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Keeping & Breeding
Tortoises in Captivity (1990)
Species
Data and Captive Breeding Chapter
By
A. C. Highfield
This
is the original text from the 1990 edition of Keeping & Breeding
Tortoises in Captivity. The current, updated and greatly expanded
edition is known as the Practical
Enyclopedia of Keepng & Breeding Tortoises & Freshwater
Tutles and
is published by Carapace
Press.
Note:
There have been a number of taxonomic changes since this original
text was published. See updated book and other articles on this
website.
The information which follows is intended as a concise
and practical guide to the basic requirements of some of the more commonly
encountered terrestrial species from both temperate and tropical climates. It
is not intended as a ‘complete’ guide to the maintenance and breeding of these
species; it should however provide a good starting point and serve as a basis
for further experimentation and progress in their captive husbandry. Most of
the data presented is based upon actual records obtained from successful
breeding groups and field studies of the species in the wild. Under the heading
of each species or genus I have included a short taxonomic note. This is
necessarily very brief, although in some instances the status of the taxon may
be anything but straightforward. Where this is the case, I have included (I
hope) sufficient information to enable identification for captive breeding
purposes and enough description to avoid inadvertent hybridization between questionable
forms.
KINIXYS - AFRICAN HINGE-BACK TORTOISES
General observations: Members of the genus Kinixys are
distinguished by their uniquely hinged carapace which allows the rear of the
shell to close giving additional protection to the tail and legs; a character
which sets them apart from all other terrestrial tortoises.
Taxonomy: The status of Kinixys species is, at the
present writing, in a state of considerable flux. Until only recently three
species had been recognised by most authorities; Kinixys belliana, K. homeana and K. erosa. These last two being clearly distinguishable from the former.
Kinixys belliana was assumed to have a wide distribution, from Senegal and
northern Cameroon, via southern Africa to Madagascar; as is often the case
where wide distributions are assumed, this in fact appears not to be the case.
This apparently extensive distribution is illusory, and what passed for ‘identical’
“Kinixys belliana” in much of its assumed range actually comprises populations
formed not only of several different subspecies, but also no less than 3
additional full species! In many respects, a situation which finds a parallel
in North Africa with regard to Testudo graeca. The
current checklist for Kinixys (based upon the pioneering work of Donald G.
Broadley with this genus) therefore includes Kinixys homeana, K. erosa, K.
belliana belliana, K. belliana nogueyi, K. belliana zombensis, K. spekii, K.
lobatsiana and K. natalensis. It is quite likely that as studies progress
additional forms will be identified. From the captive breeding point of view it
is readily admitted that such a profusion of species creates some difficulties
- not the least of which is obtaining a satisfactory identification of
specimens. Fortunately, those species most likely to be encountered under
captive conditions, K. homeana, K. erosa and K. belliana belliana are
relatively easy to identify and in the case of unusual specimens study of
specialist works on South African chelonia should provide the answer.
Description: The maximum dimensions recorded for male K. belliana belliana are
SCL (straight carapace length) 206mm and for female specimens 217mm. The
carapace is a dull yellow-buff color with darker brown or reddish-brown central
scute markings. The upper posterior section of the carapace is gently rounded.
Kinixys homeana and K. erosa are very different from K. belliana in overall
appearance, being an overall reddish-brown color with lighter rather than
darker centers to the scutes, and in both cases these tortoises are much more
sharply angular at the rear portion of the carapace than K. belliana. This characteristic
is much more marked in K. homeana than in K. erosa and may be used to separate
the two; in K. homeana there is typically a vertical descent from the 5th
vertebral scute to the supracaudal. Kinixys erosa is the largest of the
hinge-backs, with males often exceeding 315mm and females 250mm. K. homeana is
a smaller species, with males rarely in excess of 208mm and females 220mm.
Captive environment: It is not easy to generalize the requirements of Kinixys
specimens, as they inhabit a surprisingly wide range of disparate biotypes from
coastal plains and savannah to the edges of forests and swamps. Without knowing
the origin of specimens it can therefore be extremely difficult to provide the
sort of environment to which the animal is accustomed. Some experimentation is
usually required, the environment being adjusted in accordance with the
tortoises responses. As a starting point, a relatively high humidity should be
provided with a daytime temperature in the order of 24-27 oC. Water should be
available at all times, as Kinixys species like to soak and even swim on
occasions. Those from forest habitats (e.g. K. erosa and K. homeana) prefer
more shade than those from open or savannah habitats, but all tend to be
secretive and appreciate a secure retreat area. Most
Kinixys tortoises tend to be more active during wet and rainy weather and in
southern Africa K. belliana is known to aestivate during very dry periods.
These tortoises frequently also show a tendency to feed and become active at
dawn and dusk. In good weather Kinixys species can be maintained outside
successfully in both Europe and the U.S.A.
An outdoor pen is generally satisfactory provided it is well planted, kept
moist, and has plenty of shade. A heated indoor retreat may however be required
on all but the very warmest of summer nights. In cool weather these tortoises
are best maintained under tropical greenhouse conditions. In South
Africa, K. natalensis hibernates during the
winter months. Diet: Kinixys species are typically omnivorous with a marked
preference for mushrooms, slugs, snails, mixed fruit (especially banana), and
earthworms. A good variety of green plant leaf material should also be
provided. In a suitable outdoor enclosure the tortoises will find a high
percentage of their food for themselves, spending a considerable time engaged
in hunting down snails, worms and fresh shoots of weed. Breeding: Male Kinixys
can be very aggressive and it may not be possible to maintain more than one per
enclosure. K. erosa appear to be the most aggressive of all, and two males will
sometimes inflict serious injuries upon each other if allowed to. Mating can
likewise be a vigorous affair. Female K. belliana may lay more than one clutch
during the summer, often at intervals of about 5-8 weeks. A clutch typically comprises between 4-8 eggs,
occasionally as many as 10 in the case of large individuals. The eggs are very
elongate and usually measure approximately 38mm X 48mm and range from 23g to
32g in weight. There are inexplicable size variations in the literature
pertaining to the eggs of Kinixys belliana and it seems probable that the
various populations (and subspecies) in all likelihood produce eggs which are
significantly different when considered statistically in a comparative sense. The
hatchlings of K. belliana typically measure some 38-47mm SCL and weigh circa
17-25g at emergence - again there are significant differences between the
different populations. The carapace hinge is not evident in hatchlings and
juveniles. Artificial incubation is most successfully carried out at circa 30.5
oC at medium-high humidity (recommended 75-80%) in either a type I or II
incubator. At 30-31 oC the incubation period is typically 90-110 days. In the
wild the incubation period is variable according to the time of oviposition; it
can take anything up to a year. At lower incubation temperatures the eggs may
remain viable, but the incidence of dead-in-shell (DIS) increases and
incubation time becomes much extended; in their excellent ‘South African
Tortoise Book’ Richard Boycott and Ortwin Bourquin give an example of one egg
which took 10 months to hatch when incubated at 25 oC and another egg which
took 12 months. This latter publication is, incidentally, highly recommended to
anyone keeping South African species in captivity.
GEOCHELONE CARBONARIA - THE RED-FOOT TORTOISE
General observations: This is one of the most common South
American tortoises, with a wide distribution from Panama
to northern Argentina.
The descendants of introduced specimens now colonize a number of Caribbean
islands although the population of Trinidad may be a
natural one. The species is named on account of the bright red scales which
adorn its legs in profusion. Taxonomy: At the higher level, there is much
dispute about whether this species should be attributed to Geochelone or
whether the sub-genus Chelonoidis should be elevated to generic rank to include
them. Thus is it not unusual to see them listed under both headings. With a
wide and fragmented distribution, G. carbonaria demonstrates considerable
morphological variation. This is evident not only in the carapace shape but
also in coloration. However, there are no currently recognised subspecies and
at present the species is considered homogenous. Even so, in view of the
variation already noted caution should be exercised in captive breeding and
preferably this should be restricted to specimens from similar geographical origins.
