Dieser Haltungsbericht ist eine zweite Fassung. Überarbeitet wurde die erste Fassung,von Anderas S.Hennig. Hierfür bin ich ihm "Sehr Sehr Dankbar"

Für den Inhalt des Berichtes bin aber ich selbst voll Verantwortlich.

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Ewald Roddewig

Meine Erfahrungen bei der Haltung und Zucht der Schwarzknopf-Höckerschildkröte, Graptemys nigrinoda nigrinoda Cagle, 1954

Systematik

Klasse: Reptilien (Reptilia)

Ordnung: Testudinata (Schildkröten)

Unterordnung: Cryptodira (Halsbergerschildkröten)

Familie: Emydidae (Neuwelt-Sumpfschildkröten)

Gattung: Graptemys (Höckerschildkröten)

Art: Graptemys nigrinoda (Schwarzknopf-Höckerschildkröte)

Unterart: Graptemys nigrinoda nigrinoda (Nördliche Schwarzknopf-

Höckerschildkröte)

Tabellen zu den Gelegen meiner Graptemys nigrinoda nigrinoda.

My Experiences with the Keeping and Propagation of the Black-knobbed Sawback, Graptemys nigrinoda nigrinoda CAGLE, 1954

Introduction

With the Back-knobbed Sawback (Graptemys nigrinoda), we look at one of the smaller species of Graptemys – a fact that triggers the fancy of many a friend of aquatic turtles. These turtles furthermore require only a relatively small investment at present, which is something that cannot be said about the other small-sized species such as the ringed (Graptemys oculifera) and yellow-blotched map turtle (Graptemys flavimaculata). There are large-headed species of Graptemys like Barbour's map turtle (Graptemys barbouri) in which adult females have heads the size of a child's fist. Graptemysnigrinoda, in contrast, belongs to the Sawback map turtles that have small heads. What is noteworthy in all species of this genus, though, is the distinct difference in size and weight between the sexes. My observations indicate that large female Graptemys barbouri may weigh more than twenty times as much as their male counterparts. In Graptemys nigrinoda nigrinoda, this difference is not quite as extreme. The largest female in my care weighs just about six to seven times as much as one of my males. Over millions of years of evolution, Nature has here created perfect "egg-laying machines", whereas males just have to contribute a drop of sperm every now and then, so why should they grow to the same size as a female? The German pet trade offers mainly the false (Graptemys pseudogeographica pseudogeographica), the Mississippi (Graptemys pseudogeographica kohnii), and the Ouachita map turtle (Graptemys ouachitensis) to the enthusiast. These forms are commercially propagated in American turtle farms. A major disadvantage of these imported juveniles is that there are no indications yet which sex they might be. This results in beginners in turtle keeping acquiring specimens that, years later, turn out to be females and grow to sizes that by far exceed the expectations of the inexperienced buyer. They often do not know how to handle this situation, or have lost interest in the meantime anyway. The respective turtles are then dumped, for example, at reptile rescue stations. This scenario provides so-called animal activists with ammunition to demand that the private keeping of wild animals be banned in general, ignoring entirely the fact that serious terrarium keepers contribute substantially to the knowledge of wild animals in the sectors of ecology, ethology, reproductive biology, life expectancy etc. in particular, which is information that would not be available if it were not for turtles in responsible human care. Without these major realizations and data collections, our knowledge of the biology of numerous animal species would still be very deficient, and effectively protecting threatened species would not be possible in many cases. In the countries of the European Union, Graptemys nigrinoda nigrinoda is usually available only in the shape of captive-bred specimens. Prices are typically in a range that prohibits purchases on the spur of the moment and motivates a potential beginner in turtle keeping to first acquire detailed information and the required basic knowledge. Personally, I know only of less than a dozen breeders of this subspecies in Europe so that newcomers will usually be placed on a waiting list. I also have so many requests that I can select those applicants who appear to be the most qualified ones.

