How To Breed Green Iguanas
Breeding captive (pet) iguanas is an extremely controversial issue. There are people who fully support captive breeding and then there are people like me who are adamantly against adding iguanas to an already saturated market. For educational purposes and to ensure that those reading this care guide are informed, I am going to explain how to breed your iguanas and everything that is involved with it.
The miracle of watching something be born is undeniably wonderful. There are obvious educational benefits to a captive breeding program when used for educational purposes and homes are already lined up for the potential offspring. There are people who prefer to purchase captive bred babies versus store bought iguanas that have been mass produced or taken from the wild. That's it! You won't get rich selling the babies so you need to be invested in this for the miracle of learning from the process and the amazement of seeing the results.
The biggest and most obvious con to breeding iguanas is that you will be contributing to an already saturated market. There are hundreds of iguanas that already need homes and many people look at iguanas as a disposable pet due to their inexpensive purchase price. Placing the hatchlings can be very difficult and financially you will not come out ahead because of their low value. Breeding puts a tremendous strain on the females body and serious medical issues can arise. Breeding pairs have the potential to kill one another during the breeding process. Space is an issue for most people as you will have to house the iguanas properly until they are adopted out. This means you will need to invest money into proper lighting, enclosures and food to properly care for the hatchlings.
Since the actual breeding process is fairly straight forward, there are things you will need to decide upon before you begin. The most important thing you will need to consider is how many babies you intend on hatching. Allowing your iguanas to breed is nothing more than a step in the process. You need to be fully prepared for the outcome of that breeding and have decided if you will incubate the eggs or not and how many iglets you are prepared to properly house and place. This decision should be made long before you pair your male with a female or harem because you will need to have all of the proper equipment purchased and in place before the babies arrive. Take a moment to plan ahead and decide upon how many eggs you wish to incubate. Just because she laid 20+ eggs doesn't mean you need to incubate all of them. If you have enough space, time and equipment to care for 5 hatchlings properly, then 5 eggs should be your count. Choose the best looking 5 eggs from the clutch and those will be your working project eggs. The rest of the eggs can then be disposed of properly.
Knowing the sex of your iguanas seems like it would be obvious to know before breeding them but many people attempt to sex their iguanas too young, resulting in improper sexing and abnormal behavior they weren't prepared for. Iguanas should not be sexed until they reach 1 year of age. While it is possible to sex them sooner it often results in improper sexing as the sexual differences haven't developed completely. For more information on properly sexing your iguana have a look at our Sexing Iguanas page.
Gestation is the time it takes from the beginning of egg formation until egg laying begins. In green iguanas, the gestation period is roughly 8 weeks.
Iguanas are capable of breeding fairly young, with some males being ready at 1 year of age though most are 1.5 years or older. A normal and more conservative figure would be to wait 2 years of age before attempting to breed your iguana. This will allow you to sustain the maximum health of your iguana, creating optimum breeding weight and overall health.
Iguanas breed annually and your iguanas will decide when they are going to breed. For some iguanas, Spring is when they will choose to go into breeding mode whereas others choose the Fall. The good news is that once your iguanas choose when they want to breed, they prefer to adhere to this schedule annually and will elect to breed at the same time the following year.
In the wild, iguanas will normally breed during the dry season to ensure that the offspring has plenty of food available as they hatch in the wet season. (de Vosjoli, 1992) Since your iguanas environment is controlled, this isn't the normal case which is why breeding predictability is difficult in captivity.
Iguanas will normally breed with several to many females in the wild. In most captive situations this isn't practical due to the space a single iguana requires. Most people pair up their iguanas. When possible, the male should be slightly smaller than the female. This will offer the female the ability and strength to deter a pursuing male whom she isn't interested in breeding with. Special attention needs to be made to ensure that your male isn't becoming overly aggressive with your female. The courtship rituals of breeding pairs can be violent and may result in injury or death if not monitored.
Sexually Mature Male Green Iguana
As male iguanas grow and enter upon sexual maturity, you will begin to notice changes in their appearance. Sexual mature males having a remarkable rust coloration that replaces their vivid greens of childhood. As they develop into young adults the oranges may begin to appear on his head, neck, back, and the tops of the legs. Over time the color will gradually encompass a much larger surface area until it is the strongest and most vivid color present on his body. This color change indicates he is ready to breed and is believed to be used as an indicator for possible mates.
Sexually mature males may also evert their hemipenes from time to time. This isn't abnormal unless the hemipenes become prolapsed and do not retract. You can learn more about prolapses on our Cloacal Prolapse page.
The urates your male secretes may become increasingly milky in appearance. This is due to his seminal fluid being deposited alongside the normal urates and feces.
Seminal plugs may also be found within your iguanas feces. Seminal plugs are the buildup of seminal fluid and sometimes require assistance in order to expel them if they are not evacuated during defecation. Some iguanas will randomly drop seminal plugs as they move about. Seminal plugs are only an issue of concern when they are seen protruding from the cloaca. At this stage they can prevent feces from exiting the iguana, in which case you will need to remove them manually or have your vet remove them. After soaking the iguana in warm water, using a pair of gloves, paper towel or toilet paper, gently grab the protruding seminal plug and wiggle it side to side, while gently pulling it toward you. This should release the plug, which is similar in appearance to distorted incisor teeth.
