Galapagos Tortoises

Olddog

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Tail differences between female and male Galapagos (Chelonoidis nigra) hatchlings

There has been discussion on another thread regarding sexing hatchlings by tail characteristics.

I would like to offer another perspective and suggest that in some cases, it can be done with a relatively high percentage of certainty, at least in some subspecies of Galaps. I do not have enough experience with other species of tortoises to suggest if this applies.


Consider that when hatching a group of Galapagos tortoises, there may be some with long tails (6-7 dorsal scale row(s) on tail). There will also be those with short tails with 2-3 row(s) of dorsal tail scales. Those with a line of 6 -7 dorsal scales are very likely male. Those with a line of 2-3 dorsal tail scales are likely female. Most of a hatch will have 4-5 dorsal scales and, in my opinion, sex cannot be suggested.


On the islands there has been considerable studies done on Chelonoidis nigra hoodensisand the ongoing repatriation program. I have no experience with this subspecies. Temperature dependent sex determination (Sancho, Ana, et al) has been reported with a pivotal incubation temperature of 28.3 C and a range of transition temperatures of 25.2-31.4 degrees C. A limited number of incubation temperatures was utilized to generate the data. The authors caution that not all of the C. nigra complex have similar pivitol or transitional temperature ranges.


Sex determination was identified by gross observation of the gonads at autopsy, histoloical gonad examination or laproscopic examination. The number of large dorsal scales were counted as well. The numbers in the study are relatively small.


Their results include:

“The number of large dorsal scales in the tails of hatchlings identified as males ranged from 4‒7 (n = 10, x̅ =4.9), females ranged from 2‒5 (n = 10, x̅ = 3.7). Male hatchlings had significantly more large dorsal scales on their tails than did females (t = 2.48, d.f. = 18, two tailed P = 0.023).”


The above is not offered to generate argument but rather to suggest there are some individual hatchings with tail morphology to suggest sexual dimorphism.


These photos are from 2004 and are suboptimal put perhaps illustrate some of the differences in tail morphology of hatchlings. I apparently do not have good photos showing the dorsum of hatchling tails.


Reference: https://pdfs.semanticscholar.org/2e...57.2009400275.1530046409-734113714.1530046409


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CarolM

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Sleeping in the water.

Herb's harem has not been moved to another pasture due to unburned burn piles. This does not deter Herb from attempting to breed. Most evenings the tortoises will sleep in water which likely helps with mosquitos. There is a bat house full of bats with young in the adjoining enclosure which likely mitigates the mosquito bites.

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Lol. No soaking for you to do. It seems your torts are well trained.[emoji3]
 

ALDABRAMAN

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Tail differences between female and male Galapagos (Chelonoidis nigra) hatchlings

There has been discussion on another thread regarding sexing hatchlings by tail characteristics.

I would like to offer another perspective and suggest that in some cases, it can be done with a relatively high percentage of certainty, at least in some subspecies of Galaps. I do not have enough experience with other species of tortoises to suggest if this applies.


Consider that when hatching a group of Galapagos tortoises, there may be some with long tails (6-7 dorsal scale row(s) on tail). There will also be those with short tails with 2-3 row(s) of dorsal tail scales. Those with a line of 6 -7 dorsal scales are very likely male. Those with a line of 2-3 dorsal tail scales are likely female. Most of a hatch will have 4-5 dorsal scales and, in my opinion, sex cannot be suggested.


On the islands there has been considerable studies done on Chelonoidis nigra hoodensisand the ongoing repatriation program. I have no experience with this subspecies. Temperature dependent sex determination (Sancho, Ana, et al) has been reported with a pivotal incubation temperature of 28.3 C and a range of transition temperatures of 25.2-31.4 degrees C. A limited number of incubation temperatures was utilized to generate the data. The authors caution that not all of the C. nigra complex have similar pivitol or transitional temperature ranges.


Sex determination was identified by gross observation of the gonads at autopsy, histoloical gonad examination or laproscopic examination. The number of large dorsal scales were counted as well. The numbers in the study are relatively small.


Their results include:

“The number of large dorsal scales in the tails of hatchlings identified as males ranged from 4‒7 (n = 10, x̅ =4.9), females ranged from 2‒5 (n = 10, x̅ = 3.7). Male hatchlings had significantly more large dorsal scales on their tails than did females (t = 2.48, d.f. = 18, two tailed P = 0.023).”


