Galapagos Tortoises
- Thread starter Olddog
- Start date
Sesel
Well-Known Member
~ This is one does not fit, lol....she would fit just fine down south....lol.
I wish my Russian would still fit in a pickup. He's so big I need to rent a U Haul just to transport him!
When I see her lay fertile eggs, I will be convinced she is an adult. To acheive this she will likely need a mature mateNice looking female. Are you sure she's sub-adult?
.Thanks but she advised me she is already far enough south, close to as far south as are you. She is currently separated from from the male for R&R
.
Vitamin D, Cholecalciferol(D3), and Calcium (or Mushrooms, Sun and Florida Well Water)… a Subject of Ongoing Conversation
A few thoughts:
Some 40 years ago, the author naively felt comfortable in our knowledge of Vitamin D functions, its role in Calcium and Phosphorous absorption from the intestine, and prevention of osteomalacia. Everything was neatly pigeonholed into cause and effect. Vitamin D defiencies usually resulted from inadequate sunlight or UVB exposure.
Ergosterol, a plant sterol, is ingested from plants, oily fish, etc. One of the initial metabolic steps includes breaking of the B ring of the sterol which is done by exposure to ultraviolet light (UVB 280-320 nanometers) in the skin. This “pre D3”is further metabolized to the active D3. Most Vitamin D metabolism was felt to occur in the liver and proximal kidney.We fortified the milk and dairy with Vitamin D (either D2 or D3), and we fed tablets of ground up oyster shells with Vitamin D to reduce osteoporosis. Dialysis patients usually received Calcium carbonate tablets. We thought Vitamin D was all about Calcium and Phosphorus absorption and bone deposition. Simply by providing adequate Vitamin D and Calcium we could prevent rickets and ameliorate osteoporosis, reducing fracture risk in elderly people. There has not been too much controversy in this role of Vitamin D. There is not universal agreement on the amount needed by humans, as the need appears to vary with age, skin pigment, skin surface area exposed, and the amount of sun exposure. In the absence of adequate sun exposures, some have recommended 800-1000 IU vitamin D3 daily for children or adults. Much of the vitamin D used for fortification comes from UV irradiated yeast, lanolin, and even mushrooms. Overdose toxicity is possible but not very common. In the 1950’s there was an outbreak of hypercalcemia in Britain, possibly due to over-fortification of milk with Vitamin D.
Our understanding of the role of vitamin D regarding bone and skeletal formation and modeling may be oversimplified and summarized in this illustration in the following from Holick, Micheal F.,Vitamin D Deficiency page 269.
Life was simpler 40 years ago. We did not know about Vitamin D receptors, Vitamin D Response elements, and a host of other regulatory mechanisms. We had no concept of the existence of Vitamin D Receptors in most cells of the body. We did not understand its dynamic hormonal cellular effects and importance in cardiovascular disease, the immune system, cancer, diabetes, hypertension, infection, and other disease processes. For those interested in same, a slightly dated 2014 review by Bikle, Daniel D., Vitamin D Metabolism, Mechanism of Action, and Clinical Applications, may be a helpful starting point.
There is no question the role of Vitamin D in health has been underestimated. It is essential to animal well-being in many ways (in addition to Calcium/Phosphorus absorption and Skeletal development/Skeletal remodeling).
Yes, the above comments apply to humans and tortoises have not been extensively studied. Most tortoise recommendations are extrapolated from requirements of other studied animals and corrected for metabolic rates.
What does this backyard tortoise breeder do? If proper diet and sun are available, adequate vitamin D should be a non-issue. Calcium availability may be a dietary function varying with location.
In the case of many Floridians, Florida is sitting on a coral shelf and our well water is quite high in calcium. Well water is the source of tortoise drinking water. If irrigated, grass is periodically coated with extra calcium and minerals. Some plants will not tolerate this hard water. Our primary tortoise diet is grasses. Additional calcium may be occasionally be supplied with supplemental feeds, cactus, etc. Hatchlings do get periodic calcium carbonate added to their diet.
