Four Critically Endangered Galapagos Tortoises Hatch at Philadelphia Zoo, First Successful Hatching of this Species in Zoo’s History

Philadelphia Zoo is overjoyed to announce the hatching of four critically endangered Western Santa Cruz Galapagos tortoises for the first time in the Zoo’s 150+ year history.

The hatchlings’ parents, female Mommy and male Abrazzo, are the Zoo’s two oldest residents, each estimated to be around 100 years old. Additionally, Mommy is considered one of the most genetically valuable Galapagos tortoises in the Association of Zoos and Aquariums (AZA) Species Survival Plan (SSP). She is also the oldest first-time mom of her species. The hatchlings, currently behind-the-scenes inside the Reptile and Amphibian House, are eating and growing appropriately, weighing between 70-80 grams (about the weight of a chicken egg). The first one hatched on February 27 and the animal care team is still monitoring eggs that could hatch in the coming weeks. The hatchlings will make their public debut on Wednesday, April 23, which is the 93rd anniversary of Mommy’s arrival at the Zoo. Stay tuned for details on their debut and for the chance to help the Zoo name them!

The babies are part of the AZA SSP breeding program to ensure the survival of this species and maintain a genetically diverse population. Western Santa Cruz Galapagos tortoises are listed as critically endangered by the International Union for Conservation of Nature (IUCN) with threats including human-wildlife conflict, the introduction of invasive species, and habitat loss. The last clutch of Western Santa Cruz Galapagos tortoises to hatch in an AZA accredited zoo was in 2019 at Riverbanks Zoo and Garden in South Carolina. Other zoos with breeding pairs of this species include San Diego Zoo, Zoo Miami and Honolulu Zoo.

History in the Making

“This is a significant milestone in the history of Philadelphia Zoo, and we couldn’t be more excited to share this news with our city, region, and the world,” says Philadelphia Zoo President & CEO Dr. Jo-Elle Mogerman. “Mommy arrived at the Zoo in 1932, meaning anyone that has visited the Zoo for the last 92 years has likely seen her. Philadelphia Zoo’s vision is that those hatchlings will be a part of a thriving population of Galapagos tortoises on our healthy planet 100 years from now.”

“As an AZA accredited institution, we take great responsibility participating in the Galapagos Tortoise Species Survival Plan, and are thrilled for this successful pairing of Mommy and Abrazzo,” says Vice President of Animal Well-Being and Conservation Rachel Metz. “At one point, each of the Galapagos Islands had its own unique Galapagos tortoise, but sadly, several of them are now extinct. These hatchlings not only protect the species from extinction, but serve as important ambassadors to inspire guests to save wildlife and wild places.”

“This is a monumental achievement for our animal care team that worked diligently to provide the right conditions for Mommy to lay her eggs and for the eggs to incubate and successfully hatch,” says Director of Herpetology and Birds Lauren Augustine. “This successful outcome comes from years of hard work studying animal behavior and providing top-level care. Until now, Mommy’s genes were not represented in the AZA population, making these offspring extremely important in the protection of this species.”

“The Galapagos Tortoise SSP program is thrilled to help Philadelphia Zoo welcome Mommy’s offspring,” said Galapagos Tortoise SSP Coordinator and Studbook Keeper Ashley Ortega at Gladys Porter Zoo in Texas. “This feat is even more incredible considering that Mommy is the oldest first-time producing female of her species in any U.S. zoo. Prior to the hatchlings, there were only 44 individual Western Santa Cruz Giant tortoises in all U.S. zoos combined, so these newest additions represent a new genetic lineage and some much-needed help to the species’ population. We are excited to learn more about how we can replicate this success at other accredited zoos since the team in Philly has accomplished something that was seemingly impossible.”

About the Zoo’s Galapagos Tortoises

In December 2020, Abrazzo came to the Zoo on an SSP breeding recommendation from Riverbanks Zoo and Garden in South Carolina. On Giving ZOO Day 2021, the Zoo community made donations to purchase new substrate (nesting material like sand and soil) that Mommy would be able to lay her eggs in. In 2022, the animal care team worked jointly with the Zoo’s conservation education team to study the giant tortoises and create an ethogram of Abrazzo’s behaviors to see how he spent his time. Since 2023, Mommy has laid a total of four clutches of eggs. Three prior clutches did not result in viable eggs. The hatchlings came from a clutch she laid in November 2024.

Female tortoises typically lay 2-20 white, hard-shelled, spherical eggs about the size of billiard balls in a hole they dig. After Mommy laid her 16 eggs in November 2024, the reptile and amphibian team dug them up to incubate eight as male and eight as female. The sex of Galapagos tortoise hatchlings is determined by the incubation temperature. Temperatures below 82.4°F produce males and above 85.1°F produce females. Eggs hatch after four to eight months. The baby tortoises that have hatched were incubated as female.

Galapagos tortoises can be found on the Galapagos Islands in the Pacific Ocean off the coast of Ecuador. They are the largest living species of tortoise; males can grow to be 500 pounds while females average around 250 pounds. They are cold-blooded animals and spend one to two hours basking in the sun before spending another eight to nine hours grazing and relaxing. Scientists estimate they can live between 100-200 years old. There are currently 13 living species that are native to seven of the islands.

Philadelphia Zoo is home to three adult Galapagos tortoises, male Abrazzo, females Mommy and Little Girl, and four hatchlings. Guests can visit the hatchlings inside the Reptile and Amphibian House starting April 23. The hatchlings will remain at the Zoo for at least five years. The Zoo will work with the AZA SSP to determine when and if the hatchlings will move to different facilities. The Zoo is also home to two giant Aldabra tortoises, Wilma and Betty.

Guests can also meet Mommy and Abrazzo during a Behind-the-Scenes experience at the Zoo. Tours are offered Mondays, Thursdays, and Saturdays at 2:00pm. Tickets are $65 dollars and do not include Zoo admission. Members receive discounts on tickets.