Sound knowledge of the biology and ecology of a species is tantamount to conservation success. Despite their international recognition, the abundance, distribution, migration routes, diet and habitat engineering impacts of these animals have been poorly understood. The Galapagos Tortoise Movement Ecology Programme, led by Dr Stephen Blake of the Max Planck Institute of Ornithology, is in collaboration with the Galapagos National Park (GNP) and the Charles Darwin Foundation and is answering some of the following questions:
- What are the spatial needs of Galapagos giant tortoises?
- How, when, where and why do tortoises migrate?
- What factors disrupt movement?
- What habitat resources are critical for survival?
- What are the ecological roles of Galapagos giant tortoises?
- How are tortoise populations changing over time, particularly in response to management threats and interventions?
The tracking team use both traditional survey methods (e.g. behavioural observations) and high tech methods such as fixing tags to the tortoises including a GPS, accelerometer and radio beacon to track their migrations. They have tagged individuals from four tortoise populations so far – two on Santa Cruz, one on Alcedo volcano, Isabela and one on Espanola. The data from these tags are freely available on Movebank, a repository for migration data for many species around the world. This can then be plotted on Google Earth to visualise the tracks that the tagged tortoises are taking.
Galapagos giant tortoises fulfil their remit as “ecosystem engineers” in two key ways. Firstly, they act as biological bulldozers working their way through the environment, carving paths through the scrubby vegetation. Secondly they eat copious amounts of plant matter and as such are a major vehicle for seed dispersal. Data collected from this project showed that a single pile of tortoise dung contained over 6,000 seeds from nine different plant species! This means that they disperse introduced species as well as native ones raising the possibility that they could facilitate the movement of alien plants around the islands.
Educating Future Tortoise Stewards
An environmental education programme runs beside this project in conjunction with other organisations including the University of Missouri, Houston Zoo and Ecology Project International (EPI). Both in the field and in the classroom, the project is connecting local students with the importance of Galapagos on a global scale is a key objective of GCT and we are using these international education connections to augment outreach here in the UK too. In 2016, almost 200 local students were engaged via the EPI programme.
The ‘Lost Years’
The life stages most critical to the population dynamics of tortoises are from egg to juvenile, when mortality rates peak. These stages are called the ‘lost years’ because little data exist on growth, mortality rate and causes of death. Our continued research is vital in understanding the ‘lost years’ of the Galapagos giant tortoise. This project is the first of its kind with no other studies conducting research on the ecology of hatchlings with a holistic background covering scientific, conservation and educational outcomes. Almost 100 nests have now been monitored since 2013 and several hatchlings have been tracked increasing our understanding of the threats that these youngsters face.
The intensification of agriculture is affecting giant tortoise migration routes and health so it is crucial to work with the local farming community to ensure that tortoises are not negatively affected by barriers such as fences and large fields. In addition, the project aims to inform the development and implementation of land-use policies that will allow both humans and tortoises to thrive.
Ensuring that viable tortoise populations exist will not only prevent us from losing another of these iconic species, but also bring benefit to the local population through tourism. Galapagos giant tortoises provide the mainstay of land-based tourism, the main driver of the local economy, yet few local people on Galapagos appreciate either the socio-economic importance of tortoises or the extent of the threats to which they are exposed. The Galapagos giant tortoise is also a keystone species, so healthy populations are critical for habitat preservation.
For the latest updates on the project, please read our 2016 report (PDF).