Description: A large and impressive tortoise, mature
males typically measure some 300mm SCL and most of the females I have measured
appear to be of similar size although much larger examples of both sexes have
been reported. The principal dimorphic feature is the narrow ‘waist’ of males,
which according to some observers are reminiscent of an overgrown peanut (plate
xx). The tail of male specimens is also longer than that of females, and in
males also the rear lobe of the plastron exhibits a much wider and flatter anal
notch. Color does vary according to locality of origin, with Venezuelan
specimens exhibiting a yellowish plastron with a browner carapace and
Argentinean specimens a darker, almost black plastron and carapace. In all
cases the central areola of the scutes are marked with yellow. The head is
typically brightly marked with yellow scales, but some Venezuelan specimens
possess instead a reddish-orange head. Captive environment: Red-foot tortoises
inhabit grassland savannah and drier forest habitats throughout South
America. In only a few localities does it impinge upon true
tropical rainforest habitats. In
captivity, a moderately dry environment and temperature in the region of 21 C
(night) to 27 C (day) will suit most specimens. Access to water should however
be provided at all times. In most of Europe and North
America Red-foot tortoises can be accommodated out of doors during
the warm summer months, at least during the daytime, but in the winter and on
cool nights indoor accommodation is also essential. A well planted outdoor pen with access to a heated hut or
greenhouse is probably ideal for this species which is relatively easy to
manage in captivity. Diet: In the wild these tortoises prefer fallen fruits,
flowers, green leaves and will occasionally take carrion when it is
encountered. In captivity caution should be exercised when offering banana as
they easily become addicted to it and meat products should similarly be very
strictly rationed. Over reliance upon both items can result in serious dietary
problems developing. Most Red-foot tortoises will readily take melon, orange,
mango, hibiscus flowers, mulberry leaves, vegetable greens and grapes.
Breeding: The
mating ritual of Red-foot tortoises is startlingly similar in many respects to
that of T. horsfieldii; the male advances upon the female, circles her
repeatedly, extends his neck near her face whereupon he proceeds to move his
head rapidly from side to side with a strange jerky motion. This is accompanied
by occasional biting, shoving and ramming actions. Eventually he mounts from
behind and during copulation emits an extraordinary sequence of ‘clucking’ or ‘cackling’
sounds. Two male tortoises will often engage in combat, and most mating
activity occurs either during or just after rain. Nesting and egg laying
continues all year. The Red-foot tortoises in our own collection regularly lay
eggs which measure on average 45mm long by 42mm wide and which weigh some
35-50g grammes. Typically a clutch consists of between 3-5 eggs and a female
may lay 2-3 clutches each season. At
30 C in a Type II incubator at moderately high humidity incubation takes on
average 150-175 days. The hatchlings measure approximately 46mm long, are
42-44mm wide and weigh between 26-32g.
GEOCHELONE (CHELONOIDIS) DENTICULATA - THE YELLOW-FOOT OR
FOREST TORTOISE
General: These tortoises are distinguished from G.
carbonaria principally by the bright yellow-orange (rather than red) scales of
the legs. They are also light golden-brown in color, and much larger. It is
widely distributed in S. America and is found in Brazil,
Ecuador, Columbia,
Guyana, Venezuela,
Peru, Guyana
and Surinam.
Like G. carbonaria a population also occurs on Trinidad
and in much of its range it exists sympatrically with G. carbonaria. Taxonomy:
G. denticulata was described earlier than G. carbonaria (in 1766 as opposed to
1824) and in many old accounts is to be found listed under the heading ‘Testudo
tabulata’. As with G. carbonaria there is dispute over its generic attribution.
It does not demonstrate the regional variation so evident in G. carbonaria.
Description: Yellow-foot or Forest tortoises are considerably
larger animals than Red-foot tortoises; the average mean adult SCL is 400mm but
some very much larger specimens are occasionally encountered. The record is believed to be circa 700mm.
Captive environment: G. denticulata inhabit true tropical
and sub-tropical forest habitats; as such, they require higher humidity and
more stable temperatures than G. carbonaria. Continuous access to drinking and
bathing water is essential, and a frequent spray with ‘artificial rain’ is also
helpful in maintaining good health and normal activity. Day and night
temperatures in the order of 25-27 C are recommended.
Diet: As for G. carbonaria.
Breeding: Although superficially similar to G.
carbonaria, Auffenberg has pointed out that the head movement differs in G. denticulata,
consisting of a single sweep rather than in a series of jerky motions. Male G.
denticulata also lack the ‘waist’ of G. carbonaria. Clutch densities have been
reported as higher than G. carbonaria, as many as 15 on occasions, although
most specimens appear to lay between 4-5. In the wild this tortoise does not
appear to nest in the normal way, often leaving the eggs at least partially
exposed. The eggs are similar in size to those of G. carbonaria and can be
incubated under identical conditions. If anything, humidity should be a little
higher. The hatchlings are very similar in both size and overall appearance to
those of G. denticulata; so much so that it is not easy to tell them apart. At 30 oC the incubation period is usually
between 140-160days.
GOPHERUS - AMERICAN GOPHER TORTOISES
General: Because of their North American and Mexican
location, Gopher tortoises have attracted considerable interest and much
scientific investigation; this has resulted in their being among the best known
of all land tortoises. However, also because of their proximity to humankind
they are under severe pressure from collecting and from habitat destruction.
All species of Gopher tortoise are now protected by law and should not be
disturbed. Large numbers remain in captivity, both in private and institutional
hands and therefore they attract considerable interest from prospective captive
breeders. It should be noted that the ‘obvious’ solution of releasing the large
captive population back into the wild to replenish declining stocks is both
genetically and biologically highly inadvisable. Under no circumstances should
captive specimens be simply turned loose. Not only do they pose a potential
genetic risk, but recent evidence suggests that they may contaminate already endangered natural populations with fatal pathogens.
Taxonomy: Until recently it was generally thought that
the taxonomy of Gopher tortoises was relatively straightforward; this has in
fact proved to be very far from the truth. Four allopatric species are
recognised in most recent
accounts; Gopherus agassizi (the Desert tortoise), Gopherus berlandieri (the
Texas tortoise), Gopherus polyphemus (the Florida gopher tortoise) and Gopherus
flavomarginatus (the Mexican or Bolson tortoise) which was itself only
discovered in 1888 and not fully verified until 1959. Very recently however
this apparently simple picture has
been completely overturned by studies which suggest that in fact G. agassizi
and G. berlandieri should be considered separately
under the generic name Xerobates, with only G. polyphemus and G. flavomarginatus continuing
under Gopherus. Considering that Gopherus (Xerobates) are probably the most
intensively studied tortoises in the history of herpetology, that such
discoveries are still being made says much for our knowledge of the rest!. Even
as this book goes to press, reports (as yet unconfirmed) of the discovery of a
possible 5th species of tortoise in Baja, Mexico are being received. Not only that, but further
(mitochondrial DNA) results
indicate that X. agassizi itself appears to comprise at least three genetic
assemblages in discreet geographical zones as divergent from each other as X.
agassizi is from X. berlandieri; clearly these tortoises have a far from simple
ancestry, and a great deal of work still needs to be done if their phylogeny is
finally to be unraveled. Description: Xerobates agassizi; SCL to 380mm,
although most much smaller with females smaller than males. This species is
principally distinguished by its narrow head and large hind feet. Carapace
coloration is light chocolate
brown. Gopherus polyphemus; this tortoise
is externally somewhat similar to X. agassizi, of almost identical color, but the head is
much wider and typically the animal is smaller (circa
250mm although some much larger specimens are encountered). Xerobates
berlandieri; this is the smallest of the Gopher tortoises attaining a typical
adult SCL of 160mm SCL although some larger specimens are seen (to about 215mm) . The scutes have a much darker brown ground
color than X. agassizi (often virtually black), but
feature prominent yellowish central areolae; these
can however be less obvious in
very ancient specimens. The gular
projection is very well developed
in males, less so in females. Gopherus
flavomarginatus; this tortoise is the largest terrestrial chelonian in north
America, and attains the very considerable SCL of 400mm and weighs in excess of 14kg. It has two
very large black-pointed ‘spurs’ on the thighs, a brown and yellow carapace
with yellowish-horn colored plastron and the rear marginals are markedly flared
and serrate.
Captive environment: All Gopher tortoises are very highly adapted
to their native habitat conditions and are by no means easy to maintain
successfully - especially outside their natural bioclimatic range. In addition, the various species do differ
considerably in terms of
temperature and humidity
requirements. There are however common threads, one of which is their
distinctive habit of residing in burrows - these can be up to 8 meters long in
the case of G. flavomarginatus, and up
to 14m long in the case of G.
polyphemus (although X.
berlandieri burrows rarely extend for more than 30-40cm). Not only do these
provide a means of retreating from unfavourable weather conditions generally,
but they provide a microclimate where humidity as well as temperature are
relatively stabilised.
