Status, Ecological Characteristics and Conservation of the Pancake Tortoise, Malacochersus TorniEri in Nguni and Nuu Areas, Kenya
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Date
1999-06
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Addis Ababa University
Abstract
Pancake tortoise MaiacocherslIs tomieri is a rock crevice-dwelling terrestrial testunid
inhabiting rock outcrops and kopjes discontinuously distributed throughout the semi-arid
and arid savannas (Somali-Masai floristic zone) of Kenya and Tanzania. Their
distribution overlaps with that of Precambrian rocks of the basement complex system.
The capture-mark-recapture technique used showed that the species population size in
Nguni and Nuu areas is low and declining. Crevice rich rock outcrops with wellvegetated
substrates are specifically preferred. Pancake tortoises are thus patchily and
discontinuously distributed within their overall range. The species is very specialized in
its microhabitat requirements with regard to crevice configuration in which individuals,
pairs and occasionally large assemblages reside. The orientation of inhabited rock
crevices varies from horizontal to vertical. Suitable crevices that provide protection from
predators, overheating and desiccation are limited in number and they may regulate
population size.
The species pair bonding is seasonal and restricted to breeding season. There was no
significant difference (P > 0.05) in mean body weight and straight-line carapace length
of males and females. Sexual dimorphism is not well marked. There was a highly
significant positive linear correlation (r = 0.964) between straight-line carapace length
and body weight. Outside crevice activity is very limited and only some hatchlings were
found basking on rock surfaces during the wet season. During the dry season all
specimens were within their crevices presumably aestivating. Movement in Pancake
tortoises is very limited and centered on their rock crevices as the core areas. Males are
more wide ranging than females. Females are relatively sedentary. Age structure of
Pancake tortoise shows that adults dominate the population with very few young
signifying a declining population. Considerable variation in adult color patterns was
observed. The use of growth rings in estimation of age was found to be less reliable as
age increases. Habitat alteration by humans in the form of shifting cultivation was
identified as the major threat to Pancake tortoise population. Isolation of suitable habitats
coupled with limited dispersal abilities of the species and low recruitment rates make
, recovery of depleted populations unlikely. In situ conservation through establishment of
publicly and/or privately owned nature reserves is recommended over that of tortoise
farms. Tortoise farms may provide incentive to manage and conserve the species,
although it may in turn encourage illegal off-take.
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Biology