Giant Tortoise Movement Ecology


Project background

Whilst giant tortoise numbers are beginning to increase in Galapagos, they remain under threat from human impacts including invasive species, urbanisation and land use change. Therefore, understanding the ecological needs of tortoises and incorporating them into landscape planning will be important for their successful conservation.

Project specifics

The Galapagos Tortoise Movement Ecology Programme, led by Dr Stephen Blake aims to fulfil several research objectives, including:

  • Determining the spatial needs of Galapagos giant tortoises.
  • Understanding the ecological roles of Galapagos giant tortoises.
  • Assessing how tortoise populations are changing over time, particularly in response to management threats and interventions.
  • To understand the impacts of human activities on tortoise health.

Tracking tortoise movements

The tracking team use both traditional survey methods (e.g. behavioural observations) and high tech methods such as fixing tags to the tortoises to track their migrations. They have tagged individuals from four different tortoise species so far – including two species on Santa Cruz and a single species on both Isabela and Espanola. To learn more about the techniques used for tracking tortoises, visit our Discovering Galapagos case study here.

The team published a paper in 2019 in the journal Ecology which found that Galapagos giant tortoises might be unable to adapt their seasonal migrations in the face of environmental change. Read our blog to find out more.

Projects, Giant Tortoise Tracks (c)Steve Blake

Map A shows the three islands on which the team has tracked adult female tortoises, including Isabela, Santa Cruz and Espanola, whilst Maps B, C and D show the migration routes of the tracked tortoises on Isabela (B), Santa Cruz (C) and Espanola (D) © GTMEP

Measuring nesting success, hatchling survival and health

Adult female tortoises have been tracked on Santa Cruz using GPS to determine whether they use the same nesting sites throughout their lifetime. The results have so far shown that females are using the same migration routes each year, ending their journeys at roughly the same location. The team intends to continue monitoring any changes to migration routes in response to varying environmental conditions. Gaining an insight into how they react to such changes could be critical to understanding their adaptive responses to climate and likely land use changes.

Since 2013 the project’s ‘lost years’ (the years from hatchling to sub-adulthood about which we know very little) study has tagged over 50 hatchlings with VHF radios in El Chato on Santa Cruz. So far the results suggest that those born at the middle zone of elevation have lower levels of mortality than those in the upper and lower zones. This research is helping us to understand the rates and causes of non-natural mortality (for example from introduced pigs, ants and other threats) in tortoise hatchlings, which will help in the development of better management strategies. 

To find out more about how the team are investigating health, please read this blog.

Local education and outreach

Galapagos giant tortoises are one of many species affected by the increasing Galapagos human population so the team is closely involved in outreach and education initiatives. For example, they are working closely with key stakeholders to understand how tortoises interact with the human population in order to reduce tortoise-human conflict. They are also engaging younger generations in their research initiatives, as well as helping to spread their work to the local population. This includes running afternoon sessions with local NGO Ecology Project International’s ‘Mola Mola’ youth club, which is a group of young, local conservation enthusiasts that are based on Santa Cruz. Education activities have revolved around the project’s work tracking tortoises and on seed dispersal.

The team is also investigating human-tortoise conflict, including looking into the costs, benefits and risks posed by giant tortoises to different landowners on Santa Cruz. The team have also been working with land-owners to look at how they can improve tortoise-human relationships including reducing the number of barriers (such as farmland fencing) to tortoise migration routes.

Future plans

As well as continuing the work above, in 2019 the team hopes to deploy new, smaller GPS devices provided by the International Cooperation for Animal Research Using Space (ICARUS) onto newly emerged hatchlings, with data being uploaded to the International Space Station automatically and then sent to the internet. These tags will allow the team to increase their sample size, expand to other islands and species of tortoise, and obtain near real-time data when death occurs that will help identify the cause.  

How you can help

Why not buy one of our Giant Tortoise digital adoptions or become a GCT member and help fund the conservation of this species for years to come!

This program is a multi-institutional collaboration among the Charles Darwin Foundation, the Max Planck Institute of Ornithology, the Galapagos National Park, Saint Louis Zoo Institute for Conservation Medicine, the Houston Zoo and Galapagos Conservation Trust.

This work has been made possible thanks to the support of GCT members as well as generous grants from the Woodspring Trust and British Chelonia Group .