There are other, less quantifiable warnings: Some city pet store owners say that customers who at the height of the pandemic scooped up creatures like bearded dragon lizards, and hamsters as playmates for cooped-up children have brought them back.

People who foster guinea pigs in New York say they are overrun. In Central Park, rescues of domestic red-eared slider turtles nearly tripled to 29 this year so far — though the parks department cautioned that the numbers could mean more sightings of distressed turtles, not more animals. Rabbits and guinea pigs have also been found. It is illegal to release animals in city parks.

A constellation of factors is apparently driving the surge. Christa Chadwick, the vice president of shelter services at the American Society for the Prevention of Cruelty to Animals, suggested that part of the uptick may be because many shelters were not taking in animals over the course of the pandemic. And, she noted, shelters are glutted with small animals in part because adoptions overall have slowed.

“It’s important for the public to come back in droves to shelters,” she said. “Whether it is for cats or dogs or chickens or hamsters.”

Rising rents, inflation and housing insecurity have also forced people to make difficult decisions about keeping even beloved pets, said Hilary Hager, vice president of outreach, engagement and training at the Humane Society of the United States. “I would never want to suggest to anyone that people don’t care,” Ms. Hager said. “There are just a lot of other factors that are coming into play.”

Jade Perez’s family acquired a dog and two kittens to stave off the loneliness of lockdown, she said. But when rising rents forced her family to downsize to a smaller Staten Island apartment, she put Honey, the guinea pig she had bought just before the pandemic, up for adoption on Craigslist.

“We have a lot of animals, and we just can’t take care of the guinea pig now,” said Jade, who is 17, citing inflation’s toll on the prices of food and supplies. “He’s not living the best life he can.”