Appearance

The presence of conspicuous black protuberances ("knobs") on the medial keel of the dorsal shell formed the basis of the name when CAGLE first described Graptemys nigrinoda nigrinoda in 1954, both for the scientific specific and its vernacular name in most languages. In females, these black elevations become increasingly pale and inconspicuous with age. Another eye-catching trait is the weakly orange loops on the scutes of the carapace. Hatchlings are initially light grey dorsally, but darken visibly within a few weeks. Over the years, the dorsal shell becomes even darker, until it shows a blackish grey that appears "dirty", often with a hint of olive. The ventral shell is cream in colours sometimes lightly pinkish yellow. The transversal sutures of the plastral scutes are marked with black bars, which fade with age in females. Males instead often develop greyish black plastral scutes as they grow older. The soft parts (limbs, head and tail) often exhibit a bright white to yellowish pattern of lines. The upper side of the head is marked with a Y-shaped figure. A light-coloured dot is often present posterior to the eye. Secondary sexual differences typically become recognizable at an age of about two years. From this point of time on, the females (which become sexually mature at an age at an age of five to seven years; [GLASER pers. comm., own obs.]) start growing ever larger while male specimens continue to add only very little to their size; they already mature at about three years of age (own obs.). Males have long claws on the front feet, and their tails are thicker and longer than that of a female. If the tail of a sexually mature male is stretched out, the cloaca will be situated about 1 cm behind the rear carapace scutes, but flush with them in a female.

Systematic position

Class: Reptilia (Reptiles)

Order: Testudines (Turtles)

Suborder: Cryptodira (Hidden-necked turtles)

Family: Emydidae (New World pond turtles)

Genus: Graptemys (Map turtles)

Species: Graptemy nigrinoda (Black-knobbed Sawback)

Subspecies: Graptemys nigrinoda nigrinoda (Northern Black-knobbed Sawback)

Distribution and natural habitats

Graptemys nigrinoda nigrinoda lives in the rivers Tombigbee, Black Warrior and Alabama (US states of Alabama and Mississippi). These rivers drain into Mobile Bay, where the distribution range of Graptemys nigrinoda delticola begins and where the ranges of these two subspecies overlap in an intergradation zone (IVERSON 1992, ERNST & LOVICH 2009).

This region is marked by hot summers with temperatures of 30 °C and more and winters with varying low temperatures and a distinct possibility of snow, ice and values below freezing (MÜLLER 1996). Climatic charts, like those found on the Internet (e.g., www.klimadiagramme.de), are therefore quite informative, as are reports containing field observations such as the write-up by SCHUZ (2001), who travelled in the natural habitats of various map turtles and pointed out the impressively intense lighting situations there.

Ecology

The points of origin of all species of Graptemys lie at about the same latitudes as Central Europe and North Africa. This results in summers and winters that determine seasonal periods of activity and low or no activity, respectively. The transition periods in spring and autumn are shorter in North America than in Central Europe, though. Owing to the fact that these transition periods are fairly unstable in the latter region, keeping these turtles in a garden pond is hardly safe. Map turtle are therefore best accommodated in a greenhouse or conservatory. The active season begins with the first warm days in spring. Attracted by the warmth of the sun, the turtles emerge from their hibernation quarters and hiding places. They bask, preferably on logs that have fallen into the water, in a quest to reach "operating temperature". Once the water temperatures have risen to 18-20 °C, Graptemysnigrinodanigrinoda will also resume feeding (SCHULZ 2001, MEINHARDT pers. comm., own obs.).

A typical day in the life of these turtles looks about as follows: Awakened by the first sunrays in the early morning the turtles emerge for basking. Once they have reached an adequate body temperature they will enter the water to forage for food, mainly feeding on small to very small invertebrates. They will then return to their basking sites. This sequence may be repeated several times in a day.

Mating may occur right after the winter period of dormancy. The females are able to store sperm transferred on this occasion for fertilizing all clutches in a year (KUCHLING 1999, HERTWIG 2001). Clutches of usually three to five eggs are produced several times throughout spring and summer, with up to eight having been recorded in human care (HERTWIG 2001, STETTNER 2005 [three clutches], own obs. [up to six]). Thus, the days pass to late summer and autumn. Singular mating events may then be observed again in autumn (HERTWIG 2001, ERNTST & LOVICH 2009). If the water temperatures drop to below l0 °C in winter, Graptemys nigrinoda becomes inactive (WATERS i974), with the period of activity in Graptemys nigrinodadelticola falling into the time between early April and late November (LAHANAS 1982).

