Much like people, some animals take to parenthood later than usual. A pair of Western Santa Cruz Galápagos tortoises at the Philadelphia Zoo have just become parents as they approach the century mark.
This month, the Philadelphia Zoo announced the arrival of four hatchlings born to the male tortoise Abrazzo and the aptly named female Mommy. The hatchlings are the first ever born in the Zoo’s 150-year history, and Mommy is the oldest documented member of her species to become a mother. More hatchlings could emerge in the coming weeks as well.
Galápagos tortoises, named for the islands off Ecuador where they reside, are the largest tortoises in the world, and can live for over 170 years in captivity. Western Santa Cruz Galápagos tortoises are one of 13 living subspecies.
The tortoises underwent a steep population decline starting in the 19th century, fueled by hunting and the introduction of invasive species to the area. Conservation efforts have boosted their numbers as of late, but there are still only around 20,000 total in the wild today. Western Santa Cruz tortoises in particular are critically endangered—making the arrival of these hatchlings all the more important.
It’s been a long journey for Mommy to reach motherhood, though. She’s lived at the Philadelphia Zoo for over 90 years. In 2020, as part of the Association of Zoos and Aquariums’ (AZA) Species Survival Plan, the Zoo agreed to take in Abrazzo from Riverbanks Zoo and Garden in South Carolina so he could hopefully mate with Mommy. The blind date pairing worked, and by 2023, Mommy began to lay clutches of eggs.
Sadly, the first three clutches failed to result in viable eggs. But Mommy’s fourth clutch, laid in November 2024, was finally a success. A Galápagos tortoise’s sex is determined by the temperature of the buried holes they’re incubated in as eggs. Mommy laid 16 eggs, and the Zoo team buried them at temperatures that would yield up to 8 male and female hatchlings each. The four hatchlings seen so far are all female.
“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,” said Lauren Augustine, director of Herpetology and Birds at the Zoo, in a statement. “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.”
These hatchlings are the first seen in an AZA-accredited zoo since 2019, and there are only 44 individual Western Santa Cruz Giant tortoises in all U.S. zoos combined, according to the Philadelphia Zoo. So the hatchlings are vital to the continued conservation of this rare subspecies. And fortunately, Mommy’s contribution to the gene pool might not be over yet. Her first tortoise hatched on February 27, and the team is still monitoring additional eggs that could hatch in the next few weeks.
The Philadelphia Zoo plans to publicly debut Mommy’s hatchlings on April 23, the 93rd anniversary of her arrival to her zoo. They also plan to have the public name the crucial next generation of these long-lived reptiles.
