GEOCLEMYS HAMILTONI
(Hamilton’s Black Pond Turtle)
(Strahlen-Dreikielschildkröte)
(Driekielstraalschildpad)
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GENERAL
Geoclemys Hamiltoni is one of the oldest turtle species on earth: fossil remains of this
turtle have been found in the Siwalik Hills in Northern India (SMITH 1973;
TIKADER and SHARMA, 1985). Despite their fairly large range of distribution, there
is very little known about this species, although it has been described in specialist
literature, but that is all.
As far as we know the species is found in an area which stretches from Pakistan to
Northern India and Bangladesh to West Bengal (TIKADER and SHARMA, 1985). In
detail this means:
India
: Assam, Bihar, Punjab, Uttar, Pradesh, Western Bengali
Bangladesh
: Jessore area
Bhutan
: No specific area
Pakistan
: Sind area, Saidabad, Punjab
The species was mostly found in the lower parts of Bangladesh. After many floods of
the rivers in recent years, a lot of nests have been lost in this place.
The animal is aquatic and lives, if possible, in stagnant, shallow, clear water with lots
of water plants, like Chinemys Reveesi. The turtle is carnivorous and it is thought that
in the wild their main diet consists of snakes (DANIEL, 1983; INDRANEIL, 1991).
Geoclemys Hamiltoni is a severely threatened species and is placed on List 1 of the
Washington Convention. The principal cause being that the local population eats
animals and eggs. Juveniles, but also adults which live in the dried up swamps, are
eaten by the locally abundant white vulture. Furthermore, many nests are devastated
by the development of agriculture, the cleaning of riverbanks and digging up of banks
for extraction of sand (TIKADER and SHARMA, 1985). In recent years the turtles
have been found on the food market in China, by which we many conclude that this
reptile too has become part of the Chinese diet.
In the wild the animal seem to lay their eggs twice a year. After the monsoon in or
after the month of January and October (TIKADER and SHARMA, 1985). There is
no data on the number of eggs and the incubation period. Temperatures in the areas
where the turtle lives vary from 20 gr. C (in the winter) to 30 gr. C (in summer). In
some areas, the temperatures in summer will be considerably higher.
DESCRIPTION OF THE ANIMAL.
It is a large and powerfully built animal: the length of the shell of an adult is ca. 30
cm (all literature), but larger animals are known. About the growth/size ratio of these
turtle can be said that this length of 30 cm is reached after an age of 19 to 22 years
when feeding normally (two to three times a week). In view of the fact that
considerably larger animals are known (40/50 cm), it would mean that this species is
capable of reaching a (very) high age. They will probably grow older than humans.
My adult pair of Hamiltonii has an age of about 40 years.
This species has a comparatively large head, a very muscular jaw, legs and tail, which
is relatively short. The lower jaw is hooked.
The legs (mainly the back legs) are big with powerful claws; maybe the turtle needs
them in the wild in fighting with snakes. Considering the large webs between their
toes, the animal should be pretty quick in water.
The carapax has three ridges, which are clearly marked in younger animals.
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The color of the upper shell is black, where in young animals the costalia are enriched
with a lot and the marginalia with slightly less white/yellow dots and spots.
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As often seen with older turtles, the pattern diminishes when getting older. The
plastron is mainly black with an irregular marking of white/yellow stripes and spots.
A German colleague, ELMAR MEIER, owned two animals in which the plastron was
mainly white/yellow with on every marginalia a small dark spot.
It is not impossible that different patterns are related to their place of origin;
something not uncommon in turtles. It is implausible to speak of a subspecies.
HOUSING
Because I have been keeping this species for many years and I have moved quite a
lot, my animals have been housed in a lot of different dwellings. My principle was and
still is that the turtles need a lot of space (in water as well as on land). In my opinion
is this considered all turtle species.
For example: 10 young turtles (up to about 8 cm) can be raised in a terrarium with a
water surface of 1.35 x 0,70 m. For the land part, it is sufficient to have several
floating platforms over which a light bulb is placed so the animals can bask.
On reaching the adolescent stage, they will need of course more room and a real land
part.
To keep one adult pair (30 cm), a water surface of 2.00 x 0,80 m and a water height
of 25 cm should be maintained. In such a space it is possible to keep (apart from the
adult pair) several other adult turtles. It is recommendable, because outside the
meeting season, the dominant female will reject the male
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At the right: the female, left: the male.
and turn him away. The other adult turtles divert the attention.
When the water surface is even larger than suggested above, the better it is of course.
In the water part some hiding places should be made in order for the male and female
to hide from each other. When fossilized wood etc. is used, it should be screwed
firmly together and fastened. Adult animals are able to develop enormous power,
which can be clearly seen and heard in the mating season. MEIER keeps male and
female apart most of the time in a significant smaller space of 1.00 x 0,50 m.
Although this could be beneficial to mating behaviour, I am not in favour of that
because much of the natural behaviour of male and female will be lost in this way.
To stimulate natural behaviour it is recommendable to create a land section next to the
water basin of about 1.60 x 0.80 m. with a sand layer of about 15 to 23 cm depth. It
should be easy for the animals to walk from water on to land. On land hiding and egglaying places must be created by placing a few sturdy plants and some pieces of wood.
The water temperature in my enclosure lies around 23 degrees C. An aquarium filter
in which a thermostat heater has been built, maintains the temperature. Equipment in
an enclosure with adult animals is not recommendable, because it is easily damaged
by the animals. The air temperature is usually about 5 degrees higher, which is done
by means of pressed glass lamps (80 Watt). Beneath these lamps the temperature is
much higher of course.
Recently pressed glass lamps are replaced by halogen lamps. These lamps are a bit
more expensive, but they are sturdier, last longer and give another light which
enhances the colour.
On sunny days the temperature van reach 30 to 32 degrees C, while beneath the
lamps the temperature will rise to 34 to 42 degrees C. When it gets any warmer, the
lamps will switch off.
BEHAVIOUR
All information on this subject has been obtained by actual observation in captivity.
The animals have a quiet nature, get attached to their keepers and cast off their natural
wariness at a later age, become tame and eat literally from your hand. They are a little
shy and won’t accept strangers easily. When veterinary treatment is necessary, like
injections for example, it is best that another person other than their keeper does it.
The animals are aquatic, but when their surrounding is calm they will sunbathe on
land. In captivity it is remarkable that they prefer to sleep out of the water at night.
During the day they are usually in the water in their regular hiding places apart from
each other. Adults can be ferocious towards each other; especially outside the mating
season, the female can be aggressive when the male tries to get her attention.
Hamiltonii pays no attention whatsoever to other animals in the same enclosure. They
do notice it when a new animal is added, it will be ‘sniffed’ but left alone. They
recognize their own keeper and know he supplies the food.
When they are hungry, they make it obvious by begging, standing upright against the
glass.
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Begging
FEEDING
Geoclemys Hamiltoni is carnivorous (all literature).
The animals should be fed as varied as possible with cat food (tinned and soft dry cat
food from a pack), earthworms, boiled mussels, shrimps, pollack, squid, ox heart,
meal- or morioworms. My adult pair turtles have a definite preference for mussels and
earthworms. Sometimes they accept slices of banana, tomatoes or boiled eggs. Young
animals have a clear need for calcium while growing up.
The first two years of their lives, young animals should be fed almost daily, but be
sure that they don’t grow to fast. It turns out that fast growing animals are not entirely
viable in the end. Adults are fed a fairly large portion twice to three times a week.
Two adults can put away a pound of boiled mussels in one go. Beside that, piece of
sepia is put into the water, from which the animals sometimes bite off pieces.
Hamiltonii always begging for food, but take care that they did not become fat.
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TOO FAT MALE
Fatness hinders good egg-laying.
MATING BEHAVIOUR
As stated above, the author is keeping a breeding pair for many years now. Below, you
will find a short overview of breeding Hamiltonii.
After many years I saw the behaviour of male and female suddenly change towards
each other. The first change was that the male became noticeably more active: he
swam a lot without really getting in the vicinity of the female. The female became
evidently influenced by this, because after a while she came out more of the water.
Sometimes she even sunbathed at length on the wood in the water part. The male
almost never appeared on the water surface at first. A short time later the male tried to
approach the female cautiously. When given the opportunity, he ‘sniffed’ her shell.
When the female noticed this, she would go her hiding place, where the male could
not easily approach her.
After that there was a period in which the male tried to approached the female more
openly; she was not amused at all at first and fended him off in several ways. The first
matings where not seen, but suddenly the female seemed to accept the male. They
swam together and she didn’t fend him off anymore. The matings observed at a later
date were certainly impressive: the mating process takes place with a lot of noise and
swirling water. After a period of one month, the old behaviour returned for a large
part: both animals sit in their own hiding place and go their own way. The hole cycle
took about 15 months. In hindsight it looked like a kind of trial period.
EGG-LAYING
According to most literature, in nature egg-laying takes place twice a year: before and
just after the monsoon in February and October.
However from 1993 on, I dug up three nests namely in May, June and July
(Simulating the rainy season in January and September did not have any effect on the
egg-laying).
After 2 or 3 days before egg-laying, trial pits are dug in different places. The
impression is that they are testing the moistness of the sand.
After the trial pits, egg-laying commences, usually at night. With their big and
powerful legs they dig pits with a depth of 15-18 cm and a diameter of 10 cm, in
which 20-24 eggs are laid. The eggs are about 4 cm long with a diameter of 2,5 cm.
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Eggs and hatchlings
Immediately after laying the eggs and the extensive cover-up of the nest, the female
returns to her search for food and shows her normal behaviour. The eggs are incubated
in a baby incubator with a temperature of 30 degrees C and an air humidity varying
from 70 to 85 %. A number of years the remarkable fact occurred, that the eggs
incubated in exact 4 weeks, you could set your watch by it. Lately, the incubation
takes place in a different location, where the biological clock ticks slightly different. A
satisfying explanation has not been found yet.
YOUNG ANIMALS
When hatching, the young are about 3,5 cm. They are conspicuously spotted and have
three clear and high ridges.
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First feeding
When the egg-sack has fallen off, the young animals should be fed on live food
immediately. There is a slight problem concerning the size of the animals: mosquito
larvae seem too large at first. To swallow one is often quite a struggle. Maybe these
larvae are too tough for the little ones.
Feeding is in the first time done with water fleas, tubifex and very small pieces of
earthworm. Ample food is necessary of course. Calcium supplements should not be
forgotten. After a hesitating begin, most young animals start to eat. When seeing other
animals eat, they will also start themselves. After a few months, their diet can be
extended to: mosquito larvae, dry and tinned cat food, ox heart, white mealworms,
fish, shrimps, squid and boiled mussels. In the wild the young animals will eat pieces
of snails, earthworms and larvae of dragonflies.
In captivity they are pretty shy at first and hide all the time when they are disturbed;
hiding places should be plentiful. In the following months the depth of water can be
increased slowly, so they can swim more freely. Again, after a period of hesitation
they will do so. Remember that this turtle species is not an outright swimmer so take
care to make hang/lean possibilities so they can rest under water while breathing.
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Threatening hatchling
Young Hamiltonii are very active and inquisitive and can threaten with their mouth
open. The upper and lower shell show apparent growth rings pretty quick.
Concerning growth, I raised Hamiltonii with Chrysemys species of the same size and
age under the same circumstances. The remarkable fact is that the much bigger
Hamiltonii had a slower growth rate than the Chrysemys species. It takes about 17 to
20 years before they reach 30 cm.
FINALLY
A few years ago I read an article written by a scientist, who found a nest containing 6
eggs (it appeared later they were from Hamiltonii), and put them in an incubator. It
emerged that the incubation period for 3 eggs was exceptionally shorter than for the
other 3. Two hatched at the end of July and one on the 1st of August. For years my
own experience is that they hatch in a month. Perhaps it is worth investigating this
further.
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Unfortunately I cannot find the article any more. If a reader of this recognizes the
article, please contact me.
CONCLUSION
Hamilton’s Black Pond Turtle (Geoclemys Hamiltoni) is an interesting and enjoyable
animal, which is unfortunately threatened with extinction, and should get every
attention and help it needs to survive. Up to now, there is little known about this
animal.
They will probably grow to an age of 60 to 70 years, if kept under the right
circumstances. It is carnivorous, but a later age they will occasionally accept pieces of
banana, tomato and egg.
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After 17 to 20 years they reach a length of 30 cm when fed normally. Obviously, they
keep growing because larger animals are known.
It is unknown when they reach maturity (See at the foot of this article: A Few Notes).
Larger animals need a water surface of 2.00 x 0.80 m at minimum; a water depth of 24
to 29 cm is sufficient, because they are not outright swimmers. From 1993 onwards, I
have been successful in breeding this turtle species, in recent years in pleasant
coordination with Rotterdam Zoo in The Netherlands.
Consulted literature:
Daniel J.C., 1983
Society, Bombay.
The book of Indian Reptiles; The Bombay Natural History
Ernst C.H.
Barbour R.W., 1989
Turtles of the world ;
Smithsonian Institution Press, Washington D.C.
Gotch, 1986
Reptiles-Their Latin names explained
Blandford Press, England
Indraneil Das, 1985
Indian turtles- A field guide
World Wildlife Fund-India
Indraneil Das, 1991
Colour guide to the turtles and tortoises of the Indian
Subcontinent: RNA Publishing Ltd., Avon England
Smith M.A., 1931/1973 The fauna of British India, Vol. I; Reptilia and Amphibia;
Ralph Curtis Books, Hollywood V.S.
Tikader B.K.
Sharma R.C., 1985
Handbook Indian Testudines: Zoological Survey of India,
Calcutta
Pritchard P.C.H., 1979 Encyclopedia of Turtles: T.F.H. Publications, Inc. Ltd
July 1997
H.J. Rotmans
Email address: [email protected]
A FEW NOTES
The survival of Geoclemys Hamiltoni in the wild is still alarming. Unfortunately there
are still reports of supply and demand on the food market in China. But also breeding
Hamiltonii in private collections gives problems. You can read about it in the
Studbook Breeding Programme Geoclemys hamiltoni, Annual Report 2003, chapter
‘Discussion’, in which is spoken about the market for private turtle keepers.
Since about 1997 I have changed a few things. In not one basin in which Hamiltonii
live is heated by an aquarium thermostat heater. I use only halogen lamps for lighting
and heating. Even for baby turtles it is enough. But in the environs of the basins the
temperature never sink under 20 degrees C.
During the year the adult male and the adult female live in separated basins. In this
way the female gets more rest. Only during the mating period the male moves into the
basin of the female.
By placing the animals together again it is watched that the mating goes of course
more frequently and vehement. This proceeding is practiced by mostly breeding pairs
of turtles. I separates also growing up Hamiltonii. The last few years it strikes me that
young Hamiltonii (F2 population) with a length of 11 / 14 cm already shows a fanatic
behaviour of mating. The females are not leave alone by the males. Therefore it is
better to separated.
At the size of 11 / 14 cm the difference between male and female is visible in the tail.
Concerning the food I can inform you that I give the Hamiltonii now also regular
endive and a special kind of lettuce called ‘iceberg lettuce’.
Striking is now that the number of eggs / hatchlings strongly deviates: look after the
Studbook, Annual Report 2003. As so far I can not find an explanation for this fact.
The possibility of laying eggs is demonstrable dependent on a good feeling of the
female. It seems to be clearly not only a question of good health. You will also see
this by other turtle species. A restful environment is also always better for good
results.
I find that the nature of individual animals sometimes rather deviates. I have a
Hamiltoni-female that is remarkable aggressive to all other Hamiltoni-turtles as well
as to other turtle species. It bites to blooding wounds. This situation is not
a matter of feeding too little, illness or a too small accommodation.
On the other hand I have a specimen that is naturally very tame and also friendly to
the keeper.
I would it appreciate very much if you have experiences with Hamiltonii you contact
me by email. If there are any questions or remarks I demand you to mail me as well.
March 2004
H.J. Rotmans
Email address: [email protected]