Seminal plugs should not be confused with the waxy plugs found in the femoral pores. The waxy plugs in the femoral pores are believed to be used to mark territory as they rub against things while the iguana is patrolling. You can get a clear visual of the waxy plugs on our Sexing Iguanas page.
A sexually mature male will breed all year. This isn't the case with females who usually cycle once per year. A male in the presence of a female will begin a courtship ritual to try and persuade her into breeding. Male iguanas may exhibit posturing, head bobbing, head swaying, hatcheting (lateral compression of the torso), dewlap flaring, tail swaying and crab walking. Some of these motions are also done as breeding aggression indicators. More information on breeding aggression can be found on our Breeding Aggression page.
Male iguanas sometimes take preference to human females and will look at male humans at competitors for her affection. This can lead to serious aggressive behaviors toward the male. A past adopted male I was housing was very human male aggressive during breeding season and would lunge from his perch at the mere site of me, bouncing off of the lexan of his door as he strived to rip my face off. I was happy to find him his forever home as this behavior made working with him nearly impossible. An iguana bite can be very serious, as our Iguana Bite Wounds page shows.
If your female is receptive to the males advances and is willing to breed, she will allow the male to mount her from behind. He will position himself behind her and will bite the side of her neck/shoulder to hold her in place. This will lead to small cuts and abrasions, with some requiring stitches. This is something you need to be prepared for. Even the most compatible iguanas have a high likelihood of sustaining injuries since breeding involves teeth and nails. Not all injuries will require stitches.
Once the male is in position, he will align his cloacal vent with hers and will evert a hemipene which he will insert into her cloacal vent. Their tails will be slightly wrapped around one another during this time. Copulation can last for several minutes. Female iguanas can can save sperm for several years (Frye, 1995), allowing them to fertilize eggs at a much later date. (De Vosjoli, 1992; Frye, 1995)
Only healthy female iguanas should be bred. Underweight females will not be able to sustain the eggs she will be carrying. Gravid (pregnant) females will hunt out a nesting spot and will lose their appetites for several weeks before they lay their eggs. This isn't an issue for a healthy iguana to endure. Underweight females, or those with poor nutrition, may not have the required reserves and this can be detrimental to their health. The developing eggs within the female occupy a large amount of space and prevent her from being able to eat and replenish the depleted nutrients the eggs require to grow. In order to ensure that the eggs survive, she will utilize all of her fat reserves and will draw calcium from her own body to supplement the eggs. Calcium is crucial in the development of the eggs and the female will go to all lengths to ensure their survival, including drawing the calcium from her own bones. Unhealthy females can encounter a number of health issues as a result of sacrificing their own bodies. Medical issues such as Metabolic Bone Disease, Dystocia, Tetany and even death can occur. Tetany is a very common response to a lack of calcium and the convulsions can be slightly noticeable to extreme in nature.
Nesting boxes should be provided for iguanas who have developing follicles. Female iguanas will only lay eggs when they have a suitable lay area. The stress associated with this can cause her further issues that could lead to Dystocia. In an effort to locate a suitable egg laying location, if you haven't presented her with a suitable area, your female will seek one out on her own and this could result in property damage. The female will dig around your rugs, uproot plants and generally attempt to find a spot anywhere she can. You can learn more about nesting boxes on our Nesting Box page and we offer instructions for building a nesting box on our Building An Iguana Nesting Box page. The harder your female needs to work to find a suitable area, the more reserves she is using and the higher likelihood of issues arising.
Ensure that you supply a suitable nesting box, maintain a healthy female with proper calcium levels or simply don't breed because you aren't prepared and your female isn't ready.
Your iguana will become very active prior to laying her eggs. She may spend days digging in the nesting box you supplied or become restless in her behavior. Once she is ready to deposit her eggs, she will dig into the sand and should lay all of her eggs in a single egg-laying session. If you find that your iguana is laying eggs over the course of several days, she should be seen by a vet. If she starts laying eggs and then burries them but appears to have more eggs inside her, she needs to see a vet. Dystocia (egg retention) can be fatal and needs to be addressed. Eggs that are too large or that have fused together can make it difficult to pass them, causing an obstruction that will require medical intervention.
Author: Richard Brooks
Barten, S.L. 1996, Reptile Medicine and Surgery. Mader, D.R., pp. 47-61. Saunders
DeNardo, D. 1996, Reptile Medicine and Surgery. Mader, D.R., pp. 370-373. Saunders
DeNardo, D. 1996, Reptile Medicine and Surgery. Mader, D.R., pp. 212-223. Saunders
Iguana iguana - Animal Diversity Web
Breeding Iguanas - Green Iguana Society
Iguana Breeding Season - Anapsid