Completing My Thesis Amongst Giant Tortoise Scat

September 1, 2016

By Jennifer Vásconez Robalino 

Sorting seeds in tortoise scat

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After an intense four years of studying biology at university, I began to look for a thesis project, which is how my story of participating as a member of the Giant Tortoise Restoration Initiative (GTRI) began. On November 16, 2015, I started working with Galapagos Conservancy and the Galapagos National Park Directorate.

While scientists and Park rangers were on the expedition to Wolf Volcano in search of hybrid tortoises with genes from the extinct tortoise species of Pinta and Floreana Islands, another group of Park rangers and I began eliminating all fruits and seeds present in the corrals on Santa Cruz Island where the tortoises from Wolf would be housed. This was necessary to ensure that the tortoises brought from Wolf would not consume seeds during their first weeks on Santa Cruz. I was to find out how long the seeds from Wolf stayed in their gut, to determine the required length of quarantine, so it was important that they not eat additional seeds after their arrival.

Cleaning the seeds and fruit from the corrals turned out to be the easiest part of my time with the GTRI. Everything became more complicated on November 29, when 32 adult tortoises arrived from Wolf. My task was to collect all scat produced by these tortoises, separate out the seeds, and determine the species of each — until there were no seeds left. Our aim was to ensure that no plants from Wolf Volcano were deposited in the soil of Santa Cruz where they might become established. In Galapagos, it’s important that species not be transported among the islands, as each island has its own composite of species. The second part of my project was to identify the plant species of the seeds to provide data on the diet of the tortoises on Wolf Volcano.

Collecting tortoise scat

For seven weeks, my routine included two daily visits to the tortoise corrals to collect scat. Each day I sifted through the scats, removing all seeds for future identification. After seven weeks, the day finally arrived when I found no more seeds. This meant that all of the food, including the seeds that the tortoises had eaten on the volcano prior to their trip to Santa Cruz, had passed through their intestines. It also meant that I could stop collecting scat and that the quarantine period had reached its end.

Identifying seeds

Over the course of seven weeks, I collected more than 1,500 pounds of feces produced by 32 tortoises! The work, both to separate and to identify the seeds, was challenging — I needed continued support from volunteers, scientists (especially in the identification of seeds), and friends, as well as my family. I acquired specialized knowledge on the Galapagos flora and its seeds, as well as of the behavior of giant tortoises.

Jennifer reviewing seed manual

On several occasions, although it sounds incredible, the Park rangers responsible for the Tortoise Center and I discovered a few escaped tortoises that had climbed over the rock wall and out of the corral. They were never out for more than a few hours. I didn’t think much about this until six months later: while identifying the species of the extracted seeds, I was surprised to discover a button mangrove seed. When I checked to see if this species grew within the range of the giant tortoises on Wolf Volcano, I was assured that it did not; neither did it grow inside the corral on Santa Cruz where the tortoises were housed.

Sorting seeds in tortoise scatI then remembered the escaped tortoises and considered the possibility that during their short time outside the corral, at least one of them might have reached an area where the button mangrove grows. I explored the route the tortoises had followed and found a button mangrove growing just outside the entrance gate to the rearing and incubation area for hatchling tortoises. It is probable that whichever tortoise consumed the fruit found it there.

During my stay in Galapagos, I learned many new things and made new friends. I had the opportunity to spend time with international scientists as well as with staff from three different institutions: Galapagos Conservancy, the Galapagos National Park Directorate, and the Charles Darwin Foundation, all with the same objective — to contribute to the conservation of Galapagos.

Leaving this incredible project will be difficult. I found that being part of a group of people dedicated to their conservation was inspiring and I hope to continue. Through research and discovery we can all help to ensure the future of Galapagos. In my case, the discoveries came from scat, material that we normally find repugnant, but which actually holds hidden stories within.

Jennifer photo

Jennifer Vásconez, a native of Galapagos, is 23 years old. She studied biology at the Galapagos campus of Central University of Ecuador. She is currently completing her senior thesis on the diet of the giant tortoises of Wolf Volcano, Isabela Island. A key component of her work is determining the time necessary for all seeds to pass through the digestive tract.  The study of seeds from tortoise scat from the tortoises collected on Volcán Wolf provided an opportunity for Galapagos Conservancy and the GTRI to involve an Ecuadorian university student in our priority work, at the same time allowing her to complete her thesis.

 

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  1. Thanks for giving us this perspective on giant tortoise research and what we can learn from scat. We’ll all be interested what you do next, Jennifer.

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