Galapagos Tortoise Hatchings Mark First In Philadelphia Zoo History

PHILADELPHIA — The Philadelphia Zoo welcomed a new member to its menagerie, as our critically endangered Western Santa Cruz Galapagos tortoises hatched recently.

According to officials, the hatchings are the first in the zoo's more than 150-year history.

The hatchlings’ parents, female Mommy and male Abrazzo, are the zoo’s two oldest residents, each estimated to be about 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, which are behind-the-scenes inside the Reptile and Amphibian House, are eating and growing appropriately, weighing about as much as a chicken egg.

Feb. 27 marked the first hatching, and the animal care team is still monitoring eggs that could hatch in the coming weeks.

The hatchlings will make their public debut on April 23, which is the 93rd anniversary of Mommy’s arrival at the zoo.

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 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.

"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," Philadelphia Zoo President & CEO Dr. Jo-Elle Mogerman said. "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."

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 — a nesting material like sand and soil — that she used 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 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 degrees Fahrenheit produce males and above 85.1 degrees Fahrenheit produce females. Eggs hatch after four to eight months. The baby tortoises that have hatched were incubated as female.