Toledo Zoo’s Galapagos collection grows with arrival of 3 tiny tortoises
Babies acquired with eye on local breeding effort
TOLEDO ZOO/R. ANDREW ODUM
The Toledo Zoo is caring for a new trio of little ones that are destined to become legacy animals for the institution.
Three baby Galapagos tortoises arrived at the zoo earlier this month from the Gladys Porter Zoo in Brownsville, Texas. They are the much younger and much smaller counterparts to Emerson, the wild-born Galapagos tortoise estimated at 100 years old that arrived in Toledo in August.
The babies arrived via air freight at Detroit Metro Airport on Nov. 4. They had been carefully packed and weathered the trip with ease.
“They were eating the next day, alert and happy,” said R. Andrew Odum, director of herpetology at the zoo.
The trio is not on exhibit while they remain in quarantine for about six more weeks. They will then be in the Reptile House when their exhibit is completed.
The little tortoises are of a subspecies from Darwin Volcano on Isabela Island, the largest island in the Galapagos archipelago off the coast of Ecuador. Two of them were hatched in 2013, the third in 2012. Their shells are only about 4 inches across, and they all weigh less than a pound. Emerson, by comparison, weighs 442 pounds.
Male or female?
They are presumed to be females, though their sex hasn’t been confirmed and likely won’t be until they are at least 15 years old when they’ve matured some.
“You can confirm it, but it’s highly invasive,” Mr. Odum said. “You have to do surgery and laproscope them. Right now, it’s not a piece of information that’s going to change any management of the animals. We’re going to be patient.”
Galapagos tortoises’ sex, like many reptiles, is determined by subtle differences in the temperature at which eggs are incubated. Lower temperatures produce males, while higher temperatures produce females.
Colette Adams, general curator of the Gladys Porter Zoo and vice coordinator of the Galapagos Tortoise Species Survival Plan, said the trio came from eggs incubated at 85 degrees, which produces females. For males, the zoo incubates eggs at 83 degrees.
The youngsters remain unnamed, and the zoo does not have any particular plans to name them. All zoo animals are tracked by an identification number, though many are given house names by their keepers for the sake of convenience.
The Toledo Zoo plans to build a breeding program with the tortoises, though they won’t be sexually mature for 20 to 30 years. Experts estimate Galapagos tortoises can live for 150 to 200 years on average.
“This is a long-term commitment by this institution to make sure that we have Galapagos tortoises for the people of Toledo and support the perpetuation of Galapagos tortoises in the United States,” Mr. Odum said.
Emerson will not be prevented from mating, but he will not be part of the official breeding program because his genetics are uncertain. Conflicting tests to determine his subspecies indicate he is either a natural hybrid of tortoises from the Wolf and Alcedo volcanoes on Isabela Island or is from Santiago Island.
The purebred babies will be monitored very closely to track their growth, shell condition, and overall health. Their diet — consisting mostly of greens — is strictly controlled because overfeeding results in too-rapid growth. That leads to shell deformities and long-term health problems.
“Rearing one of these tortoises is something that has to be done very carefully,” Mr. Odum said. “You don’t want to push them. They naturally grow very slowly. They have just about as perfect a shell now as you could expect in a young tortoise.”
Jeff Sailer, executive director of the zoo, said Galapagos tortoises in the wild have to search for their food.
“They are not designed to eat constantly,” he said. “If they stumble across a cactus fruit in the wild, that’s a really great nutritional find. But they won’t get access to a cactus every 15 minutes.”
Ms. Adams said all three babies have the same father, a wild-born male named Mopey who came to the United States in 1928 and is now at the Phoenix Zoo. He was brought to the states by Charles H. Townsend, and Mr. Odum believes Emerson was also part of the Townsend expedition.
The New York Zoological Society naturalist and director of the New York Aquarium was one of the first to notice the plight of Galapagos tortoises after examining logbooks from whaling ships and realizing how many had been taken. He led an expedition to the archipelago in an attempt to preserve them.
The oldest baby’s mother was Houston, who is also a Townsend tortoise. She is an unusually large female at about 400 pounds.
The other two babies were from a clutch of eggs laid by Myrtle, a captive-hatched tortoise who is on the smaller side at 300 pounds. But she has a unique behavioral quirk that Ms. Adams said her offspring also exhibit.
“When you spray her with a garden hose, she stands up tall on all fours and extends her head fully and acts like she’s in a trance,” Ms. Adams said. “And all her babies have done that too.”
The Brownsville zoo hatches an average of 15 Galapagos tortoises each year. The zoo works to keep a 3-1 ratio of females to males, so the incubation temperature is set for males only every four years or so.
“We know from experience that an excellent breeding group is one that has at least twice as many females as males,” she said.
Ms. Adams said she plans to send the Toledo Zoo a baby male from a completely different bloodline sometime in the next several years to ensure the Toledo herd is genetically diverse and has tortoises of similar sizes when breeding may begin.
As it is, the three youngsters will be kept separate from Emerson for a number of years to avoid injury. If Emerson tries to mate with them, they need to be able to get away from him and be large enough to withstand his weight.
“They will be good-size tortoises by the time they are 15,” Ms. Adams said, estimating they will be about 3 feet long at that age. “We have had females in captivity that have produced eggs as early as 20 years of age. However, we don’t recommend pushing them that fast.”
The babies will grow the most in their first 15 years or so, but tortoises can continue to grow throughout their lifetimes.
“They have indeterminate growth,” Ms. Adams said. “They are capable of growing, even if only incrementally, until they die. That is determined by food supply, genetics, and environmental conditions.”
Mr. Sailer noted that the young tortoises will provide visitors the opportunity to create family histories with the zoo. Parents and grandparents can tell the younger generations about how they saw the same tortoises when they were tiny babies that could fit in one hand.
“A kid coming here could bring their grandchildren to see these tortoises, or their great-grandchildren,” Mr. Sailer said. “That’s pretty cool. There are not a lot of animals that allow you this opportunity.”