In addition to grasses, young tortoises occasionally get mushrooms from the store as a treat. They love them! Mushrooms are an excellent source of ergosterol, a Vitamin D precursor mentioned above. (If the mushrooms were sun-dried (UVB irradiated), their effective Vitamin A content would go up.) Tortoises may receive occasional extra Vitamin D from a feed supplement but that is not the usual.
Essentially, as tortoise stewards, we depend on sun (UVB) to allow tortoises to synthesize appropriate amounts of Vitamin D. With appropriate amounts of D3, Calcium absorption should be appropriate. With appropriate diet and UVB, there should not be a need for Vitamin D supplementation although moderate Vitamin D fortification of the diet is not harmful. Over-supplementation can potentially result in toxicity.
A few thoughts:
Some 40 years ago, the author naively felt comfortable in our knowledge of Vitamin D functions, its role in Calcium and Phosphorous absorption from the intestine, and prevention of osteomalacia. Everything was neatly pigeonholed into cause and effect. Vitamin D defiencies usually resulted from inadequate sunlight or UVB exposure.
Ergosterol, a plant sterol, is ingested from plants, oily fish, etc. One of the initial metabolic steps includes breaking of the B ring of the sterol which is done by exposure to ultraviolet light (UVB 280-320 nanometers) in the skin. This “pre D3”is further metabolized to the active D3. Most Vitamin D metabolism was felt to occur in the liver and proximal kidney.We fortified the milk and dairy with Vitamin D (either D2 or D3), and we fed tablets of ground up oyster shells with Vitamin D to reduce osteoporosis. Dialysis patients usually received Calcium carbonate tablets. We thought Vitamin D was all about Calcium and Phosphorus absorption and bone deposition. Simply by providing adequate Vitamin D and Calcium we could prevent rickets and ameliorate osteoporosis, reducing fracture risk in elderly people. There has not been too much controversy in this role of Vitamin D. There is not universal agreement on the amount needed by humans, as the need appears to vary with age, skin pigment, skin surface area exposed, and the amount of sun exposure. In the absence of adequate sun exposures, some have recommended 800-1000 IU vitamin D3 daily for children or adults. Much of the vitamin D used for fortification comes from UV irradiated yeast, lanolin, and even mushrooms. Overdose toxicity is possible but not very common. In the 1950’s there was an outbreak of hypercalcemia in Britain, possibly due to over-fortification of milk with Vitamin D.
Our understanding of the role of vitamin D regarding bone and skeletal formation and modeling may be oversimplified and summarized in this illustration in the following from Holick, Micheal F.,Vitamin D Deficiency page 269.
Life was simpler 40 years ago. We did not know about Vitamin D receptors, Vitamin D Response elements, and a host of other regulatory mechanisms. We had no concept of the existence of Vitamin D Receptors in most cells of the body. We did not understand its dynamic hormonal cellular effects and importance in cardiovascular disease, the immune system, cancer, diabetes, hypertension, infection, and other disease processes. For those interested in same, a slightly dated 2014 review by Bikle, Daniel D., Vitamin D Metabolism, Mechanism of Action, and Clinical Applications, may be a helpful starting point.
There is no question the role of Vitamin D in health has been underestimated. It is essential to animal well-being in many ways (in addition to Calcium/Phosphorus absorption and Skeletal development/Skeletal remodeling).
Yes, the above comments apply to humans and tortoises have not been extensively studied. Most tortoise recommendations are extrapolated from requirements of other studied animals and corrected for metabolic rates.
What does this backyard tortoise breeder do? If proper diet and sun are available, adequate vitamin D should be a non-issue. Calcium availability may be a dietary function varying with location.
In the case of many Floridians, Florida is sitting on a coral shelf and our well water is quite high in calcium. Well water is the source of tortoise drinking water. If irrigated, grass is periodically coated with extra calcium and minerals. Some plants will not tolerate this hard water. Our primary tortoise diet is grasses. Additional calcium may be occasionally be supplied with supplemental feeds, cactus, etc. Hatchlings do get periodic calcium carbonate added to their diet.
In addition to grasses, young tortoises occasionally get mushrooms from the store as a treat. They love them! Mushrooms are an excellent source of ergosterol, a Vitamin D precursor mentioned above. (If the mushrooms were sun-dried (UVB irradiated), their effective Vitamin A content would go up.) Tortoises may receive occasional extra Vitamin D from a feed supplement but that is not the usual.
