Western Santa Cruz Giant Tortoise
Chelonoidis porteri
At the Zoo
East end of Lion House
Fascinating Facts
- Western Santa Cruz Giant Tortoises are a subspecies of Galápagos tortoise. Altogether, there are 13 living and 2 extinct subspecies of Galápagos tortoises. The tortoises are so closely associated with the Galápagos Islands, that the word “galapago” is Spanish for “tortoise”. In the 1600s, there were an estimated 250,000 Galápagos tortoises living throughout the islands, but pirates, sailors and whalers found them easy to hunt and plentiful food sources. Today, the Galápagos islands are protected and there are conservation programs in place to restore habitat, cull introduced species and breed and release native species. The different subspecies of Galápagos tortoises have different shell shapes, depending on the ecology of their island. Tortoises with a “saddleback” shaped shell are found on drier islands with sparser vegetation. These tortoises are typically smaller overall, but with longer limbs and neck. The more humid and densely vegetated islands are home to larger tortoises with domed shells and shorter necks and limbs. It is believed that these differences evolved in relation to feeding habits – having to reach for food or grazing in place. The variations in shell shapes between the islands helped Charles Darwin formulate his theory of evolution.
Physical Characteristics
Western Santa Cruz Giant Tortoises have dark gray or black skin, with a similarly colored shell. They have a domed carapace, or shell. They are one of the larger subspecies of Galápagos tortoises, and males can grow up to 600 – 700 pounds and females 300 – 400 pounds. As an ectothermic, or cold-blooded animal, their larger size helps them regulate temperature variations. They migrate seasonally and spend part of the year at higher elevations with cool fog. They have a good sense of smell and vision. They will vocalize during copulation.
Diet
They are herbivores and eat a variety of vegetation, including cacti, grasses, leaves, berries and fruits. They get most of the moisture they need from the foods that they eat.
Habitat
They are found in forests, scrub and grasslands, up to 1,500 feet.
Range
Western Santa Cruz Giant Tortoises are found on the southwestern end of Santa Cruz Island in the Galápagos Island chain of Ecuador. https://www.iucnredlist.org/
Social Behavior
While some Galápagos tortoise subspecies can be solitary, Western Santa Cruz Giant Tortoises tend to stay in herds and will migrate seasonally from wetter to drier areas of Santa Cruz Island. These migratory paths are called “tortoise highways”. Males will fight for breeding rights. After mating, a female will dig a hole in a sandy area near the coast and deposit up to 16 eggs. Depending on the time of year, it will take between 4 – 8 months for the eggs to hatch. The babies are 2.5 inches long at hatching. They can live well over 100 years – “Harriet,” a Western Santa Cruz Giant Tortoise was estimated to be 175 at the time of her passing. She lived at the Australia Zoo made famous by Steve and Terri Irwin.
Status In The Wild
IUCN – Critically Endangered
Other
Threats to Western Santa Cruz giant tortoises include habitat destruction and introduced species. Historic threats included hunting and poaching, although they are now a protected species in Ecuador and are no longer a food source for humans. There are approximately 3,400 Western Santa Cruz Giant Tortoises in the wild on Santa Cruz Island.