The iconic desert tortoise may be threatened with extinction in the wild, but its numbers in captivity are overly abundant.

And that’s a problem for the tortoise and for the wildlife officials hoping for the imperiled reptile to make a comeback in the Mojave and Sonoran deserts.

Once tortoises are taken from their natural habitat or hatched in captivity, they should not be returned to the wild because there’s a high risk that they could spread disease to the reptiles still living in their native ranges.

In fact, releasing a pet tortoise to the outdoors is a misdemeanor crime — just as it is to take one from the wild, say officials with state Department of Fish and Wildlife.

Animal welfare volunteers in Southern California and Nevada are dealing with a glut of captive tortoises that need homes. More than 200 of the reptiles in Southern California are up for adoption. The animals are being cared for by members of the 13 Southern California chapters of the California Turtle and Tortoise Club.

Chapter locations include Chino Valley, San Bernardino, Palm Desert, Santa Ana and Long Beach.

“There are so many tortoises in captivity, we can’t place them all,” said Linda Crawford of Arcadia, the adoption chairwoman of Foothill chapter of the club.

The problem stems from the long-time practice of people finding tortoises during treks to the desert and taking them home as pets. Many of the reptiles were captured before 1990, when the species was listed as threatened with extinction in the wild.

But since tortoises live as long as 80 years, many of pets outlive their owners. And they breed in captivity.

Tortoise populations have declined in the wild partly because of an upper respiratory infection caused by bacteria that spreads easily among different species of turtles and tortoises. The disease causes lesions in the animals’ nasal passages, causing them to lose their appetites and sense of smell. Other reasons include the loss of habitat and increases in the number of coyotes and ravens, which prey on tortoises.

Not only are wildlife officials concerned about the spread of this disease, they’re also afraid that captive tortoises could bring in new, potentially devastating pathogens, said Roy Averill-Murray, the desert tortoise recovery coordinator for the U.S. Fish and Wildlife Service.

Another problem is that over the eons, the desert tortoises have adapted to specific regions. Desert tortoises in the Mojave Desert, for instance, are genetically different than those in the Sonoran Desert, and the wrong genes should not be introduced to the wrong area, said Averill-Murray.

To keep the number of captive tortoises down, the wildlife service trains veterinarians to spay and neuter tortoises, said Averill-Murray, who is based in Reno, Nevada.

“Don’t breed them,” said Averill-Murray, a wildlife biologist. “Backyard breeding is not helping the recovery of the species.”

Meanwhile, Crawford and her fellow tortoise club members, are looking for homes for the hundreds that need to go somewhere. People who adopt them must first show that they have adequate fenced yard space is that safe from dogs or swimming pools, among other considerations, she said.

Anyone interested in adopting a tortoise may download an application from the club website at www.tortoise.org/cttc/adoption.html The club also issues required permits for pet tortoises for the state Department of Fish and Game.

Crawford, 75, a retired Los Angeles Zoo animal keeper, has cared for tortoises nearly all her life. When she was just five, her father brought home a desert tortoise he found loose on a Los Angeles street.

She now has four of her own tortoises. On Tuesday, May 2, she had another five in foster care up for adoption.

“Tank,” her roughly 60-year male reptile, eagerly munched on a pink hibiscus flower as she explained that tortoises shouldn’t be feed Romaine lettuce, broccoli and most other produce from the grocery store. They instead need high-fiber vegetation, such as grasses, dandelions, prickly pear cactus, and ice plant.

Averill-Murray says he focuses on two messages when dealing with human interaction with desert tortoises: “One, keep captive tortoises captive. And two, keep wild tortoises wild.”