In captivity, all
Gopher tortoises tend to do badly if overcrowded and if mixed at random with
other species. Ideally, they should be provided with an outdoor area of light
but excavatable soil, lightly planted with scrub, grass and succulents. An
overnight shelter is essential, a
small wooden hut is generally satisfactory if provided with a ramp for exit and
entry. An even better option is to provide a natural or artificial burrow. Damp
environments are categorically not suitable for Gopher tortoises - with the
possible exception of X.
berlandieri which I have found to
positively thrive under more humid conditions and G. polyphemus which also
prefers a relatively high level of ambient humidity . Cold and damp however are
definitely to be avoided. In general however, most Gopher tortoises prefer it
hot and dry, and will readily take advantage of both natural sunlight and
artificial basking facilities. The only moisture in desert tortoise
accommodation should comprise the drinking pool - this should be 25-35mm deep and the water changed daily. Gopher
tortoises hibernate during the winter (usually from November or December through March). The best
place for such hibernation is a natural or artificial
burrow. Temperatures for hibernation as
described previously and are similar to those for T. graeca and T. hermanni. Diet: In their native
habitat Gopher tortoises are virtually 100% herbivorous, with X. berlandieri
alone showing some interest in the occasional snail and chance piece of
carrion. The bulk of their diet consists of grasses and low growing herbs,
flowers, succulents and cacti; Opuntia
pads and fruits are especially favoured but grasses generally comprise more
than half of the total dietary intake. In
captivity it is vitally important that the basic chemical balance and profile
of the natural diet is followed as closely as possible, even if exactly the
same constituents may not be available (see Appendix I). Breeding: In such a
diverse group of animals as the Gopher tortoises it is hardly surprising that
considerable variation is found between the various forms in respect of their
reproductive biology; X. agassizi typically lays clutches of 4-8 eggs
(sometimes as many as 14) each
approximately 39mm x 44mm. Incubation in the wild takes approximately three and
a half months. In captivity, they can be successfully incubated artificially at
30-31 C in a type I incubator at low to
medium humidity which typically results in emergence at 80-130 days. The
hatchlings typically measure about 48mm SCL and weigh circa 28g. X. berlandieri
have a lower average clutch density typically depositing 3 or 4 eggs -
sometimes as few as 1, just occasionally as
many as 5. The eggs from a single clutch
may be also laid in different nests, singly.
These eggs are quite different from those of X.
agassizi and when freshly laid are somewhat pliable. They rapidly harden to normal consistency, are markedly elongate
and usually measure circa 48mm X
35mm. The hatchlings are smaller than those of X.
agassizi, measuring on average 40mm long and weigh about 21g. Somewhat
surprisingly considering the shape of their egg, they are rounder and less
elongate than X. agassizi hatchlings. They can be incubated at the same
temperature as X. agassizi eggs but seem to require a much higher level of
ambient humidity throughout the incubation process if embryonic dehydration is to be avoided. A Type II
incubator is recommended for this species. Gopherus polyphemus
lays much more spherical, hard-shelled eggs measuring approximately 40mm in
diameter in clutches ranging from 4 to 7. The incubation period in the wild
varies from 80-110 days but little data is available on incubation times under
artificial conditions. Gopherus flavomarginatus are unlikely to be encountered
in captivity as it is estimated that the total world population is less than
10,000 individuals. However, their eggs, which closely approximate those of X.
agassizi in size can be incubated under very similar conditions. It is
interesting to note that the conservation captive breeding program for this
tortoise in Mexico
has made extensive and routine use of oxytocin injections to induce egg laying.
TERRAPENE - AMERICAN BOX TURTLES
General: Box tortoises are so named because they have
unusually kinetic plastron hinges which in most cases enable to tortoise to
withdraw completely behind a protective “draw-bridge”. The location of these
hinges are important, as they must not be confused with Hinge-back (Kinixys) tortoises which achieve a similar
result but by means of a hinge in the rear of the carapace. This is an
effective defence mechanism and examples of the same evolutionary solution to a
common problem are found not only in the New World
genera Terrapene and Rhinoclemys, but also in the Asiatic genera Cuora and
Cyclemys (Pyxidea).
Taxonomy: American
box turtles belong to the Emydid genus Terrapene. In the U.S two species occur
each of which is further divided into sub-species as follows; Terrapene carolina which is currently considered to have four geographical
subspecies - Terrapene carolina carolina (the common or Eastern box turtle), T.
c. triunguis (the Three-toed box turtle), T. c. major (the Gulf Coast box
turtle) and T. c. bauri (the Florida box
turtle). The second U.S species is Terrapene ornata which has two subspecies -
Terrapene ornata ornata (the Eastern ornate box turtle) and T. o. luteola (the Salt
Basin or Texas
ornate box turtle). Description: Box turtles have characteristically high domed
carapaces which in some forms is somewhat ridged or keeled in the vertebral
region. Terrapene carolina
carolina occurs from Maine
to the deep south; it is quite variable in coloration, but often features
yellow or orange streaks and blotches on a brown colored ground. T. c.
triunguis occurs in Georgia,
eastern Texas and Missouri;
again it is variable in color, some specimens are merely olive or reddish brown
whilst others display a fine pattern of radial flecks on a brown-red ground.
Its main diagnostic feature is that it has three toes on its hind legs rather
than the usual four - although this is by no means an infallible indicator and
it is not always easy for the inexperienced observer to tell T. c. carolina and
T. c. triunguis apart. They are both of similar proportions, most adults
attaining circa 120-130mm SCL and weighing around 470g. Indeed, any description
of U. S. Box turtles can only be regarded in a general sense as a great
deal of hybridisation appears to occur between certain races and evident
intergrades are frequently encountered. The Gulf Coast box turtle, T. c. major
is very much more distinctive in both appearance and size. This, the largest of
the U.S. box turtles, occurs from south-west Georgia to eastern Texas. A female
specimen in our own collection measures 160mm SCL and weighs 635g. T. c. major
is uniformly dark in color, almost black, with radiating light marks and
blotches on the carapace - although these can be absent on some individuals. The feet of T. c. major are more
evidently webbed than in other members of the T. carolina
group. The last of the T. carolina
assemblage is T. c. bauri, the Florida
box turtle. The carapace of this race is similar in appearance to that of T.
ornata, but typically the plastron is unpigmented and featureless and it boasts
two yellow head stripes in contrast to the characteristic orange-white
irregular spotting of T. c. triunguis and T. c. carolina. The Ornate box
turtle, Terrapene ornata is a smaller, very attractively marked species
normally featuring distinctive bright green-yellow eyes. This Box turtle’s feet
show little evidence of webbing, a testimony to its more typically terrestrial
habits than T. carolina. The two
subspecies are very similar, but are considered separate on the basis of a lack
of plastral pattern, typically less distinct carapace radiations and yellowish
head scales in T. o. luteola. This yellow coloration is more evident in females
than males which are typically a more greenish yellow color.
Captive
environment: The various species and subspecies of U. S Box turtle occupy a
variety of alternative habitats. These range from open woodlands in the case of
T. carolina carolina to wet marshes in the case of T. c. major; given such a
range of habitat preferences it is difficult to generalise even for a single
species. However, despite their inclusion
in the Emydid family they are all basically terrestrial in habit. From the captive point of view, the main
essential variable is the degree of preferred humidity and the time spent in or
very near water. Some Box turtles, notably T. c. bauri and T. c triunguis are
more aquatic than others; these turtles will swim in a pond and even dive to
the bottom to forage among the weeds. They are most active in warm, wet weather
- thunderstorms are especially welcomed. Others,
including T. ornata seem to prefer somewhat drier conditions, T. ornata in
particular is essentially a prairie species with a preference for pastures and
open woodlands. All Terrapene species can be safely maintained out of doors in
the U.S.A and most of europe at least during the spring,
summer and early autumn months. The advice sometimes given that a vivarium
environment is ideal is not true. Provided outdoor temperatures are
approximately similar to those experienced in their native habitat, then an
outdoor environment is infinitely preferable. The Tortoise Trust has maintained
all the U.S species of Box turtle in an outdoor terrarium area, very
successfully, for several years. A vivarium environment is only employed with
sick animals or those we wish to place under observation or to isolate for any
reason. A good outdoor terrarium should
provide several square meters of land area, a reasonable sized pond for drinking
and swimming, and should be thoroughly escape and predator proof - ours is
constructed of plywood with a removable wire-mesh top cover. One part can be
glazed, thus creating a ‘mini-greenhouse’
for extra warmth. A good range of weeds and plants should be allowed to grow
within the terrarium, and some hollowed out logs make ideal hides and retreats.
Box turtles are generally shy creatures, and need to feel secure in order to
feed well and to breed. Box turtles do hibernate, typically from November to March.
