Tegus (Colombian) — Breeding & Reproduction

Colombian tegus reach sexual maturity at approximately two to three years of age, though the exact timing varies depending on the individual's growth rate, diet quality, and overall husbandry conditions. Males generally mature slightly earlier than females and can begin showing breeding behaviors as early as 18 months in well-fed, fast-growing individuals. However, the fact that a tegu is physiologically capable of breeding does not mean it should be bred at the earliest opportunity.

Before committing to a breeding project, both the male and female should be in peak physical condition. This means they should be at a healthy weight without being obese, free of parasites and illness, and well established in their husbandry routines. A pre-breeding veterinary examination for both animals is strongly recommended to screen for any underlying health issues that could complicate mating, egg production, or recovery. Females in particular should have adequate body reserves to support the significant nutritional demands of egg development.

The keeper should also have a clear plan for the resulting offspring before breeding takes place. Colombian tegus can produce clutches of 10 to 35 or more eggs, and finding responsible homes for that many juvenile tegus requires advance preparation. The reptile market fluctuates, and breeding without a realistic placement plan contributes to the problem of unwanted and surrendered reptiles. Connecting with experienced keepers, local reptile groups, and reputable retailers well before eggs are laid helps ensure that each hatchling has a committed home.

Proper sexing of the breeding pair is essential and should be confirmed by an experienced keeper or veterinarian. Visual sexing based on head size, body proportions, or behavior is unreliable, particularly in Colombian tegus where sexual dimorphism is less pronounced than in Argentine tegus. Cloacal probing or ultrasound by a qualified professional provides definitive identification.

Colombian tegu courtship and mating behavior can be vigorous and sometimes appears aggressive to keepers unfamiliar with the process. Courtship typically begins with the male displaying heightened activity, increased tongue flicking, and persistent following of the female. The male may bob his head, rub his chin along the female's body, and attempt to mount her by straddling her back and gripping her neck or shoulders with his jaws.

The neck-biting grip used by the male during mating is a normal part of tegu reproductive behavior, but it can cause minor abrasions or superficial wounds on the female. These injuries should be monitored and kept clean but are generally not cause for alarm unless they become deep, infected, or the female is being excessively harassed. If the male is overly aggressive or the female is clearly stressed and continuously trying to escape, the pair should be separated and reintroduced after a waiting period.

Successful copulation typically lasts 10 to 30 minutes, and multiple matings over the course of several days to a couple of weeks increase the likelihood of fertile eggs. Some breeders introduce the female to the male's enclosure rather than the reverse, as the male's territorial familiarity can stimulate breeding behavior. Others house the pair together during the breeding season and separate them afterward.

After mating, the female should be returned to her own enclosure if the pair was introduced temporarily. Providing an enriched diet with increased calcium and protein supports the developing eggs. The female's appetite may increase notably in the weeks following successful mating as her body diverts significant resources to follicle development and egg formation.

Following successful mating, the female Colombian tegu will carry developing eggs for approximately four to six weeks before laying. During this gravid period, the female's body undergoes visible changes as the eggs grow. Her abdomen will become noticeably swollen, and individual egg outlines may even be visible or palpable through the body wall in the later stages. Appetite typically increases early in the gravid period and then drops sharply in the days immediately before laying.

A suitable nesting site must be provided well before the expected laying date. The female needs a large, enclosed area filled with moist substrate deep enough for her to dig a chamber and deposit her eggs. A nesting box or a designated corner of the enclosure with at least 12 to 18 inches of damp soil, vermiculite, or sphagnum moss gives the female a secure and appropriately humid environment for egg deposition. If no suitable nesting site is available, the female may become egg-bound, which is a life-threatening emergency.

Colombian tegus typically lay clutches ranging from 10 to 35 eggs, though clutch sizes outside this range are not unusual. The laying process itself can take several hours to a full day, and the female should not be disturbed during this time. Once laying is complete, the female will usually cover the eggs and may rest in or near the nest for a period before resuming normal activity.

After the female has finished laying and moved away from the nest, the eggs should be carefully removed for artificial incubation. Eggs should be kept in the same orientation they were found and should not be rotated, as tegu eggs lack a chalaza and rotating them can kill the developing embryo. Transfer the eggs to a pre-prepared incubation container as quickly and gently as possible.

