When it comes to identifying differences between sexes, lizards are a rather tough bunch. Savannah monitors (Varanus exanthematicus) are no exception. Some visual clues can help you make an accurate gender determination, and behavioral patterns can also sometimes be hints of gender in the African reptiles.
Glancing at the heads of your savannah monitors might provide helpful context for determining gender. Male savannah monitor lizards in glowing physical condition usually possess bigger heads than the females, but not by much. Their heads also usually are a little wider than those of female specimens. Mature savannah monitors sometimes grow to around 5 feet long. They can weigh upward of 154 pounds but are sometimes much smaller than that.
Presence of Hemipenes
One key sign of a male savannah monitor is the presence of hemipenes, which are reproductive organs situated on their tails' foundations. The organs are not visible just by looking at the males' exteriors. The males are equipped with two of these organs. Identifying the hemipenes is usually pretty simple in youthful specimens but not so in mature lizards, who typically get irritated with touching and examination. Refrain from trying this on adults. Recruit a trusted helper to carefully support your savannah monitor. Then, place your finger about an inch under the lizard's excretory opening. From there, smoothly push your index finger and thumb over the tail moving in the direction of the back limbs. If you do this, it might apply enough force to encourage the hemipenes to jut out from the excretory opening. If you see them, the lizard is a boy. If you don't, she's probably a girl. A savannah monitor breeder or herpetological veterinarian should be able to initially demonstrate the procedure for you. Wait to do this on your own until you've seen a professional do it and are confident that you can do it yourself.
Although female savannah monitors lack hemipenes, they do have tiny red specks that flank their excretory openings. The presence of these specks are an indication that you're dealing with a girl rather than a boy. These are usually much easier to see than the hemipenes of the boys, as they're in an external location.
Male and Female Behavior Differences
Observation of behavior can help identify genders in savannah monitors. Male specimens generally possess extremely territorial streaks and, as a result, can be highly truculent around each other, with aggressive battles that often involve biting. If you keep savannah monitors, avoid letting males live together. Before establishing housing arrangements for your pets, confirm all of your lizards' genders with a veterinarian or breeder. These professionals can look for the hemipenes for you, or they can determine the genders via probing. The turf-oriented actions of the males aren't the only behavioral differences that exist between male and female savannah monitors. The females are often markedly meeker and more timid in disposition than the males. They're frequently more reluctant to feed in front of others, as well.
- ReptileChannel.com: Monitor Sexing and Breeding
- Lizards; Jennifer Coates
- Monitors, Tegus and Related Lizards; Richard D. Bartlett
- ReptileChannel.com: Breeding Savannah Monitors
- ReptileChannel.com: Savannah Monitor Reptiles
- University of Michigan Animal Diversity Web: Varanus Exanthematicus
- IUCN Red List of Threatened Species: Varanus Exanthematicus
- African Savannah Monitor: Varanus Exanthematicus Albigularis
- Cincinnati Zoo: Savannah Monitor