We normally allow the Tortoise Trust colony to hibernate out of doors
naturally, the turtles burying themselves deeply under some large half rotted
logs in mud, loam and leaf litter. There are reliable accounts of some Box
turtles choosing to hibernate over winter buried in the bottom mud of iced-over
ponds; this is not a procedure which should be encouraged under normal captive
conditions as natural ponds are biologically active to a much greater extent
than artificial ones and anoxia could very easily occur if conditions are
anything less than absolutely ideal. If they are to be overwintered, then a
humid vivarium at a minimum of 21 C is necessary with additional basking
facilities and preferably equipped with full spectrum fluorescent lighting. Do not allow it to become too dry, or ear and
eye problems are almost certain to develop. In the wild, under prolonged
drought or heat-wave conditions Box turtles aestivate, disappearing underground
for weeks on end. Diet: Terrapene species are omnivorous. In the wild they
consume not only berries and other fallen fruit but also snails, insect larvae,
earthworms, crickets, tadpoles, slugs and beetles in addition to toadstools and
green plant material. Juveniles are noticeably more carnivorous in nature than
fully grown adults. In captivity, if a natural outdoor type environment is
adopted then a certain amount of the turtles dietary needs will also be met
from natural resources; our own colony can often be observed hunting for small
prey in the early morning and late evening, especially during or just after a
heavy rainfall. Some supplementary feeding is however essential. This should
comprise a wide range of berries and fruits such as cherries, apple, banana or
melon plus additional vegetables and salad materials including cauliflower,
green and red sweet peppers, lettuce, tomato, mushrooms and even surplus cooked
potato. The animal protein requirement can be met from low fat dog food and
whole dead mice, locusts and snails. Cat food is not recommended as a staple item
as it is dangerously high in fat content. The food should be liberally dusted
with a high ratio calcium supplement to counter the high levels of phosphorous
present in the animal matter. Breeding: Sexing box turtles can be somewhat
difficult; however, in T. carolina males tend to have a red eye whilst females
have a yellowish brown eye; sometimes this also applies to T. ornata
(especially T. o. luteola) but by no means always as a bright yellow-green eye
is more usually seen in this species. Males also have longer and thicker tails
than do females. There is some difference in plastral concavity, typically very
evident in the T. carolina group
but entirely absent in T. ornata. American Box turtles can all be captive bred
under virtually identical conditions. T. c. carolina and T. c. triunguis for
example typically lay 3-5 elongate eggs (occasionally as many as 8) which are
somewhat leathery in texture and on average measure approximately 32mm by 20mm.
These should be incubated in a Type II incubator at high humidity in a sphagnum
moss substrate. If incubated at 26-28 C hatching usually occurs in 70-85 days.
The hatchlings, on average, measure 28mm SCL. If the eggs are allowed to become
too dry during the incubation process then embryonic dehydration will occur and
the eggs will crumple and collapse. The mating process of Terrapene species is
most curious; at one stage the males legs frequently become trapped in the
posterior plastral hinge of the female - the process can also take several
hours in contrast to the very rapid mating procedure of most terrestrial
tortoises. This is preceded by a more typical biting, circling and shoving
phase - during which the males frequently use their front legs to ‘spin’ the
females around.
GEOCHELONE PARDALIS - THE LEOPARD TORTOISE
General: The Leopard
tortoise is the second largest African mainland tortoise (after G. sulcata).
The largest male ever recorded measured 656mm and weighed 43kg. The largest
recorded female measured 498mm and attained a weight of 20kg. Most are substantially
smaller, but it is not unusual to find specimens of both sexes in the 350-450mm
length range and weighing above 15kg. G. pardalis occur from Sudan
and Ethiopia
and extend their range throughout southern Africa. It is
named on account of its strikingly marked carapace which in practice
constitutes an excellent camouflage. Taxonomy: The only currently disputed area
of G. pardalis taxonomy concerns its division into two sub-species; G. pardalis
pardalis and G. pardalis babcocki. Not all authorities accept that two clearly
defined geographical races do in fact occur. However, the evidence for them is
fairly compelling. What is not clear, and what might be the cause of at least
some of the confusion, is whether these are the only races; certainly some
keepers and field-workers I have spoken to are convinced that there may be
more. Intergrades are in any case reported which further confuses the
situation. There are consistent reports of infertility between pairs which are
dissimilar in appearance although which theoretically belong to the same
sub-species. The best fertility is obtained from pairs which are visually very
similar in terms of overall body morphology, coloration and marking. Of the two
recognised forms, G. p. pardalis occupies a limited range in Cape
Province and in the southwestern sector of the Orange
Free State, whereas G. p. babcocki (sometimes known as the tropical leopard tortoise)
enjoys a much wider distribution and appears to be subject to a higher degree
of morphological variation than its Cape relative.
Description: Whilst juveniles of the two currently recognised subspecies are
relatively easy to differentiate, the same is not always true of adults. In
juveniles, G. p. pardalis feature two or more blackish dots in the centre of the
costal and vertebral scutes whereas G. p. babcocki typically feature only one.
In the nominate form the plastral scutes are typically blotched with margins;
in G. p. babcocki the plastron
is typically plainer and lacks the central spots. In adults G. p. pardalis are
said to be typically flatter than G. p. babcocki which is highly domed as well
as being considerably smaller in most cases - although this last stated
character does not coincide with my own observations; I have seen some
extremely large G. p. pardalis. Captive environment: In good weather G.
pardalis should be allowed as much access to an outdoor grazing area as
possible. Shade in the form of low growing shrubs and bushes should be included
to allow retreat from the mid-day sun. During cold weather and over winter, a
large heated shed, greenhouse or indoor penned area is essential which should
attain daytime temperatures in excess of 20 C if activity is to be maintained.
Spot or infra-red basking facilities will usually be quickly taken advantage
of. Overnight temperatures should remain in excess of 10 C. In the wild, the
southern race G. pardalis pardalis is known to hibernate or at least to
experience a winter dormancy period, often seeking retreat from the cold in
other animals’ discarded burrows. In captivity, most keepers prefer to keep the
animals alert and feeding over winter by means of artificial light and heat.
Diet: Leopard tortoises are very typical grazing herbivores; in the wild their
diet consists very largely of grasses and succulents such as prickly pear.
Several authors refer to their consuming bones and hyena faeces for their
calcium content. In captivity G. pardalis should be maintained on a diet very
high in fiber otherwise diarrhoea and intestinal parasite problems will quickly
be encountered. For some years I have maintained a colony of seven G. pardalis
babcocki on a diet consisting of natural graze (grass and assorted weeds)
supplemented with cabbage and other coarse green leaf material in the winter
when graze became in short supply. To supply fluid, a few tomatoes and
cucumbers are included from time to time. This basic diet is heavily
supplemented with ‘Vionate’ and ‘Nutrobal’ as these very large (and rapidly
growing) tortoises have a prodigious demand for calcium. Breeding: Leopard
tortoises, if provided with good accommodation and a well balanced diet, can be
induced to breed quite readily in captivity. Males and females can be diagnosed
by a number of characters; in males the tail is longer and the hind section of the
plastron is depressed (only very slightly so in the case of G. p. babcocki);
males are also somewhat more elongate and narrower than females. In G. p. babcocki the males are smaller than
females, whilst in G. p. pardalis males tend to be larger than females. Males
kept together will often fight, levering at each other with the gular until one
or other desists in defeat. Males court females in a similar manner, with much
pushing and battering with the gular. Finally, the male mounts the female and
accompanies the process with a great deal of deep throated ‘croaking’ and ‘grunting’.
Females carrying eggs may go off their food for a while immediately prior to
laying, and may dig one or more ‘trial nests’ in sunny areas of open ground.
The nest itself usually measures about 25cm deep and accommodates the typical
clutch of 8-10 eggs. Again, differences in clutch size are reported between the
two recognised forms with G. p.
pardalis typically laying more eggs than G. p. babcocki. However, the absolute maximum recorded clutch size for G. p.
pardalis is 18 eggs whilst figures as high as 30 have been reported for G. p. babcocki which appears to contradict
this. The rounded eggs of G. p.
pardalis typically
measure some 43mm in diameter and weigh 50g or more whilst those of G. p.
babcocki often are said to be smaller at circa 35mm with a typical weight of
only 25g. However, this does not accord with my own observations based upon
Kenyan and Tanzanian specimens where the average egg size is closer to 42mm
with a weight of 45g. The hatchlings are also claimed to differ in size, those
of G. p. babcocki at about 38mm in
length and weighing circa 17g whilst those of the southern race are said to be
somewhat larger at approximately 48mm in length and up to 35g in weight. Once
again however I know of 46mm hatchlings which weighed 33g produced by a female
of Kenyan origin. Females may go on to produce several clutches per season - as
many as six totalling 52 eggs in all has been recorded. Incubation times in the wild are very variable, from 178 days in Zambia
to 384 days in Natal. Eggs
incubated artificially in a type I incubator at 28 C hatch in about 180 days;
at 30 C hatchlings can be expected from 130 days onwards but most often emerge
between 140 - 155 days after laying. Incubation humidity should be moderate.
From the moment when the egg is first pierced by the hatchling it may be many
hours or even days before it is finally ready to leave the egg; this is true of
most tortoises including all Testudo, Furculachelys and Geochelone species.
