WASHINGTON - It's Friday night in Eckington, a quiet residential corner of Washington, and the back alley is crawling with feral cats - rich pickings for seasoned cat-trapper Marty King.
"Here, kitty kitty kitty kitty," said King after setting four metal traps baited with flaked shrimp and fish cat food and lined with fresh newspapers.
"If they're hungry and they haven't seen traps before, they're not hard to catch," she explained.
"But some of them are very smart. There's a female I've been trying to get for a couple of years now and I haven't been able to get her yet."
Within 20 minutes, a young gray cat takes the bait - and by Sunday lands on a veterinary operating table to be spayed or neutered under an ongoing programme to bring Washington's feral cat population under control.
Coast to coast, the Humane Society of the United States estimates there are as many as 50 million feral cats, or "community cats" as their advocates prefer to call them. That compares to 95.6 million cats kept as pets.
For decades, standard procedure has been to round them up and euthanise them, but in recent years the trend has swung towards TNR - trapping, then neutering, then returning cats to the places they were captured.
"Ultimately, our goal is to sterilise all outdoor cats and have them pass on through attrition," Scott Giacoppo, vice president for external affairs at the Washington Humane Society, told AFP.
"So if our plan or our goal happens, there won't be any feral cats."
Bird lovers disagree
Not everyone is convinced. Bird lovers in particular see a proliferation of homeless cats - neutered, sterilized or otherwise - posing a deadly threat to many avian species.
They cite a study from the Smithsonian Conservation Biology Institute and US Fish and Wildlife Service that estimated that "free-ranging domestic cats" kill a median of 2.4 billion birds and 12.3 billion mammals every year.
"Un-owned cats, as opposed to owned pets, cause the majority of this mortality," said the 2013 study, published in the scientific journal Nature, which called TNR "potentially harmful to wildlife populations."
The Centers for Disease Control has meanwhile asserted that "cats are more likely to be reported rabid in the United States" than dogs. Others say feral cats are potential carriers of infection and parasites.