Essentially, as tortoise stewards, we depend on sun (UVB) to allow tortoises to synthesize appropriate amounts of Vitamin D. With appropriate amounts of D3, Calcium absorption should be appropriate. With appropriate diet and UVB, there should not be a need for Vitamin D supplementation although moderate Vitamin D fortification of the diet is not harmful. Over-supplementation can potentially result in toxicity.
Last edited:
~ great post!
Needless to say, my Beethoven, Bach, and Brahms love mushrooms. Now I don't feel so bad giving them the occasional shroom with their meals. I will say, I'm amazed at how much they have grown.
ColaCarbonaria
Well-Known Member
Bush hoggin ain’t easy... Love th custom exhaust work!
Really appreciate the photos of your farm that you share.
Really appreciate the photos of your farm that you share.
You are such a welcome addition to our Forum! I'm so glad you found us and joined.
~ I second that!
Thank you!
After repacing the exhaust manifold, the customized muffler is loosly attached by a U bolt pending completion of clearing. Hopefully will "pull off" prior to breaking replaced exhaust manifold. Will post photos of torts on recently cleared area soon.
Thank you.
Thanks.
You may find some of the following of interest if not already in your library. Crude notes attached:
GIANT TORTOISE AND VEGETATION INTERACTIONS ON ALDABRA ATOLL – PART 1: INLAND ARTHORS: Merton,L.F.H., Bourn.D.M., Hnatiuk, R.J. 1976
https://www.researchgate.net/profil...eractions-on-aldabra-atoll--Part-1-Inland.pdf
Food resources limiting growth on Grande Terre, the area of 97% of the tortoises. Noted the size of the typical animal as 24 kg (52.9 lbs) and curved length 70 cm (27.6 inchs). Noted a “tortoise turf, seldom exceeding 5 mm height but intensively grazed. consisting of a mixture of primarily genetically dwarfed grasses, sedges, and herbs ( composition table page 301). Suggested the large areas of tortoise turf evolved under grazing pressure from tortoises and likely the result of selective removal of other potentially competitively plant species by tortoise activity. Noted a reduction in the amount of shade cover available to tortoises likely to lead to high rates of mortality. Suggested a possible decline in tortoise numbers due to high tortoise densities causing overgrazing, erosion, and loss of shade trees. This was from 1974 observations.
The Biomass, Production and Carrying Capacity of Giant Tortoises on Aldabra
Author(s): M. J. Coe, D. Bourn and I. R. Swingland 1979
https://www.researchgate.net/profil...ng-Capacity-of-Giant-Tortoises-on-Aldabra.pdf
Suggests that the population is greater than the potential large herbivore “carrying capacity” in part due to long generation times, the ability to stop growing during drought and reduce annual production, and in times of increased rainfall and food, the ability to increase the number of eggs per nest and mean egg weight. Additionally, on Grand Terre fresh water is raised close to the surface by high spring tides making water available for plant growth in the absence of rain. Mean Annual rainfall on Aldabra 941 mm (3.74 inches) and variable (547-1487mm).
The giant tortoise population of Aldabra (Cryptodira: Testudinidae)
DM Bourn - African Zoology, 1976
https://www.ajol.info/index.php/az/article/viewFile/151293/140871
Calculated crude mortality rate per annum of 2-3%. Secondary sexual characteristic apparent in animals at about 50 cm straight length. Sex ratio 1:1 with local variations. Mating commence beginning of wet season in Nov. or Dec. peaking oin April before beginning of dry season. Nesting occurred June, July and August with recent hatchlings seen start of the following wet season. Mean number of eggs per female 10.8/female. 22% of census of the 100,000 tortoises considered to be mature females. Half of mature females examined during nesting season had mature eggs. Low daily food consumption of tortoises on eastern Grande Terre of 22-88 gm of dry matter per day due to food availability.
The Size, Structure and Distribution of the Giant Tortoise Population of Aldabra
Author(s): D. Bourn and M. Coe
Source: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, Vol. 282, No. 988 (Feb. 3, 1978), pp. 139-175
https://www.researchgate.net/profil...-the-Giant-Tortoise-Population-of-Aldabra.pdf
Information on the population size and sex of both Malabar and Grande Terre populations based on third dorsal scute curved width. This correlated well with mass of both sexes for tortoises on Grande Terre. Shape of population pyramids are indicative of declining population with reproductive size forming a relatively small proportion. They published a relationship between age (determined by growth ring counts) and cubed width of the third central scute. They went on to say it was extreamely difficult to reliably count more than 27 growth rings on any Aldabra tortoises in the field. Growth ring counts greater than 17 for Grande Terre animals were considered unreliable and excluded. The growth rates for the Malabar tortoises was approximately twice that of those to the southwest. It is assumed the tortoises continue to grow through life, based on white seasonal growth rings, with growth of very large animals being 1-2 mm per year. They calculated the age of tortoises on Malabar as 0-55 and those on Grande Terre 0-70 years. Growth rates from the 4 areas of Aldabra studied based on sequential study were not the same with faster growth rates on Malabar than tortoises on Grande Terre.
547 Mortalities were studied. 17% died due to being overturned and unable to right themselves, being trapped in deeply pitted terrain, or being wedged under tree roots. 3/4v of the remaining 83 % had died in open, unshaded positions, about half of which were more than 50 meters from shade. “The cause of the majority of the deaths was considered to be heat stress due to an inability to find shade cover in the hottest part of the day. Deaths from this cause were witnessed during the summer months and were probably the most common then.”
They felt the Aldabra tortoise population was 150, 466 (95% confidence 134,026-166,9070
Features of tortoise mortality and decomposition on Aldabra
D Bourn, MJ Coe - Phil. Trans. R. Soc. Lond. B, 1979
https://www.researchgate.net/profil...se-Mortality-and-Decomposition-on-Aldabra.pdf
The rise and fall of the Aldabran giant tortoise population. June 1999
David Bourn, Charlie Gibson, Dave Augeri, Cathleen J. Wilson, Julia Churchand Simon I. Hay
https://www.researchgate.net/profil...population/links/53e9f4bc0cf28f342f41681b.pdf
Decrease in population to estimated 100,000 in 1997 census. 1974 census estimated 129,000. Decline of 1/3 population on southeastern Grande Terre however lower density populations on Malbar and Picard (representing less than 5% of population) had almost doubled. Felt decline in population due to “natural population regulatory mechanisms, exacerbated by low rainfall in years 1980-1997, including two consecutive years of below average rainfall in 1995-1996 and 1996-1997.”
Persistence of distinctive morphotypes in the native range of the CITES-listed Aldabra giant tortoise. (2015)
Lindsay A. Turnbull, Arpat Ozgul, Wilna Accouche, Rich Baxter, Lindsay ChongSeng,
Jock C. Currie, Naomi Doak, Dennis M. Hansen, Pierre Pistorius, Heather Richards, Janske van de Crommenacker, Rainer von Brandis, Frauke Fleischer-Dogley& Nancy Bunbury
https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.1764
Population stable over past 15 years. No evidence of substantial declines in any of four monitored subpopulations. Suggest differences in size in each population likely due to differences in vegetation. “Phenotypic differences have even increased over the last 15 years: Animals have decreased slightly in size on Grand Terre (despite the recent eradication of competing feral goats), while they have continued to increase in size on Picard.” Large animals are never found on Grand Terre, and small animals are rarely encountered on Picard. Further, when small animals are found on Picard, they are clearly juveniles. …” How- ever, the observed morphological variation appears to have been stable over 50 years.“ Discussion of possible reasons for size differences in different subpopulations.
