Congratulations are in order for Mommy, a Galápagos tortoise and a longtime resident of the Philadelphia Zoo, who recently became a first-time mother at the estimated age of 100.
Mommy, who has lived at the zoo since 1932, laid 16 eggs in November. Four of them have since hatched — the first successful hatching for her species at the zoo, which opened in 1874.
She had help, of course — from Abrazzo, a male tortoise who is also estimated to be about a century old.
Mommy and Abrazzo, both members of the Western Santa Cruz subspecies, are the oldest animals at the Philadelphia Zoo. But Galápagos tortoises can live as long as 200 years, the zoo said, putting them squarely in middle age.
The first hatchling emerged on Feb. 27, the zoo announced on Thursday. The others followed within days, with the last one hatching on March 6.
The hatchlings, none of which have been named, are expected to be on view to the public starting on April 23, the zoo said. They are doing “fantastic,” according to the zoo’s director of herpetology, Lauren Augustine. (Herpetology refers to the study of reptiles and amphibians.)
“They are about the size of a tennis ball and they are pretty feisty, actually,” Ms. Augustine said.
The arrival of the hatchlings is significant because Western Santa Cruz Galápagos tortoises are considered critically endangered by the International Union for Conservation of Nature. Before the new arrivals, there were only 44 Western Santa Cruz Giant tortoises in all of the zoos in the United States, according to the Philadelphia Zoo.
The baby tortoises will likely never share the same physical space as their parents. Their imposing size — Abrazzo is 410 pounds and Mommy is around 280 pounds — poses a risk that the hatchlings could be crushed.
Unlike his mate, Abrazzo is not a first-time parent. In 2011, he was part of a successful pairing that led to the unexpected discovery of five hatchlings at his previous home, the Riverbanks Zoo and Garden in Columbia, S.C.
Abrazzo came to the Philadelphia Zoo on the recommendation of the Association of Zoos and Aquariums, which identified him as a potential genetic match for Mommy.
Abrazzo and Mommy were introduced in 2022, and Mommy began laying eggs in 2023. She has now laid four rounds of eggs. The first three rounds were not viable. The fourth, however, was.
Once she laid the eggs, members of the zoo’s staff weighed and measured them, and set them up to be artificially incubated at two different temperatures: one known to produce female offspring and a higher temperature known to produce males.
The four hatchlings born this year are all female, but Ms. Augustine said that three additional eggs were still being incubated.
“It’s sort of a testimony through the excellent care that she must be receiving at that institution,” Stephen Divers, a professor of zoological medicine at the University of Georgia, said of Mommy. “It’s not easy keeping a giant tropical tortoise appropriately in the northern hemisphere.”
The hatchlings will be kept in captivity for at least five years. After that, the zoo will determine what to do with them, in consultation with the Association of Zoos and Aquariums. They could end up at another zoo if they are a genetic match for other tortoises, or they could live out their days in the wild on the Galápagos Islands, off the coast of Ecuador. But that would carry risk, said Rachel Metz, the Philadelphia Zoo’s vice president of animal well-being.
“They’re at extreme risk from natural disasters, disease potentially, climate change and invasive species,” she said.
Centuries ago, the Galápagos tortoise population numbered in the hundreds of thousands, but it declined over time as they were hunted for human consumption. In the last half-century, however, the population has rebounded to around 17,000 because of conservation and breeding programs.
Population estimates for the Western Santa Cruz tortoise vary widely, but Stephen Blake, an assistant professor of biology at St. Louis University who has worked extensively with Galápagos tortoises, says it is likely in the thousands. The population appears to be stable and growing, he said.
Because the population is small and reproduction in captivity is so uncommon, the hatchlings will give researchers a rare chance to study the tortoises from a young age in captivity, said Juan Manuel Vazquez, a biologist who has studied aging in long-living animals, including Galápagos tortoises.
“Every additional tortoise counts,” he said.
Dr. Blake said it wasn’t uncommon for Galápagos tortoises to reproduce at 100 in the wild. Given that, the hatchlings at the Philadelphia Zoo are not likely to have a significant effect on conservation efforts, but they could help raise awareness about giant tortoises generally.
“This one reproducing tortoise, in my opinion, isn’t going to do much for what’s going on in the wild in direct terms,” he said. “But in indirect terms, if the zoo can promote the wonder of a 100-year-old reptile producing babies for the first time and use that as a vehicle to promote wonder among people and a conservation ethic, then so much the better.”
