Field ecology of Karoo dwarf tortoises (Chersobius boulengeri)

Aim
Gathering information on the species’ ecology, given its decline and rarity of published ecological data. Gathered information should enable conservation.

Materials and methods:
GPS, mark-recapture, radiotelemetry, and radiography.

Timeframe
From 2005 to 2017, several intensive surveys were conducted to locate a population dense enough for a meaningful ecological study. Eventually, a population was found in February 2017. A population study started in 2018 and fieldwork ran until 2022. The data processing and publishing continued until 2025.

Collaborators
The study was a collaboration with the Chelonian Biodiversity and Conservation programme of the University of the Western Cape (South Africa). The study also collaborated with Utrecht University and Van Hall Larenstein University of Applied Sciences (Netherlands) by providing internship positions for BSc and MSc students. In addition, the following field assistants participated: Sheryl Gibbons, Courtney Hundermark, Andreas Iosifakis, Mark Klerks, On Lee Lau, Clara Lemyre, Esther Matthew, Olda Mudra, Sharon Pavoni, Susannah Peel, Bonnie Schumann, Sérgio Silva, Paul van Sloun, and Carlos Voogdt. The Abraham Esau hospital in Calvinia provided radiographs.

Sponsors
The following sponsors enabled the project: Knoxville Zoo, Turtle Conservation Fund and Conservation International, Holohil Systems, British Chelonia Group, Crocodile Zoo Prague, Turtle Survival Alliance Europe, Dutch-Belgian Turtle and Tortoise Society, Pedak, Soek ‘n Slapie, Jan Barth, Kurt Engl, Sheryl Gibbons, Silja Heller, Brian Henen, Retha Hofmeyr, Courtney Hundermark, Lutz Jakob, Johann Klutz, Martijn Kooijman, Matthias Kupferschmid, Koos and Coby Loehr, Frank van Loon, Marcel and Lydia Reck, Peter Sandmeier, Uwe Seidel, and Paul van Sloun.

Publications

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Field ecology of speckled dwarf tortoises (Chersobius signatus)

Aim
Determining baseline information on population size, population dynamics, morphology, growth, natural diet, tick infestations, and reproduction, for a population in the northern part of the species’ distribuiton range.

Materials and methods
GPS, mark-recapture, radiotelemetry, thread-trailing, radiography, and ultrasonography.

Timeframe
The study started in 2000, and fieldwork was completed in 2004. The data processing and publishing took until 2007, and was completed with a PhD dissertation in 2008. Subsequently, a follow-up study was started in 2012 that ran until 2015, with data processing and publishing continuing until 2020.

Collaborators
Although the work started as a short-time project, it was eventually incorporated in the Chelonian Biodiversity and Conservation programme of the University of the Western Cape (South Africa). Retha Hofmeyr and Brian Henen supervised the work, and were actively involved in fieldwork. In addition, the following field assistants participated: Patrik Abramsson, Mats Blohm, Tamara Harris-Smith, Chris Hobson, Janne Karlsson, Mark Klerks, Linn Lagerström, Tom Licitra, Frank van Loon, Peter van Putten, Jacobo Reyes, Ina Schettler, Fabian Schmidt, Sebastian Scholz, and Marsha van Tilborghs. The Dr. van Niekerk hospital in Springbok provided radiographs.

Sponsors
The following sponsors enabled the project: Chelonian Research Foundation (Linnaeus Fund), National Research Foundation (South Africa), University of the Western Cape, Tortoise Trust, Dutch Foundation for the Advancement of Herpetology, Schildkrötenfreunde Österreich, Dutch Turtle and Tortoise Society, World Chelonian Trust, Basel Zoo, University of Colima, Seneca Park Zoo, AnTech instruments, Barbour Threads, CamCode/ StatsDirect, Cellpack, Microscoop Service Rob Engelhard, Mulder-Hardenberg, Röbke Agenturen, Blohm family, Jaco Bruekers, Erol Engin, Michael Hebbeler, Chris Hobson, Gerrit Hofstra, Janne Karlsson, Mark Klerks, Martijn Kooijman, Tom Licitra, Koos and Coby Loehr, Frank van Loon, Bill Sawey, Ina Schettler, Julian Schlömer, Fabian Schmidt, Sebastian Scholz, Paul van Sloun, Rob Verhoeks, Sabine and Thomas Vinke, and Lars and Petra Wolfs. 

Publications

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Field ecology of greater dwarf tortoises (Homopus femoralis)

Aim
Determining baseline information on population size, population dynamics, morphology, growth, natural diet, and reproduction, for a population in the Karoo.

Materials and methods
GPS, mark-recapture, radiotelemetry, radiography, and ultrasonography.

Timeframe
The study started in 2006 with the selection of a study site, and fieldwork ended in 2011. Papers were published until 2013.

Collaborators
This project was a collaboration with Retha Hofmeyr’s Chelonian Biodiversity and Conservation programme at the University of the Western Cape (South Africa). In addition, Francois Busson and Siebren Kupurus assisted in the field. Beaufort-West Hospital provided radiographs.

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Thermoregulation in speckled dwarf tortoises (Chersobius signatus)

Aim
Determining if speckled dwarf tortoises are challenged by low environmental temperatures at times when food is available (i.e., winter and early spring), and assessing potential vulnerabilities for anthropogenic impact.

Materials and methods
Radiotelemetry, iButtons, and tortoise models.

Timeframe
The study started in 2012, and would finalise in 2014. However, it was extended to 2015 as a result of low tortoise activity in 2014. The data processing and publishing started in 2014 and ended in 2018.

Collaborators
Two BSc students from the Van Hall-Larenstein University of Applied Sciences (Netherlands) measured individual time budgets. The study was a collaboration with the Chelonian Biodiversity and Conservation programme of the University of the Western Cape (South Africa). In addition, the following field assistants participated: Michael Hebbeler, Mikolaj Kazmierczak, Martijn Kooijman, Olda Mudra, Fabian Schmidt, Sérgio Silva, Sabine Sommer, and Susanne Sommer.

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