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December 1, 2018
The Galapagos National Park Directorate and Galapagos Conservancy recently carried out the first comprehensive census of the Eastern Santa Cruz Giant Tortoise (Chelonoidis donfaustoi) as part of the Giant Tortoise Restoration Initiative (GTRI) in order to determine the status and range of this species and identify any threats. These activities will inform the development of management actions to ensure the conservation of this species.
In October and November of this year, 40 Galapagos National Park rangers, scientists from Galapagos Conservancy, and technicians from the Tortoise Movement Ecology Program completed the census over 18 days total. They covered an area of 80 sq km, both within the Galapagos National Park and on private property adjacent to the Park.
The Eastern Santa Cruz Giant Tortoise was listed as a new species in October 2015. This census resulted in a population estimate of 500 tortoises, with many juveniles, based on a preliminary analysis. This is about 100 more than the previous estimate (used for the recent listing of the species on the IUCN Red List of Threatened Species). Galapagos Conservancy’s Washington (Wacho) Tapia, Director of the GTRI, indicated that two nesting zones were located within the range of this species. The primary nesting area is located at Cerro El Fatal.
“This census included locating all individuals and marking them with a microchip, analyzing the population structure (number of males, females, and juveniles), defining the geographic range, threats facing the population, reproductive success, and other aspects of the population. This will aid the Galapagos National Park in adopting management measures to conserve the species,” said Tapia.
A total of 403 tortoises were located during the census. The survey teams also collected scat samples as part of a broader tortoise diet study throughout Galapagos. A gratifying aspect for park rangers and scientists was finding many juvenile tortoises between two and ten years old, all in very good condition despite the extreme drought currently in the area where the juveniles live.
Jorge Carrión, Director of the Galapagos National Park, added that “we are collecting and incubating eggs and raising young tortoises of this species in the Fausto Llerena Tortoise Center, which will ensure the entry of even more juveniles into the population.”
The park rangers and scientists who participated in the census also conducted control of fire ants (Solenopsis geminata) in the area. This invasive species is a voracious predator of tortoise eggs and hatchlings.
The technicians estimate that the information collected will help them develop management measures to protect the species and help increase its population. This includes improving interactions with farmers, as the tortoises represent an important resource for nature tourism in the area. The goal is to ensure that the tortoises maintain their normal behavior in the most natural conditions possible, even when in farmland.
Content based on a press release from the GNPD, translated with their permission.