planted with caution.

• Swamp milkweed prefers wet conditions in the wild but also does fine in average garden soil, according to Rose Franklin, the owner of a perennial nursery in Pennsylvania and author of Fast Track Butterfly Gardening. Franklin says this species is a favorite of egg-laying female monarchs.

• Showy milkweed is a long-lived plant with 3-inch-wide clusters of pink, star-shaped flowers. It thrives in most western habitats except deserts

MONARCH CATERPILLARS(Right) eat only milkweeds, which provide toxins that make both larvae and adults unpalatable to predators.

Frequent contributor DOREEN CUBIE groups several native milkweeds on her 1.8-acre Certified Wildlife Habitat site in Awendaw, South Carolina.

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The Case for Summer Bird FeedingFeeders help nurture our feathered friends during the warm months while providing hours of bird-watching pleasure03-11-2013 // Laura Tangley

“Some of my greatest backyard bird-watching moments have been in summer, when parent birds brought their fledglings to introduce them to my feeders and baths,” says Wisconsin naturalist George H. Harrison, the author of seven books about backyard birding. “I’ve seen fuzzy, rotund

baby chickadees, red-capped downy woodpecker young and spot-breasted American robin chicks, many begging for food from overworked parents.” Summer is also the time to spot species not present during winter and to admire the birds’ colorful breeding plumage.

Rose-breasted grosbeaks in the East and black-headed grosbeaks in the West, for example, migrate to the Tropics in winter but are active at feeders in the United States during summer. Many hummingbird and oriole species—also missing from northern regions in winter—

SHOULD YOU TAKE BIRD FEEDERS DOWN for the summer? Conventional wisdom may say the only times of year to put out food for birds are fall and winter, when natural foods seem scarce. But feathered creatures will visit feeders all year long, and summer can be the most rewarding time of all to watch them.

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flock to sugar-water feeders across North America during the warmer months. Other seasonal regulars include bluebirds, American robins and some buntings and sparrows.

For the majority of these and other species, the natural food sources they find in your yard are the most important foods of all. “Feeders should be seen only as supplements to the natural habitat you provide by cultivating native plants,” says NWF Naturalist David Mizejewski.

During the breeding season, most birds nurture themselves and their offspring with insects—often only particular kinds of insects that eat only particular native plants. Chickadees and warblers, for instance, rely on caterpillars for 90 percent of their diet during spring and summer. University of Delaware entomologist

Doug Tallamy has found that the number and diversity of caterpillars and other herbivorous insects decline when nonnative plants displace natives, posing potential threats to some of your favorite backyard birds.

Don’t forget to provide water during the warm months. On hot, dry days, birdbaths, pools and ponds will lure a wide variety of summer-only birds for a dip, which is essential for maintaining healthy feathers. Indigo and lazuli buntings, gray catbirds, brown thrashers, red-eyed vireos and red-winged blackbirds are just a handful of likely bathers that may be hundreds or thousands of miles away later in the year.

Keeping birdbaths and feeders clean is particularly important in summer. Be sure to change the baths and other standing water daily to keep it

fresh and to prevent mosquito larvae from hatching. Switch to all-weather suet during hot weather so it won’t melt or spoil, and place suet feeders in the shade. Check all feeders regularly, and throw out any wet or moldy birdseed. Change the nectar in hummingbird feeders at least every three days.

Following these few simple rules should be a small price to pay for the pleasures summer feeding can provide. “Perhaps the greatest advantage of summer bird feeding is that warmer temperatures encourage up-close and personal viewing,” Harrison says. “If you have a patio or deck near the feeders or baths, birds will become accustomed to your presence and will eat and bathe only a few feet away while you enjoy the calls and songs masked during winter by windows and walls. In my experience,” he adds, “there is no better way to enjoy a summer day.”

