By Kate Daly | Special to the Almanac

At the Hufty-Alegria home in Portola Valley, the sign posted on the gate clearly states: "Keep out, endangered wildlife habitat." In reality, though, Dr. Mary Hufty, a family doctor at the Palo Alto Medical Foundation, couldn't be more welcoming in sharing her unusual pets: two California desert tortoises named Duke and Heston.

Chances are they once lived in the wild since captive breeding is illegal in the state. Also known as Gopherus agassizii, the official reptile of both California and Nevada can live for up to 80 years and is naturally found in the Mojave and Sonora deserts in Southern California, Nevada and Utah.

Dr. Hufty explains that the problem starts when people pick up a tortoise in the desert, and then the animals "can't be put back out in the wild because they have colds and diseases" that could wipe out a native population. Also, pet owners can tire of taking care of a tortoise, or "get old, and die or are disabled," and that triggers the need for a tortoise to find a new home.

Dr. Hufty figures Duke and Heston probably lived in three or four homes by the time she adopted them a couple of years ago. "They're like refugees, they came as a pair," and are "theoretically 60 and 40 years old," she says.

Dr. Hufty's interest in tortoises started when she was a little girl growing up in central Florida. They are one of the many natural draws on the large expanse of land where her family founded the Archbold Biological Station. She now serves as board chairman of the ecological research facility.

Twenty-five years ago, Dr. Hufty's sister-in-law surprised her with an African leopard tortoise named Leo. Dr. Hufty recalls feeling so overwhelmed with juggling a family of young kids, a husband, and a career, that she put Leo in a box to hibernate for a year.

After that he became a part of the family, along with the dogs, cats and horses until he mysteriously disappeared from their yard two years ago. Dr. Hufty says, "I was sad, lonely, and felt deserted," and that's what led her to go online and adopt Duke and Heston.

The tortoises arrived wearing endangered species tags and suffering from a respiratory illness that required six weeks' worth of antibiotic injections. They appear healthier these days, weighing about 11 pounds each, with shells measuring 12 inches by 7 inches.

"These guys are really mellow. They just hang out," Dr. Hufty says, watching them explore rocks and nibble on plants and weeds in her fenced-in side yard.

She feeds them alfalfa, grass, romaine lettuce, vegetables and cherries, and gives them warm baths about once a month. They spend every night and most of the winter (when they hibernate) in a wooden shed, comfortably tucked in under domes that rest on top of piglet warming pads set on low.

She picks up the tortoises whenever she needs to get them quickly from point A to point B, and they occasionally make a slight hissy, clucking noise. "They're totally gentle ... everybody loves my tortoises," Dr. Hufty says with a smile.

She belongs to the California Turtle & Tortoise Club's Silicon Valley Chapter. The group meets in San Jose every month and has about 100 members. The organization is involved in hundreds of adoptions each year.

President Gilbert Castro says lately he's "seeing more adoptions due to lack of education," and refers people to the club's website, tortoise.org, for more information.