Can/Will Tortoise Siblings Try to Mate?

Tortoise siblings can certainly try to mate, as it is something that may occur in the wild, even though it is rare. It is very risky, though, and it should certainly not be encouraged, as it can lead to complications for the offspring.

If you love tortoises, you may end up getting more than one. Sometimes, you might even find you have siblings in your care, either knowingly or not.

If you do have a brother and sister you’ll watch them grow together, and in the back of your mind you may wonder whether the two may mate at some point.

This of course would be a concern.

After all, it isn’t a mystery that inbreeding has some very severe implications when it comes to most species, so the last thing you want is to see your tortoises suffering.

In any case, I wouldn’t keep two tortoises in the same enclosure, whether related or not, but I do realize there are a range of opinions on that subject, which I won’t get into here, but that you can read about here.

But I digress, this article will talk about tortoise sibling mating and give you all the answers you are looking for on this topic. Let’s get started!

Is It Possible for Two Tortoise Siblings to Mate?

Mating between two siblings is possible when it comes to tortoises. While it is very rare given that tortoises are solitary animals who ‘fly the nest’ as soon as they hatch, some tortoise siblings may find each other and breed while in the wild.

After all, unlike humans, tortoises don’t live their life with any comprehension of genetic diversity or morality. Their brains aren’t capable of understanding the world to any meaningful extent. All they want to do is eat, bask, mate and sleep!

So, when it comes to mating, they may take whatever partner they find along their path, even if that means a “relative”. Considering that tortoises are solitary, they don’t always have a partner around them to mate, which is why they will seize the opportunity when they get it.

Tortoises don’t know what inbreeding is and how it can affect the offspring, so they will not refrain from breeding with a brother or sister.

Now again, in the wild, the mother tortoise just leaves after her little tortoises hatch. Thus, they are left to live by themselves and find their own food, water, and mates, as well as their own safe places to retreat to.

The little tortoises will also leave in different directions, so it is very unlikely for them to find each other again in the future and mate, but it is not impossible.

Also, if there are other tortoises in the area and they are not related to the little ones, they will make sure that every hatchling is banished to another geographical area. This also decreases the likelihood of inbreeding happening.

In fact, it often seems as though Mother Nature tries to prevent tortoises from inbreeding even before hatching, as a batch of eggs often ends up producing members which are all the same sex.

Moreover, tortoises are able to have homosexual relationships at certain points, but of course this is not harmful as such behaviour cannot result in offspring being produced.

Should Tortoise Siblings be Allowed to Mate?

Despite the fact that interbreeding is generally considered a bad idea all round, it is in fact not 100% known what would happen if two tortoise siblings ended up breeding.

Still, it’s safe to say that it wouldn’t be a sound moral decision for someone to inbreed two tortoises for the sake of research. There might be an argument for documenting what happens when tortoises are encouraged to inbreed, I just can’t think of one!

Inbreeding two siblings from the same species may lead to physical deformities in some cases, but it may also lead to less obvious health issues and bad genetic mutations, making it less likely the offspring will be able to live for as long as it otherwise would have.

Taking two siblings and breeding them together may lead to an increased chance of their genetic weaknesses being passed on to the following generation.

This applies to other animals as well of course, and with every next incestuous relation, the likelihood of deformity will grow more and more likely.

In the wild especially, inbred tortoises may not even end up surviving for long after hatching. After all, any deformity will either make them more likely to contract diseases, or make them an easy target for predators.

Sand Lizard Research

Interestingly enough, research has been carried out on sand lizards that revealed inbreeding in this species could result in a smaller clutch of eggs.

More confusing is the fact that said research also suggests that some of the lizards that did end up hatching went on to live a normal life.

Furthermore, research suggests that short-term incest may not result in the same terrible consequences that it does in different species.

However, let’s keep in mind that tortoises and sand lizards are completely different reptiles, and while the research data may apply to them, the reality may be quite different.

Some species may even be more likely to inbreed than others, so it is hard to know whether the research results apply or not.

For me, it’s better to air on the side of caution and not to allow inbreeding to take place.

How Can You Prevent Inbreeding?

If you do not want two sibling tortoises to breed in captivity, you should separate them by sex after hatching. You might not even have to do this since most clutches are made up of tortoises of the same-sex, but if it happens, you should know that separating them can prevent inbreeding.

Let’s be clear though, there is no risk of inbreeding when tortoises are still juvenile, it’s just good practice to seperate them as soon as is practical.

Also, the best thing you can do should you be faced with multiple tortoises hatching is only keeping one for yourself if they end up being of different sexes. The others can be rehomed or sold at this young age fairly easily.

This way, you’ll ensure there is absolutely no chance of a future incestuous relationship. Crucially, it also ensures there will be no issues with hatchlings in the future.

Another option is to have the male tortoises castrated if for some reason you absolutely have to keep the siblings together. This way, they will not be able to produce offspring.

The Bottom Line

While tortoises may end up mating in the wild or captivity, it is not ideal, and it should be prevented. Otherwise, you may end up allowing the creation of tortoises with possible deformities or health problems.

Whether by separation, rehoming, or male neutering, you can prevent tortoises from inbreeding, so there really isn’t an excuse for a responsible owner to have this happen on their watch.

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