The above is not offered to generate argument but rather to suggest there are some individual hatchings with tail morphology to suggest sexual dimorphism.


These photos are from 2004 and are suboptimal put perhaps illustrate some of the differences in tail morphology of hatchlings. I apparently do not have good photos showing the dorsum of hatchling tails.


Reference: https://pdfs.semanticscholar.org/2e...57.2009400275.1530046409-734113714.1530046409


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~ That is so interesting.
 

Olddog

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Lol. No soaking for you to do. It seems your torts are well trained.[emoji3]

No training on our part. they will make their own mud wallows in rainey season. This group would benefit from petroleum jelly to clobber the seconday fungus growth associated with the frequent immersion. They had coconut oil six weeks ago but that does not last as well as petroleum jelly in warmer weather. They usually prefer a shallow mud wallow with a few inches of water over a deeper pond like area.
 

Olddog

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Thoughts on Giant Tortoise Nutrition

A few over-simplified thoughts on the nutrition of adult and juvenile giant tortoises (Over the years the author has probably made many mistakes, and, in some cases, should have known better. Fortunately, the reptile community’s knowledge and resources have improved with time). This writer is not a veterinarian or nutritionist and these comments should not be considered a substitute for professional consultation.

The Aldabra and Galapagos tortoises are Herbivorous Reptiles. That said, they have some opportunistic Omnivorous tendenciesand will occasionally eat higher protein in the wild when available. They have a relatively large “large intestinal tract” which is very important in their food absorption and metabolism. In this large bowel (hind-gut) the tortoises absorb soluble carbohydrate and ferment crude plant fiber. This is quite different from human metabolism and this large intestinal fermentation process must be remembered when feeding giant tortoises. Again, they are hind- gut fermenters (Mammalian equivalent - horses). This difference can be critical when considering their diet and need for bodily warmth. The following are basic guidelines to be followed when creating giant tortoise diets from available foods.

With the above in mind, giant tortoise need a minimum of 15% crude fiber in their diet (dry matter (DM)) (Range 15-40%). If feeding fruits, fruit lack of crude fiber should be countered with adequate dried forage to get the crude fiber content to greater than 15%. (If only fruit is fed and there is not adequate forage or crude fiber, the sugar laden fruit may be rapidly fermented in the large intestine resulting in lactic acidosis.)

Fat should be about 5% (5-10%). Most Herbivores have digestive difficulties with fat content greater than 12%. Fats are usually absorbed in the small bowel. Short chained fatty acids are produced from fermentation of crude fiber in the large intestine.

Protein (plant) should constitute approximately 20% of the diet (15-35%). Periodic additional protein may be beneficial.

Carbohydrates should make up approximately 50% of the diet (starch and fiber). Calculation of conversion of crude fiber to carbohydrate in the gut is not always exact.

The following is a table from page 268 of Douglas Mader’s 2005 Reptile Medicine and Surgery textbook chapter by Susan Donoghue which may be helpful as a starting point. Unless you have unlimited grass forage, it may be useful to consider most hays will have 25-35% crude fiber and calculate accordingly to get a minimum of 15% crude fiber when supplementing greens, sprouts, fruits and vegetables.
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Additionally, the “regular diet” may be supplemented with the addition of a higher protein diet as often as weekly. This has been done with horse chows, low fat dog foods, antelope chow, croc chow / tortoise pellets, etc. These supplements are a fraction of the daily diet such that the total fat content is appropriate. The Calcium to Phosphorus ratio should be high in the supplemental protein source. This supplement may be particularly helpful during breeding and laying periods.

Pyramiding is probably multifactorial and likely associated with individual genetic tendencies. Hatchlings need high humidity. Tortoises raised on high protein diets in high humidity have shown pyramiding despite exercise room and UV light. Growth rate may be a factor. Secondary hyperparathyroidism may also be evidenced. Judicious protein supplementation is felt beneficial, but it can be overdone.

Most of the greens tortoises eat have what is considered a relatively high oxalate content (Calcium oxalate, oxalic acid) by human standards. Calcium oxalate may potentially not dissociate, and oxalic acid can bind free Ca. Tortoises may have a higher tolerance to oxalates than mammals, but it is not well studied. They may inhibit Ca absorption. Other factors such as adequate D3 resulting from sufficient UV exposure facilitates Ca uptake from the small intestine..