Reintroduction of Giant Tortoises, Geochelone gigantea, to the Seychelles’ Islands Kari A. Geurts 1999
https://conservancy.umn.edu/bitstream/handle/11299/59297/1/4.4.Geurts.pdf
Discusses the establishment of a daughter colony of Aldabra tortoises on Curieuse near Mahle with the advantage s of expanding the tourist industry and creating an opportunity to study the ecological and biological aspects of the giant tortoise. Ninety-five were released near the residence of the warden in approximately 1978. First hatchlings were observed in 1980. 78 more tortoises were released in April of 1980. 1n 1986 a field study was done. There was a significant impact by tourists. Tourists were unsupervised going anywhere on the island. Tourists were standing or sitting on the tortoises for photography. They could damage nest sites or hatchlings. Pollution by tourists is mentioned as well. “The most dramatic results of the study were that the researchers were only able to find fewer than half the tortoises originally introduced. In addition, the number of hatchlings found was extremely small, numbering only 17. The authors concluded that the tortoise population was declining. Only 102 individuals were found and according to estimates of population growth there should have been 400 individuals between the ages of 0-5 years. They attribute the low population to poaching and theft done by the locals able to sell them on the illegal market for large profits.” A 1990 population census showed a total of 117 individuals (73.38.6). Of the estimated 2100 tortoises hatched on Curieuse few had survived. Although environmental conditions appeared adequate, poaching and predation appeared to have severe consequences on the ability of the giant tortoises to form a self -sustaining population on the island.
“The tortoises are not being adequately protected even though they have a "rare" status and the island was designated a National Park. The growing demand from the international market to obtain giant tortoises and the easy money that this trade offers imposes a temptation on the locals and visitors. Stricter legislation may be necessary to combat the poaching and illegal market that is responsible for some of the tortoise losses. In addition, tighter control of tourists and tourist mobility will be increasingly necessary as more visitors come, to prevent damage to tortoises and their nesting sites. The loss of hatchlings from feral cats and rats must also be addressed. One option would be to implement a removal program but this may be expensive and difficult to accomplish.
Another option would be to create a properly managed tortoise nursery. This option could provide both a popular attraction for visitors and ensure the hatchlings and juveniles are able to survive. The Curieuse reintroduction has provided valuable knowledge to the field of restoration and demonstrates the need for further research in this area to assist in the recovery of rare, threatened, or endangered species and their environments.”
Current census? Was a nursery established?
Control and biology of feral goats on Aldabra Atoll, Republic of Seychelles
RE Rainbolt – 1997
http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/m039k884s
Removal of the feral goats from Grande Terre.
ESTIMATING AGE OF TURTLES FROM GROWTH RINGS: A CRITICAL EVALUATION OF THE TECHNIQUE -2003
DAWN S. WILSON1,3,4, CHRISTOPHER R. TRACY2,AND C. RICHARD TRACY1
https://www.researchgate.net/profil...petologica/links/09e4150c6a503562ed000000.pdf
“We conclude that (a) studies attempting to calibrate the relationship between growth rings and age are few, (b) a majority of the papers that we surveyed referenced other papers that did not themselves include a test justifying growth ring counts as an estimate of turtle age, (c) aging turtles from counts of growth rings might be feasible in some types of studies, for some species at some locations, but only after calibrating the relationship between ring counts and age for each circumstance, and (d) there is currently no justification for generalizing the use of growth rings to estimate turtle age for many species.”
GIANT TORTOISES OF THE INDIAN OCEAN 2007
Justin Gerlach
http://www.britishcheloniagroup.org.uk/testudo/v6/v6n4gerlach
“An extensive morphological study and a preliminary genetic study concluded that there are three living species: the Aldabran and two Seychelles species (D. hololissa and D.arnoldi) (Gerlach & Canning, 1998) (Fig. 2 & 3). More detailed genetic research has failed to find clear differences between the species although subsequently the captive breeding programme has shown that the morphological differences are also shown by the captive-bred juveniles – the morphology therefore has a genetic basis even though the genes used in standard analyses have so far failed to locate this.”
Breeding groups of six D. hololissa and six D. arnoldi(saddle back) established 1997. Some two hundred eggs infertile. Both groups put together in 2002 as a social group size of 12 had been recommended as minimum size for breeding. First hatchlings later that year and since 80% of eggs fertile. End of 2006 16 juvinile D. hololissa and 138 D. arnoldi. Release of adult D. arnoldi at Grande Barbe on Sihouette Island. Juveniles to be released when over 10 kg.
Effects of diet on the systematic utility of the tortoise carapace.