Once the immediate demand for oxygen has been met, the hatchling may remain in
the egg whilst the remains of the egg-sac are absorbed. The only real danger
(under normal captive circumstances) during this time is if the tortoise becomes
dehydrated or if the mucous-like residue inside the egg literally glues the
hatchlings mouth, nose or eyes up; mortality can occur if airways become
blocked in this way. The problem is best prevented by maintaining adequate air
humidity and by gently swabbing any obstructing matter away from the head and
front legs using a damp cotton bud. Normally, human intervention will not be
required but it is as well to be alert to the possibility. Juveniles grow
quickly, and can reach sexual maturity within 5-6 years in the case of males, somewhat older in the case of females
which typically begin regular egg production as they attain a weight of 8kg or
more.
GEOCHELONE ELEGANS - THE INDIAN STAR TORTOISE
General: One of the worlds
most distinctive tortoises, this strikingly marked animal has for many years
been sought after by collectors and illegal export continues to represent a
significant threat along with habitat loss and utilisation for food. It has
been recorded infrequently in Pakistan,
with the main area of distribution in India
and Sri Lanka
where population density is said to be still good. Taxonomy: This tortoise
appears to be closely related to the almost unknown Geochelone platynota of Burma,
from which it differs principally by featuring radiating lines on the plastron
and by having more rays on the costals. According to some authorities G.
elegans has a more conical form to the vertebrals and costals than G.
platynota, but in fact this character is very variable even within G. elegans
and may be related to geographical origin. Description: The maximum recorded
size of G. elegans is circa 350mm, but most specimens are considerably smaller,
usually in the region of 250mm SCL. The carapace features the radiating ‘star’
pattern from whence it takes its name, a characteristic duplicated on the
plastron. Each of the costal and vertebral scutes has a large, yellow central
dot surrounded by a series of radiating yellow stripes. Captive environment: G.
elegans is found in the wild inhabiting dry, scrub forest areas, the borders of
sandy deserts and even man-made wastelands. It also inhabits grassy hillsides
and the borders of cultivated areas. It appears in this respect a robust and
adaptable species, yet in captivity it is generally regarded as extremely
sensitive and delicate. Certainly, it does not mix well with other species and
is best maintained in isolated groups. In other respects, the tortoise appears
to do well if kept under very similar conditions to G. pardalis. In most of
western Europe and n. America
it can be allowed out of doors in good weather, and an enclosure which is well
planted with grass is ideal. Overnight, a heated indoor retreat will generally
be required. Otherwise treat as for G.
pardalis. Diet: As for G. pardalis. Breeding: G. elegans are not a particularly
easy tortoise to induce to breed (or even mate) in captivity although it can be
done. The most consistently successful captive breeding results have been
achieved within the species natural bioclimatic range in India and Sri Lanka.
Although this species habitat is typically dry, stony and thorny for most of
the year, it is subject to seasonal rains or monsoons; it appears to be the on-set of this rainy season which initiates
interest in mating. During this period
(which occurs in India in June) the animals become especially active and feed
extensively upon the new shoots of vegetation. They can often be seen marching
in small groups in some areas, a lone female pursued by several males. In
captivity interest in mating can sometimes be stimulated by either a natural
downpour or by extensive spraying with a hose. Males rarely exhibit mutual
animosity, and aggression is not often observed in this species. Females are
typically larger in size than males (circa 290mm compared to 230mm) and achieve
sexual maturity at about 10-12 years of age. Males can demonstrate sexual
maturity in 3-5 years under captive conditions. The eggs appear to be of very
variable dimensions, although as in
most accounts no geographical origin is disclosed for the specimens it could be
that size varies with location. Most eggs measure about 42mm X 31mm, although
records indicate a range from 38mm to 50mm in length and from 27mm to 39mm in
width. Egg weight is similarly variable from 22g to as much as 38g. Females lay
several clutches per year, typically three, but sometimes more. A normal clutch consists of 3 to 6 eggs.
Incubation periods in the wild demonstrate considerable variability depending
upon how late or early in the season laying occurs; data from captive specimens
within the bioclimatic range indicates that it can take as little as 47 days or
as long as 147 days. Artificially incubated eggs in a Type I container at 28 C
hatch in about 100 days; at 30 C incubation takes circa 75 days. Incubation
humidity should be medium to low. The average length of hatchling G. elegans is
35mm and the average weight 15-16g (recorded minimum = 12g, recorded maximum =
22g). The hatchlings lack the distinct ray markings of the adults initially,
this first becomes really evident at about 12 months of age.
TESTUDO HERMANNI -
HERMANN’S TORTOISE
General: Testudo hermanni enjoys a relatively wide
distribution in the form of two recognised currently subspecies which includes
eastern Spain, southern France, Italy and the Balearic islands, the Balkan
peninsula, Yugoslavia, Albania, Bulgaria, Romania, Greece and Turkey. It is
also found on Corfu, Sicily and Sardinia. Taxonomy: There are, as indicated
above, two currently recognised sub-species of Testudo hermanni. However, these
are not as frequently cited in most field guides and other works of reference ‘Testudo
hermanni hermanni’ in respect of the eastern (Balkan) race and ‘T. h. robertmertensi’ in respect of the
western (French) race. In fact, by virtue of taxonomic priority the western race
is actually the nominate form and should be cited as Testudo hermanni hermanni
GMELIN 1789 with a designated Type Locality of Collobrieres, France. At the
same time, the eastern race should be cited as Testudo hermanni boettgeri
MOJSISOVICS 1889 with a designated Type Locality or terra typica of Orsova,
Romania. The western population, Testudo hermanni hermanni is relatively
homogenous and is certainly very distinctive. The recent discovery of a southern Italian ‘miniature’ form which is
extraordinarily small (adults are typically less than 115mm SCL) but which in
other respects is visually identical to normal Italian or French T. h. hermanni may complicate this state of affairs
in time. Even so it is clear that generally speaking the western populations of
T. h. hermanni are very convergent in all external characters. The same cannot
be said of the eastern sub-species T. h. boettgeri which is by no means
contiguous and which displays an alarming range of shapes, sizes, colors and patterns within what is
supposed to be a single (subspecific) form . It is almost certain that further
research will eventually lead to the identification of certain populations
which will require separate taxonomic consideration. It may also be necessary
to view the entire T. hermanni conglomerate as a complex of many very divergent
individual populations than as two simple and clearly defined geographical
sub-species. Description: Testudo hermanni was first differentiated from T.
graeca on account of the horny tip it bears upon its tail and its lack of thigh
tubercles. Unlike T. graeca, T. ibera and all other Mediterranean
or Asiatic terrestrial species with the exception of T. horsfieldi it has a
fixed and rigid xiphiplastron. It is typically a flattish animal with a broad,
low carapace which bears black markings upon an olive-yellow base. The western
population of T. h. hermanni are
typically smallish tortoises circa 120-130mm SCL whilst certain eastern
populations of T. h. boettgeri can easily reach double this length. In both cases there is marked dimorphism,
with western males attaining a typical absolute maximum of 165mm and females
190mm. I have measured several
(female) tortoises from Bulgaria however which exceed 260mm SCL and which weigh
in excess of 3,400g. Most of the tortoises
of Yugoslavia,
although considerably larger than T. h.
hermanni at an average of 180-200mm SCL do not attain such dramatic dimensions
as that. Curiously, these ‘giant’ Hermann’s tortoises from eastern europe have
all possessed 4 claws on all feet - a character usually associated with T.
horsfieldi. Hybridisation is here ruled out, as they do not occur sympatrically
in the region. It is frequently alleged that it is possible to distinguish
between the western and eastern populations of T. hermanni by determining if
the supracaudal shield is divided or undivided. It is also sometimes claimed
that T. hermanni can be distinguished from T. graeca
using the same criteria. In fact, neither claim is true and this character is
of little value in specific determination. The plastral markings of Testudo
hermanni hermanni are characteristically formed of two almost solid dark bands
running longitudinally down the plastron. Every
specimen of this sub-species examined by the author (several hundred in both
France and Italy) have possessed this feature. The
plastral markings of the eastern form T. hermanni boettgeri appear to be
somewhat more variable. Some specimens examined have possessed plastrons with
dense markings which almost approach that of T. h. hermanni so this character should not
employed in isolation to diagnose speciation. Most bear a diffuse series of
blotches however. The groundcolor of T.
h. hermanni is typically a bright golden yellow. This contrasts sharply with most specimens of the eastern T. h.
boettgeri where the groundcolor could best be described as a greenish-yellow.
