SEXING & CAPTIVE BREEDING
Sexual maturity in diamondback terrapins is dependent upon size and not age. Males reach maturity at around 4" scl while females can be sexually mature as early as 6" scl. Hence, captive bred male diamondbacks can be sexually mature as early as 1.5 years and females at 3. However, growth rates in wild diamondback populations are much slower and usually take twice the amount of time for wild individuals to become sexually mature.
Here are some hints to sexing diamondbacks:
1) Length of the tail - males tend to have a larger and longer base to their tails. Their cloacal opening is further from the base than females'. Overall, a male's tail is about 1.25x longer than a similarly sized female's. Females have only a short base to their tails which tapers down in a skinny, almost concave manner.
2) Height of shell - males tend to have flatter shells than females
3) Females typically have more broad and generally larger heads than males do. This difference is typically able to be noticed in juveniles around 12-18 months of age depending on how quickly they have matured.
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While there are stories of some breeders around the world who have success breeding their terrapins year-round, this is typically not the case. Most breeders follow a similar brumation schedule as wild terrapins would by controlling the environments in which the animals live and abbreviating the extremes on either end of the hot and cold spectrum. Brumation is a natural cycle that all wild terrapins go through every year as the seasons change. Much like a grizzly bear hibernates during the winter months, terrapins similarly hunker down and sleep through the cooler seasons. While it isn't known exactly what this does for the animals, it is speculated that it has a way of somewhat "resetting" the females' reproductive cycle. One thing is for sure, after a few months of cooler temperatures and sleeping terrapins, as soon as the temps begin to rise up, there is always a noticeable increase in breeding activity.
From the male terrapin's perspective, breeding season is all the time. Even in the cooler months, it isn't uncommon to find a male attempting to mount a female if they are kept in the same enclosure. The same isn't usually true for the female terrapins. They are often "not in the mood" and will even become aggressive towards the pestering males at times. Sometimes I wonder if the females simply get "worn-down" by the males' constant attempts and finally give in to them, but I haven't gotten any of them to open up and talk to me about that quite yet.
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Once the males have had their chance to mate with the females and when the environmental conditions are right, it will take a female roughly three weeks to develop her first clutch. If the terrapin gods have multiple clutches in store for her, each additional clutch will take roughly 2 weeks to develop.
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During the breeding season, I typically check my females for eggs twice per week. I do this by palpation and by checking their weights. Palpation of a female terrapin is done by GENTLY sliding a finger in front of their hind legs on both sides and feeling into their abdomen. If she has eggs developing, they are easy to feel. Don't attempt to count them if you are palpating. Simply note that there are eggs and begin to prepare for her to nest.
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Once a gravid female is nice and plump with eggs, you will usually begin to notice her behavior change when she is getting closer to nesting. Gravid females will swim franticly in their enclosure. In the wild, they do the same thing, but we don't notice as easily since they are out in the open waters. It is easy to assume that the frantic swimming of a gravid female is just her "freaking out" because she is about to lay eggs and she is possibly scared or distressed. While she might be uncomfortable, the motion of their hind legs actually helps them to move the eggs into position for laying.
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As long as she is provided with adequate nesting areas, when the time is right, she will come out of the water and "nose" around in the substrate as she looks for the perfect place to dig her nest. When doing this, she is checking for the temperature and the moisture of the substrate. Once she is happy with a location, she will begin to dig her nest with her front legs and then turn around and complete the dig with her hind legs. It isn't uncommon for a female to dig a few "test holes" before she is happy with a location.
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When she is finally digging her nest, it's pretty impressive to watch a female cradle each egg and gently lay them down into the hole with her feet. While there have definitely been some eggs that fall and break open, most of the time, they are gently laid into the nest and then packed tight with sand when she is all done.
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Whether a breeder digs up the nesting box daily to check for eggs or has motion-detecting cameras on the nesting areas, those eggs will almost always need to be dug up and moved to an incubator to ensure proper development.
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Terrapin eggs take roughly 60 days to incubate. That number varies a little bit depending on what temperature the eggs are incubated at. 85-87F produces all females and usually hatches between 45-55 days, 79-81F produces all males and generally takes 60 days +, and anything in-between produces a mix of males and females and will take anywhere from 50-60 days. While temperature is very important during incubation, humidity is equally as important. Using a substrate which can hold ample amounts of water without being too saturated is key. I use Hatch-Rite as a substrate and I make sure it is saturated prior to the incubation of any terrapin eggs.
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