My Experiences with Graptemys nigrinoda nigrinoda

It is not always easy to assemble a breeding group. I managed to acquire in 2006 three captive-bred specimens from 2005. These had been incubated at about 28 °C and, as expected, turned out to be all of the male sex. One of these turtles perished, but the remaining two today form part of my breeding group. During the course of the same year, I obtained two more specimens from a different breeder. They had been incubated at 30 °C and were females. The same source then afforded me the opportunity to take over a complete breeding group, consisting of one male and two females, in the summer of 2008. The adult male and my two small females were subsequently passed on to grateful turtle enthusiasts leaving me with a breeding group of 2,2 Graptemys nigrinoda nigrinoda.

Aquaterraria

The two males are housed together with a male Graptemys barbouri in a tank measuring 60 x 60 x 60 cm (length x width x height) with a water volume of about 200 litres (water level ca. 57 cm). The Graptemys barbouri male hardly takes any note of the other animals. On the other hand, the male Graptemys nigrinoda nigrinoda are often active together, and courtship behaviour (vibrating the claws) is occasionally seen. My observations have never suggested that one of the three turtles would be suppressed, nor have there been any diseases. The two adult females were initially accommodated in a tank of 150 x 60 x 60 cm in size (540 1 in volume minus the terrestrial section that ranges into the water; water level ca. 57 cm). It was, however, notable that the larger female was suppressing the smaller one, which made it imperative that another solution be found. The larger female therefore now shares the mentioned aquaterrarium with a female Graptemys barbouri (22 cm in carapace length). The two turtles are fully compatible and produce clutches of eggs on a regular basis. For her part, the smaller female now lives together with a four year-old female Graptemys ouachitensis sabinensis in another aquaterrarium without any problems being obvious.

Outfitting

The substrate consists of an about 2-3 cm layer of playground sand that was washed before use. The turtles love to root in the sand and occasionally ingest it in the process. Some 50% of the floor space are covered with natural rock tiles. These tiles have also been used for creating superstructures that enable the turtles to avoid each other if they wish to. The tiles are so heavy and large that the sawbacks cannot displace them. A branch of beech wood lies in the water and does not only serve to please the aesthetic needs of the human eye. It had been stored for two years prior to its use for this purpose. Releasing tannic acid on a constant basis into the water, it is meant to provide the turtles with protection from fungal diseases (SCHILDE 2004) and increase their feeling of safety by staining the water. With time, algae settle on the branch's surface, which the sawbacks will graze off together with the bark. Tap water is used for filling the tanks. It is exchanged to an extent of up to 90Yo every three weeks. Occasionally, but not with every water exchange, 2 g/l iodine-free cooking salt is added to the water for stabilising the electrolyte balance (SCHILDE 2004).

An island made of thick natural cork floats on the water surface as a basking spot. It is fixed so that it is always kept in its place under a UV-floodlight and large enough for all turtles of a tank to find a place for basking at the same time (and avoiding the hottest spot of the cone of light if they so desire). The aquaterraria are covered on top with a wooden box-like extension of about 35 cm in height. It prevents the turtles from escaping, especially in the area of the terrestrial part that serves as an oviposition spot. The box furthermore houses the timer-controlled illumination units. The aquaterraria of the females are each outfitted with a 160 W HQI flooder (Power Sun), whereas the tank of the males sports a 100 W flooder of the same make. These UV-heat emitters are mounted thus that they hang, beyond the reach of the turtles, some 30 cm above the cork island. This ensures that the basking spot is warmed to temperatures of about 45 °C right under the flooder. The turtles should be able to dry completely during basking as this eliminates the risk of fungal algal infections in particular. Light and warmth are furthermore conducive to shedding the uppermost layers of the scutes, which is necessary for an unimpeded growth. My observations showed that growing sawbacks shed older carapace scutes several times during their annual period of activity, i.e., u p to five times, depending on their growth rate.

Once they have become sexually mature, the uppermost layers will then only be shed once in summer. To enable the turtles to synthesize vitamin D₃, properly, they are exposed to UV-B radiation by means of a permanently fixed lamp (comp. KOBER & GEISSEL 2006). The HQI flooders provide light for about half a day, whereas the remaining daylight hours are created with fluorescent tubes. It would surely be possible to have the UV-flooders running all day long, but in the face of ever-increasing electricity tariffs, this is a question of operating costs. Experience has demonstrated that the turtles learn to use the shortened periods for basking right then – which does not therefore subtract from proper husbandry condition. Keeping the sun- and light-hungry sawbacks without a UV-flooder and no opportunity for regular basking is, in my eyes, impossible, however.

The (cupboard-like) substructure of each tank houses the filters. I only use one type of filter, the Eheim Themofilter Professional 2224. It permits to set the desired water temperature by means of a controller so that a heating rod (with its inherent risk of breaking) in the tank becomes unnecessary and the amount of visible technology is reduced to a minimum. Its integrated heating unit is controlled with a timer so that it is activated only between 6.00 and 18.00 h. This management results in the water cooling by 2-4 °C at night, similar to the situation in nature.

Using one Eheim2224 per 250 l of water or part thereof ensures that the entire water volume of a tank is turned over and filtered at least once per hour. In total, 28 filters are employed for my l5 aquaterraria. A spare filter is always at hand for the case of a breakdown.

The suction pipe of each filter is mounted thus that basket at its tip is pressed slightly against a tile. This prevents the sawbacks from separating the basket from the suction pipe and accidents with inquisitive specimens that might stick the head into the pipe. Then be unable to extricate it against the suction power, and possibly drown as a result. The feeder pipe of the filter releases the water right back into the tank and so creates a distinct current. The filter chambers are filled with ceramic tubes, which in turn are covered with a coarse filter sponge. I would advise against using finer filter material for the keeping of aquatic chelonians, as it would certainly clog rapidly with the waste produced by these animals and substantially reduce the filtering capacity of the filter. The filters are cleaned as necessary and never at the same time when water is exchanged. It is important that a healthy population of bacteria is maintained in the filter so that it can perform in a manner similar to a miniature biological water purification plant. The terrestrial section a.k.a. oviposition site consists of a rectangular plastic container. It measures 55 x 35 x 30 cm and is affixed to the above-mentioned superstructure so that it is sunk into the water for some 70%. This ensures that its filling of sand is warmed a little by the surrounding water. One side of the terrestrial section is further heated by a 50 W spotlight that is switched on for about three hours over midday and so creates a localized hotspot. Moreover, a heating pad (6 W) is buried in an upright position in the sand and runs around the clock. As a result, the terrestrial section offers zones with various temperatures, enabling the females to choose from a range. The sand is always kept moist enough to clot and will not collapse when a nest pit is excavated. To enable the females to access the oviposition site, a sheet of cork has been mounted to form a ramp between the water and the terrestrial section.

Breeding

I firmly believe that a species-specific, varying and high-quality diet is essential for successful breeding. Graptemysnigrinoda nigrinoda takes only very small amounts of plant matter (ERNST & LOVICH 2009). This needs to be taken into consideration when turtle jelly is mixed or complied with by offering pellets rich in algae. The turtles will occasionally also bite off pieces from aquatic plants.

In the wild, the sawbacks have available wide variety of food items, depending on the season and exact habitat. This natural diversity is impossible to emulate all the time in captivity, and it is for this reason that I include types of food (always low in fat) that do not occur in the turtles' natural environment. By this, I ensure the required variety.

The females are fed on a daily basis – sometimes they receive a lot of food, but not too often, again in an attempt to recreate the situation in the wild. My observations indicate that it is particularly important to feed the egg-producing females in an optimal manner right to shortly before they begin to hibernate in order to build a proper foundation for the next oviposition period (comp. HERTWIG 2001). Males have a much lower food intake, which is not surprising considering their smaller body sizes. They are fed only every two to three days. I also do without supplementing the food for both sexes with vitamins, as I deem this measure unnecessary if their diet is composed properly.

The menu for my Graptemys nigrinoda nigrinoda includes crickets, roaches, grasshoppers, a wide range of beetles, caterpillars, worms, frosted and freeze-dried shrimps and Gammarus, furthermore small fish (frozen rudd, smelt, topmouth gudgeon; freeze-dried fish from the Asian supermarket), octopus, fowl meat, beef heart, giant mealworms (Zophobas), mealworms, flies and spiders, woodlice, snails and slugs, frozen pink mice, and many others more. When I go out to hunt native invertebrates, I always have an eye on not collecting protected species, and native amphibians are never collected for feeding, not at least because they are protected as well. I prefer to offer live feeder animals, but also use freeze-dried and frozen foods, the latter are of course first defrosted. Turtle jelly is a possible substitute, provided it is made after a thought-through, balanced recipe (e.g., SCHULZ 2001). The females always have cuttlefish shell at their disposal, which serves to satisfy their great need for calcium. It continues to amaze me just how much of the cuttlefish shell they consume.

My recipe for turtle jelly

Ingredients:

500 g beef heart

300 g octopus pockets

4 eggs, with shell, boiled

1/4 l low-fat milk

2 large cuttlefish shells, crushed

1 handful boiled natural rice

1 carrot of medium size

1/2 medium-sized horseradish with 2 leaves

1/2 apple

1 small banana

1 small handful of spinach leaves

½ red pepper with skin

Adding some beetroot lends the stirred mix an attractive colour. Only high-quality gelatine is used and mixed at twice the recommended concentration in order to produce a really solid mass.

Preparation:

Beef heart and octopus are minced. The resulting mass is briefly boiled in half a litre of water. The remaining ingredients, of course except the milk and gelatine, are also run through the mincer, then mixed with the milk, and thoroughly stirred. This gruel is then added to the meat and left to simmer at 90 °C for a few minutes. Once done, the gelatine, which has been prepared as per instructions, is added. Everything is mixed well once more, but kept from boiling. The still-liquid mass is then portioned by filling it into containers of the right size. It may also be cast on a baking tray, for example, cut into blocks of the required size once it has set and cooled, and then be wrapped in clingwrap. Once the turtle jelly has fully solidified, which is usually the case after 12 to 18 hours in a cool room, the blocks can be stored in the deepfreezer. It obviously needs to be defrosted slowly before used for feeding.

Besides dietary considerations, matching pairs is the next important factor, and it is not always easily resolved. Sometimes the male shows intentions to mount, but the female will not permit him to do so. At other times, the male specimens show no interest in their potential mating partners. It is typical for the females in my care that they will agree to copulation only once every year. This almost exclusively happens in unheated water and usually shortly after hibernation. However, I have also developed a routine that appears to be safer in my view and that can be applied prior to hibernation: In October, the water in the males' tank is exchanged, using cold tap water for refilling. The same is then done in the tank of the females. Following a waiting period of a few hours, the males are placed with the females, where they will immediately start courting them. The male turtles will swim in circles around their chosen females, occasionally emphasizing their intentions with vibrating claws. Copulation then involves a rather "solid" connection between the male and the female that persists for some 20 minutes. Initially, the female will remain lying quietly on the bottom, permitting the male to mount. After a while, however, the female will start swimming through the aquaterrarium, towing the attached male with her, and force the connection to break by fast and agitated movements. Now, something unusual can be seen: the exposed penis looks like the flower of a field bindweed, save for its dark blue to dark greyish black colour, and shows elegant movements that resemble a jellyfish in the current of the sea. This display does not last long, though, and ends when the penis is eventually retracted into the cloaca of the male's tail.

Provided the sawbacks were awakened from their hibernation around mid-February my two females produce eggs between March and July. Oviposition events are heralded two or three days prior when the female moves from the water to the terrestrial section. A potential laying spot is first examined and rechecked once or twice or even up to six times. Oviposition eventually takes place in the early morning or late in the afternoon. If the sand is not moist enough and therefore not in an optimum condition for excavating a nest pit, the female will moisten the selected spot with fluid from her anal bladder. She will then excavate a pit of 12-15 cm in depth with her hind legs. Once she has laid her eggs, she will reuse the excavated sand to refill the pit with her front and hind legs. The surface is finally smoothed by the female sliding on her ventral shell over the closed pit. The entire process of oviposition, including closing the nest pit, does not even take an hour in the females in my care. However, no person may be present in the room, which makes observing these events rather challenging.