Similarly, the carapace markings of the western population seem to be unusually
clear and well defined compared to most eastern specimens. Captive environment:
The natural habitat of T. hermanni is evergreen Mediterranean oak forest; this
habitat has however been substantially degraded and reduced as a result of
human activity. Present-day populations are therefore found in (secondary)
maquis type environments - coarse, arid and scrubby hillsides. In only a very
few places does T. hermanni continue to inhabit surviving primary forest. In
captivity T. hermanni is a comparatively
resilient and adaptable tortoise. It seems equally at home in arid or even
moderately damp environments but plenty of sun and warmth is essential. An
ideal captive situation would provide a large outdoor enclosure, planted with
low growing herbs and shrubs on well drained soil. There should be a slope or
gentle hill to encourage basking and to provide a nesting site. For overnight accommodation, a wooden
hut can be provided although most tortoises will make a ‘scrape’ under a
suitable bush. In the wild, T. hermanni
hibernate from November to April. Diet:
The natural diet of T. hermanni consists of herbaceous and succulent plants
native to the mediterranean zone. In captivity as wide a range of weeds and
green vegetation as possible should be provided. Lettuce alone is far from an
adequate substitute. A natural grazing area is much better than artificial feeding.
Although most T. hermanni enjoy fruits, an excess should not be given as their
sugar content can increase the probability of digestive problems and diarrhoea. T. hermanni require a diet
which is very high in fibre and will often take dried leaves in preference to
fresh. Just occasionally in wet weather T. hermanni will take advantage of a
passing slug or snail but this does not comprise a significant dietary
component. They should not be provided with any meat-based food items in
captivity; if they are, then serious consequences may be encountered in the
long-term. During heavy rain T. hermanni raise themselves on their back legs
and place their noses to the ground in order to drink from shallow puddles;
typically they also void urine at the same time. As with many arid-adapted reptiles they normally choose not
to lose fluid unnecessarily until it can be easily replenished. It is important
to note that as with all mediterranean tortoises, seasonal variations in the
quantity, quality and constituency of the food intake is an important factor;
in spring abundant moist food is available in the form of fresh shoots and
flowers but in summer the land becomes dry and unable to support much green
vegetation. During this period the tortoises consume food with a higher
dry-weight ratio than they do earlier in the year. In extreme conditions (as
experienced in north African mediterranean zones for example) the tortoises may
actually aestivate during this barren period. The early autumn rains result in
a renewal of green vegetation allowing for a final feeding period before
hibernation. Breeding: The breeding behaviour of T. hermanni is very different
from that of all other mediterranean species. Unlike T. graeca or T. ibera male
hermanni do not engage in the same degree of violent ‘ramming’ activity during courtship, instead
resorting much more to head and leg biting which can become quite vicious in
nature to the extent of occasionally drawing blood. The horny tip of the tail
is also used to stimulate the females cloacal region. Males are also frequently
observed apparently ‘resting’ on females backs almost mechanically stroking the
carapace of the female with the front legs; this behaviour, which is conducted
in a seemingly trance-like state can persist for hours. It is not known what
purpose it serves, if any. Mating is a vigorous affair, accompanied by high
pitched ‘squeaks’ from the male during copulation. Egg laying in the wild takes
place from April to June and hatching usually occurs immediately following the
first rains of September. There is a very marked difference both in clutch
density and egg size between the western T. h. hermanni and eastern T. h.
boettgeri; the average clutch size of T. h. hermanni
in France is 3, whilst in eastern T. h. boettgeri it is typically 5-8 and can
be as high as 12. The eggs of T. h. hermanni are fairly small at 30mm long by
24mm wide on average, whilst those of T. h.
boettgeri are by comparison enormous at 40mm long by 29mm wide. Hatchling T. h.
hermanni typically weigh 9-10g or so, whilst eastern T. h. boettgeri hatchlings weigh in at an
average of 12-14g. Statistically and in taxonomic terms, these are very
significant differences. Both sub-species frequently lay more than one clutch
per year. In captivity artificial incubation
at 30.5-31 C normally results in hatching at about the 8th or 9th
week.
TESTUDO (AGRIONEMYS) HORSFIELDI - THE AFGHAN,
RUSSIAN OR STEPPE TORTOISE
General:
The Afghan tortoise has to date been little studied and much remains unclear
concerning its biology, taxonomy and ecology. In
Pakistan T.
horsfieldi occurs in Baluchistan and in very low
densities in the North West Frontier
Province. It also occurs in the
U.S.S.R where it is subject to heavy exploitation. Taxonomy: At the species
level there is little dispute; at genus level its taxonomic status is very
confused. The morphological evidence is conflicting. The cranial characters
suggest a close affinity to Testudo, but the carapace osteology is sufficiently
different for it to be allocated to the genus Agrionemys by several authorities. Externally, it expresses a
marked phenetic relationship to T. hermanni with which it shares the
morphological features of fixed xiphiplastron and horny tip to the tail -
although this latter is reduced compared to T. hermanni. Description: The
carapace is typically flattish, roundish and yellow-green or olive in coloration.
There are some ill defined dark brown markings on the larger scutes. The
plastron is typically blotched with black, or may be black all over on some
examples. There is typically a group
of enlarged scales or tubercles to each side of the tail; these appear to be
larger on males than females. The tail has a hard, horny tip. The feet all have
four claws. The skin is yellowish. A
breeding pair of male and female T. horsfieldi now maintained by the Tortoise
Trust measure 140mm590g and 187mm1,390g respectively. Captive environment: T.
horsfieldi inhabit very arid, barren and rocky areas frequently in excess of
1500m altitude. They burrow deeply into sandy or clay soil in valleys and the
walls of dried-up river beds or ravines. They
often initiate their burrows under clumps of grass and extend the burrow for up
to 2 meters excavating an enlarged chamber at the end. They are most active immediately after hibernation in March and
April. In the extreme heat of summer the tortoises spend most of the day in
retreat deep within their burrows, often emerging only for an hour or two in
the morning or late afternoon to forage. In this, they closely parallel
American Gopher tortoises whose lifestyle they in many respects emulate. In
captivity, T. horsfieldi cannot tolerate damp but otherwise can be successfully
maintained under similar conditions to T. hermanni. Burrowing facilities should
however be provided. This species hibernates during the winter. Diet: As for T.
hermanni. Some reports state that T. horsfieldi rarely take grass, but I have
found that they very much enjoy young green shoots and consume it avidly.
Breeding: In the wild most mating occurs early on in the season. Males are
frequently very aggressive. They chase females, biting at their head and legs
with sufficient ferocity to regularly draw blood. Two males will often fight
viciously if confined together in the breeding season, but at other times seem
to co-exist peacefully. Males court
females by means of a strange ‘head nodding’ ritual, staring directly into the
females face whilst simultaneously jerking their head up and down in a rapid
motion. They emit a series of high pitched squeaks during copulation. The eggs
are usually laid within 8 weeks of successful mating, and typically measure
some 47mm long by 34mm wide but considerable variability is seen between
individual females. Eggs usually weigh between 23-25g. Clutch density is
usually between 3-5, but again this is very variable. Two to three clutches are
often deposited during a season. In the wild, incubation usually takes 80-110
days, but if incubated at moderate humidity in a Type I incubator at a more or
less constant temperature of 30.5 C 60-75 days is more usual. The new
hatchlings typically measure between 32-34mm long and weigh from 9-12g. In
their first year they tend to grow more quickly than hatchlings of either T.
hermanni or T. ibera.
TESTUDO IBERA -
THE SPUR-THIGHED TORTOISE
General: This tortoise occurs throughout Turkey,
north-eastern Greece,
Bulgaria, Romania,
western Iran, Syria,
Jordan, Iraq
and the Republic Georgia in the U.S.S.R. from where the type specimen was taken
in 1814. There is a considerable degree of
morphological variation throughout this very considerable range, principally in
respect of color but also in size; specimens from asiatic Turkey
and Syria tend
to be very much lighter and often feature a bright yellow head and limbs. In north-western Turkey
T. ibera tends to be much more melanistic, and on occasions almost entirely
black. An introduced colony of T. ibera
also exists on Sardinia where it is sympatric with not
only similarly introduced T. hermanni but also T. marginata. Taxonomy: In 1946
the German herpetologist Robert Mertens designated Testudo ibera PALLAS 1814 as
a sub-species of Testudo graeca LINNAEUS 1758 but this suggestion appears
seriously flawed in the light of recent investigations. There are in fact major
structural, biotypic and behavioural
differences between T. graeca and T. ibera which Mertens (and most subsequent
authors) have completely overlooked. Thus, this tortoise should be considered
separately from T. graeca which
it only very superficially resembles. Within the very large and widely distributed
population of T. ibera however there are a considerable number of very distinct
geographical forms or races some of which occur in relative isolation, some of
which appear to represent extremes of clines; only a few of these have so far
received separate systematic recognition. To date only Testudo (graeca)
nikolskii from northwest Transcaucasia and T. (graeca)
anamurensis from southwestern Turkey
have been proposed. It should be noted that although assigned by their
respective authors to ‘Testudo graeca’ if T. ibera is considered a true and
separate biological species these would instead be amended to T. ibera
nikolskii and T. ibera anamurensis. Of the lighter colored and frequently much
smaller Syrian and Jordanian forms very little field data currently exists and
these are sometimes in error referred to as examples of ‘Testudo graeca
terrestris’ with which it also allegedly intergrades (for more details of which
see under ‘T. graeca’). Description: T. ibera is readily distinguished from
true T. graeca; it is considerably larger with males typically reaching 180mm
SCL and females 201mm SCL, although even larger examples are very frequently
seen. It is also much broader and flatter
than T. graeca which is characteristically high domed in lateral profile (the
length-height-width ratios of T. graeca and T. ibera are totally dissimilar). The groundcolor of T. ibera is quite
variable but ranges from a greenish horn color to light orange-brown. The
carapace markings are brownish-black and the vertebral and costal scutes
typically feature a dark central areola with anterior and lateral borders. Very
aged specimens sometimes lose the outer layer of keratin revealing large
irregular bright orange areas underneath.
