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C. angulata Successful Hatching @ GardenStateTortoise

Discussion in 'Bowsprit tortoises' started by HermanniChris, Mar 15, 2018.

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  1. HermanniChris

    HermanniChris Well-Known Member TFO Sponsor

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    Anyone who converses with me regularly probably recalls the ongoing issues I've had with hatching bowsprit (angulate) tortoises (Chersina angulata). Well, as of yesterday, March 14th, 2018, I am happy to report that the curse has finally been lifted. We have finally successfully hatched a healthy and robust baby. We are over the moon about this.

    To give some background, for the past 3+ years, we have experienced frequent egg laying by our multiple adult females. The girls typically lay from September to April and deposit 1 egg per clutch, up to 6 times yearly. This is fairly consistent with what Chersina angulata does in nature. Eggs are always deposited in the evening (and sometimes into the night) in shallow nests dug into the substrate provided which is a mix of top soil, crushed oyster shell, mason sand and organic potting mix. Our adults are housed exclusively indoors in our external tortoise building dubbed "The Tortoisery". Males are housed individually or with females for breeding periods. Males are relentless breeders and initiate courtship at any time. Season does not seem to matter. Because of their tireless attempts, they are only housed with the females for a few weeks before being separated again.

    This species is common in nature. In fact, the density of populations found in South Africa far exceeds many other tortoise species according to various reports. One would think that reproducing such an abundant species in captivity would be rather easy but for us (and many others) it has proven to be quite the challenge. Species that are listed as endangered, critically endangered and even functionally extinct (T. h. hermanni, T. coahuila, G. platynota, T. kleinmanni to name a few examples) are bred frequently here without any issue whatsoever, yet for our angulate tortoises, it has been nothing but failure....until now.

    We have had several eggs begin developing under what many consider to be "straight forward incubation methods" only to find the embryo to perish inside the egg before hatching.

    Eggs maintained on slightly moist vermiculite (5:1 ratio of vermiculite to water by weight) in perforated deli containers developed until between 61 and 93 days only to perish before hatching. We experimented with temperatures and subjected the eggs to anywhere between 83F and 90F. Humidity was kept at between 70 and 80%. One egg fooled us and we actually believed it had hatched. It was actually dead and whether or not it pipped and died or the egg began to decompose pushing the baby out is a mystery to us. It did smell rather bad upon opening the incubator and according to incubation duration, this one was too early.

    We then offered a cooling period to the eggs much like what we do for our South African leopard tortoises (S. pardalis pardalis) and Burmese star tortoises (Geochelone platynota). Eggs were kept on very slightly moistened vermiculite again in deli containers but were kept at between 65 and 68F for 30 days immediately after being laid. After 30 days, they were placed in the same incubation temperatures and humidity levels listed above. Only one egg developed for about 2 weeks before stopping and beginning to decompose. Of the other 4 eggs we tried this with, 3 never developed and were discarded while one remained in a "torpor" of sorts. It chalked and revealed one small blood vessel. The egg was removed from incubation after 3 weeks and placed back into cooling for 2 more weeks. After that it was placed back into incubation. It developed until about 90 days before perishing inside the egg.

    We then tried straight incubation on dry perlite with 70% air humidity and 84F in an open top container inside the incubator with the next 2 eggs we received from our females. One egg proved to be infertile while the other developed to 65 days. Yet again the embryo perished inside the egg.

    At this point in time I began reaching out more than ever especially after the start of the Chersina angulata Working Group. I received several opinions and advice on how to hatch this apparent difficult species. Some simply had dumb luck with their limited success while a few others could explain exactly what they did...and of course, some simply didn't care to share or even reply.

    On December 22nd, 2017, upon opening up The Tortoisery that morning I noticed that one female who had been restless for weeks (usually meaning she is gravid and oviposition is near) was suddenly very calm and felt lighter in weight. That told me she must have deposited an egg. Sure enough, I unearthed 1 egg in the substrate.
    The building that morning was only 55F and had been anywhere between 61 and 57F for several weeks in the mornings. We allow the nighttime drop in our building because it promotes wonderful breeding activity for other species kept in there such as our Egyptian tortoise (Testudo kleinmanni) colonies. The cool nights, cool mornings and then a significant rise in heat for the day replicate some of the coastal expanses that Egyptian and bowsprit tortoises experience in nature. It's proven to be a great way to urge them to breed and produce fertile eggs throughout winter and early spring.

