A pair of Galápagos tortoises in their 90s recently made headlines for successfully producing offspring for the first time. The female tortoise, aptly named Mommy, at Philadelphia Zoo is now considered the oldest recorded first-time mom for the Western Santa Cruz Galápagos tortoise (Chelonoidis porteri), at the age of 97.
Mommy, who has been with the zoo since 1932, was paired with Abrazzo, estimated to be 96, who was transferred to Philadelphia in December 2020 from Riverbanks Zoo and Garden in South Carolina. The transfer was part of the Association of Zoos and Aquariums (AZA) Species Survival Plan (SSP) breeding program.
After the team prepared nesting material, Mommy started laying eggs in 2023. Although the first three clutches produced eggs that weren’t viable, the 16 eggs she laid in November 2024 have so far resulted in four hatchlings, all of them female. The sex of tortoise hatchlings is influenced by temperature, so the zoo incubated eight eggs below 28° Celsius (82.4° Fahrenheit) to produce males and the other eggs above 29.5°C (85.1°F) to produce females. The team say they hope there will be more baby tortoises since eggs can take four to eight months to hatch.
Western Santa Cruz Galápagos tortoises are critically endangered, with only 3,400 individuals remaining. Several Galápagos tortoise species and subspecies have gone extinct. There are 13 different species of Galápagos tortoises alive today, most of them are threatened by human-wildlife conflict, invasive species, and habitat loss.
Lauren Augustine, Philadelphia Zoo’s director of herpetology and birds, said it took a lot of hard work to study the tortoises’ behavior and ensure the right conditions for Mommy to lay eggs and for the eggs to hatch. “Until now, Mommy’s genes were not represented in the AZA population, making these offspring extremely important in the protection of this species,” she said in the zoo’s statement.
Galápagos tortoise SSP coordinator and studbook keeper Ashley Ortega, from Gladys Porter Zoo in Texas, said in a statement that the species survival plan program is “thrilled to help Philadelphia Zoo welcome Mommy’s offspring.”
“This feat is even more incredible considering that Mommy is the oldest first-time producing female of her species in any U.S. zoo,” she said, adding that before Mommy laid her eggs, there were only 44 individual Western Santa Cruz Galápagos tortoises in all U.S. zoos.
The last of the species to hatch in an AZA zoo was in 2019, at Riverbanks Zoo.
“So these newest additions represent a new genetic lineage and some much-needed help to the species population,” Ortega said. She said they’re keen to replicate at other AZA zoos what Philadelphia Zoo accomplished, which she described as “seemingly impossible.”
The hatchlings, which currently weigh around 70-80 grams (2.5-2.8 ounces), as much as a chicken egg, will be presented to the public on April 23, coinciding with Mommy’s 93rd anniversary at the zoo.
Banner image of Mommy, the Western Santa Cruz Galápagos tortoise, courtesy of Philadelphia Zoo.
