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5 rare tortoises born at Riverbanks Zoo
It’s hard to imagine something as large, old and slow-moving as a Galapagos tortoise being stealthy, but one female at Riverbanks Zoo and Garden managed to bury a clutch of eggs several months ago without her keepers noticing.
Kathy Vause, a senior reptile keeper, got a surprise when she went into the tortoise exhibit early Tuesday and discovered four recently hatched babies in a buried nest. A more precocious fifth hatchling was found short while later, already having ventured out into the exhibit.
“It was early and no one else was around,” Vause said. “I called (curator of herpetology) Scott (Pfaff) on his cellphone, and he couldn’t tell what I was screaming about.”
Kathy Vause, a senior reptile keeper, got a surprise when she went into the tortoise exhibit early Tuesday and discovered four recently hatched babies in a buried nest. A more precocious fifth hatchling was found short while later, already having ventured out into the exhibit.
“It was early and no one else was around,” Vause said. “I called (curator of herpetology) Scott (Pfaff) on his cellphone, and he couldn’t tell what I was screaming about.”
These are the first successful Galapagos hatches ever at Riverbanks and the first babies from two Santa Cruz tortoise parents ever in a U.S. zoo.
The tortoises on each of the islands in the Galapagos chain — including the island of Santa Cruz — are considered separate species. Until about 15 years ago, the various island species were mingled in U.S. zoos, creating many hybrid babies. Both the Riverbanks mother, Alberta, and the father, Abrazzo, have had offspring with non-Santa Cruz tortoises at other zoos before coming to Riverbanks in 1995.
“We had been hoping for this for some time but knew the tortoise’s age could definitely be a factor with fertility,” Pfaff said. “These hatchlings are of great importance, representing a significant addition to the captive population of Santa Cruz Galapagos tortoises.”
The species is considered to be endangered, with about 10,000 to 15,000 tortoises living on the Galapagos.
The hatchlings look much like their giant parents, only they’re small enough to fit in the palm of a human hand. The babies aren’t yet on public display. They’re being kept in a nursery while zoo officials discuss plans for a public display.
The tortoises can live up to 200 years and reach up to 900 pounds. Alberta, who arrived in the U.S. in 1951, and Abrazzo, who was brought to the U.S. in 1928, are thought to be more than 100 years old.
Keepers can’t be 100 percent sure of the parentage of the hatchlings, but the zoo’s other female, Conchita, hasn’t laid eggs in recent years, The other Riverbanks male, Bravo, seldom mates with Alberta. Frequent visitors to the zoo probably have seen Alberta and Abrazzo mate. They aren’t exactly shy about it.
Alberta had dug out a nest and laid eggs several times in recent years, but they all had been infertile. Her routine was to lay the eggs on a hill in the exhibit, usually in late afternoon during the spring. That’s when keepers kept an eye out for nest-building, Vause said.
Vause theorizes that this time Alberta laid the eggs later in the year, when the tortoises are allowed to roam their enclosure after dark. She covered up the nest well and did a good job of keeping it secret during the incubation period of three to six months. Only recently had Alberta started hinting something had happened.
“She started acting like she wanted to lay eggs this past week,” Vause said. “We’d have to urge her into the house at night.”
Vause decided to check Tuesday to see if Alberta recently had laid eggs. Instead of eggs, she found hatchlings ready to roll.
“She snuck them in on us,” Vause said.
