Ever aiming to allay turtle guilt (regular readers will know what I’m talking about), welcome to a very brief article - mostly published because I still don’t have time to produce anything more substantive - on leopard tortoises…
Caption: captive Leopard tortoise in the UK, showing high-domed carapace and a good view of the thorn-like forelimb scales. Image: Darren Naish.
The Leopard tortoise Stigmochelys pardalis is a spectacular African tortoise, sometimes with an exceptionally tall-domed carapace. Leopard tortoises can be enormous, reaching 70 cm in carapace length (there are rumours of Ethiopian specimens 1 m long) and 54 kg in mass. This makes them the fourth largest living tortoise species (though that ranking depends on how many taxa you recognise within species complexes like the Galápagos Chelonoidis species, of course). Leopard tortoises are variable across their range, individuals varying a lot in how ‘blotchy’ they are (some old individuals almost lack blotching entirely and can be mostly dull brown), in whether the scutes are flat or strongly domed or pyramidal (this can depend on the nutritional history and health of the individual), and in the shape of the beak. It ranges from heavily serrated to lacking in serrations entirely.
Caption: contrary to stereotype, tortoises are confident, active walkers, striding around at reasonable speed and engaging in combat and chasing during the breeding season. Image: Bernard Dupont, CC BY-SA 2.0 (original here).
Leopard tortoises have endured a tumultuous taxonomic history and most older-ish sources include them in the genus Geochelone. However, it’s been recognised for some time that the most familiar version of this genus is a polyphyletic mess (more kindly, a grade), and major attempts have been made to tidy things up. Fritz & Bininda-Emonds (2007) found leopard tortoises to be most closely related to the southern African Psammobates tortoises and to be well away from Geochelone proper (the type species for which is the Indian star tortoise G. elegans). Accordingly, they followed Gerlach (2001) in advocating use of Stigmochelys Gray, 1873 for leopard tortoises. Stigmochelys, Psammobates and Geochelone all belong to a separate clade from Testudona, the tortoise clade that includes Indotestudo, Testudo and their close relatives (Parham et al. 2006, Fritz & Bininda-Emonds 2007).
Caption: tortoises - the family Testudinidae - are more diverse than most people realise, with substantial variation in size, shell shape, neck length and ecology. This montage (incorporating images of various species done for my in-prep giant textbook project) shows a variety of ‘normal’ and giant species, including the ‘giraffe-necked’ Saddle-backed Rodrigues giant tortoise Cylindraspis vosmaeri and the enormous Megalochelys. Image: Darren Naish.
Ecology and behaviour. What do we know about leopard tortoise ecology and behaviour? They’re herbivorous and mostly favour crussulas, spekboom (no, I don’t know what that is either… I checked; it’s a succulent), thistles, prickly pear (an invasive in the region) as well as fallen fruit and fungi (Ernst & Barbour 1989). They are apparently highly dependent on short grasses present in areas grazed by big ungulates (in which case you have to wonder if there’s some sort of dependency on big mammals), though grassy areas cut short by people for decorative reasons serve the same job (Alexander & Marais 2007). Like all tortoises they will also gnaw at bones and even eat mammal faeces (especially that produced by hyenas, apparently).
Caption: Leopard tortoise face; this individual shows a serrated rhamphotheca, something not present in all individuals. Image: Muhammad Mahdi Karim, CC BY-SA 2.5 (original here).
In cool weather, they sit still in hollows beneath vegetation or in sediment or rock crevices, sometimes for weeks. Ernst & Barbour (1989) report that they can produce as many as seven clutches in a season, these consisting of between 5 and 30 eggs. That gives some idea of how remarkably fecund some reptiles can be, but is obviously linked to a high rate of juvenile mortality, since baby tortoises are good eatin’ for a great many predators.
Conservation and captivity. The Leopard tortoise has a wide range and is comparatively still abundant, though it is exploited for meat and the pet trade and is CITES listed. Leopard tortoises are now widely bred in captivity, this alleviating pressure on wild populations. The USA banned import of the species in 2000 since its ticks can carry Ehrlichia ruminantium, a bacterium responsible for the disease termed heartwater, cowdriosis, nintas or ehrlichiosis in cattle and other ruminants. Tortoises are resistant to the disease (as are guineafowl) and studies indicate that they’re unlikely to spread it to new areas, but they can at least serve as a reservoir for it (Peter et al. 2001).
Another interesting aside about the influence of captive populations is that people across southern Africa have released forrmer pets such that there are now feral populations around the outskirts of several towns, mostly in areas where the species did not historically occur.
Caption: useful photo (part of a sequence) showing female Leopard tortoise excavating a hole, laying eggs, and covering it back up. Tortoises are excellent diggers, with feet well adapted for this task. The depth and tidiness of the nest hole is impressive. Image: Louisvdw, CC BY-SA 4.0 (original here).
Ok, that’s that. For previous TetZoo articles on tortoises and other turtles, see…
Gilbert White’s pet tortoise, and what is ‘grey literature’ anyway?, October 2008
Giant African softshells – wow!, Jan 2010
Giraffe-necked giant tortoises, May 2010
Giant fossil matamata turtles (matamatas part V), April 2011
In case you forget, softshell turtles are insanely weird, December 2011
Turtles that eat bone, rocks and soil, and turtles that mine, April 2014
Turtles I Have Recently Seen, June 2015
Tortoises as Consumers of Carrion, March 2021
Tortoises as Consumers of Carrion, Part 2, June 2021
Ernst, C. H. & Barbour, R. W. 1989. Turtles of the World. Smithsonian Institution Press, Washington, D. C. & London.
Fritz, U. & Bininda-Emonds, O. R. P. 2007. When genes meet nomenclature: tortoise phylogeny and the shifting generic concepts of Testudo and Geochelone. Zoology 110, 298-307.
Gerlach, J. 2001. Tortoise phylogeny and the ‘Geochelone’ problem. Phelsuma 9 (Supp. A), 1-24.
Parham, J. F., Macey, J. R., Papenfuss, T. J., Feldman, C. R., Türkozan, O., Polymeni, R. & Boore, J. 2006. The phylogeny of Mediterranean tortoises and their close relatives based on complete mitochondrial genome sequences from museum specimens. Molecular Phylogenetics and Evolution 38, 50-64.
Peter, T. F., Mahan, S. & Burridge, M. J. 2001. Resistance of leopard tortoises and helmeted guineafowl to Cowdria ruminantium infection (heartwater). Veterinary Parasitology 98, 299-307.
