Are Female Reptiles Bigger Than Males? The True Differences

Although some animal species’ males and females are easy to tell apart, it’s a lot more difficult when it comes to most reptiles. Often close examination – or even examination by an expert is needed to tell the difference. One way to possibly tell the difference is through the reptile’s mature size. 

Among reptiles like snakes and turtles, the females are most often bigger than the males as they need to carry clutches of eggs, but when it comes to lizards, the males are usually the bigger of the two.

In this article we’ll focus on the sizes of lizards, specifically the leopard gecko, bearded dragon, and crested gecko. We’ll look at the ways in which the males and females differ in size as well as how to tell males and females apart without looking at their sizes for comparison. 

In Which Ways Do Male and Female Lizards Differ in Size?

When a male or a female lizard is larger than the other sex of its species, it’s usually in a very specific way instead of simply being a “larger copy” of the smaller one.

For example, various studies, including one by Olsson in 2002, of the same and of different lizard species showed that the heads of the males are usually larger and broader than that of the female – even when the female is the larger sex. 

There are four distinct body parts that differ in size between male and female lizards, their:

  • heads
  • bodies
  • legs, and
  • tails. 

Let’s have a look at each of these body parts separately as well as the possible reasons for the difference in size. 

Are female snakes bigger than males?
The female boa constrictor gets way bigger (up to 14ft.) than male boa constrictors (up to 8ft.)

The Difference in Head Sizes

Generally, a male lizard’s head is broader and larger than that of a female of the same species. This is the case even when the male and female of the species are basically the same size; as with bearded dragons. 

A female’s head is, therefore, smaller and narrower than that of the male. As you can imagine, this difference is easier to see when you have more than one lizard to sex, especially if you’re new to lizards or that specific species of lizard.  

One reason why the males may have larger heads than the females, are to enhance their chances of winning in male-male rivalry.

Another reason may be to ensure that the two sexes prey on different sized insects, with the males eating larger insects. It’s thought that this will lessen competition between the sexes for the same food. 

The Difference in Body Sizes

The body size and length of male and female lizards also differ for the most part. As with their heads, the male lizard’s body is usually of a larger, broader build than a female’s body.

However, when measured from either head to vent or front legs to vent, the female’s body is usually longer. The reason for this length is thought to be to give her the space she needs to be able to carry clutches of eggs. 

The Difference in Leg Sizes

A 2005 study by Thompson and Withers noted that there are some differences in leg measurements, and that these differences “might contribute to the dominance of one male over another, or provide greater access to mating success with females”. 

The Difference in Tail Sizes

The lizard males’ tails are usually broader and/or thicker than the females’ tails.

However, as with the other body parts, it’s easier to tell what is meant by “broader” or “larger” when you already have a male and female that you can compare to each other (or you are very skilled and experienced, and are almost able to tell a lizard’s sex blindfolded). 

are male lizards bigger than females
Male chameleons are not only bigger than females, they are often more colorful as well. Male Jackson’s chameleons (image) even have three horns that the females do not have.

The Best Way to Tell The Difference Between Male and Female Lizards 

The most accurate way of finding out whether your lizard is male or female – apart from taking them to the vet – is to have a look once they’re old enough to see whether you can spot gender-specific body parts

Step 1: Pick Up Your Lizard Carefully 

To do this, you will need to pick up your lizard – for example a leopard gecko – and look beneath its tail without stressing them out so much that they drop their tail.

You’ll therefore need to be careful and not just pick them up and turn them over or lift up their tail (which can cause injury as well). 

Tip: By the time your lizard is old enough to be sexed, they should be used to being handled and picked up. If your lizard is new to your home, however, first give them a chance to settle in before trying to sex them. It will be less stressful for everyone involved! 

Step 2: Check For Hemipenile Bulges, Pre-Anal Pores, and Femoral Pores  

When checking whether your lizard is a male or a female, you basically check whether they have male characteristics or not (with the “or not” meaning you have a female). The reason for this is that it can be quite difficult to tell the two sexes apart even when they are sexually mature. 

To check whether your lizard is male, you will need to check for pre-anal pores, femoral pores, and hemipenile bulges. Now, you may read those words and go “you want me to check for what?” but don’t worry, this is all non-invasive. 

Femoral Pores

Both males and females have femoral pores, although the males’ pores are much more visible due to size and color. The femoral pores are found on the bottom of their back legs and secrete pheromones; chemicals that the lizards use to communicate with each other, especially when it’s time to mate. 

Pre-anal Pores

Like the femoral pores, both males and females have pre-anal pores. While the males have a v-shape of pre-anal pores that can usually be seen with the naked eye, while those of the female can’t be seen as easily. 

Hemipenile Bulges

Finally, the most concrete way of telling male and female lizards apart is by looking at the base of their tails to see whether or not they have two hemipenile bulges.

These bulges may be difficult to spot if the lizard is not yet sexually mature and too young and small. In these cases, a penlight may be used as a way to check whether or not the two bulges can be spotted within the tail. 

This video shows how to tell the sex of even young bearded dragons using a pen light:

However, when the lizard is large enough and/or is sexually mature (which usually goes hand in hand), you’ll be able to spot two bulges at the bottom of the lizard’s tail with the naked eye if it is a male lizard. These are the hemipenes. 

A female lizard will, instead of having two bulges with a “dimple” in-between, have one bulge in the centre of their tail. This one bulge will also be visible as a single shadow if a pen light is used to sex the lizard (see the video above to see how it’s done). 

Note! It’s very important that you don’t bend the lizard’s tail too far up or too quickly. Not only can you break your lizard’s tail if you’re not careful, your gecko can even drop their tail in some cases. If you find that your lizard doesn’t want to sit still or be held, give them some time and try again. 

If you’re still unable to tell whether or not your lizard is male or female – and they’ve reached sexual maturity – it’s time to call in the help of professionals. 

Ask Your Vet or Breeder for Help in Sexing Your Lizard 

If you need to have your lizard sexed and it’s either still a bit young (juvenile, but not baby as then it is really very difficult to tell the sexes apart) or it’s sexually mature but you can’t seem to spot the correct gender-specific body parts, you can ask your vet or a trusted breeder to help you. 

If needed, they will be able to use more invasive techniques – that should only be used by professionals – to tell what the sex of your lizard is. 

Tip: If possible, use a vet that specializes in exotic pets and/or reptiles. 

Conclusion 

Female reptiles are larger than male reptiles when you’re referring to snakes and turtles. However, when you’re dealing with lizards, like the leopard gecko, bearded dragon, and crested gecko, you’ll find that the males are bigger than the females, although usually not by much. 

The body parts that does differ in size between the males and females are as follows:

  • Head – Males have a larger head than females
  • Body – Females have a longer body than males 
  • Legs – Males have larger legs than the females 
  • Tails – Males have broader tails than the females. 

To tell the difference between the males and females of the species, you should rather rely on looking for body parts that are sex specific to the males once your lizard is sexually mature. 

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