![]() Hawks are probably the only native predator of young tortoises. These hatchlings weigh less than 1/1,000th of what they will weigh as an adult. The young tortoises hatch between November and April, taking a month to dig their way out of the nest. Nest temperatures determine the sex of the hatchlings, with lower temperatures producing more males. After covering the nest, the female returns to the highlands, leaving the eggs to incubate for the next 4 to 8 months. Between 2 and 20 eggs are laid, each about the size of a tennis ball. While digging the hole with her hind legs, a task that can take several hours, the female urinates frequently to soften and bind the soil. Then, between June and December, the females migrate to the arid zones to nest. They mate during the rainy season, usually between January and June. Giant tortoises reach maturity at 20 - 30 years. Sadly, a 4th subspecies from Pinta Island is represented by only one surviving male - "Lonesome George". The remaining 5 are from the large Island Isabela - each geographically confined to one of the island's 5 major volcanoes. Nine of these subspecies evolved separately, on individual islands. The 14 subspecies of Galapagos tortoises all evolved from a common ancestor. Larger, dome-shaped tortoises are typical for higher, lusher islands, where they feed on grasses, other low growing vegetation and fruits. Although they usually eat fallen cactus pads and low growing vegetation, they sometimes have to reach up high for taller shrubs, when the lower vegetation is unavailable. They are well adapted to the environment on lower, drier islands. The smaller saddle-backs have long necks and limbs and a shell that is raised in the front. From island to island, the tortoises vary in size and the shape of their shells. The word "galapago" in Spanish means "saddle" and refers to the shell of these huge reptiles. Since the official discovery of Galapagos in 1535, the islands have been known for their namesake - the giant tortoise. However, these slow moving reptiles are threatened by humans and the animals humans have introduced on these remote islands. They can weigh up to 270 kilograms, and they have very few natural enemies. Giant tortoises can only be found on Galapagos and on the Aldabra Atoll in the Indian Ocean. Courtesy of The Charles Darwin Foundation for the Galapagos and The Galapagos National Park Service
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |