Tortoises are oviparous vertebrates that can’t be pregnant because they lay eggs to reproduce. Instead, they become gravid, which means that they carry eggs.
A female may be gravid at any point once she’s reached sexual maturity. For most tortoise species, that’s once she reaches 15-20. However, it could be just 4-5 years in captivity.
Tortoises can gestate their eggs for 50-150 days. During this time, gravid tortoises may change their behavior, becoming quiet and withdrawn.
The female may also become aggressive, prone to defending her space and biting others. You can feel around the tortoise’s belly using abdominal palpation to detect small, round eggs.
How Do I Know If My Tortoise Is Gravid?
Here are the signs of a pregnant tortoise:
1/ Appetite Reduction
According to Physiological and Biochemical Zoology, pregnant tortoises eat less than normal. Researchers concluded that gravid females often had emptier stomachs due to a lack of capacity.
The presence of eggs in the oviduct pressed up against the tortoise’s stomach, and since the tortoise couldn’t fit more food in the stomach, her appetite was significantly reduced.
However, some tortoises ate less during each meal but wanted more regular meals. This gives the body more time to digest food, creating the space needed for a higher frequency of meals.
The tortoise will gain weight despite a reduced appetite and less food consumption.
2/ Increased Calcium Needs
Gravid females will need more calcium carbonate.
Tortoises will develop weak bones without sufficient calcium, as any calcium will be used during egg production. On other occasions, the female will be fine, but she’ll produce soft-shell eggs that are more likely to break or hatch into weak/sickly offspring.
According to the Peabody Museum of Natural History, gravid females supplement a lack of calcium in their diet with calcium-rich foods to produce healthier eggshells.
3/ Leg Wiggling
Pregnant tortoises use their back legs to bury their clutches in soil.
Also, she’ll rotate her legs to push the eggs out through their cloaca during the egg-laying process. A gravid tortoise may exercise her back legs more in preparation for this.
So, check for the tortoise wiggling in a gentle, circular motion.
4/ Scratching and Sniffing
When a tortoise is pregnant, she’ll find a suitable place to lay her eggs.
You’ll commonly find a gravid female doing the following:
- Nudging the soil with her nose
- Sniffing around different areas
- Exploring all corners of her tank
- Rubbing her head against the substrate
- Scraping the top layer of topsoil away with her front legs
She’s seeking a safe area that’s easy to dig out while testing the temperature and moisture levels. This will determine how well her young can dig out once they’ve hatched and how well they can incubate.
4/ Digging Around The Enclosure
Shortly before laying eggs, a gravid female will begin digging out her nest.
In the coming hours, she’ll create a nesting area that’s deep and secure enough to keep her eggs safe from predators and other threats, such as adverse weather conditions.
5/ Behavioral Changes
Aside from physical changes, a gravid tortoise will undergo behavioral changes.
When a female tortoise is suddenly acting out of character, she may be preparing to lay eggs:
Tortoises don’t protect their young or attempt to raise them. However, she’ll be defensive of herself and her nesting area before laying her eggs.
Quieter Than Usual
A pregnant tortoise may become quieter than usual, so she’ll avoid vocalizing and seek to hide more.
It’s a tactic that gravid females use to avoid drawing attention to themselves. This limits the chances of predators taking notice and following her to the nest once she’s laid her eggs.
How Do I Know If My Tortoise Is Going to Lay Eggs?
You can also use the palpate technique to determine if your tortoise is gravid.
“Palpate” comes from the Latin word “palpare,” meaning stroking or caressing. It’s a term often used to describe feeling out an area to gain insight. You’ll feel along its belly to see if growing eggs are inside.
This was found to be effective by Amphibia-Reptilia, where researchers used abdominal palpation to verify the results using radiology (x-rays).
The only discrepancy was in determining how many eggs were present.
How To Check For Tortoise Eggs
The ventral surface of the shell covers a tortoise’s stomach, so you’ll need to press closely to reveal any subtle bulges. To use the palpate technique safely:
- Gently lift your tortoise
- She’ll resist and kick her legs
- When she does, move your finger to block one back leg
- This will provide access to the inside portion of her abdomen, close to the leg opening
- With gentle pressure, use your fingers to feel the side of your tortoise’s abdomen.
- If it’s soft and squishy, she’s unlikely to be pregnant.
- When there’s a firm and round object inside, she’s gravid.
If you have difficulty locating the eggs, don’t push harder or prod more forcefully.
How Long Does a Tortoise Stay Pregnant?
The tortoise will remain gravid for 8-10 weeks.
In the wild, the female will deposit an average of 4-8 eggs in her nest after the gestation period. In captivity, females can lay 6-10 eggs.
Tortoise eggs are slightly oblong and hard-shelled with a dull white color.
Do Tortoises Lay Eggs Without Mating?
Once a female tortoise reaches sexual maturity, she can lay unfertilized eggs without a mate.
Most female tortoises produce eggs in anticipation of being able to mate. However, if she doesn’t find a mate, she’ll still have eggs in her body and be forced to lay them.
To tell if your tortoise eggs are fertilized, check for “chalking.” Chalking describes how the eggshell whitens after being laid, usually by a white circle or band running around the center.
This circle or band will have a transparent, pinkish color when laying. Eventually, the whitening will spread across the entire egg when fertilized.
You can also use “candling.” As the name suggests, this technique involves shining a bright light (a high-intensity LED flashlight is ideal for this purpose) through the egg.
Turn off all the lights in the room and shine the flashlight on the eggs. If you can see a network of blood vessels inside, this means the eggs are fertilized.
What Age Do Tortoises Stop Laying Eggs?
Tortoises never stop laying eggs so that they can breed and reproduce for their entire lives.
If you own an elderly female tortoise, she may still ovulate without the presence of a male. The sperm the male produces will be viable for up to 4 years, so there’s always a chance she’ll lay fertile eggs.
When Is Mating Season In Tortoises?
The mating season for tortoises starts around April and ends in June.
The eggs hatch sometime between August and October. Some indoor tortoises will never be able to see or feel nature’s mating cues, which can lead to them mating at any time or not at all.
Tortoises each have their preferences and may shift their breeding season based on the following:
- Food availability
- Amount of sunlight
According to Copeia, tortoises may forgo reproduction during dry seasons with limited rainfall. As food and water will be in limited supply, they understand that the likelihood of producing healthy offspring is reduced.
The best way to tell if your tortoise is gravid (or will become gravid) is by monitoring her behavior and habits. Pregnant tortoises may become quieter than usual, aggressive, or experience a loss in appetite. She may also wiggle her legs more often and start digging out a nest.