    Upon inspecting this new egg I noticed it had already chalked and had one tiny blood vessel in it. Considering others have hatched this species by allowing a nighttime drop (Kingsley Rodrigo & friends at the Turtle Conservancy) in incubation (and the fact that they urged me to do so as well) I decided to continue to allow the egg to experience this. The egg was placed in an open top deli container on the substrate from the enclosure (mix of top soil, crushed oyster shell, mason sand and organic potting mix). Temperature was then set to 86F. The incubator (a simple styrofoam "Hovabator" used for chicken eggs) was hooked up to a timer that would turn on at 7:22 am and then shut off at 10:22 pm. Each night, the temperature would drop down to between 65 and 68F and then rise back up rather quickly when the timer kicked the incubator on in the morning. During the day, the humidity inside would drop to as low as between 53 and 61% only to rise to sometimes up to 85% at night. I allowed for fluctuation which is of course what eggs experience in the wild. I would only add a little bit of water to the egg's substrate if the nighttime humidity dropped below 70%. About 1 week ago changed the time on the timer to turn on 1 hour earlier.

    About 3 weeks ago with the egg well into development I took advice I was given regarding sanding down the egg shell from Austin Miller & Max McGlasson. This has been done to successfully hatch Galapagos tortoises (Chelonoidis nigra) and Guerrero wood turtles (Rhinoclemmys rubida) to my knowledge. Reports concerning oxygen deprivation with tortoise eggs (thanks for that info Dan Sterantino) have surfaced and so, I went ahead actually sanded down this egg. Using 600 grit sand paper I carefully held the egg on a bed spread and sanded away. It's difficult for me to gauge just how much I sanded but about 50% of the egg became glossy white and very polished looking. I checked the embryo by candling and it was in fact alive and moving.

    Last night while pulling babies from another incubator, I peaked in at the C. angulata egg and to my amazement it was hatching. The baby is fully out of the egg already today with the yolk sac fully absorbed. It's healthy, robust and flawless.

    The wife dubbed this little ray of hope "Ayanda" which is South African for "they are increasing". I don't normally name but she does and this certainly seems fitting.

    I attribute this success to the nighttime drop during incubation and/or the sanding down of the egg. Perhaps my issue all along was oxygen deprivation regardless of the fact that many other species hatch in that same style incubator and even right next to the bowsprit tortoise eggs consistently.

    We have another egg in there right now and will of course be replicating this method for it and any other eggs to come from the Chersina angulata group.

    Below are some photos of little Ayanda hatching and I will surely post the progress to come.

    Thanks for reading and I hope this helps anyone else possibly having issues hatching this fascinating species.
    -Chris

    Attached Files:

    Last edited: Mar 16, 2018
    Loni, Huckleberry, Koen and 16 others like this.
  2. no one

    no one Guest

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    I am happy for you... love the name and what it stands for.
  3. wellington

    wellington Well-Known Member Moderator

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    Big CONGRATS! Hope he continues to thrive and that it's a success from here on.
    Keep us updated.
  4. CarolM

    CarolM Well-Known Member

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    That is really awesome news. Congratulations - I am very happy for you. Ayanda is a little beauty. I will certainly be following this thread to watch how Ayanda grows.
  5. Maro2Bear

    Maro2Bear Well-Known Member 5 Year Member

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    Great going. I’m always amazed at the dedication and peseverence demonstrated by breeders here on the Forum, especially with stories like this. Your first new baby looks perfect. Best of luck in future.

    But...who or what sands the eggs in nature? Eggs ever so gently grinding against sand and grit over time, like polished sea glass?
  6. Thomas Anderson

    Thomas Anderson Member

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    Awesome work Chris congrats
  7. Sterant

    Sterant Well-Known Member Platinum Tortoise Club

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    A sincere congratulations Chris - I know the work and perseverance that went it to this success. I'm really proud that the Chersina Angulata Working Group was of value and am excited for the future of this species in the US.
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  8. Markw84

    Markw84 Well-Known Member 5 Year Member

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    Chris:

    Congratulations! That is really great.

    I also want to thank you for such a great accounting of the details. So much is yet to be learned about chelonians and it is the private breeders that so often take the time and effort to really advance our understanding. Only by sharing, as you have graciously done, will this knowledge actually have an impact on any substantial knowledge base. I am so grateful for those, like you, who are willing to share and actually contribute to the advancement of our understanding.

    thank you!!!!!
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  9. Tom

    Tom The Dog Trainer 5 Year Member

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    Fascinating info. It raises so many questions! Thank you for sharing Chris!

    And CONGRATULATIONS!!!
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  10. HermanniChris

    HermanniChris Well-Known Member TFO Sponsor

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    Thanks everyone. I truly appreciate the kind words and comments! Ayanda is fully out and already in her new enclosure.
  11. tglazie

    tglazie Well-Known Member 5 Year Member

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    Well, folks, I never would have imagined that this community would've garnered success so quickly. Now, I'm not one to count the chickens before they hatch (or in this case, just after they hatch), but this is some fantastic progress. I hope these little beasts become as common a mainstay in the hobby as star tortoises, as I would jump at the chance to work with this species in the future, see how they fare in the South Texas climate.

