Tortoise day

 Wednesday February 25

This morning we visited the Charles Darwin Research Center (CDRC) in the town of Puerto Ayora on the island of Santa Cruz. The research center was established in 1962, shortly after the Galapagos National park was created. The purpose of the research effort, customized to each island, is to reduce the presence of invasive species and to re-establish iconic species and their necessary habitat. While the research center works with land iguanas, endangered plant species and species of birds, the largest and most visible project is their work with tortoises. 

The CDRC baseline survey in 1964 identified 15 species of tortoise across the islands, of which 3 were already extinct, and a total population of less than 10,000 animals. It is estimated that prior to the whaling era of the 18th and 19th centuries, that the population would have been closer to 200,000. Whaler’s logs document taking over 150,000 tortoises for food. In modern times the tortoises are threatened by habitat loss and the presence of introduced rats, cats, and goats on the islands. 

Tortoises lay 5-20 eggs in a pit dig in the sand near the shoreline. The eggs incubate for 4 months just by the heat of the sun. Once hatched they stay within the nest for about an additional month before they emerge. The baby tortoises are on their own once they hatch. 

The researchers collect eggs from nests on the islands where tortoises are at risk. The eggs are marked to ensure that they stay right side up, and set in a controlled environment to incubate. After the babies hatch they are raised for two years in enclosures with wire screen lids to prevent cats or rats from getting in. Then for another two years they are kept in larger open enclosures with rocks and obstacles so they learn how to navigate in the terrain of their home environment. At age five they are released to the wild. This past week, 185 tortoises were released on Floreana, the first tortoises there in many years. The released tortoises were only 80% Floreana tortoise DNA but they hope that over time as the new population reproduces the percentage will increase. 

Most of the islands have “dome shell” style tortoises; a few have “saddle shell” style. Dome tortoises forage on the ground, while Saddle tortoises have to be able to stretch their neck to reach shrubby food, enabled by the higher neck of the Saddle. The saddle style is the first kind the Europeans saw, so the word “Galapagos” is the world for “saddle” in Spanish. 

In the afternoon we drove up into the highlands to the “Tortoise Camp”. This is a 12 hectare piece of land formerly farmed, that Natural Habitat is permitted to use for conservation and ecotourism. They have already removed most of the introduced/invasive plant species (blackberry and guava in particular) and are starting to work to replant Scalesia, a giant daisy.  As the habitat improves, more tortoises is the property as a corridor for the females to get to and from the ocean shore to lay their eggs. 

Pictured: Dome and Saddle shelled tortoises, baby tortoises, some tortoise closeups, scalesia