Marginated
Tortoise
The Marginated Tortoise (Testudo marginata) is the largest
European tortoise, reaching a weight of up to 5 kg (11 pounds) and
a length of 35 cm (14 inches).
Marginated
Tortoise, Testudo marginata sarda
Its shell is oblong and has a notable thickness around the middle
of the body. The posterior end of the shell has a saw-like
formation, flanged outward like a bell. The carapace of adult
specimens is almost completely black, with yellow highlights. The
ventral shell is lighter coloured and has pairs of triangular
markings with the points facing the rear of the animal. The front
sides of the limbs are covered with large scales. In old female
specimens, the rear flaps of the underside of the plastron are
somewhat moveable. The tail is notable for a lengthwise marking and
for an undivided carapace over the tail. Males have a longer tail,
which is thicker at the base than the females. Their underside is
more strongly indented. Males are also often larger than the
females. The females lay their hard-shelled spherical eggs in the
soil in May and June.
Habitat and feeding habits
The natural range of the Marginated Tortoise is southern Greece,
from the Peloponnesus to Mount Olympus. They are also found in
isolated zones of the Balkans and Italy, with a somewhat broader
range in northeastern Sardinia.
The Marginated Tortoise lives in more mountainous regions than
Herman's Tortoise (Testudo hermanni). It can be found in elevations
as high as 1,600 m (5,250 feet). The black color of the carapace is
helpful for survival in this environment, as it allows the tortoise
to absorb a great deal of heat in a short time, helping it maintain
its body temperature. Similarly, the lighter colored underside
slows the radiation of body heat into the cold ground. Early in the
morning, Marginated Tortoises bask in the sun to raise their body
temperature, and then search for food. After feeding, the tortoises
return to their shelters in the hot midday hours, leaving them
again in the late afternoon.
Marginated Tortoise's food source consists primarily of plants from
their native Mediterranean region. In captivity, the primary
foodstuffs are dandelions, clover, salad leaves such as rocket or
watercress, and also leaves from bean, radish, and crowfoot plants.
Sometimes even grass and hay will be eaten, along with fruits.
Lettuce will be eagerly devoured, but owing to its low nutrient
value should not generally be given. They are primarily
herbivorous, but they need a small amount of animal protein in
their diet, particularly in the case of babies and egg-laying
mothers. This protein is generally provided by earthworms and
snails.
Subspecies and related species
The primary subspecies of Testudo marginata is Testudo marginata marginata (Schoepf, 1789), described
above. Two additional varieties are generally mentioned in
connection with the marginated tortoise. Testudo marginata sarda (Mayer, 1992)
is a separate population in Sardinia. This subspecies has less
strongly bent tiles in the posterior of the carapace, and the
posterior of the carapace is almost smooth compared with the
saw-like Testudo marginata
marginata.
T. marginata marginata (left) and
T. marginata sarda (right).
A particularly small variation of the marginated tortoise was
discovered in the southwestern part of the Pelopponesus. However,
the Dwarf Marginated Tortoise is not a subspecies, but rather a
related species in the same genus (Testudo weissingeri, Bour,
1996).
Testudo marginata is also closely related to the Greek Tortoise or
Spur-thighed Tortoise (Testudo
graeca). Both have very similar bodily characteristics, for
example, an oblong carapace, large scales on the front legs, large
covering for the head and cone-like scales on the upper thigh,
undivided tail covering, moveable stomach plates, and lack of a
tail spike. Presumably, Testudo marginata evolved from Testudo
graeca as a population more suited for life in the mountainous
regions. Evidence in favor of this is the wide geographical region
and the extremely large number of subspecies of Testudo graeca,
including a subspecies in Turkey with strongly bent carapace tiles,
like the Marginated Tortoise. Testudo marginata on the other hand,
despite the two subspecies, presents a much more unified
appearance, which points toward an earlier appearance in
evolutionary history. In captivity, the two species often
cross-breed.
Mating and reproduction
Immediately after waking from hibernation the mating instinct
starts up. The males follow the females with great interest,
encircling them, biting them on the limbs, ramming them, and trying
to mount them. During copulation, the male opens his mouth, showing
his red tongue and making loud cries. The tone of the copulation
cry is almost sobbing with long, deep tones, in contrast to Testudo
hermanni, in which there is a much higher-toned peeping
noise.
During mating, the female stands still and holds her head to the
side, looking up to see the opened mouth of the male. It appears
that the red tongue serves a signalling function. The female moves
her head from left to right in the same rhythm as the male's
cries.
Afterwards the female seeks out an adequate location to lay her
eggs. Once such a place is found, the female stands still, propping
both front legs firmly against the ground. Then she digs out a hole
with her hind legs, alternating between left and right, beginning
with simply scratching the ground but eventually moving large
quantities of soil which are piled up beside the hole. The depth of
the hole is determined by the length of her hind legs. If the
ground is too hard to dig, the female releases water from her anal
gland to soften it.
Once the hole is dug egg laying begins. Each egg is gently rolled
back into the hole. After the last egg the female immediately
begins refilling the hole, again using her hind legs. Finally, she
stamps the opening closed with her feet so that the ground regains
its natural hardness. Larger animals may lay eggs as many as three
times per summer, with about 15 eggs per clutch.
Issue #376