Artificial incubation gives the keeper control over temperature and humidity, resulting in better hatch rates and healthier hatchlings than leaving eggs in the enclosure. The incubation medium should be vermiculite or perlite mixed with water at a ratio of roughly one part water to one part medium by weight. The substrate should feel damp but not wet, and eggs should be partially buried with the top third exposed to air.

Incubation temperatures for Colombian tegu eggs should be maintained between 82 and 86 degrees Fahrenheit. Temperatures within this range will produce healthy hatchlings, and some breeders have reported that slight variations within this window may influence sex ratios, though temperature-dependent sex determination in tegus is not as well established as it is in some other reptile species. Consistent temperature is more important than the exact degree, and fluctuations of more than a few degrees can reduce hatch rates or produce developmental abnormalities.

Humidity within the incubation container should remain high, around 80 to 90 percent. The container should be ventilated with small air holes to prevent stagnation and mold growth while retaining moisture. Checking the eggs every few days to ensure the substrate remains appropriately damp and that no eggs are developing mold or showing signs of collapse is part of responsible incubation management. Infertile or failed eggs will typically discolor, collapse, or develop mold and should be removed to prevent contamination of viable eggs.

The incubation period for Colombian tegu eggs generally falls between 60 and 90 days, depending on temperature. As the hatch date approaches, viable eggs may show increased condensation, slight dimpling, or visible movement from within. Hatchlings use an egg tooth to slit the shell and may take 12 to 48 hours to fully emerge. Resist the urge to assist the hatching process, as premature intervention can injure the hatchling or disrupt yolk sac absorption.

The egg-laying process is physically demanding for female Colombian tegus, and postpartum recovery requires attentive care. After laying, the female will be depleted of energy and nutrients, having invested significant bodily resources into producing eggs. Her body condition may appear noticeably thinner, particularly along the flanks and tail base, and she may be lethargic for several days following the laying event.

Immediate post-laying care should focus on hydration and gentle reintroduction of food. Offering fresh water and a shallow soaking dish encourages the female to rehydrate, which is critical after the exertion of digging and laying. Food can be offered within 24 to 48 hours of laying, starting with easily digestible, nutrient-dense options like scrambled egg, lean ground poultry, or gut-loaded insects dusted with calcium and multivitamin supplements.

Calcium supplementation should be increased during the recovery period, as egg production drains the female's calcium reserves and can lead to hypocalcemia if not replenished. Signs of calcium depletion include muscle tremors, lethargy, and weakness in the limbs. A veterinary checkup within a week or two of laying is advisable to assess the female's body condition, confirm that all eggs were successfully expelled, and screen for any complications such as retained eggs or reproductive tract infection.

The female should not be bred again until she has fully recovered her body condition and weight, which may take several months. Back-to-back breeding seasons without adequate recovery time can shorten the female's lifespan, reduce clutch quality, and increase the risk of complications such as egg binding and follicular stasis. Responsible breeding schedules allow the female at least one full year between clutches.

Breeding Colombian tegus carries responsibilities that extend well beyond the mechanics of mating and incubation. The reptile hobby as a whole benefits when breeders prioritize animal welfare, genetic diversity, and responsible placement of offspring over volume production or market trends. Before breeding, every keeper should critically evaluate their motivation, resources, and commitment to the animals they will produce.

Genetic responsibility means avoiding the pairing of closely related animals and selecting breeding stock that represents healthy, well-proportioned examples of the species. Inbreeding depression can result in reduced fertility, weakened immune function, congenital abnormalities, and generally poorer health outcomes in offspring. Maintaining detailed records of lineage and exchanging breeding stock with other responsible keepers helps maintain genetic diversity within captive populations.

Every hatchling produced deserves a committed, knowledgeable home. Colombian tegus are long-lived animals with specific environmental and dietary needs, and placing them with unprepared owners contributes to a cycle of neglect, surrenders, and reptile rescues that are already overstretched. Screening potential buyers for basic knowledge of tegu husbandry, willingness to invest in appropriate enclosure setups, and an understanding of the long-term commitment involved is part of being a responsible breeder.

The broader ecological impact of tegu breeding also warrants consideration. Tegus, particularly the closely related Argentine tegu, have become established as invasive species in parts of the southeastern United States, where they threaten native wildlife. Ensuring that captive-bred Colombian tegus are never released into the wild and that all buyers understand the legal and ecological implications of ownership is a fundamental ethical obligation for anyone producing these animals in captivity.