Herbert Meier & Ingo Schaefer Fig. 6. Courtship sees even matamatas to become rather lively. about continuously. Both females largely displayed disinterest. The male would stop in front of a female from time to time and close in on her until the tip of his nose almost touched hers. In this position the male would start moving his head slowly from side to side in front of the female’s head. These swinging motions approximately followed a semicircular pattern and were continued for between ten and fifteen times. The male would then freeze in his position, slightly lift one of his front legs, and bob his head up and down at a rapid beat. No physical contact was established during this encounter. This display lasted for about a minute or two before the male discontinued it and resumed his restless wandering through the tank. Occasionally, the male would place himself next to the female. He would then show the same sequence of motions as described above. Depending on whether he was to the left of right of the female, he would use the near front leg for his gestures. All the while, the courted female did not show any signs of a response. Every now and then, the male would swim and place himself on the female’s back, bending his neck slightly towards her momentarily, but leave this position soon without any further attempts at copulating. The Chelus fimbriata in the care of Meier show the described waving motions with the front leg only rarely, but the bending of the neck often. The male will then typically swim over the female or mount her, bend the neck down, and press his chin on the female’s occiput. Sometimes, his tail will feel for the female’s cloaca. The female will usually remain unimpressed, but her lifting her posterior body portion has also been noted on occasion. Copulation has never been observed so far. In order to promote reproductive activity, the sexes were kept separated from late May through mid July every year beginning from 2001. The possible effects of other potential stimulants such as changes in water quality 26 RADIATA 17 (3), 2008
The Matamata, Chelus fimbriata and availability of food in relation to the seasons are investigated as well. The aim is to create an annual rhythm that corresponds to that experienced in nature, the fundamentals of which are detailed in the chapter on reproduction below. The seasonal separation of the sexes was discontinued from 2005. Readjusting the males to the common tank simply took too long. To this was added that their adjusting to the smaller tank also caused them stress; at the least the males were very reluctant to feed during the first few weeks. Through the courtesy of Zwartepoorte, another male could be added to the existing group in February of 2008. In spite of all previous experiences with the joint accommodation of matamatas, this male proved to be very aggressive towards his co-inhabitants. He started courting the females after just three days of acclimatization, partly resorting to massive molestation tactics after a week. The two original male inhabitants of the aquaterrarium were attacked with bites, and if they tried to flee, they were pursued throughout the tank. All matamatas ceased to feed for a minimum of three weeks after the introduction of the new male. By now, this specimen is kept in isolation. Reproduction Although breeding matamatas in captivity has been successful on several occasions, these events have been sporadic and produced only a very small number of babies (comp. Heinroth 1943, Hausmann 1964, Drajeske 1982, 1983, Schaefer 1986). Only McCord (pers. comm.) managed in 2001 and 2002 to hatch several juveniles. The reasons for this being so are likely to be based on inadequate husbandry conditions like tanks that are too small, and insufficient knowledge of the biological requirements of this turtle species. What triggers reproductive activity is as yet an enigma. Taking into consideration that all chelonians are subjected to natural seasonal rhythms, it should be here that the triggers for breeding Chelus fimbriata in captivity are to be found. Climatic charts (Müller 1996) provide information that is only of limited use. An annual mean temperature of 26.2 or 27.2 °C does not really permit conclusions on a distinct annual cycle. Data on average minimum and maximum temperatures do likewise not provide clues. What is conspicuous, though, is the variation of the amounts of precipitation during the course of a year. And what is even more significant is the fluctuation of water levels. Depending on the width of a river and the height of its banks, the difference between low and high water can be more than 10 metres. Precipitation maxima and maximum water levels are causally related, but occur with an offset in timing. Under the conditions of a terrarium it is attempted to emulate annual rhythms through changes in the intervals at which the water of the turtles is renewed. To this effect, Meier exchanges about 15-20 % of the water every week during winter, whereas in summer, which is the period when water levels are high in the wild, about 10 % are renewed every day. This is based on the supposition that the actual depth of the water plays a subordinate role. In nature, the turtles will retreat to the mainstream river beds when water levels begin to Fig. 7. A clutch may comprise 12-22 eggs. RADIATA 17 (3), 2008 27
