This is a carousel. Use Next and Previous buttons to navigate

A guinea pig munches on veggies at Ratical Rodent Rescue in Vallejo, which has had dozens of pets left at its door.

A guinea pig buries itself in a bundle of hay at Ratical Rodent Rescue in Vallejo, Calif. Thursday, Dec. 2, 2021. Ratical Rodent Rescue has seen people surrendering or dumping small pets more than normal with adoptions down significantly. They have cages full of small critters and are looking to become a sanctuary with more outdoor space because they have so many animals.

The day before Thanksgiving, eight fluffy angora rabbits appeared in cardboard boxes on the doorstep of Marin Humane’s Novato animal shelter. A few days later, San Francisco Animal Care and Control received a throng of 20 unwanted hamsters. In Vallejo, staff at Ratical Rodent Rescue suddenly became caretakers to 44 guinea pigs, all left in a box in the rescue’s parking lot.

The furry, squirmy pets — cute as they may be — have recently become a big problem for animal shelters across the Bay Area and California. “Pocket pets,” as the small animals are sometimes called, are being surrendered or dumped at shelters at rates never seen before, and it’s coinciding with adoptions sinking to their lowest level in years, leaving animal shelters over capacity, and their staff perplexed and overwhelmed.

“This guinea pig and hamster thing is out of control,” said Jenn Paz, director of Ratical Rodent Rescue. “We’re just getting slammed and slammed and slammed with more and more animals and we have to come up with the money, with the space, the staff.”

While there were reports that pets acquired during the early days of the pandemic were being returned in high numbers after people began returning to workplaces, many shelters did not experience that, and the recent flurry of pocket pets specifically is without precedent, shelter managers said. One theory behind the surge is that families have lost interest in the animals since children returned to school in August for the first time since 2020.

“This guinea pig and hamster thing is out of control,” says Ratical Rodent Rescue director Jenn Paz whose site has been flooded with abandoned pets.

In the past few months, Paz’s rescue has had nearly 100 guinea pigs dumped — not surrendered — at its door, and by the end of November her staff of three was taking care of more than 130 of the rodents. Normally, “if we have 70 it’s a lot,” she said.

Meanwhile, unlike dog and cat adoptions, small animal adoptions are down significantly, not having rebounded after a precipitous drop caused by the pandemic. San Francisco Animal Care and Control is on track to fall short of last year’s already shrunken small animal adoption total, and those adoptions are down 45% so far this year compared with 2019, according to data provided by the shelter.

“It’s a problem,” said Virginia Donohue, executive director of San Francisco Animal Care and Control, which had 81 small animals in its shelter on Dec. 1 — more than three times the normal amount. The shelter’s small-animals room is set up to hold only about 24 animals because they almost never have more than that, Donohue said. They have had to expand into other spaces usually reserved for kittens.

A guinea pig looks out from its cage at Ratical Rodent Rescue in Vallejo, Calif. Thursday, Dec. 2, 2021. Ratical Rodent Rescue has seen people surrendering or dumping small pets more than normal with adoptions down significantly. They have cages full of small critters and are looking to become a sanctuary with more outdoor space because they have so many animals.

“On the small-animals side, it’s all out of whack,” Donohue said. “We’ve never had so many, and they’re not leaving.”

The pocket pets began arriving at shelters in wave after wave just a few months ago, around the start of the fall, Donohue and other shelter administrators said. It’s not clear why people were suddenly dropping off the animals in such large numbers — people who drop off unwanted pets generally don’t have to provide a specific reason for doing so — but shelter managers think it could be due to a mix of circumstances.

The uptick might be a result of kids having returned to in-person school last summer for the first time in more than a year. Some families may have decided that they did not have the time or interest to take care of the pets they had gotten for their children during the monotony of remote learning.

A group of guinea pigs sit in their enclosure at Ratical Rodent Rescue in Vallejo, Calif. Thursday, Dec. 2, 2021. Ratical Rodent Rescue has seen people surrendering or dumping small pets more than normal with adoptions down significantly. They have cages full of small critters and are looking to become a sanctuary with more outdoor space because they have so many animals.