Another carapace character which also distinguishes T. ibera from T. graeca is
found at the 1st vertebral scute which is very angular compared to
the rounded form of T. graeca. The head (and underlying cranium) of T. ibera is
quite different from that of T. graeca, the nose in particular is broader and blunter
and the eyes are characteristically much larger by comparison. The limbs are by
comparison to T. graeca much thicker and shorter (there are acute osteological
differences involving certain limb bones) . The supracaudal shield is only
occasionally divided and the thighs feature either a single or double ‘spur’. Some geographic populations have
significantly flared or serrate posterior marginals, occasionally upturned or
reverted, a character which is more prevalent in males than females. Captive environment: Generally as for
T. hermanni . Testudo ibera are a relatively tenacious and robust species
capable of withstanding considerable extremes of climate. Along with T.
hermanni they tend to do well under captive conditions and breed very readily. Diet:
As for T. hermanni. Breeding: For best breeding success, pairs should be
closely matched on the basis of general coloration and markings. Although
dissimilar pairs can and do produce viable offspring, this is noticeably less
consistent than is the case if pairs are more closely matched. Clutch density
ranges from 4-12 but more typically numbers 6-8. Large females tend to produce
higher clutch densities than smaller specimens. The
eggs of T. ibera throughout its range appear remarkably consistent in both size
and weight; on average they measure 36mm long by 30mm wide and weigh about
18-20g. They can be incubated in a Type I incubator in a medium humidity
environment and at a more or less constant temperature of 31 C can be expected
to hatch in 60-80 days. The hatchlings
typically weigh in the region of 14-16g and measure 32-34mm SCL. Contrary to
popular belief the hatchlings can usually be hibernated without difficulty -
indeed, it is preferable that they should hibernate if at all possible. However, under
artificial conditions the very greatest care must be taken to ensure
temperatures remain at between 4-6 C and that excessive weight loss does not
occur. Due to the reduced body mass of hatchlings, their core temperature
fluctuates much more rapidly than that of adults in response to sudden
environmental temperature changes - a temperature deviation which might cause
no problem for a large adult can easily kill a tiny hatchling. Nor should
hibernation periods be excessively long - between 65-80% of the normal typical
hibernation period in the wild is usually the advisable maximum. We believe
however that even a short hibernation is beneficial - provided it is correctly
managed. There is simply no rom for error. If overwintering is preferred for
the first year, then a heated and illuminated vivarium will be required.
TESTUDO GRAECA - THE NORTH AFRICAN OR MOORISH LAND TORTOISE
General: Testudo
graeca was for years in europe considered the archetypal
‘pet tortoise’. So much so that it became generally known as the ‘common
tortoise’. However, in reality this creature is little known and is very far
from common. It is found only in certain limited areas of north Africa and a
small population also occurs in southern Spain. I have examined osteological material of north
African descent from the Balearic islands.
Taxonomy: ‘Confusing’ would be the most
appropriate description. Despite being described for the first time in 1758
even today few are aware of its true nature. For many years, Testudo graeca was
considered to be the only land tortoise in n. Africa
with the exception of Testudo kleinmanni which is found in Egypt
and Libya.
Other mediterranean tortoises were considered to be closely related to it and
were thus regarded as sub-species. These included Testudo (graeca) ibera, Testudo (graeca) zarudnyi and Testudo (graeca)
terrestris. This latter is itself the subject of yet more taxonomic confusion
not to say mayhem in that it sometimes also passes for Testudo (graeca) floweri - yet another alleged form which to
all intents and purposes is completely unknown and which entirely lacks any
adequate type description. Both T. ibera and the rarely encountered Iranian T.
zarudnyi are in this authors opinion full and separate biological species
bearing only the most distant relationship to the African T. graeca. Meanwhile
T. (graeca) terrestris simply does not exist in the commonly understood sense.
The name is simply a convenient a ‘catch-all’ for a variety of currently poorly
defined and little known tortoises
which inhabit a herpetologically almost unstudied region. It should be noted
that the allegedly ‘tiny’ terrestris form has never been scientifically
described in any meaningful way and
that some authors versions of this mysterious creature measure in excess of
250mm SCL!. If this situation was not complex enough, it now transpires that
the Testudo graeca described by Linnaeus is far from the only tortoise species
which occurs in north Africa. These recently discovered (or in one case,
re-discovered) tortoises are really very different in almost every respect from
the Linnaean holotype. It is beyond the scope of this particular book to even
begin to describe their complex morphology, osteology and phylogeny; however it
is worth noting that at their most extreme these ‘new’ tortoises include
distinct geographical forms which range from ‘giants’ which attain an SCL of
345mm and weigh almost 5kg (thus equaling T. marginata in length and totally
eclipsing it in body mass) to true ‘pygmy’ or miniature species which even as
fully grown adults measure only 130mm and weigh less than 400g. Certain aspects
of their osteology have caused some to be placed in an entirely new genus
Furculachelys. Others remain in Testudo. The current checklist of north African
tortoises therefore includes not only Testudo graeca (Western
Algeria and Morocco)
and Testudo kleinmanni (Libya
and Egypt) but
also Furculachelys whitei (central coastal Algeria),
F. nabeulensis (Tunisia)
and T. flavominimaralis (Libya).
This latter little tortoise incidentally, with its bright yellow elongate
carapace, bright black eyes, bright yellow ‘masked’ head and yellow scaled legs
is one of the several entirely different tortoises which have frequently been
mistaken for Testudo graeca terrestris on the erroneous basis that as they are
obviously not a ‘normal’ T. graeca they can’t be anything else!.
Description:
True Testudo graeca are a relatively small tortoise but by no means as small as
T. flavominimaralis or F. nabeulensis from which they differ not only
osteologically but also in terms of their external morphology and marking.
Males typically attain no more than 145 mm SCL (the average is 130mm) and weigh
circa 535g. Females are considerably larger and demonstrate a high degree of
dimorphism; 180mm SCL and a weight in the region of 1,300g would not be
untypical. The carapace is not at all flattish but is highly domed. The groundcolor
of the scutes is bright yellow and features an irregular series of small
black-brown flecks or spots. The areola of each large scute has a central black
dot which is bordered laterally and anteriorly. The scales of the head and legs
are yellow. The frontal vertebral scute is roundish in form, somewhat pinched
in or depressed on the lower half. The rear marginals are not at all flared or
serrate, even on males. The supracaudal is not projected and is not ventrally
introflexed. There are small tubercles or ‘spurs’ on the upper thighs, next to
the tail.
Captive environment: T. graeca (and all north African species
generally) are extremely environmentally sensitive and cannot tolerate any
mishandling. They usually tend to do badly in captivity and very few survive in
the long-term. If mixed with other more robust, competitive and aggressive
species such as T. hermanni or T. ibera they rapidly succumb to alien diseases
and stress. They should be maintained separately. They require conditions of
higher ambient humidity than T. hermanni or T. ibera. In the wild when
conditions become too hot and dry they aestivate underground. If deprived of
this facility they soon develop respiratory diseases. Some authors have
mistaken T. graeca aestivating in August (when temperatures regularly soar into
the high 90’s F) as the beginning of their hibernation period!. In fact, some
coastal populations do not naturally hibernate at all - it never gets cold
enough. The coldest months are January and February where it only just falls
below 60 F. In north Africa I have found tortoises grazing and otherwise
behaving perfectly normally on Christmas day. Inland populations at the higher
altitudes are more inclined to hibernate - but only for a very short while.
Extended hibernation periods can be fatal and they should not be subjected to
them.
