How to Determine the Sex of a Snake: A Beginner’s Guide

Identifying whether a snake is male or female is crucial for breeders, and hobbyists alike. While many species exhibit no external sexual dimorphism, several techniques can help determine a snake's sex accurately. This guide explores the most commonly used methods, their pros and cons, and their applications.

1. Visual and Behavioural Clues

Some snake species exhibit subtle visual or behavioural differences between males and females.

Tail Shape and Length: 

Males typically have longer, thicker tails (the portion of the body after the cloaca) to house the hemipenes. In contrast, females usually have shorter, tapering tails. 

Pros: Non-invasive and easy for experienced keepers. 

Cons: Requires experience and varies significantly by species.

Spurs: 

In some species, like boas and pythons, males have larger pelvic spurs (small claw-like structures near the cloaca), which they use during mating. 

Pros: Useful for specific species. 

Cons: Not definitive, as spur size can vary substantially.

Colouration:

Certain species of snakes vary in colouration between male and female. Many of the Tree Vipers are sexually dimorphic and the sexes are easily recognisable based on their appearance.

2. Manual Techniques

Probing: 

A blunt, lubricated metal probe which is specifically designed for this purpose, is gently inserted into the cloaca and directed toward the tail. In males, the probe will slide further in (into the hemipenes), usually 6-10 subcaudal scales deep. In females, the probe will stop sooner, around 2-5 scales deep. 

Pros: Highly accurate when done correctly. 

Cons: Requires skill and the right tools. Incorrect technique can injure the snake.

Popping: 

A technique often used for hatchlings and juveniles. By applying gentle pressure to the base of the tail, the hemipenes may be everted in males, while females will show no such structures. 

Pros: Effective for young snakes. 

Cons: Risk of injury if done improperly (especially species such as green Tree Pythons); less effective on adult snakes.

3. Advanced Methods

Ultrasound: 

Ultrasound imaging can identify internal structures, such as ovaries or testes. 

Pros: Non-invasive and very accurate. 

Cons: Requires specialized equipment and expertise.

Endoscopy: 

A small camera is inserted into the cloaca to visually inspect the reproductive organs. 

Pros: Provides definitive results. 

Cons: Invasive and requires anaesthesia and professional training.

DNA Testing: 

A lab analysis of a DNA sample (usually obtained from a shed skin or blood) can determine the sex of a snake. 

Pros: Non-invasive and highly accurate. 

Cons: Costly and time-consuming.

Choosing the Right Method

The choice of method depends on several factors, including the snake's age, species, and the handler's experience. For casual hobbyists, visual assessments and consulting a professional are often sufficient. Breeders and researchers, however, may need more precise techniques like probing or ultrasound.

Key Considerations:

Always prioritise the snake's welfare.

Seek training from an experienced handler or veterinarian before attempting manual techniques. When in doubt, consult a reptile vet or experienced herpetologist.

Sexing snakes is an essential skill for responsible snake keeping and breeding. By understanding and correctly applying these techniques, you can ensure the health and safety of your reptiles while meeting your husbandry goals.

JP Wittstock

1 December 2024