The soft-shelled eggs are then recovered and carefully freed of adhering substrate. They weigh about 14-16 g and are some 35-40 mm long. One of the two incubators used is set to a temperature of 26 and the other to 30 °C. Incubated at 26 °C, the hatchlings emerge after 78-83 days and are certainly of the male sex. Eggs that are incubated at 30 °C hatch after only 58-62 days and yield female turtles. These incubation temperatures are a failsafe method of determining the sex of the offspring. I cannot, however, as yet state where exactly the vertex point lies; as far as other species of Graptemys are concerned, BULL et al. (1982) and EWERT& NELSON (1991) suggested 29.0-29.5 °C. I always incubate these eggs at a constant temperature, i.e., without decreasing nightly values. Vermiculite is used as a substrate. It is soaked in water and then squeezed out so that it forms a moist mass. It is then filled into a rectangular freezer tubs until these are about four fifths full. I take care that tub and filling make up quite exactly 450 g so that the subsequent loss of moisture can be quantified and compensated by remoistening.

A small depression is made into the surface of the vermiculite so that every egg can be placed there, without changing its original positions, and be buried for about one third. This is done by handling every egg individually. A small paintbrush is used to carefully plane and slightly compact the surface of the vermiculite so that the eggs hale proper contact with it.

It just takes a day or two for a white blotch to appear on the upper side of the egg and subsequently spread all over it, which indicates that it is fertile. The originally translucent egg so turns into a truly white opaque one. Infertile eggs take on a glassy amber colouration, start collapsing, and need to be removed. The incubator is checked every five days. The vermiculite is remoistened if and when necessary, and the water in the designated bow in the incubator is replenished to guarantee a constantly high level of humidity.

A number of experiments have shown that the procedure described afore works best for me. I have noted, however, that not every clutch of eggs develops exactly in the same manner, even if the conditions are identical. The eggs from the smaller female are much easier to incubate successfully than those from the larger female. For example, some clutches from the latter consist of eggs that are prone to inflating. While soft-shelled eggs are supposed to absorb moisture, i.e., water, they are certainly not supposed to balloon in the process. If this happens nevertheless, I found you could prick them carefully with a very sharp pin, which will reduce the pressure inside. I have used this method with success on several occasions, but it does obviously not remedy the actual cause, i.e., the excess moisture.

Hatching of the baby turtles begins with a cut appearing in one of the tips of the egg, which the hatchling makes with its egg tooth. It may now take several days until the baby turtles actually leave their eggs. I let them take their time and do not manipulate the eggs. Ideally, the yolk sac sticking out from the plastron of the hatchling will be almost fully used up. If the yolk sac is still too large, the affected hatchlings may die. To me, oversized yolk sacs are an indication of inadequately high moisture levels during incubation, which caused the hatchlings to emerge prematurely from their eggs. In such a case, it helps to bury the babies slightly in vermiculite and leave them in the incubator until they have resorbed the remaining yolk. This point of time has come when the baby turtles begin to walk about. When the baby sawbacks are ready to be removed from their incubator, I first place them into small cricket boxes with ventilation holes that are filled to a level of about 5 mm with water. These boxes are then closed with a lid and placed in a spot that is no too brightly illuminated and offers a temperature of 28 °C. The water used originates from the tanks of the adults, which serves the purpose of exposing the juveniles to the bacterial fauna present there so that they can pick it up to the benefit of their own intestinal flora (SCHULZ pers. comm.). Possibly still existing remains of the yolk sac will now be resorbed within the next 24-48 hours, and the baby turtles start feeding. They are now transferred to small nursery tanks with water about l0 cm deep.

These tanks are outfitted with a small pyramid made from natural rock onto which they can climb and exit the water, a few aquatic plants, and a small cork island. Their water is kept at a temperature of 28-30 °C by means of an aquarium heater. The baby turtles are excellent swimmers right from the start.

They are fed with mosquito larvae, daphnia, small earthworms, Gammarus and flies, for example. It is remarkable what and how much food they can take in. Food is offered twice every day at amounts that can be consumed without leftovers. After just ten days, the juveniles will eat everything the adults also eat, only that it sometimes needs to be cut up to fit into the mouth. A few days later, the babies are transferred to a larger nursery tank. It only takes a short while for them to adapt to even deeper water.