UPDATE: Since this article was published, a reader pointed out that in areas where black bears are common, it may not be a good idea to leave feeders up during summer. See our article "When Carnivores Come Calling" to learn more about coexisting peacefully with predators.

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Creating Bird-Friendly Urban Landscapes

FEATURE ARTICLE

By helping birds, residents of cities and suburbs can contribute to con-03-11-2013 // Laura Tangley

Bird CityOrioles are far from the only

birds getting ready to breed in Baltimore. According to a long-term survey sponsored by the National Science Foundation (NSF), more than six dozen avian species nest and rear their young within this major metropolitan area—from common backyard denizens like blue jays, chickadees and

American goldfinches (left) to elusive warblers and wood thrushes to shore-loving herons, gulls and cormorants. Scientists conducting the ongoing survey tally birds in a handful of the city’s parks, but have recorded the majority of species and individual birds in the places where Baltimore’s human residents live and work.

“Traditionally, people tended to view metro areas like Baltimore as biological deserts,” says John Kostyack, NWF’s vice president for wildlife conservation. “But it turns out that many of us live where the wild things are.” Home to 82 percent of the nation’s population, cities and suburbs in the United States house two-thirds of all North

IT'S SPRINGTIME, and the Baltimore Orioles are coming back to Baltimore. While baseball fans gear up for their team’s first game in early April, birders and other nature lovers are looking forward to the real deal: arrival, by the end of the month, of Maryland’s strikingly beautiful state bird. After wintering thousands of miles south in Mexico or Central America, Baltimore orioles will soon show up in parks and backyards not only in Baltimore but across the eastern and central part of the country, where they breed and rear their young during summer.

Because orioles nest and forage for insects, fruit and nectar primarily in the canopy of deciduous trees, “they are more often heard than seen,” says Peter Marra, a research scientist at the Smithsonian Migratory Bird Center in Washington, D.C. “Yet the birds are relatively common in urban areas.” Marra encounters orioles regularly in his own leafy suburban yard about an hour south of Baltimore. “It’s a real treat to spot a long-distance migrant that might have been flying over a jaguar a few weeks earlier,” he says.

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American wildlife species, including many imperiled plants and animals. According to the report Endangered By Sprawl, published by NWF, Smart Growth America and NatureServe in 2005, the country’s 35 fastest-growing large metropolitan areas (those with populations of 1 million or more) are home to 1,200 rare or endangered wildlife species, 553 of which live only in large metro areas. A coauthor of the report, Kostyack has witnessed a subtle shift in perspective among his conservation colleagues since the document was published. Though sprawling development still is considered a major threat to native wildlife, he says “there’s also a recognition that people in developed areas have enormous opportunities to protect biodiversity where they live.”

As an increasing share of the world’s growing population moves to cities and suburbs that gobble up what’s left of natural areas, conserving urban biodiversity has never been more important. “If you look at an aerial photo of the United States at night, it’s clear that the urban-suburban matrix has overtaken more than half the nation’s territory,” says University of Delaware entomologist Doug Tallamy, author of Bringing Nature Home: How You Can Sustain Wildlife with Native Plants. Moreover, activities within urban areas—including water use, wastewater treatment

and the cultivation of invasive, nonnative plants—affect wildlife far beyond city boundaries. “There’s simply no way we can conserve the biodiversity needed to sustain ourselves and all life on Earth if we ignore urban areas,” Tallamy says.

Barriers to Green Development

The good news is that many policymakers, urban planners and homeowners are beginning to agree. “There’s been growing interest in green development in recent years,” says Mark Hostetler, a wildlife ecologist at the University of Florida–Gainesville. “More people also want to see wildlife in their yards. Conserving urban biodiversity fits both of these goals.” Unfortunately, many green developments fall short of meeting their objectives. “The potential is there, but developers spend most of their time on design and too little time on construction and post-construction phases of projects,” says Hostetler, author of The Green Leap: A Primer for Conserving Biodiversity in Subdivision Development.

