Liam loves cats. Since he was 5 years old, he has put $1 from his allowance into a jar every week. Twice a year, when he reaches $20, he tells his parents to donate the money to the Washington Heights Cat Colony. Now 8 years old, Liam is known as the colony’s “biggest donor,” the treasurer said.

According to the New York City Feral Cat Initiative, tens of thousands of free-roaming cats consider alleyways, backyards and other public spaces their homes. The Washington Heights Cat Colony, along with other animal rescue groups around the city, practice trap-neuter-return to control the feral cat population.

Trap-neuter-return, or TNR, means that the cats are trapped and taken to local clinics such as Uptown Veterinary Associates. There, they are vaccinated against rabies, spayed or neutered and ear tipped.

Ear tipping is the removal of the top quarter of a cat’s ear in order to tell colony volunteers or animal control officers that the cat has already been trapped, sterilized and vaccinated. Healthy adult cats are then returned to the colony.

When Cat Colony founder Sherri Laurence moved into her Washington Heights apartment in 2004, she noticed a cat and her six kittens living in the basement. Unsure of what to do, she took a trap-neuter-return course offered by the Neighborhood Cats at the ASPCA and got certified.

Neighborhood Cats, founded in New York in 1999, helped introduce the TNR process. It provides support and funding to other groups nationwide to establish TNR programs of their own.

With help from her neighbors, Laurence branched out to help other neighborhood cat colonies. Volunteers put up posters to get neighbors involved in managing the colonies.

“The benefit of TNR is to help humanely manage feral cat populations,” said Laurence. “The removal of cats does nothing but open up a territory for more to move in. It’s not effective.”

Financed solely by donations, the Washington Heights Cat Colony has about 20 volunteers and fosterers from all walks of life, including doctors, nurses, a lawyer, a yoga instructor and a children’s book artist. “Volunteering is a fantastic way to get connected to a neighborhood,” said Trish Bogle, treasurer of Washington Heights Cat Colony.

The volunteers hold fundraisers, like tag sales, to help raise extra cash, donate their own money and give cat lovers the option to donate on their website. As treasurer, Bogle says that she always worries about money. “My worst days are those when I have to tell the group that we don’t have enough funds to do a particular TNR project or to help a particular street cat in need,” she said.

Those are the kind of days that motivate Bogle to work harder to raise money. “I just think of all the cats that need help and all the improvements we’ve made to the neighborhood and say, ‘Who wouldn’t want to give to this great cause?’” she said.

The city pays roughly $250 each time it picks up, houses and euthanizes a homeless cat. The trap-neuter-return program can take care of five cats for the same price, says the New York City Feral Cat Initiative, formed by two non-profit organizations, Neighborhood Cats and the Mayor’s Alliance for NYC’s Animals. Its mission is to raise awareness about feral and stray cats, or “community cats,” living outdoors throughout the city’s five boroughs. It works to improve the lives of homeless cats while humanely reducing their total number.

While the cats in the colonies won’t be snuggled next to a fireplace this winter, they will be safe from the cold and snow. With winter approaching, the Washington Heights Cats Colony buys insulated shelters and fills them with straw. Two to three cats can fit in each shelter; their combined body heat helps them stay warm.

“Once feral cat colonies are managed, they look like different cats than when you started the project,” Laurence said. “They look shiny, have good weight on them, healthy and basically look like house cats. It just takes a little attention, warmth, food and love.”