Searching for giants

An update from the field as GTMEP tortoise researchers visit Alcedo volcano, Isabela

by Lisa Wheeler

In coordination with the Galapagos National Park and support from Galapagos Conservation Trust, the Galapagos Tortoise Movement Ecology Programme (GTMEP) team carried out a week-long expedition to Isabela island in December 2020 to continue their vital work in tracking and protecting Galapagos’ giants. All fieldwork adhered to local COVID-19 safety restrictions. While in the field, the team downloaded the tortoises’ movement data, collected samples such as blood and oral swabs and took measurements such as size, weight and tail length, to assess the health status of tortoises from Alcedo volcano (species Chelonoidis vandenburghii).

Looking for Anne inside the crater © GTMEP

Looking for Anne inside the crater © GTMEP

The team, consisting of GTMEP researchers and a Galapagos National Park ranger, used radio telemetry to locate eight giant tortoises tagged with GPS devices. Each tortoise is known by name and were found in various locations in and around Alcedo volcano. Christian, Janeene, Isabela and Greg were on the top; Sparkey, Franz, and Spikey were located on the external slopes. The last one, Anne, was located inside Alcedo’s crater. The team was especially pleased to have found Spikey, as she had not been spotted since 2016. Therefore, her movement data has not been downloaded for almost five years. Spikey was located on the southern slope of the volcano, and upon finding her, the team replaced her old GPS with a new, more modern solar powered device.

Greg's movement on the top and inside the crater of Alcedo volcano © GTMEP

Greg’s movement on the top and inside the crater of Alcedo volcano © GTMEP

Giant tortoises have diverse migratory behaviour. During the warm-wet season (January to June) some individuals, like Spikey, go down towards the outer slopes and others, like Greg (see figure below) and Anne, go down inside the crater. They are all going to nesting areas at lower elevations although, similar to land iguanas, as seen on the recent BBC Perfect Planet, we are not yet sure why some individuals choose to nest inside the crater rather than outside. During the cool-dry season (July – December), they all head uphill, towards the top of the volcano where they can find more food and water than in the nesting areas, as a product of the garúa (mist) typical of this season in the highlands.

Tortoises on the slopes of Alcedo volcano © GTMEP

Tortoises on the slopes of Alcedo volcano © GTMEP

In 2021, the GTMEP team will continue to undertake field studies, in line with COVID-19 restrictions, to continue their vital research. The team will monitor tortoise health and the interactions between tortoises and local infrastructures such as farmland and fences. With the data the team has collected over the last ten years of the project, they will focus their attention on ensuring the conservation of these ecosystem engineers.

The Galapagos Tortoise Movement Ecology Programme is a multi-institutional collaboration among the Charles Darwin Foundation, the Max Planck Institute of Ornithology, the Galapagos National Park, Saint Luis Zoo Institute for Conservation Medicine, the Houston Zoo and Galapagos Conservation Trust.

How you can help

You can help us protect Galapagos giant tortoises by donating today or by purchasing one of our Giant Tortoise digital adoptions.