Week of 04/01/2007

Dear EarthTalk: I have heard that wind power turbines kill a lot of birds, including migrating flocks, and that some people oppose wind power for that reason. If this is true, to what degree do they harm birds and what is being done about it?

—Ken Lassman, Lawrence, KS

It is ironic that non-polluting, renewable wind energy, long touted as a potential savior in the fight to stop global warming, is getting a bad rap for killing wildlife. High profile examples such as at California’s Altamont Pass—where outdated, oversized wind turbines kill some 1,000 birds of prey each year—plague the growing wind power industry; even though more modern, better-sited wind farms kill far fewer birds.

According to a 2002 study of anthropogenic (human-caused) bird mortality conducted by researcher Wallace Erickson, birds face daily threats far more lethal than wind turbines. Erickson’s study found that between 500 million and one billion birds are killed annually in the United States alone from collisions with man-made structures including communications towers, buildings and windows, and contact with power lines. Hunting, cat predation, pesticides, commercial fishing operations, oils spills and cars and trucks also take a heavy toll. All this is important to realize, say wind power advocates, in putting the relative impact of windmills on bird populations in perspective: Contact with wind turbines represented less that one percent of the total number of human-caused bird deaths in Erickson’s study.

There are, however, steps that can be taken when constructing wind power turbines to minimize their impact on birds. The American Bird Conservancy (ABC) advises that lighting on turbines should be minimized, tension wires and lattice supports should be avoided, and wind turbine power lines should be placed underground whenever possible. Also, already more modern wind towers are being designed in ways that prevent birds from perching on them (solving one of the problems with the Altamont Pass towers)—and the turbine blades rotate much more slowly than earlier designs.

In addition, says ABC, careful reviews of potential wind turbine sites should be conducted. Known bird migration pathways, areas where birds are highly concentrated, and landscapes known for their popularity with birds should be avoided "unless mortality risk has been analyzed and the likelihood of significant mortality has been ruled out." Wind farms should be situated on already disturbed land, such as in agricultural areas, so as not to displace existing bird habitat or travel corridors. Sites should also be reviewed for use by birds listed under the Endangered Species Act.

Ever-growing concerns about global warming and pollution from fossil fuel use demand that we move as quickly as possible toward clean, renewable energy sources, even if they are as yet imperfect. "When you look at a wind turbine," says John Flicker, president of the National Audubon Society, the world’s pre-eminent bird advocacy organization, "you can find the bird carcasses and count them. With a coal-fired power plant, you can’t count the carcasses, but it’s going to kill a lot more birds." Indeed, according to Erickson, for every 10,000 birds killed by human activities, less than one death is caused by a wind turbine. And if greenhouse gases are not reduced significantly in the next decade, we could bear witness to a large number of plant and animal extinctions in the coming years.

CONTACTS: American Bird Conservancy; American Wind Energy Association; National Audubon Society

Dear EarthTalk: What kinds of cat litters are kinder to the environment: traditional clay litters (so-called clumping litters) or other varieties? What about some of the new alternatives, such as those made out of wheat and corn?

—Stef Gandolfi, Oakland, CA

Traditional clay-based clumping cat litters are the most common and widely sold in supermarkets and pet supply stores. Clay litters do not biodegrade and instead pile up in landfills, producing chemicals that can potentially harm human health. According to the International Agency for Research on Cancer, clay litters also produce dusts that contain silicon particles, which are known human carcinogens. In addition, the clay used for litter is obtained through strip-mining, a practice that causing adverse environmental effects on surrounding soil, water and air.

Some pet owners have reported respiratory and other health problems in their cats due to both the inhalation and ingestion of clumping clay litters. Once inside the lungs or digestive tracts, the litter can expand from moisture and cause irritation and blockages. In the lungs this can lead to infection, and in the intestines dehydration and a decrease in nutrient absorption can result. Scientific studies and documented cases of such incidents seem to be in short supply, however, and such claims seem to only be anecdotal.

To be safe, however, there are a number of environmentally friendly alternatives that are deemed safer for people and cats alike. Recycled newspaper, for one, can be used to create cat litter in pellet form. It is biodegradable, flushable, burnable and 99 percent dust-free. It also has the advantage of not getting tracked around the house, unlike clay litters. Fibre Cycle, a company with the primary mission of finding innovative and environmentally friendly uses for recycled paper, sells such paper-based cat litter and claims it to be highly absorbent, biodegradable, long lasting, lightweight and virtually dust-free.

Plant-based litters are made from materials such as corn, corncobs, cornhusks, wheat by-products, wheat grass and beet pulp. According to Worldwise, a leading manufacturer of environmentally responsible pet products, plain ground corncobs are a good choice because they are made of natural, flushable biodegradable materials, have no odor, are very absorbent and don’t produce the same kind or volume of dust as clay litters.

Litters made from pine and cedar saw dusts offer yet another clay-based alternative. As with the plant-based offerings, they are made from natural scrap materials that biodegrade. They also eliminate odor naturally—due to the innate ability of both pine and cedar to absorb and neutralize ammonia—rather than cover up odors with chemicals and perfumes. Feline Pine, from Florida-based Nature’s Earth Products, is a wood litter made from 100 percent natural pine that has been heated and pressurized to remove any harmful wood oils. When ready for changing, the biodegradable litter—available in both clumping and pellet varieties—can be simply emptied into the backyard compost or mulching pile. One caution about pine, though: Some cats have a sensitivity to pine aroma and as a result could shun the litter box altogether.

CONTACTS: Fibre Cycle; Feline Pine; Worldwise