Range:

The Galápagos Islands, 600 miles west of Ecuador

Habitat:

Open, grassy areas to rocky, volcanic outcrops

Adapting and surviving

Galápagos tortoises are the giants of the tortoise world. Males can weigh more than 500 pounds (227 kilograms), and females average about 250 pounds (113 kilograms). They have thick, sturdy legs to hold up all that weight, but they still spend a lot of time lying down to conserve energy. There are two types of Galápagos tortoises. The largest, with big, round shells, are called “domes.” The smaller kinds of tortoises have shells that curl up in front like a saddle and are called “saddlebacks.”

A historic observation

Naturalist Charles Darwin made his historic voyage on the HMS Beagle from 1831 to 1836. When the ship sailed around the Galápagos Islands, he and his shipmates marveled at the animal life they found, from blue-footed boobies and marine iguanas to giant tortoises. One thing that caught his eye was that each of the 13 larger islands in the Galápagos Islands had a slightly different form of giant tortoise.

Each was uniquely suited for survival on that particular island’s environment. For example, domed shells were found on tortoises living in highlands with lush pastures. Saddleback shells gave the tortoises on other islands more flexibility to reach sparse vegetation found higher off the ground, allowing them to stretch their neck to eat from bushes and cactus. On islands with sparse vegetation, the tortoises have longer legs to climb a little and reach food growing up high; these tortoises tend to be smaller, possibly to help them travel through their harsher habitat.

Las Islas de los Galápagos, or the Islands of the Tortoises, are named for the famed giant tortoises found nowhere else in the world.
"Galápago" is one of the Spanish words for tortoise.
When we make jokes about tortoises being slow, we mean slow! Galápagos tortoises amble along at an astonishing 0.16 miles per hour (.26 kilometers per hour). Humans walk at an average speed of 2.8 miles per hour (4.5 kilometers per hour).
Galápagos tortoise Speed arrived at the San Diego Zoo in 1933 as an adult—which makes him more than 100 years old!
The oldest life span on record belongs to an adult female Galápagos tortoise in an Australian zoo that was documented to be at least 171 years old at the time of her death.
A Galápagos tortoise can go without eating or drinking for up to a year because it can store food and water in its body.

The giants arrive

The San Diego Zoo has one of the largest colonies of Galápagos tortoises in the world. We have had these giants in our collection since 1928, making them the oldest residents in the Zoo. That’s the year when Charles Townsend of the New York Zoological Society began his efforts to save the tortoises from extinction by collecting juvenile tortoises and setting up colonies for them in North American zoos. These tortoises weighed between 11 and 30 pounds (5 to 13 kilograms), and it would be years before they reached breeding size.

Famous tortoises

In 1933, an adult tortoise was brought from Isabela Island and weighed a respectable 475 pounds (215 kilograms). Named Speed at the time, he is still at the Zoo and is still our largest tortoise. The original tortoises sent to the San Diego Zoo (yes, 10 of them are still with us!) are well over 100 years old today. Our first Galápagos tortoise hatching occurred on October 21, 1958. Since then, we’ve had 94 successful hatchings at our Zoo.

One of our tortoises, a large male named Gerty, participated in the making of the 1941 movie Malay, with Dorothy Lamour and Jack Haley. In the film, the hero is very thirsty after hours in the jungle and at long last comes to a beautiful pool of water. Sitting down on a log, he is badly frightened to discover that his “log” is a live alligator. He rushes to the bank, where he sits on a large stone. The stone, of course, turns out to be Gerty.

Our current tortoise herd

Currently, our tortoise herd numbers 17 individuals, representing at least five subspecies. Numbers painted on each animal’s shell help the keepers identify their charges: white-numbered tortoises are males, red numbers indicate females. For example, Speed has a white #5 painted on his shell. Each tortoise has its own unique personality: some are really shy while others are more interactive with their keepers, stretching up for a neck rub or to eat right out of the keeper’s hand.

The Fetter Family Galápagos Tortoise Exhibit

Our tortoise yard was remodeled in 2010 to include a touchable collection of replica tortoise shells and a more spacious, heated barn with a deep, indoor nest area, walls coated with a special cushiony rubber to prevent shell injury, and skylights and windows to give the building a bright, airy feel.

