And then there were none:disappearing tigers, toads and pollywogs
|ast fall I visited Monteverde in Costa Rica, a "bird and beast paradise," according to my guidebook, and home to the golden toad, which is found nowhere else in the world. I never saw a golden toad. Neither has anyone else, since 1988. At the same time, reports were surfacing about mysterious disappearances of amphibians from places where they once thrived, including many areas of the United States. In the general crash of species worldwide, there's a tendency to feel more alarmed about the shrinking of tropical rainforests than about habitats in the United States, including our own backyards. I realized that it is time to look out for domestic species, as well.|
Some things you can do ...
(The following can also be adapted into excellent science projects to do with children):
Buy organic and local food, rather than imported. Choose diversity in your food. According to Kenny Ausubel, author of Seeds of Change (Harper Collins, 1994, $18), only nine food plants account for 3/4 of the human diet.
Grow an organic garden based on nurturing, not chemical control. Plant groundcover such as ivy or jasmine to prevent soil erosion. Add plants that attract pollinators to your garden. Send the Brooklyn Botanic a SASE and request a free-to-Green Guide readers "Pollinators List" of plants, by region and season, Attn: Publications Dept., Brooklyn Botanic Gardens, 1000 Washington Ave., Brooklyn, NY 11225.
Set up a bat house (bats are also pollinators). Contact Bat Conservation International, (512) 327-9721.
Take a child birdwatching, wherever you live. Urban Roosts: Where Birds Nest in the City, by Barbara Bash (Sierra Club/Little Brown, $5.95) shows how finches, sparrows, peregrines and owls find homes on skyscraper ledges, in traffic lights, and more.
Choose certified wood and wood products. Contact the SmartWood Program of the Rainforest Alliance, (212) 677-1899, or the Good Wood Alliance, (802) 862-4448.
Do your part, not only to tread lightly on the earth, but also to help check the expansion of new treaders by supporting population control.
More than 500 of our domestic species already may have disappeared forever, and about one-third of U.S. plant and animal species are threatened, according to a 1997 report by the Nature Conservancy with the Natural Heritage Network. Globally, according to the Species Survival Commission of the World Conservation Union ("The Red List of Threatened Animals," October, 1996), nearly a quarter of all known species of mammals and 11 percent of all known bird species are threatened. The unknown is vast. Only about 13 percent of the total number of species on earth have been scientifically described, reports the United Nations Environment Program's (UNEP) November 1995 Global Biodiversity Assessment. And while we should fight against the disappearance of the world's last wild tigers, reduced from 100,000 strong at the turn of the century to 3,000 to 5,000 now, we should not overlook the passing of the humble toad.
According to the Declining Amphibian Populations Task Force (DAPTF), amphibians provide an early warning about deteriorating environments. The largest breeding population of the flatlands salamander, native to the U.S. Southeast, has virtually disappeared. Strange deformities grotesquely misshapen limbs, smaller-than-normal sex organs, missing eyes have been reported in frogs across Minnesota. The Houston toad is on the brink of extinction due to habitat loss.
In the United States, amphibians, shellfish and fish "that depend on freshwater habitats... are in the worst condition overall," the Nature Conservancy reports. Amphibians, DAPTF says, are particularly vulnerable to environmental degradation because of their permeable skin, and because they rely on both land and water for survival.
"If we cannot act as responsible stewards in our own backyards, the long-term prospects for biological diversity in the rest of this planet are grim indeed," laments Dennis Murphy, senior research scientist at the Center for Conservation Biology at Stanford University, in the National Academy of Sciences (NAS) 1986 report "Biodiversity." Biological diversity, or biodiversity, is the variety of life on earth, including ecosystems and species.
The loss of biodiversity is "the most fundamental issue" for the environment, according to Thomas Lovejoy, Ph.D., of the Smithsonian Institute. A University of Minnesota study of native prairie plants, published this year, has shown, for the first time, that a greater number of species improves the productivity of an ecosystem.
The planet's most remote life forms have been affected. "The amazing finding, in the past year, is that even birds whose homes are in the middle of the ocean, such as the albatross, have been contaminated by organochlorine chemicals," says Pete Myers, Ph.D., director of the W. Alton Jones Foundation and coauthor of Our Stolen Future (Plume/Penquin, 1997), which chronicles the adverse effects of hormone-disrupting and carcinogenic chemicals, such as PCBs, DDT and dioxins, upon wildlife. Our lifestyle is what is fueling the destruction, but we can change that. As David Quammen writes in The Song of the Dodo (Scribner's, 1996), "The number of children you produce, the number of miles you drive... all have their impacts on... the cohesiveness of ecosystems." Preserving habitat is crucial. The conversion of open space to residential and commercial developments disrupts biodiversity, whose "...single greatest threat... is the destruction of natural habitats and their conversion to other uses," Dennis Murphy writes.
... and some things to avoid
Coral and ivory jewelry.
Shoes by Adidas, Browning, Florscheim, and Puma, which use skins from threatened Australian kangaroos for leather, according to the International Wildlife Coalition.
Mitsubishi cars, Nikon cameras, Texaco gas, and Georgia-Pacific wood. These companies contribute to rainforest destruction, according to the Rainforest Action Network, (415) 398-4404. Write the above companies and tell them why you boycott their products.
Pesticides (that includes herbicides) in your home and garden.
Groups that oppose habitat destruction
Southwest Center for Biological Diversity, PO Box 710, Tucson AZ 85702
Sierra Club, San Diego, (619) 299-1741, 3820 Ray St., San Diego CA 92104
The Nature Conservancy, (703) 841-5300
Ducks Unlimited, Inc., (901) 758-3825
The Forgotten Pollinators Campaign, 2021 N. Kinney Rd., Tucson, AZ 85743
International Wildlife Coalition, (508) 548-8328
Wetlands: These forested swamps, marshes, bogs, and prairie potholes provide habitat for about one-half of the fish, one-third of the birds, one-fourth of the plants, and one-sixth of the mammals on the U.S. threatened and endangered species lists. About half of the estimated 220 million acres of wetlands that existed in Pre-Columbian America have been lost to crop production and, increasingly, to residential and commercial development. In Los Angeles, Steven Spielberg's planned 1,000-acre "Dreamworks" studio would destroy one of the area's last wetlands.
Forests: According to "Last Frontier Forests: Ecosystems and Economies on the Edge," a report released by World Resources Institute (WRI) on March 4, 1997, only 20 percent of the world's major virgin forests remain. WRI reports that the United States only has 1 percent of its original forest cover left. That includes Alaska's Tongass National Forest, home to threatened species like the Sitka black-tailed deer and its predator, the Alexander Archipelago wolf, and the Hawaiian rainforests, which contain indigenous species found nowhere else on earth.
Northern and Neotropical habitats are linked by species like migratory songbirds, who live in both. In 1996, researchers from Hawk Mountain Sanctuary in Pennsylvania, Tufts University, and the U.S. Fish and Wildlife Service discovered a possible connection between pesticide use, in Latin America and the United States, and migratory populations of U.S. sharp-shinned hawks. The hawks' blood samples contained a number of chemicals, including DDE (the metabolite of DDT) and chlorinated hydrocarbons. The study theorizes that the hawks' exposure came through eating songbirds migrating from Latin American countries. (Pesticides like DDT persist for many years.) "The songbirds eat insects that have been sprayed with chemicals. Then the hawks eat the contaminated songbirds," says Len Soucy, Ph.D., of the Raptor Trust in Millington, New Jersey, who has observed a decline in migratory populations of this important indicator species. At the same time, overall breeding populations of hawks in Pennsylvania are increasing "from their pesticide-induced lows earlier in the century," says Keith Dildstein, Ph.D., a researcher at Hawk Mountain. Dr. Dildstein attributes the recovery to "... forest restoration and the banning of DDT (in the U.S.)."
Kids' Book: Where Once There Was a Wood, by Denise Fleming (Holt, 1996, $15.95), a picture book, shows the species that once lived in our backyards, and tells how to make your backyard a better shelter for all kinds of species.
For adults: In Search of Nature, by E. O. Wilson (Island Press, 1996, $19.95), is a collection of short essays about the interrelationship between animals and humans. And, newly out in paperback: Our Stolen Future, by Theo Colborn, Dianne Dumanoski, and John Peterson Myers (Plume/Penguin, 1997, $13.95)
"Soil governs the productivity of plants and, therefore, the sustainability of agriculture, forestry, and natural ecosystems," writes Rita Colwell, president of the University of Maryland's Biotechnology Institute, in the 1997 NAS report, "Biodiversity II." Just a spoonful of healthy soil contains more microorganisms than there are people on earth, including bacteria, fungi, worms, tiny arthropods and millipedes. And recently, a compound from soil bacteria has proven to be exceptionally effective against Kaposi's Sarcoma, a skin cancer afflicting AIDS sufferers.
According to E.O. Wilson, Ph.D., an entomologist at Harvard University considered the world's leading expert on biodiversity, if all the invertebrates (including insects and bacteria) disappeared tomorrow, our own species could last no more than a few months. We depend on their endless work of breaking down and recycling dead plant and animal matter, Wilson writes in In Search of Nature (Island Press, 1996). On the other hand, Wilson says, if humans disappeared tomorrow, the earth would go on with little change.
Our modern agriculture is dependent on just a few crops, but the gene pool of wild and diverse plants is crucial to maintaining our food supply. Wild plants are crossbred with domesticated plants to increase disease and pest resistance, crop yields, and nutritional quality. For example, in the 1970s, genetic material from several wild corn species originating in Mexico were used to stop a blight which had previously wiped out 15 percent of the U.S. corn crop.
The U.S. demand for exotic, out-of-season produce can stimulate pesticide-heavy agriculture in developing countries. Some pesticides "volatilize" says Pete Myers. "That is one reason that our American eagerness to buy tropically grown fruits and vegetables comes back to haunt us. Chemicals used in the tropics evaporate and are carried by air currents to the North, where they are deposited."
In "Biodiversity," Dennis Murphy of Stanford describes this scene from the shores of the San Francisco Bay just 150 years ago: "Jaws, claws, an explosion of spray, and a grizzly emerges from the shallows, a salmon in its grasp. Mixed herds of elk, deer, and pronghorn antelope graze rolling, grassy slopes. A cougar surveys from broken chaparral and woodland above." What will our great-grandchildren see, 150 years from now? The answer depends on us.
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