“People were just buying them and now they’re going back to school, they’re going back to swimming, back to camp, they’re moving, they’re traveling, they’re allergic,” Paz said. “Since the shelter-in-place, it seems everyone and their brother bought hamsters and guinea pigs for their kids, and now they’re like, ‘OK, we’re done.’”

Another possibility is that people bought the animals from pet stores, which shelter administrators said are known for sometimes labeling the animals with the wrong sex, leading to uncontrolled and usually unintentional breeding once the pets are brought home in pairs.

Why adoptions are down for small animals has puzzled shelter managers and remains somewhat of a mystery. Perhaps people are buying more from pet stores and adopting less from shelters. Many people don’t realize that shelters often have pocket pets available and in need of stable homes, Donohue said.

Ratical Rodent Rescue volunteer Nicole Perry checks in with a group of guinea pigs at Ratical Rodent Rescue in Vallejo, Calif. Thursday, Dec. 2, 2021. Ratical Rodent Rescue has seen people surrendering or dumping small pets more than normal with adoptions down significantly. They have cages full of small critters and are looking to become a sanctuary with more outdoor space because they have so many animals.

Some shelters or rescues, including Ratical Rodent Rescue, have had to stop accepting surrenders. Still, people continue to reach out on social media or by phone, asking if they will take their animals. Some continue to dump their pets at shelters’ doorsteps.

“We’re turning people away every single day,” Paz said. “I don’t even want to answer the phone; I just want to cry.”

Shelters that may have more resources are doing everything they can to avoid that. Marin Humane offers a pet safety net service that provides struggling pet owners with funds to pay for pet food, vet appointments and assistance with re-homing. It’s all part of an effort to keep the animals out of shelters and in a loving home, said Lisa Bloch, Marin Humane’s director of marketing and communications.

A bald guinea pig sits in its cage at Ratical Rodent Rescue in Vallejo, Calif. Thursday, Dec. 2, 2021. Ratical Rodent Rescue has seen people surrendering or dumping small pets more than normal with adoptions down significantly. They have cages full of small critters and are looking to become a sanctuary with more outdoor space because they have so many animals.

“Even the nicest shelter is not a home, and animals always do better in homes,” she said.

Ratical Rodent Rescue has reached the point where Paz is now looking for land she can rent, or property that someone will donate, to convert it into a sanctuary space to house surplus guinea pigs.

San Francisco Animal Care and Control, Ratical Rodent Rescue and Marin Humane do not euthanize their animals due to a lack of space or time. They generally work with a network of other shelters to move adoptable animals around based on need, but lately that system has not been working as intended because so many shelters are at capacity, Bloch said.

Ratical Rodent Rescue director Jenn Paz holds a guinea pig while taking care of animals at Ratical Rodent Rescue in Vallejo, Calif. Thursday, Dec. 2, 2021. Ratical Rodent Rescue has seen people surrendering or dumping small pets more than normal with adoptions down significantly. They have cages full of small critters and are looking to become a sanctuary with more outdoor space because they have so many animals.

With just weeks to go before Christmas, shelters are working hard to get the word out about their surpluses. Through new marketing techniques, they hope to draw prospective pet owners — or their parents — to shelters rather than large pet stores chains. Hamsters and guinea pigs have been listed on sale or even for free. At San Francisco Animal Care and Control, a part-time employee is doing holiday-themed photo shoots with the animals and making TikToks starring some of the available pets, reminding viewers to “separate males and females,” “adopt same-sex pairs” and “adopt, don’t shop.”

“Now we really have to make sure that within the marketplace we remain competitive,” Donohue said. “We don’t want to miss an opportunity for a new home.”

Andy Picon is a San Francisco Chronicle staff writer. Email: andy.picon@hearst.com Twitter: @andpicon

Andres Picon is a breaking news and general assignment reporter for the San Francisco Chronicle via the Hearst fellowship program. Previously, he covered education at the San Antonio Express-News, was a reporter and researcher at the Boston Globe and participated in the New York Times Student Journalism Institute. Andres has a bachelor's degree in journalism from Boston University. He is a native Spanish speaker and a devoted New York sports fan.