    T.G.
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  12. Sterant

    Sterant Well-Known Member Platinum Tortoise Club

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    It is very exciting and promising. Just within the CAWG, we now have 4 colonies with breeding adults. The group has been working very well together in many ways. We have been transferring animals to make sure we have viable breeding groups, and moreso, we have been transferring information which is helping all of us. I am hopeful that we will see real progress this year and in years to come.

    Dan
  13. tglazie

    tglazie Well-Known Member 5 Year Member

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    Oh, and congratulations, Chris. Should've said that first.

    T.G.
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  14. HermanniChris

    HermanniChris Well-Known Member TFO Sponsor

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    No worries, and thank you.
  15. HermanniChris

    HermanniChris Well-Known Member TFO Sponsor

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    Not sure what happened with the pics I tried to post but here are some from today. Ayanda3.jpg
    Ayanda4.jpg Ayanda5.jpg
  16. Sterant

    Sterant Well-Known Member Platinum Tortoise Club

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  17. CarolM

    CarolM Well-Known Member

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  18. KevinGG

    KevinGG Well-Known Member 5 Year Member

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    So happy for you. The best part is you have lots and lots of eggs coming from your group.:)

    Thank you for sharing all of this with us. As you get a larger pool of successes, people will surely follow your lead. Great job
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  19. Markw84

    Markw84 Well-Known Member 5 Year Member

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    @HermanniChris I have a few thoughts in thinking about your efforts and the changes you made that seem to make a difference. For what its worth, here are some of my thoughts.

    I have been researching and discussing incubation techniques and the possible effects of the media used as it may effect calcium uptake from the eggshell, water mobilization through the eggshell, and the transfer of respiration gasses. One speaker at this last TTPG conference has done a lot of work, more in the area of aquatics, but his insights I find are offering ideas that I feel are applicable.

    For example, Matamatas lay hardshelled eggs. They have found if incubated on/in vermiculite, the eggshells will remain too hard for the babies to emerge. If they add a mixture of peat, the babies are able to hatch successfully, plus they are of an average size that is larger with the addition of peat. It seems this aids in the utilization of calcium and calcium uptake from the eggshell. It has also been found in some works that increasing the surface area in contact with the incubation media increases the water exchange in and out of the eggshell. A paper on snapping turtle eggs (also a hard shelled egg) looked at calcium mobilization from the eggshell. They found that most of the calcium that was used from the eggshell during incubation, came from the sides and bottom of the egg. - the areas that were in contact with the incubation media. While the top and exposed part of the egg had little calcium mobilization occurring there. Dave points out that humic substances chelate calcium. His belief is that the presence of humic substances help catalyze eggshell dissolution. So this could be an important factor.

    He also uses oscillating temperatures in incubating. He has found this not only lowers the average temperature the egg experiences, but allow for higher, female producing temps without constant high temperatures. He was motivated to try this in an attempt to minimize possible scute deformities. However, he also found the oscillating temperatures created corresponding humidity fluctuation where the differential in temperatures as they rose and fell, also created condensation and changes in moisture uptake in the eggs.

    My thought is that since this is such a small species, it cannot dig a nest very deep. So at such a shallow depth the nest would be much more subjected to daily temperature swings than a nest that is 12" deep. The difference is substantial in ground temperature studies. So I see great value in oscillating temperatures. Additionally, the swings in humdity may also facilitate water, and ionic exchanges.

    Since only one egg is laid in a clutch, the egg is probably more buried in substrate as opposed to stacked in an open chamber with neighboring eggs creating substantial air exposure to most of the egg. So with the single egg, there would be far more substrate in direct contact with the eggshell. If the female seeks out areas of more mixed organic matter in the soil - around bushes, and leaf litter, than you would have your humic matter mixed in with the substrate that would naturally facilitate calcium uptake and natural degradation of the eggshell as the embryo grows and uses this source of calcium.

    Since you found sanding the eggshell of possible value, perhaps that is an indication that the egg is not able to properly be utilized by the growing embryo. that the addition of a humic substance, and greater contact with the substrate could facilitate this. Nature does not sand the eggshell. But nature does provide the substrate that allows for substantial thinning of the eggshell (and therefore respiratory gas exchange) though the moisture, humic content, and greater contact with the eggshell, and combines this with a fluctuating temperature that causes daily changes in available water exchange through condensation changes.

    Things that could be tried that would do that:

    Perhaps a mixture of vermiculite and peat.
    Eggs anywhere from 50% to totally covered in that mixture. This would probably require a bit drier substrate.
    A covered container with minimal ventilation
    Oscillating temperatures that will also create periods of condensation in the container and a cycle of in/out of moisture in the egg.
    Weigh the egg and entire container to monitor water loss and adjust accordingly.
  20. MichaelaW

    MichaelaW Well-Known Member

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    Very interesting.
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