Large quantities of cabbage, broccoli, kale, brussel sprouts, mustard greens, etc., contain high levels of thiocyanates which inhibit the thyroid uptake of iodine which in turn may cause a goiter. Supplemental iodine may be indicated but caution is indicated if using kelp due to potential toxicity from variable iodine concentrations.

Galapagos tortoises generally do not do well in the long term when fed for rapid or maximum growth. A C.nigra beckiwill likely never grow to the size of the other subspecies and should be fed accordingly. Survival is better in those tortoises initially grown slowly. Once they get a few years growth, they can probably safely forage as much grass as available without difficulty.

Again, in my opinion, it is critical to remember the giant tortoises are hind-gut fermenters. Food stays in the hind-gut a long time (days)*. An easily digested predominately corn based diet without adequate crude fiber, IMHO, does not constitute good long-term nutrition with possible disastrous results.

Some supplementation of macro and micro mineral is likely generally needed under most forage conditions although toxicity can result if overdone.

According to the AZA Galapagos studbook keeper, many of the Galapagos tortoises hatched in the 90’s are no longer with us due to husbandry issues. As stewards of these magnificent animals, we need to do a better job.

*Aldabra gut transit time is 10-20 days based on the Patterns of activity and body temperature of Aldabra giant tortoises in relation to environmental temperature link posted in th Aldabra forum.

Galapagos gut transit time has been reported 8 to greater than 20 days although transit time appears faster in our observations when animals are fed beets. It is conceivable they may not eat as much forage at times when fruits and vegetables are plentiful, or they may be fed more in captivity than in the wild.

 

Olddog

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Iodine supplementation (while on pasture).

On occassion, tortoises are given breads in moderation. This is in supplementaion to a high fiber diet and must be done in moderation.
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This young lady prefers berries in her bagel.

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Olddog

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~ Beautiful photo's
Thank you. Really enjoy your photos and videos. Very prominent on FB with all the shares. Often see 3 or 4 links to your videos when logon to FB.
Only have the one pair of subadults. I believe he s still very much too young and small to reproduce. Feeding area no longer has grass.
 

Olddog

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Wait....bagels do what?

Great photos!

Thank you!

Please consider:

I do not know the iodine content of the bagel. That said, most bread in the US is reported to have 10 - 32 mcg of iodine per slice. It was higher when iodinized salt was utilized or iodantes were used as preservatives. Food ingredient lists do not reflect the iodine content of foods. As the tortoises are not fed dairy products, breads may be a reasonable source of iodine supplementation assuming adequate fiber from other sources. Of course, other sources can be utilized for iodine supplementation. Over supplemtation can be problematic. Anything which effects iodine metabolism may effect thyroid function.

Goitrogens are found in broccoli, cabbage, cauliflower, kale, etc. Reportedly goiters are more prevalent in the giant species from the Galapagos and Aldabra Islands. Estimated daily level of dietary iodine is approximately 0.3 mcg/kg body weight. (page 165, Mader, Reptile Medicine and Surgery).

 

Sesel

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Do you moisten the bread before giving it to them?
I remember we use to give our Aldabras moistened bread a long time ago. It's been a while since. It was not for the Iodine, they simply loved it :D
 

Olddog

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Do you moisten the bread before giving it to them?
I remember we use to give our Aldabras moistened bread a long time ago. It's been a while since. It was not for the Iodine, they simply loved it :D

Have not moistened the bread. Frequently used as a treat. If time permits, will hand-feed it, but feeding is pretty slow with some of the girls as the approach and feeding is very much on their terms. Some of the males will just stand for bread, open their mouths, and expect you to fill it. One has to be careful a finger is not included with the bread as that boney ridge can be unconfortable. Also have used bread to bribe some tortoises when moving. Although they want you to feed it to them, it appears they are not nearly as excited when bread is distributed on the ground. Probably not good as a steady diet but nice as a treat.
 

Olddog

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Moving large tortoise to another pasture.

When moving a single animal to another pasture, just used pickup rather than hooking up and pulling trailer through wet grounds. In retrospect, ramp was too steep, wet and should have had more battens.


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galapagosgirl1

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Moving large tortoise to another pasture.

When moving a single animal to another pasture, just used pickup rather than hooking up and pulling trailer through wet grounds. In retrospect, ramp was too steep, wet and should have had more battens.


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The final outcome was one happy Diego as evidenced by the grass sticking out of his mouth! Well done! This is a difficult time of year in Florida.
 
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