Finding a way to summon them into the barn at night was challenging, yet the answer may be clear as a bell—a cowbell, that is! Starting off with baby steps, keepers ring the bell and offer a small pile of carrots in front of the tortoises so they learn to associate the sound of the bell with delicious treats, gradually increasing the distance over time, where a jackpot of treats await. Cowbell training may also come in handy for weighing the tortoises; keepers ring the bell and offer rewards once the animal is on the scale, making the process easy for all!

Years ago, Zoo visitors had direct contact with the tortoise herd, and many people remember “riding” on the tortoises as children. Times change, and since our tortoises are ambassadors for an endangered species, we have new ways for people to connect with our tortoises. A life-size Galápagos tortoise bronze figure allows guests to “sit on a tortoise” for photos.

And we now have an interactive zone for close encounters: when a keeper is present, guests can enter the zone and feed vegetable snacks to the tortoises and, perhaps, offer a neck scratch, which the animals love! Tortoises are attracted to the colors found in flowers, which are one of their favorite foods. Try wearing your brightest clothing, and see if you get the attention of a Galápagos tortoise!

The arrival of humans

The Galápagos Islands were discovered in 1543 by Spanish explorers. The animals on these islands had never seen humans, and there were no large predators there to hunt them. They were completely unafraid, because they had never been threatened. But the humans became a threat to the tortoises. They hunted them for food for many years, and settlers also introduced new animals to the islands—goats and cattle ate the plants the tortoises needed, and pigs rooted for tortoise eggs and ate them.

When pirates, whaling ships, and merchantmen came through the Galápagos Islands from the 17th through 19th centuries, sailors loaded the large tortoises on their ships to use for food during the rest of their long voyage. Tortoise populations that once numbered in the tens of thousands were reduced to thousands, then hundreds, and even tens. What nature had taken millions of years to create, humans had nearly destroyed in a few generations.

Galápagos National Park

By 1959, when the Galápagos tortoise was in danger of becoming extinct, the Ecuadorian government stepped in and created the Galápagos National Park to protect tortoise habitat. Although visitors are allowed on the islands, these visits are strictly regulated. All groups must have a guide and are asked to stay on the paths so the vegetation isn’t trampled and the animals are not disturbed.

In 1969, San Diego Zoo Global became a partner with the Charles Darwin Research Station on the Galápagos Islands, funding a new tortoise-rearing facility and helping with captive propagation and release programs. Today, the greatest threats to the tortoises come from introduced nonnative species such as rats, dogs, and cats, which eat tortoise eggs and young tortoises. This is one reason why Research Station staff give hatchlings there a head start by raising them until they are big enough to survive on their own. They also must still compete for food with nonnative goats and cattle. At best, there are about 10,000 to 15,000 tortoises living today on the Galápagos Islands.

As Hood Island tortoises are so rare (estimates were 12 females and 3 males in the 1970s), the Zoo’s male, Diego, was sent to the Charles Darwin Research Station in 1976 to be part of the breeding program there. So far he has fathered hundreds of tortoises!

The next 10 years

In 2012, renowned geneticist Oliver Ryder, Ph.D., was invited to an international workshop on the Galápagos Islands to plan the next 10 years of Galápagos tortoise conservation efforts. He is the director of genetics at the San Diego Zoo Institute for Conservation Research and Kleberg Chair, as well as a creative problem solver with a deep capacity to understand the big conservation picture. The workshop utilized the expertise of people around the world in many different fields, including ecology, biology, horticulture, herpetology, physiology, genetics, and wildlife diseases, among others. Dr. Ryder was particularly pleased that the people who would be managing the areas and implementing the ideas, like park guards and local ecologists, were full participants.

Issues facing the delicate ecosystems of different islands, like invasive plant species (guava and blackberries), health and recruitment of wildlife populations, the elimination of nonnative species like goats and rats, and the containment of farm animals to protect native species, were addressed. “The San Diego Zoo has a long history of contributing to Galápagos tortoise conservation,” said Dr. Ryder. “This workshop was another great opportunity to provide thoughtful ideas and suggestions to the Galápagos authorities to guide conservation strategies into the next decade.