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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
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
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