A shelter in the Mission Hills area of Los Angeles houses one of the city’s half-dozen neonatal kitten nurseries, all of which have sprung up in recent years as part of an ambitious bid to lower euthanasia rates at six municipal facilities. Part of keeping the kittens alive is bottle feeding the newborns.

LOS ANGELES — They are brought into shelters in crates, boxes and flower pots at this time of the year: Tiny, mewing kittens with eyes barely open, with pink, toothless mouths — and usually with no mother to nurse them.

And here’s what it takes to keep them alive: people to hand-feed formula through a syringe or tiny bottle every two to three hours around the clock, until the newborns are 4 weeks old. Most shelters do not have the resources to do this, so kittens younger than 8 weeks — the earliest age of adoption — are typically euthanized.

Not so at a stucco-sided facility on the north side of Los Angeles. Sophia Lim, one of its many volunteers, knows the routine. Hands clad in blue surgical gloves on a spring afternoon, she gingerly weighs a 4-week-old beige kitten named Osbourne on a small tabletop scale, then places him belly-down on her chest and holds a travel shampoo-sized bottle to his lips. A few minutes later, she moves on to one of the other 81 unweaned kittens who needed to eat.

“Sometimes I can’t believe how many kittens come in here,” said Lim, a nurse who regularly drives 33 miles from her home to help keep baby cats alive.

The shelter in the Mission Hills area houses one of this city’s half-dozen neonatal kitten nurseries, all of which have sprung up in recent years as part of an ambitious bid to lower euthanasia rates at six municipal facilities. Before the effort began, in 2012, about 57 percent of animals left the shelters alive; that percentage, or “live save rate,” is now in the mid-80s. And the goal is to reach 90 percent by year’s end, which would make this the nation’s largest “no-kill” city – where only very ill or dangerous animals are put down.

The cat problem is not unique to Los Angeles, of course. Although shelter euthanasia rates are falling nationwide, felines, many of them young, still make up nearly 60 percent of animals killed, according to the American Society for the Prevention of Cruelty to Animals. Experts say that is partly because many cats are feral or “semi-owned” by people who feed but do not necessarily sterilize them, nor do they search at shelters when they go missing.

Yet while cats can be harder to place, one demographic is a clear exception — those between 8 weeks and about 5 months of age. So despite the incredible manpower kitten nurseries require, the idea is gaining traction among shelter experts, and operations are now found incities including Austin and New York.

“It was clear that one of the best ways to raise our live save rate was to save these bottle babies,” said Brenda Barnette, the general manager of Los Angeles Animal Services.

Millions of strays roam the streets of this sprawling city, where sunshine makes outdoor living easier and the breeding season longer. In 2011, city shelters killed nearly 7,300 kittens, or about 8 of every 10 admitted.

The number of kittens euthanized was down to 2,642 last year, in part because of the nursery where Lin volunteers. It is in a public facility managed by the Utah-based Best Friends Animal Society, which partnered with the city to lead the no-kill campaign, and it pulls unweaned kittens from shelters across Los Angeles.

“If you invest in this population, you will see a return, because people want kittens,” said Matt Bershadker, the president and chief executive of the ASPCA, which runs the New York City nursery. “There’s an outlook for these animals.”

The Mission Hills nursery is just one quiet section of a fairly large facility, but the patients need little space. The tiniest — which on this day included 2-week-old siblings named Leroy, Lucas, Lacy and Loraine — snooze on blankets spread over heating pads in rectangular fish tanks, cuddling up to stuffed animals that stand in for missing mothers.

Older litters are in cages, and there are generally a few adult females lounging with their kittens in a “mommy and me” room.

The staff took in 23 kittens in January but 646 in May. Things will get more crowded daily for the next several months as more cats breed – a time of year people in the animal-shelter world sometimes call “kitten mountain,” in reference to the bell curve of intake between spring and late fall. And by December, the annual count is expected to surpass a record 3,000. Some 2,600 kittens came through in 2016.

Helping keep them fed is a volunteer corps of about 80, who work two-hour shifts weighing kittens, taking notes on their eating habits and mixing gruel for those more than a month or so old.

“This is really a triage center,” said Marc Peralta, executive director of Best Friends’ Los Angeles office. The organization spends about $6 million a year on the nursery and other programs to lower the city’s euthanasia rates.

Several hundred “fosters” also care for unweaned kittens at home. Lim, who was in the midst of a week off from work last month, said she had two of those kittens at her house. She’d fed them at 1 a.m. and again four hours later.

“So this is how I spend my vacation,” she laughed.

The outlook is less clear for some of the center’s other creatures, which occupy a screened-in outdoor area filled with crates and climbing structures draped with sheets, a sort of rec-room fort for felines. They represent the city’s — and the country’s — other difficult cat conundrum: ferals.

Stray-cat management is a hugely controversial topic that pits wildlife and environment groups against companion-animal organizations. Hundreds of cities have decided that because many feral cats are too unsocialized to be adopted, the best way to avoid euthanizing them is by fixing them and returning them to the streets. But wildlife advocates say such policies are ineffective and prioritize cats over the many birds and other animals they hunt.

The debate has led to an eight-year state of limbo in Los Angeles. A 2010 court injunction, sparked by a lawsuit filed by wildlife groups that said such trap-neuter-return programs violated California environmental law, has prevented officials from leading or funding them. The city now has an $800,000 study in the works on the environmental impact of sterilizing this population, which Barnette hopes will lead to a reversal of the injunction.

“What we really want to do is reduce the number of cats in the city humanely,” she said.

For now, unsocialized cats that end up at shelters either must be euthanized or taken on as “working” cats — for vermin control — by businesses that promise to keep them indoors, Peralta said. Breweries have claimed some, as have garment district warehouses.

That’s what the four dozen or so cats in the screened area behind the Mission Hills center were candidates for: jobs. But Peralta confessed it has been slow going. Last year, about 50 feral cats were rehomed as workers. He’d like to see that number at close to 500 annually.

Given how long they may stay at the no-kill facility, some of the felines end up being more social, and therefore more adoptable as pets, than they initially seem, he said. As Peralta looked on, one black-and-white cat rolled flirtatiously around on the wooden floor, practically begging for attention.

“We’ve got to get him out,” Peralta said. “He’s not feral.”

The cat — who turned out to be a she named Fleur — was moved later that day to the adoption rooms at the front of the center. Within 48 hours, she had found a new home, and the city’s millions of homeless felines were one stray fewer.