Gerlach, J. 2004. African J. Herp. 53(1):77-85.
http://islandbiodiversity.com/Afr J Herpetol 2004 tortoise diet.pdf
Studied effects of diet on Aldabra and Greek tortoises. 240 T. iberaBritish captive raised and 354 D. dussumieri captive bred and reared in Seychelles. Several measurements including degree of pyramiding on the 3rd vertebral scute (Scute height, scute width) as well as carapace slope (carapace height at 3rdvertebral scute /height at 1stvertebral scute). One pyramidal and one distorted Aldabra.
For Aldabras, all but 2 in natural light. Two raised in dark from hatchling to age 15 years. Highly distorted with carapace slope of 0.5. Specimens form one collection raised in dark building to age 3 years all strongly pyramidal (vertebral height /width = 0.4 – 0.5). Were on natural diet and morphology changes attributed to lack of UV exposure.
Not clear separation of morphology of tortoises raised on protein rich diets vrs phosphorus rich diets. Same carapace distortion by both diets. Felt minimal Calcium / Phosphorus ratio less than 1.8 for T. ibera or 2.0 for D. dussumieri to prevent pyramiding or carapace sloping. Correlated carapace abnormalities with changes in long bone dimensions.
“The present study confirms earlier reports that inappropriate diets can cause morphological abnormalities in tortoises. Specifically low calcium - phosphorus ratios (as a result of phosphorus rich diets or calcium deprivation in excessively high protein diets) results in scute pyramiding and excess protein can cause the extreme carapace deformation manifest in cases of ‘metabolic bone disease’ (nutritional secondary hyperparathyroidism). These distortions can also be caused by a lack of ultra vio- let light exposure in the absence of dietary problems; in hatchlings UV deprivation may cause pyramiding whilst long term deprivation results in severe metabolic bone disease. All these factors of calcium, phosphorus and UV levels combine in the process of calcium metabolism which is an essential process in skeleton formation and modification. From the present study it is apparent that tortoise cara- pace distortion and pyramiding occurs in the first few years of development, with tortoises kept on a phosphorus rich or protein rich diet retaining a normal carapace shape if initially reared on a balanced diet.”
Discusses bone formation and remodeling via calcium metabolism, osteoclastic and osteoblastic activity.
Influence of environmental humidity and dietary protein on pyramidal growth of carapaces in African spurred tortoises (Geochelone sulcata )
CS Wiesner, C Iben - Journal of Animal Physiology and Animal Nutrition, 2003
http://www.amazonreptile.com/tortoisepyramiding.pdf
Shows photo of Aldabra with pyramiding but studies done on 50 Sulcata hatchlings over 5 months in glass terraria with front sliding panes. Five groups with variables of dietary protein content and environmental humidity. Calcium/Phosphorus ratio higher than 3:1. Humidity from bowels of water and electronically controlled atomizers. Reptisun 5 at 25 cm above a bark humis substrate illumination 11 hours daily.
Tortoises raised “dry” showed very prominent humps whereas those raised “humid” were almost smooth. Those raised “dry” with different levels of dietary protein showed differences in “hump size” but may have been due to absolute hump size in bigger animals with higher protein. In “humid” conditions those fed the 19% protein and those fed the 30 % protein (dry matter) had differences in size (weight gains of 205 g vrs 284 gm) but both had “smooth” carapaces. Measured Hct, plasma Ca and Phos without sig differences? No measures for possible protein related disease as gout. Suggested providing areas with relative humidity of nearly100% for “hiding”. Study clearly correlated high humidity with smoother carapaces in hatchlings (5 months).
Body size development of captive and free-ranging African spurred tortoises (Geochelone sulcata): high plasticity in reptilian growth rates. (2010)
Julia Ritz1, Eva Maria Griebeler2, Ruth Huber1 & Marcus Clauss1
https://www.researchgate.net/profil...High-plasticity-in-reptilian-growth-rates.pdf
Last edited:
Opened the Connecting Gate and last weekend, 5 days later, took a few photos. After the pasture was "opened", young males quickly made a path around the perimeter fencing. None of the larger tortoises had migrated from the 3 acre pasture where they had been fed to the newly cut rough pasture.
Two inches of rain the preceding day.
Two inches of rain the preceding day.
Similar threads
New Posts
-
Setting up for a Russian Tortoise - Constructive comments welcome
- Latest: David Steere
-
-
-
-
