Dear EarthTalk: What"s the big environmental controversy over feral cats?
—Johanna Berg, Brooklyn, NY
According to the U.S. Census, Americans own more than 60 million domestic cats. But analysts estimate that another 40-60 million formerly pet cats and their offspring roam free. These so-called wild or "feral" cats are blamed for wreaking havoc on already stressed populations of songbirds and other small animals.
While roaming domestic cats also hunt birds and small mammals, their feral cousins—since they are beyond the control of human owners—take the brunt of the blame for the decimation of threatened species such as Least Terns, Piping Plovers and Loggerhead Shrikes.
Cat advocates, however, say the real problem is not feline but human. "Cats are not the primary culprit in dwindling bird populations," says Becky Robinson, co-founder of the Washington, DC-based Alley Cat Allies (ACA). "The Worldwatch Institute and other environmental research groups verify that the decline in bird and other wildlife populations is directly linked to the loss of natural habitat," she says. "Urban sprawl, deforestation, shopping malls, roads and golf courses, and increases in pesticide use and pollution are to blame. We need to put constraints on our own behavior, not the normal processes of nature."
ACA cites a number of scientific studies on feral cat diets which indicate that their impacts on bird populations are negligible. These studies conclude that cats are rodent specialists. Birds comprise only a small portion of their diets, and cats can prey on birds on large land masses without destroying their populations. Cats are opportunistic feeders, and live mainly by scavenging and on handouts from humans.
Feral cats are also blamed for transmitting new diseases to wild animals, and this is probably a legitimate charge. Cats have spread feline leukemia to mountain lions and may have recently infected the endangered Florida Panther with feline panleukopenia (feline distemper) as well as an immune deficiency disease. Some cats also carry diseases that can transmit to humans, including toxoplasmosis and rabies.
Despite these issues, ACA endorses sterilization and long-term management of feral cat colonies, as opposed to removal and extermination programs which they deem ineffective, costly to taxpayers and wasteful of scarce animal protection resources.
Regardless of one"s personal beliefs about feral cats, individuals can play an important role in keeping cats off the "most-wanted" list. Most veterinarians recommend neutering pet cats, and keeping them well fed and indoors as much as possible to limit unwanted reproduction, predation and the spread of disease.
Perhaps most important, people shouldn’t release unwanted cats into the wild. According to the Colorado-based Cat Care Society, this practice enlarges feral cat populations and is inhumane. Cats suffer in unfamiliar settings, even if they are good hunters. Contact local animal adoption organizations and agencies for help if you need to give up a pet cat.
Dear EarthTalk: I’ve been told that automobile air conditioners are bad for the environment. Exactly why and what part of the air conditioner is bad?
—Susan Vogel, Somerville, NJ
The harmful effects of automobile air conditioners can be directly attributed to leaking of CFC R-12, one of a number of cooling ingredients patented by DuPont and popularly known as Freon. In December 1995, the U.S. banned the manufacture of this ozone-depleting chlorofluorocarbon (CFC) in order to adhere to standards set by the Montreal Protocol, an international treaty phasing out the production of such chemicals. But existing stockpiles of the gas—and pre-1994 autos that still use it—could keep its toxic legacy around for years.
The cooling ingredient HFC134A, also known as tetrafluoroethane, has since replaced CFC R-12 as the main cooling ingredient in car air conditioners. But while HFC134A does not contribute to ozone depletion and is a more eco-friendly choice than R-12, it is a gas that contributes to global warming. In fact, because of this, the European Union has slated a phase-out of HFC134A to begin in 2011 and be completed by 2017, despite the fact that alternatives are still only in experimental phases of development.
Owners of pre-1994 automobiles can spend a few hundred dollars to modify their air conditioners to use HFC134A, though the Environmental Protection Agency (EPA) cautions that not all systems designed for R-12 work as well using HFC134A and recommends such conversions only on cars made after 1980.
When air conditioners in cars that use CFC R-12 are being refilled or repaired, federal regulations require that the service shops recycle the refrigerant instead of releasing it into the air. Regulations also require that the refrigerant be removed from vehicles that are scrapped or have been abandoned. The refrigerant is then filtered so that it can be reused.
If the refrigerant in your vehicle"s air conditioning system needs to be replenished, always have a professional do it. You can damage your system if you improperly change it yourself, and only certified mechanics can legally purchase refill cans of CFC R-12. Additionally, if your air conditioning system is leaking refrigerant, have it repaired—don’t just refill it. This will both protect the environment and save you money in the long run.
There are other environmental considerations with auto air-conditioners, such as energy use. In an attempt to reduce the amount of energy car air conditioners use, Toyota has created a lightweight compressor—the heart of the air-conditioner—that consumes 60 percent less fuel.
Of course, the most environmentally sound and cheapest way to cool your car is to open your windows and let in the fresh air. According to the National Safety Council"s Safety and Health Policy Center, driving without using the car"s air conditioning increases fuel efficiency by about 2.5 miles per gallon.
CONTACTS: EPA Motor Vehicle Air Conditioning, www.epa.gov/ozone/title6/609; Toyota Air Conditioning Compressor, www.toyota-industries.com/environment/product/compressor.html; National Safety Council"s Safety and Health Policy Center, www.nsc.org/ehc.htm .