Seasonal changes in activity patterns and body temperature (Tb) were investigated in free-ranging leopard tortoises in the Nama-Karoo. Leopard tortoises had unimodal daily activity patterns in winter, bimodal in summer, and there were diurnal and seasonal differences in the extent to which certain behaviors were practiced. Heating and cooling rates of leopard tortoises were studied in the field and under controlled laboratory conditions to determine whether the tortoises maximize operational daily activity periods and to determine the effect of behavior and size on heat flux rate.
Free-ranging leopard tortoises had faster heating rates than cooling rates and their heat flux was largely independent of Ta. Therefore, this study also considered whether leopard tortoises adapted food transit rate, food intake and water loss to cope with a diet varying in fiber and water content, and whether body mass, energy and water balance were maintained.
Introduction 1
Body temperature (Tb) is the most important variable affecting reptile behavior and physiology, and regulation of Tb is an effective method for dealing with spatial and temporal heterogeneity in the thermal environment (Angilletta et al., 2002). Increasing body mass may lead to increasingly stable body temperatures and decreased heat flux, however, the response time of Tb to changes in the thermal environment is much longer in larger reptiles (Seebacher et al. , 1999). The influence of body size on heat flux in juvenile and newborn leopard tortoises was considered in captive studies.
The final chapter discusses the plasticity of leopard tortoises in the Nama-Karoo and how they compare to other chelonians living in unpredictable climates. Thermal preferences, voluntary maxima, and heating and cooling rates in the American alligator, Alligator mississipiensis.
Thermal variability in body temperature in a large ecotherm: Are
Preliminary observations on the ecology of the angular tortoise (Chersina angulata) in the Eastern Cape Province, South Africa. The status and ecology of the leopard tortoise (Geochelone pardalis) on agricultural land in the Nama-Karoo. Thermal behavior and maintenance of stable body temperatures by leopard tortoises (Geochelone pardalis) in the Nama-Karoo.
Individual leopard tortoises were alert in the early morning when Ta minimum approximated Ta maximum (Figures 3-6). External Tbs were similar to Te in the early morning, with temperature increases steadily towards midday. Branch WR (1984) Preliminary observations on the ecology of the loggerhead turtle (Chersina angulata) in the Eastern Cape Province, South Africa.
Loehr VJT (2002) Population characteristics and activity patterns of the Namaqualand speckled path runner (Homopus signatus signatus) in early spring.
Heating and cooling rates of leopard tortoises (Geochelone
Therefore, the heating and cooling rates of leopard tortoises of different mass classes were investigated in the laboratory and in the wild. It was hypothesized that leopard tortoises differ in the rate at which they warm up and cool down, and that this is independent of mass. The heating and cooling rates of each captive turtle were measured in summer and winter, respectively, to determine seasonal differences.
To investigate heating and cooling rates of free-ranging turtles in the field, a post-hoc method was used. Cloacal cooling and heating rates (ºCmin-1) of summer and winter leopard tortoises for juveniles, juveniles and adults are shown in Table 1. Heating and cooling rates were consistently similar between adults within a season, despite small differences in body mass (Table 2; Appendix I).
Perrin and Campbell (1981) measured the heating and cooling rates of three species of South African tortoises, including five leopard tortoises ranging in mass from 0.69 kg to 11.11 kg. The heating and cooling rates of adult and juvenile models were significantly faster than those of live turtles of the same size in all seasons. Dead tortoises were used as models by Perrin and Campbell (1981), who measured the heating and cooling rates of five leopard tortoises under laboratory conditions, killed the tortoises, and remeasured the rates of temperature change on the same individual.
Leopard tortoises in this study had higher cooling rates than heating rates and heating and cooling rates were higher in This suggests that leopard tortoises adjust their rates of heating and cooling to prevent overheating in summer while maximizing their heat gain in winter. Heating and cooling rates and their effects on heart rate in the loggerhead turtle, Chersina angulata.
Plasticity in the metabolic rate of juvenile and hatchling leopard
Oxygen consumption was measured in juvenile and juvenile leopard tortoises (Geochelone pardalis) with the hypothesis that metabolic rates would differ seasonally. Oxygen consumption (VO2) was measured using a flow-through respirometer system with the equipment and methods described in Boix-Hinzen and Lovegrove (1998). The average oxygen consumption per hour (ml O2 h-1) for each individual was calculated for the remainder of the period in the respirometer, at each experimental temperature and for summer and winter, respectively.
Oxygen consumption in the lizard genus Lacerta in relation to food variation, maximal activity and body weight. Oxygen consumption in the turtle, Testudo hermanni G., subjected to sudden temperature changes in summer and autumn. Seasonal variations of oxygen consumption and blood glucose concentration under low temperature conditions in the male tortoise, Testudo hermanni hermanni Gmelin.
