PHILADELPHIA -- Every summer, Julie Crowe's back patio becomes overrun with stray cats. They climb on her barbecue grill, feast on her garden and leave a putrid stench that forces her to keep the windows of her home shut.

No amount of eggshells, chili peppers or bleach keeps the felines out of her trash bins. Just last week, she discovered a litter of six kittens and a momma cat living off of leftovers.

“I got an estimate to try to enclose the patio, and it's $3,000,” said Crowe, “I don’t have it and shouldn’t have to pay it to enjoy my own backyard.”

Philadelphia’s feral cat population has long been an issue. But in recent years, the number of stray cats roaming the streets has exploded, with hundreds of colonies clustered in vacant lots, abandoned buildings or neighborhood yards.

Philadelphia is now home to nearly half a million stray or feral cats. And residents say they have had it.

"An unmanageable situation," said Alley Cagnazzi, coordinator of the city's Animal Care and Control Team, or ACCT, who said her department alone cannot handle the uptick of feral cats.

As cities across the country began a kinder, gentler approach to the feral cat problem -- the felines years ago were immediately euthanized but many places now spay them – some places began seeing a growing litter of stray cats. Shelters in Philadelphia are crammed with feral cats and, because adoption is not an option, the untamed animals mostly roamed free.

"Every single shelter in the city would be overflowing, there is literally not enough space," said Cagnazzi.

But now cities like Philly have turned to neighborhood “volunteers” to serve on the front lines of the war to control the feral cat problem.

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Honorary soldier Jean Van Sciver, or neighborhood "cat-mom," responded quickly to the city's call for help. Van Sciver, who unexpectedly died after her interview with Fox News, said she had taken care of a few hundred cats over the last few years.

Every evening after work, she would set out paper plates loaded with wet and dry kibble, and watch from her window as the cats tip-toed into her yard to eat. She pointed out each of “her” cats have a clipped left ear indicating it had been spayed or neutered. Van Sciver had trapped them herself and, once fixed, she treated them as quasi-pets.

"I'm not going to see them starve," she said, “They live here, they are just [my] outside cats.”

Colony caretakers, like Van Sciver, are community volunteers who help trap strays and get them fixed. In Philadelphia, this is a free service provided by ACCT, which will then return the cats to their neighborhoods or colony caretakers in a process known as "trap, neuter, release," or TNR.

Though the program’s impact isn’t crystal clear, some believe it can make a difference.

Benefits of TNR

“There are a lot of misconceptions surrounding TNR and, in order for community volunteers to be successful, education and support are key,” said Karen O'Rourke, president of Stray Cat Relief Fund, or SCRF, a volunteer-run, non-profit providing shelter, and medication to the felines.

According to the Humane Society, for decades feral cats were not much of a municipality concern. Animal control officers would round up strays only after a complaint, a practice that typically ended in euthanasia. The problem with that system, O’Rourke said, is that too many colonies were going uncontrolled, and cats that were taken off the street were swiftly replaced. Females can have litters every 63 days.

Nationally, the TNR program has been adopted by more than a dozen states, including California, where recent wildfires exposed hundreds of strays, and in cities like Chicago, where it is credited with reducing the feral cat population.

The most famous test case for TNR came in Newburyport, Mass., a tourist town where hundreds of stray cats hung out along the waterfront, dining on Dumpster scraps. Volunteers set out humane traps, and eventually managed to get every cat sterilized.

The population steadily dropped, and in 2009, reportedly the last feral waterfront cat died at the age of 16. Cats only live about five years after being spayed.

Cats versus wildlife

However, some have objected to program, saying outdoor cats are a menace to birds and other wildlife. They claim the effort to be more compassionate to wild cats has come at a steep price.

A 2012 study co-authored by Peter Marra, the chief of the Smithsonian’s migratory bird center, found that an estimated 2.4 billion birds and 12.3 billion small mammals in the U.S. are killed annually by free-roaming cats.

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In Philadephia, the city’s parks department has not taken an official stance. In a recent interview with Philadelphia’s WHYY, city officials said their main objective is not the welfare of feral cats, but to maintain safe and accessible park spaces for city residents.

The city posted an article on its website written by environmental planner Tony Croasdale that said the kitties are not as innocent as they look.

“These outside cats will kill hundreds to thousands of wild prey in their lifetime,” the article said. "While it is understandable that some people have a strong emotional attachment towards outside cats since cats are such a popular pet, many other people feel similarly towards wildlife.”

Making progress

More than 60,000 feral cats were sterilized through the Philadelphia's TNR program in 2017. Though the city is still overrun by cats, some say the practice appears to be working.

"Boots on the ground," said Kelsey Lauder, a volunteer with the Stray Cat Relief Fund. "It's going to take neighbors in their back alleys working together before we see any significant change."

Lauder said her organization is getting the friendly kittens off the street and putting them into homes, and the neutering and spaying efforts are reducing the population.

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O’Rourke said sterilizing even a single feral cat can make a huge difference in controlling the overall population, and can even improve a cat's behavior.

“Fixed and vaccinated cats are healthier,” said O’Rourke. “They are also less aggressive so no more fighting, howling and spraying. And ultimately one more fixed cat means one less litter of kittens.”