An estimated 50 million feral cats live in colonies across the United States. Here, three cats near a feeding station run by volunteers in Atlantic City, photographed last year. Vernon Ogrodnek/AP

The calls and emails come in at all hours. "Last night, I received an email from a distraught person whose neighbor trapped her outdoor cat and took it somewhere," said Barb Wehmann, the president of Scoop, Inc, a Cincinnati, Ohio-based nonprofit devoted to rescuing and spaying or neutering feral cats. "She suspects he killed it.'' The woman with the missing cat had called police, but the neighbor said he had trapped a raccoon, denying he had touched the cat. So Wehmann urged her to contact the county animal shelter, which would be required to start an investigation. Not exactly equipped to reason with a gun-toting neighbor, Wehmann couldn't do much else. Now 54 and retired from her posts as a school psychologist and an adjunct instructor at the University of Cincinnati, she started Scoop almost a dozen years ago with her husband, Ed Lentz, 66, a psychology professor at UC. The United States is overrun with feral cats, many of them living in colonies. The Humane Society pegs the number of feral cats at 50 million. And across the country, a patchwork of advocates like Wehmann are working to find innovative and humane solutions to reduce the feral cat population. Wehmann and her husband estimate they spend at least $25,000 of their own money every year on the feral cat cause. It’s the couple’s passion, she said, adding: “It’s a way to give to the community and help with a societal problem that affects us all, whether cat lovers or not. It feels good to be part of a compassionate solution, even though we’re a small part.”

Cute, but also dangerous

So what real danger do the cats present? Unlike the burgeoning deer population, cats don't cause wrecks. They're also cute and keep the mice away. But feral cats leave feces in gardens and use patio furniture as a scratching post, and stories abound in local newspapers of residents, frequently in trailer parks and apartment complexes, complaining about the smell of cat urine and being awakened by screeching cat fights. In particular, birdwatchers consider the outdoor cat their nemesis; earlier this year, the scientific journal, Nature Communications backed up their concerns, stating that as many as 3.7 billion birds across the continental U.S. are killed by feral cats. About the same time, the scientific journal Zoonoses and Public Health published a report suggesting that cat colonies could become a breeding ground for rabies. "I think everybody agrees, we'd like to see fewer cats outdoors," said Aimee Gilbreath, executive director of the Found Animals Foundation, a nonprofit animal welfare organization in Los Angeles. "The challenge is finding the resources to solve the problem." In that spirit, Found Animals Foundation is holding a competition in which they will award $25 million to the individual or organization that creates a single, safe, non-surgical method of sterilizing cats and dogs. "We have 25 groups that have received grant funding," Gilbreath said. "Unfortunately, medical research takes time. They're still working in test tubes and not close to having a product finished." Still, she hopes that within 10 years, something might be developed.

Putting cats to work

Elsewhere, nonprofits are doing what they can — such as rat population control programs. "We have a total of 177 working cats in nearly 50 urban, suburban and rural locations," said Jenny Schlueter, spokesperson for The Tree House Humane Society, a Chicago nonprofit that primarily rescues and rehabilitates sick and injured stray cats. "We've received overwhelming positive reports about the number of rats being reduced quickly and substantially," Schlueter said, adding that they ask the caretakers to make a lifetime commitment to the cats. Few other cities have adopted the cats-killing-rats practice, although it has been attempted in scattered communities. Disneyland, the resort in Anaheim, California, is well known for managing a cat colony to keep the rat population down. In Wehmann's corner of the country, she said that she sees a lot of progress. She cites the Cincinnati Pet Food Pantry, which provides pet food to cat colony caregivers and qualifying low-income pet owners. "With the help of pet food during a family's rough times, fewer animals are relinquished or abandoned," Wehmann said.

Life is rough for a feral cat and that’s what draws so many advocates to their cause.

Feral cats recovering from being neutered or spayed at the Great Plains SPCS in Merriam, Kan., earlier this year Shane Keyster/Kansas City Star/MCT/Landov She also said that some clinics utilize transport vans "to pick up cats from people so that cats can be spayed and neutered. Transportation is a problem in some of the low income places." She mentions that the Neuter Scooter -- an organization servicing five states so far -- will travel to large cat colonies and spay and neuter on the premises. People who feed feral cats, especially colonies, often need financial assistance. "In Indiana, if you feed the animal, it's legally yours, but the general population doesn't know that," said Cathy Alinovi, a veterinarian in the community of Pine Village. In other words, you're legally obligated to spay or neuter your stray. "Fortunately," Alinovi said, "there are TNR programs to help with the cost." TNR stands for trap, neuter and release, and Wehmann's nonprofit, among other services, raises money for vouchers to be given to those unable to pay to have a cat spayed or neutered.

A human problem