Diet: Similar to T. ibera, T. marginata and T. hermanni but flowers
appear to be a more important dietary constituent. These tortoises are all
coprophagous to a greater or lesser extent, feasting whenever the opportunity
arises on mammalian dung - in north Africa sheep, goat and camel droppings are
all taken with relish. It is quite likely that this does in fact play an
important biochemical and digestive role but to date this aspect has been
little studied.
Breeding: Unlike T. hermanni, T. marginata or T. ibera, north
African T. graeca are rarely bred at all in captivity. In addition, very little
data is available on their natural reproductive biology or behaviour. In the last 12 months however the Tortoise
Trust has succeeded in captive breeding north African tortoises from several
different localities including true T. graeca. The eggs are much smaller and
rounder than those of T. ibera typically measuring 30mm long by 27mm wide. The
hatchlings weigh a diminutive 7-8g and measure circa 28mm SCL. A typical clutch
consists of 4-5 such eggs. Incubation is best accomplished at between 30.5 C and
31.5 C in a Type I unit at medium humidity. At this temperature range
incubation takes approximately 68-80 days. The hatchlings are light
brownish-yellow in color without distinct markings which develop as they grow.
By 1 year of age they are approximately half the size of T. ibera hatched at
the same time.
TESTUDO MARGINATA - THE MARGINATED TORTOISE
General: Testudo
marginata is one of the largest circum-mediterranean tortoises (comparable only
to Algerian F. whitei which surpasses it in body mass) and is distinguished not only by its extremely flared, serrate and
projecting rear marginals (from which it takes its name) but also by its
unusually marked plastron which is unique among the tortoises of the region
(see however my note concerning T. kleinmanni). The main population
concentration of T. marginata occurs in the Peloponnese
and along the associated Greek coast to Mount
Olympus. Smaller populations occur
on several Aegean islands, and an introduced population occurs on Sardinia.
A small population also survives to this day in Tuscany,
Italy where it
is assumed to have been introduced by the Etruscans. Taxonomy: This tortoise
was described by Schoepff in 1792 and has since acquired a number of synonyms
including ‘T. nemoralis’ and the rather descriptive ‘T. campanulata’. The
Marginated tortoise is distinctive both visually and zoogeographically and its
status has rarely been the subject of any dispute. Early records of alleged ‘T.
marginata’ from north Africa (of which, surprisingly, there are plenty) are the
result of confusion either with the similarly sized F. whitei of Algeria or
equally surprisingly with the diminutive Testudo kleinmanni; despite all the
other differences this little tortoise does feature an approximately similar
set of markings on its plastron - not similar enough to cause any confusion you
would have thought, but nonetheless this mistake has occurred several times.
Description: In addition to the obviously flared posterior marginals noted
above, T. marginata feature several other key distinguishing features. The soft
skin of the upper limbs and tail is typically very creamy pale; much more so
than on either T. ibera or T. hermanni and very noticeably so in young animals.
The plastron of T. marginata characteristically features a large brown-black
triangular marking on each of the larger scutes. The head is relatively small
and the eyes are also smaller and more almond-shaped than those of T. ibera. It has been claimed that T. marginata
have 5 claws on all feet and that the rear plastral lobe is not mobile; neither
statement is in fact true. Adult females typically measure circa 240-280mm SCL
and weigh on average between 2-3kg, whilst males are normally somewhat longer
than females of equivalent age measuring 250-295mm SCL but weigh in the same
range. Length for length females typically weigh more than a male of identical
SCL but are considerably broader in girth. The assumed homogenous genetic
continuity of T. marginata is thrown into some doubt however by recent
morphometric results which indicate that in at least some populations adult
males do not exceed 230mm SCL and females do not exceed 215mm. Other dimorphic
indicators typical of males in this species include tail length, a considerably
narrower mid-line and more prominent marginal flares.
Captive environment: As for T. ibera and T. hermanni
Diet: As for T. ibera and T. hermanni.
Breeding: T. marginata breed readily in
captivity; possibly the fact that there appears to be relatively little genetic
diversity from one part of their range to another (with the exception of the ‘miniature’
populations noted above) plays a part in this. Certainly, almost any male will
mate successfully with almost any female and viable eggs will usually result.
Clutch density is typically 8-10 (occasionally more) and the eggs measure on
average 30.5mm long by 28mm in width. They normally weigh between 16-18g. If
incubated at circa 31 C hatching usually occurs in 60-70 days. Incubation
humidity does not appear to be especially critical, good results having been
noted in low (- 65%), medium (80%) and high (90% +) environments. One of the
most successful breeders of T. marginata I know has used a simple Type II
incubator of the most basic design for several years and invariably succeeds in
hatching large numbers of this species every year. The hatchlings usually
measure some 30mm SCL and weigh between 10-14g. Juveniles are roundish in
overall shape, lacking both the elongate body form and flared marginals of the
adults.
MALACOCHERSUS TORNIERI - THE PANCAKE TORTOISE
General: Malacochersus
tornieri, the Pancake or Soft-shelled tortoise, is in many ways the most
unusual tortoise in the world. It is certainly one which demonstrates a
remarkable degree of adaption. Not only is it almost completely flat, but throughout
life it remains soft and surprisingly flexible - a capability it employs to
useful effect in defense by wedging itself in rocky fissures, expanding itself
and thereby ‘jamming’ itself in very effectively. In order to effect this
remarkable ability, the underlying bones are fenestrated. It is in addition
rated as possibly the worlds fastest tortoise, and surprised specimens will
usually run for cover rather than seek withdrawal into their shells for
protection . Its distribution is limited to Kenya
and Tanzania
where it occurs in thorn covered rocky outcrops to an altitude in excess of
1600m. Taxonomy: This tortoises taxonomy and nomenclature is not currently in
dispute. There are no recognised sub-species. Description: Both males and
females are flat and entirely lack any evidence of the usual carapace ‘dome’.
Females are only marginally deeper in the body than males. The normally
encountered maximum size of males is circa 167mm (height 36mm) whist that of
females is 177mm (height 45mm). A male and female in our collection measure
160mm long by 34mm high and 170mm long by 43mm high respectively. The male
weighs 360g and the female 550g. The ground color of the carapace is typically
a golden brown or horn color with a distinct pattern of radiating black-brown
marks. Females tend to have more of a rayed pattern than males which are
characteristically more ‘mottled’ in
appearance.
Captive environment: Pancake tortoises prefer a dry, rocky
environment in captivity as they do in the wild. If a large, artificial ‘mountain’
can be provided with plenty of retreats and cracks then so much the better.
These tortoises will spend hours scrambling over even the most precipitous
terrain. Peak activity occurs in the morning and early evening, much of the day
being spent in retreat under a convenient rocky ledge. They are inclined to be
gregarious in habit, with several tortoises ‘stacking’ themselves on top of the
other in a particularly favoured retreat. Two males placed together will
however fight viciously during the breeding season, biting and snapping at each
others heads and attempting to turn each other over. Their agility is such
however that they can right themselves with little difficulty. Daytime
temperatures should be in the order of 25 - 29 C although as is frequently the
case with tortoises which inhabit high, dry places Malacochersus tornieri can
withstand considerably lower temperatures overnight. In captivity a minimum of
13 C is recommended. Damp is not much appreciated and should be avoided. This
tortoise rarely drinks water, seemingly obtaining almost all of its fluid
requirement from its food.
Diet: As for G.
pardalis with a preference for grass and succulents. In captivity cabbage,
lettuce, tomatoes and cucumber are taken readily. They seem little interested
in most fruits, although melon is often an exception to this general rule. The
diet should be supplemented as required with multi-vitamins and calcium -
especially for egg laying females and juveniles.
Breeding: M. tornieri mate in
a state of high excitement, the male vigorously snapping and biting at the
females head and legs as he quickly and repeatedly circles her. Eggs are laid
singly, and often at intervals of 6-8 weeks. A female in our own collection
regularly produces such eggs which on average measure 47mm long by 31mm wide
and weigh 35g. At 30 C incubated in a Type I container the incubation period is
typically 140 days, but this does appear to be quite variable sometimes taking
much longer. Incubation humidity should be medium to low. In the wild, eggs are
laid in July or August, but the natural mean incubation period remains unknown.
In captivity, females may choose to nest either during the daytime or early
evening digging a fairly normal nest approximately 100mm in depth, or
alternatively simply secreting the egg in a convenient nook or cranny among the
rocks. Hatchlings upon emergence are strangely not particularly odd looking,
and are even somewhat domed. Their profile is not dissimilar to that of T.
hermanni for example. The hatchlings have a bright yellow groundcolor and
plastron with deep brown-black spots on the vertebral and costal scutes.
Typically, newly emerged hatchlings measure about 40mm in length and weigh
about 16-18g.
(C)
1990-2004 by A. C. Highfield. All rights reserved.
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