Herbert Meier I have never managed to be present when the turtles started copulating so nothing can be said about durations. Podocnemis vogli Growing to just a little over 30 cm in carapace length, the Orinoco river turtle ranks amongst the smaller species and is therefore better suited to being kept in human care. In nature, it occurs in the flood zones of the Llanos and therefore needs to make do with water of very poor quality at least during the dry season. As a consequence, it is rather tolerant of the composition of the water in captivity as well. Being an inhabitant of open savannah, however, the species is quite heliophilic, however, and it can be seen basking for hours on sunny days in high summer. Four captive-bred specimens of close to two years of age and about 10 cm in carapace length were added to my collection some six years ago. At the time, no differences could be found between the specimens that would have provided clues as to their sexual identities. It was only much later that they all turned out to be males. For the first two years, they were accommodated together in a pool with a water surface of 10 m² that offered water 60 cm deep. The population of this tank changed to two males and an adult female in June of 2005. It took only minutes after the introduction of the female turtle for the two males to start courting her. Palpation of the female in November then revealed the presence of eggs, but none had been laid by Christmas. X-rays showed that Figs. 8. The nesting spots of Podocnemis erythrocephala are often situated on sandbanks or in sandy grass savannas, sometimes even in brush savannas. she was carrying nine eggs. Oxytocin was administered, but did not lead to oviposition. Another six weeks and a second dose of Oxytocin later this female eventually dropped thirteen normally shelled eggs into the water. They were incubated at 32 °C, but did not start any development. Another clutch of eleven eggs was laid in the next year, likewise after a very long period of time from when they could first be felt and after two unsuccessful treatments with Oxytocin. In spite of the extended period of gravidity most eggs were not overshelled. It would appear possible that females of this species are able to delay oviposition if and when ambient conditions are unfavourable without this having an effect on shell thickness – which would be a sensible adaptation to life in a flood zone with unreliable water levels. Similar observations have also been made in other reptiles, for example in the case of the South African bowsprit tortoise, Chersina angulata (Hofmeyr 2004), and even the garden lizard, Calotes versicolor (Shanbhag 2003). 10 RADIATA 17 (3), 2008
Experiences with the Keeping of River Turtles of the Family Podocnemididae Podocnemis unifilis The Terekay river turtle is one of the larger river turtles. Its husbandry requirements are comparable to those of Podocnemis vogli, although it grows larger and therefore needs a larger pool. In the beginning, the newly acquired Podocnemis unifilis were kept together with a group of matamatas, Chelus fimbriata, in a spacious aquaterrarium of 10 m² floor space. However, the behaviour of the river turtles introduced way too much unrest to the common tank, causing the matamatas to stop reproducing over a period of two years. The group of 2.3 Podocnemis unifilis were eventually resettled in an aquaterrarium of their own in January of 2006. This basin offers a floor space of 5 m² and water some 40 cm deep. It has been set up in a fairly dark cellar where dusk would prevail throughout the day if it were not for artificial lighting. The latter is provided in the shape of two fluorescent tubes of 20 W each and a 150 W HQI floodlight. One corner of the tank incorporates a suspended terrestrial section beneath which the turtles can find, Figs. 9. The nesting spots of Podocnemis erythrocephala are often situated on sandbanks or in sandy grass savannas, sometimes even in brush savannas. and often take, shelter. The terrestrial part offers a 30 cm-deep mix of sand and soil. It is periodically warmed on one side with a heating mat. In the water, several submerged branched logs of deciduous trees provide hiding places. The first eggs were already produced in 2005 while the animals were still housed in the first tank. The respective eggs were dropped into the water one by one at intervals of several days and already destroyed when discovered. Another instance of oviposition occurred in November of 2006 when sixteen eggs were again dropped into the water. This time, however, they were discovered only minutes later. They were retrieved and placed in an incubator that had been kept heated to 30 °C in preparation. Thirteen of these eggs began to show a white germination spot each on their surface only two days later. The first hatchlings emerged after 67 days of incubation. All of the fertile eggs showed distinct traces of scratching around the poles. The calcified outer layer had become detached in almost all of them. Four baby turtles managed to exit their eggs on their own, while the other nine were obviously unable to cut through the inner membrane and free themselves. All nine of them were dead already one day after the other four had emerged. A probable reason for this sad event is that the strong light required for filming and photographing reduced the level of humidity, which dried out the egg membrane and rendered it very tough indeed. Thus altered, the hatchling turtles were unable to cut through RADIATA 17 (3), 2008 11