At three weeks of age, the skilled swimmers then move into a fully decorated aquaterrarium of 250 l in volume where the water level is 60 cm. This is also the point of time when they can be passed on to interested and qualified keepers of aquatic chelonians.

Hatching weights range from 9 to 12 g, at which time the 35-40 mm dorsal shell is still almost circular in outline. The navel slit will have become invisible after a few weeks, which is also when the initially soft and flexible shell has hardened and rigidified substantially.

Hibernation

The Graptemys nigrinoda nigrinoda in my care hibernate in the unchanged conditions of their aquaterraria in my turtle cellar. Water temperatures are reduced to 20-22 °C by mid-October, with nightly decreases by another 4 °C at maximum. This is also the point of time when feeding them ceases. Around the beginning of November, the water level is reduced to about shell height. Filters and heating are switched off, and the heating thermostat for the room is set to zero. The lights remain on for six hours every day for a week. The windows are left open to reduce temperatures even further and will range around 10-12 °C two weeks later. The animals will by then have become very lethargic. Temperatures will then typically decrease to about 4 °C. The thermostat-controlled room heater will safeguard the cellar against freezing, though.

Some turtles spend this period in the water, while others will position themselves thus that some part of the body is on land, and yet others leave the water completely and will lie on a rock, for example. These positions are not static, though, and changed every now and then. The tanks and turtles are checked every five days with the aid of a weak torchlight until mid-February.

Mid-February is the time when the room heater is reactivated so that the environment warms up slowly. Lighting is once more provided for six hours every day. The spotlights are now of particular importance as they provide opportunities for basking. The water levels are gradually raised a few days later. The filters and integrated heaters are switched back on simultaneously.

About ten to twelve days later, room and water temperatures have been restored to around 20 °C. The turtles will by then have regained their appetite and are offered, for example, Gammarus or earthworms as first food. Their active period of the year begins between early and mid-March.

Diseases

Aside from damage to the keratinized top layer of the shell of the smaller female, the cause of which has remained an enigma to me, I do not have to report on any other injuries or health problems. The mentioned injuries to the shell healed without medical assistance.

Co-inhabitants

The aquaterraria also house guppies and suckermouth catfish during the active part of the year. The guppies feed on small remains of food left behind by the turtles and so prolong the operational life of the filters. As long as the fish are fit, they can easily avoid the turtles, and if not, they turn into a complementary quite natural source of food. For their part, the catfishes keep rocks, roots and the glass panes clean. The fish are not fed in addition.

Summary

Graptemys nigrinoda nigrinoda is a very pretty and interesting aquatic turtle from North America that grows only to a relatively small adult size. It is a terrarium animal that can be recommended to both the experienced turtle enthusiast and the educated beginner. Prices are still reasonable. Its wild populations are threatened by overbuilding of their natural habitats. Keeping in human care may therefore contribute to conserving the total population. As far I am concerned, I would be pleased to see the circle of Graptemys keepers grow over the next years. Promotion to the end is what forms a large part of my work.

References

BULL, J. J., R. C. VOGT & C. J. McCoy (1982): Sex determining temperatures in turtles: A geographic Comparison. – Evolution, Rochester, 36 (2): 326-332.

CAGLE, F. R. (1954): Two new species of the genus Graptemys. – Tulane Stud. Zool., Belle Chasse, 1 (11): 167-186.

ERNST, C.H. & J.E. LOVICH (2009): Turtles of the United States and Canada. – 2. ed., Baltimore (Johns Hopkins Univ. Press), 827 pp.

EWERT, M. A. & C. E. NELSON (1991): Sex Determination in Turtles: Diverse Patterns and Some Possible Adaptive Values. – Copeia, Lawrence, 1991 (1): 50-69.

HERTWIG, S. (2001): Ökologie, Haltung und Fortpflanzung im Terrarium von Graptemyscaglei, G. flavimaculata, G. nigrinoda nigrinoda und G. oculifera. – Salamandra, Rheinbach, 37 (1): 21-48.

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Author & Photographs

Ewald Roddewig

Birkenweg 11

85406 Zolling

Germany

E-Mail: er-picta@freenet.de