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Leopard Tortoise on Lolldaiga Hills Ranch

Grant Rowley, Lolldaiga Hills Ranch

The Leopard Tortoise Stigmochelys pardalis is the fourth largest species of tortoise in the world (up to 18 kg), and the largest and most abundant in sub-Saharan Africa (Drabik-Hamshare 2017). The distinctive black or dark grey markings on the yellow or tan shell (= carapace) is unique for each individual and tends to fade with age. The Leopard Tortoise prefers the arid and semi-arid regions of eastern and southern Africa, being distributed from South Sudan and Somalia in the north, southwards to South Africa, and westwards to Namibia. The Leopard Tortoise is negatively affected by habitat loss, fire, and the pet trade. None-the-less, this species remains common at many sites and is listed as ‘Least Concern’ on the IUCN Red List of Threatened Species.

Adult Leopard Tortoise Stigmochelys pardalis in open Whistling Thorn Acacia drepanolobium woodland on Lolldaiga Hills Ranch, central Kenya. Photograph by Grant Rowley.

Leopard Tortoise is the only species of tortoise recorded on Lolldaiga Hills Ranch, central Kenya, where it is commonly encountered. The only other turtle known with certainty to be present on the Ranch is the Serrated Hinged Terrapin Pelusios sinuatus. During a herpetofauna survey in December 2013, droppings thought to be those of the poorly known and ‘Vulnerable’ Pancake Tortoise Malacochersus tornieri were found at the northern extreme of Lolldaiga Hills Ranch, but this species has never been sighted on the Ranch (Spawls et al. 2013).

Between 12 May and 25 June 2018, 31 Leopard Tortoises were encountered on Lolldaiga Hills Ranch and 19 on the contiguous Enasoit Ranch. Data obtained during each encounter included date, time, location, altitude, vegetation type, sex, weight, greatest circumference, and greatest length of the shell along the mid-line. Photographs were taken in order to identify each tortoise over the long-term.

Examples of the variation in shell shape and colour among adult Leopard Tortoises Stigmochelys pardalis, Lolldaiga Hills Ranch. Photographs by Grant Rowley.

Leopard Tortoises were encountered between 1,823 and 2,217 m asl (mean = 1921 m). This species appeared to be at highest density below 1,500 m asl. Of the 50 Leopard Tortoises encountered, 22 were males and 28 were females.

Adult female Leopard Tortoises are, on average, larger than adult males (Baker 2015). The measurements obtained from tortoises encountered on Lolldaiga Hills Ranch confirm this (Table 1).

Table 1. Mean measurements of 50 Leopard Tortoises on Lolldaiga Hills Ranch and Enasoit Ranch, central Kenya. Ranges given in parentheses.

Tortoises Mean circumference (cm) Mean length (cm) Mean weight (kg)
Males (n=22) 73 (55–97) 51 (40–69) 10.1 (4.5–20.5)
Females (n=28) 78 (35–104) 54 (21–69) 11.9 (4.9–20.8)
Total (n=50) 76 (35–104) 53 (21–69) 11.4 (4.5–20.8)

Four of the 31 tortoises encountered on Lolldaiga Hills Ranch were found a second time (Figure 1, Table 2).

Figure 1. Localities of 50 Leopard Tortoise encountered on Lolldaiga Hills Ranch and Enasoit Ranch, central Kenya. Localities of the four recaptured individuals are connected by a purple line.

Table 2. Distance between initial encounter and second encounter with four Leopard Tortoises on Lolldaiga Hills Ranch.

Tortoise number Distance between first and second encounter (m) Days between first and second encounter
5 67 14
7 125 1
12 625 14
18 75 6

Leopard Tortoise Stigmochelys pardalis on Lolldaiga Hills Ranch. Photograph by Grant Rowley.

References: Baker, P. J., Kabigumila, J., Leuteritz, T., Hofmeyr, M. & Ngwava, J. M. 2015. Stigmochelys pardalis. IUCN Red List of Threatened Species. Website: www.iucn.org. Drabik-Hamshare, M. & Downs, C. T. 2017. Movement of leopard tortoises in response to environmental and climatic variables in a semi-arid environment. Movement Ecology 5: 5. DOI 10.1186/s40462-017-0096-y. Spawls, S., Malonza, P. K. & Muchai, V. 2013. Report on the three-day survey of the herpetofauna of Lolldaiga Hills Ranch, central Kenya. Report to Lolldaiga Hills Research Programme. Website: http://www.lolldaiga.com/report-on-a-three-day-survey-of-the-herpetofauna-of-lolldaiga-hills/.

 

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