The effect of photoperiod, parietalectomy and eye nucleation on oxygen consumption in the blue granite lizard, Sceloporus cyanogenys. Comparison of mean (±SE) cloacal body temperatures of brooding (square symbols) and juvenile (diamond symbols) leopard tortoises a. Comparison of mean (±SE) oxygen consumption (VO2) of juvenile leopard tortoises at experimental ambient temperatures in winter.
Comparison of mean (±SE) oxygen consumption (VO2) of young leopard tortoises at experimental ambient temperatures in summer. Comparison of oxygen consumption (VO2) of leopard tortoises with body mass (both logarithmically transformed) at experimental ambient temperatures in winter. Comparison of oxygen consumption (VO2) of leopard tortoises versus body mass (both log-transformed) at experimental ambient temperatures in summer.
Digestive parameters and water turnover of the leopard tortoise
Leopard tortoises (Geochelone pardalis) occur throughout the savanna regions of Africa from the Southern Cape to the Sudan, and experience wide geographic variation in environmental conditions across their range, including unpredictable availability of food and water in some regions such as the Nama-Karoo (Dean) . and Milton, 1999; Boycott and Bourquin, 2000; Kruger, 2004). All the turtles involved in the trials had been in captivity for at least a year, as their dietary preferences were known. There was no significant decrease in daily food intake over the duration of the trial (RMANOVA, F.
Apparent assimilation efficiency (taking into account body mass and expressed as a percentage) of leopard tortoises was significantly higher in those fed tomatoes to those fed alfalfa (ANOVA, F P = 0.017), although it was variable during the experimental days and between individuals (Figure 4). The greatest amount of faecal water was lost from leopard tortoises in experiment 2, where the amount decreased during the days of the experiment (Figure 5b), but the decrease was not significant (RMANOVA, F. Daily faecal water loss of tortoises in experiment 3) initially increased and then decreased in the last three days of the experiment (Figure 5c), where the change in faecal water loss was significant during the experiment (RMANOVA, F P = 0.02).
Osmolality of urine from leopard tortoises fed alfalfa showed an initial daily increase and then showed a sharp decrease from the third day (Figure 8a), but there was no significant difference in urine osmolality during the days of the experiment (RMANOVA, F. In contrast) , the urine osmolality of urine from turtles fed tomatoes decreased slightly in the first five days, but then increased sharply (Figure 8b), with a significant difference in urine osmolality across the days of the experiment (RMANOVA, F P = 0, 03). has already been pointed out, the intestinal transit time of the turtles that ate alfalfa was significantly longer.
Increased intestinal transit time results in greater efficiency of digestion and reduced amount of faecal energy lost (Bjorndal, 1987; Meienberger et al., 1993). 128 Acknowledgments We are grateful to those who loaned turtles for the duration of the study; to Mark Brown, Dr. Radiographic anatomy and barium sulfate transit time of the gastrointestinal tract of the Leopard tortoise (Geochelone pardalis).
Concluding Remarks: And so… 141
However, there is extreme doubt as to what role the leopard tortoises will play in the future. However, in this study, leopard tortoises used physiological mechanisms to manipulate heat flux in the absence of behavior. Similarly, the results of this study have shown that leopard tortoises exhibit a behavioral and physiological plasticity in their thermoregulatory, metabolic and dietary response to temperature and resource fluctuations and are therefore adapted to survive in the unpredictable climate of the Nama-Karoo.
Most of the tortoises used in this study were in situ wild tortoises in the Nama-Karoo. The importance of leopard tortoises in the Thicket biome has already been noted (Kerley et al., 1998). Similarly, leopard tortoises in the Addo District of South Africa consumed 28 species with 6 species comprising 75% of the diet (Mason et al., 1999).
In the southern Karoo, 75 species of grasses, succulents and forbs, belonging to 26 plant families, were eaten by leopard tortoises (Milton, 1992). Historically, many of these game species occurred in the Nama-Karoo, but they were not landlocked and could migrate through the biome. As large herbivores, leopard tortoises are likely to play a crucial role in the management and survival of the Nama-Karoo.
Further research into the ecology, breeding biology, behavior and physiology of leopard tortoises in the wild will allow researchers to make informed decisions about how to manage and conserve the species in the Nama-Karoo and therefore the Nama-Karoo itself. The role of turtles in the Thicket biome, South Africa: important meso-herbivores in an ecosystem dominated by megaherbivores. Plants eaten and dispersed by adult leopard tortoises Geochelone pardalis (Reptilia: Chelonia) in the southern Karoo.