Another challenge is a shortage of scientific research on the needs of urban wildlife. Like conservationists, many biologists have treated cities and suburbs as lost causes unworthy of their attention. Part of a larger NSF-sponsored project called the Baltimore Ecosystem Study (BES), the Baltimore bird survey is a

notable exception. Launched in 1997, BES and a similar project in Phoenix, Arizona, represent the first in-depth, long-term studies of what the foundation calls “human-dominated ecosystems.”

Birds of BaltimoreFor the bird survey, dozens

of researchers have spent the past eight summers monitoring avian abundance and diversity at 132 census points scattered around the metro area. Surveyors visit and tally birds at each point three times during the breeding season. So far, they have recorded 80 species that regularly reproduce in Baltimore (including the red-bellied woodpecker, above)—more than half the breeding bird species found within the region.

“Our next step is to work out why we find different species where we do,” says BES principal investigator and bird survey director Charles Nilon of the University of Missouri–Columbia. To do that, Nilon and his students have been recording and analyzing a variety of data about the census points—including land use, vegetation cover and socioeconomic variables such as income, education and ethnicity—at three scales: the property, block and neighborhood that surrounds each point. “The number one predictor of high diversity and abundance we’ve found is vegetation cover, particularly tree cover,” Nilon says.

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Need for Native PlantsThough Nilon and his colleagues record the

numbers and types of plants at each location—trees, shrubs and vines, for example—they do not take note of species, including whether plants are native to the region. Such data should be incorporated as the study moves forward, says Tallamy. “Most biologists assume that when it comes to bird habitat, if it’s green, it’s good,” he says. “But that’s not true.” Tallamy argues that when nonnative plants replace natives, as they often do in urban areas, this affects entire food webs by reducing plant-eating insects—the most important food for animals ranging from other insects and spiders to reptiles and amphibians to mammals and birds. “Birds do not reproduce on berries and seeds; 96 percent of terrestrial birds rear their young on insects,” he says (male northern cardinal feeds its mate a beetle larva, below).

Because native insects did not evolve with nonnative plants, most lack the ability to overcome the plants’ chemical defenses so cannot eat them. In the Mid-Atlantic region, for example, Tallamy says native oaks provide food for 534 caterpillar species while gingko—a popular nonnative street tree—supports just one. Birds such as chickadees and warblers rely specifically on caterpillars for 90 percent of their diet during the breeding season.

In a large, multiyear study published in Ecosphere, Tallamy and several colleagues compared the number of caterpillars found in Delaware and Pennsylvania gardens dominated by native plants with the number found in gardens containing more nonnatives. Depending on how closely related exotics were to natives, the researchers discovered a 50 to 75 percent decrease in caterpillar abundance and diversity in the nonnative plots. “That’s a lot less bird food,” Tallamy notes.

Another study, published in Conservation Biology, demonstrates the connection between native plants, caterpillars and birds. When the scientists surveyed six pairs of properties in suburban Pennsylvania—each including one yard landscaped primarily with native plants and

the other with a mixture of natives and exotics—they found more caterpillars and birds in the native-only yards. The native-plant properties nurtured more individual birds as well as more species, including eight times more species of regional conservation concern.

Helping Urban BirdsIn the suburbs of Baltimore and Washington,

D.C., Marra is making similar observations. For the past 13 years, he has run the Smithsonian’s Neighborhood Nestwatch program, a citizen-science project with more than 250 families helping researchers band and track the life spans and reproductive success of eight common backyard birds, including northern cardinals, gray catbirds, American robins and house wrens. Based on the results, Marra concludes: “The three most important things homeowners can do to help birds are eliminate pesticides and free-roaming domestic cats and add native plants.”

By helping birds, homeowners also will be helping other wildlife. “Birds are good ecological indicators,” Tallamy says. “If you have a diverse native bird population, it’s a sign that the ecosystem as a whole is healthy.”

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