Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Dealing With Male Green Iguana Breeding Aggression

©1996, 2001 Melissa Kaplan


This document deals primarily with breeding aggression in male igs, but many of the techniques are suitable for use with just plain old aggressive (dominant to humans) igs. For further information on proper taming and socialization, please see my Iguana Care, Feeding and Socialization document. Before you get bitten, do read up on how to deal with bites.

Changes in behavior can be a sign of an underlying physical problem. We tend to think of health problems as causing lethargy and loss of appetite, but animals may also become snappy, cranky, and may react abnormally to accustomed interaction and stimuli. Some iguanas may get aggressive. When the aggression occurs in green iguanas, known for their breeding season and territorial aggression, such behavioral changes are often dismissed as "just" being related to "typical" male aggression. As an increasing number of iguana keepers are finding, abnormal aggression may also caused by huge bladder stones, tumors, abscessed organs, and other as yet undefined, pain, disorders and pathologies. When investigating the possible causes of abnormally aggressive behavior, do not discount a primary physiological cause until you and your vet have thoroughly checked it out.


Breeding Season Aggression
There is a way to deal with male breeding season aggression which does not include euthanasia, neutering or giving it away. It does include humans taking control, however! I have a friend who adopted a big 8-9 year old ig from the pound. She is tiny, and has two young kids, and freaked when he started charging. Once I talked to her about standing her ground and counterattacking, she and her kids have had no problems.

There are often triggers - the wearing of certain colors and time of the month (menses and/or ovulation) which can trigger attacks, so start paying attention to what is going on at the time of an attack. I know that when I wear blue, purple or green I incite one of my males -- he'll come flying across the room at me, or try to grab me when I walk by, so I watch him carefully during these times. I also pre-empt his strike with one of my own, picking him up and carrying him around for a bit, or getting into an extended petting session. I AM careful to keep watch, however, 'cuss the little brat knows when I'm distracted!

Tone Of Voice
They may not understand your words, but they know when you are ticked. Speak loudly and firmly - I find "Bad iguana! Baaaaaad lizard! Don't you even think of doing that!" to work quite nicely - the words don't really matter, but the tone of voice does. Shake a pointed finger at him while you are doing this.

Adopt an aggressive stance yourself: Feet planted apart, hands on hips, arms akimbo, bent forward at the waist slightly towards him. This will make you look bigger to him.

If he's still not getting the message, charge first, or charge back. Stomp your feet, make big movements. Remember, you are showing him that that you really are bigger than he is (rather than just being a big wimp! ;) and not afraid of him.

He will still have pent-up energies, and you don't want a neurotic ig on your hands... I find a green dish towel works very well. Dangle one for him, and let him grab it, roll in it, whatever. My paramour, Freddy, who is responsible for most of the bite scars on my hands, used to stalk me, and initially got a few good bites in (see the paragraph on him in Male Iguanas In Season and Human Females), and then, knowing there was no way I was going to let him get me, would sneak up on my couch and the green throw I kept on it, grabbing it, rolling up completely in it, laying still for a bit, then unrolling and doing it all over again. Three or four times of doing this, and he was ready for a cigarette and a nap. I will also come home sometimes and find my green dish towel all twisted up (and slightly damp) in the middle of the kitchen floor or dragged into the den. He also vigorously attacks the green flannel shirt I keep hanging on the back of my computer desk chair. I've even come home sometimes to find the blanket or dish towel in a tangle on the floor and in need of laundering. While he still looks at me with lust in his eye, and expends a great deal of energy posturing me and following me around, the his actually attempts at grabbing me have fallen off considerably, now primarily accruing when he knows my reflexes are impaired more than usual.

Other iguanas have different sex toy preferences: sweatshirt, stuffed toy iguana or other lizard, baseball glove, or a nice warm, rice-filled Luv Sock.

In talking to many folks with suddenly super-aggressive breeding season igs, I have found one common factor between them - all have their supplemental lights on for more than 12 hours a day...some as long as 16 hours. We have been trying cutting down the supplemental lighting period to only 10 hours, from 8 am to 6 pm. This allows for a natural sunrise (about 6 am during the summer) and sunset (about 8:30 during the summer).

Another way that has worked to cut through a prolonged breeding season is to trick the iguana's system. Provide a comfortable basking area in a dark room - use heating pads and nocturnal lights or ceramic heating elements to provide the heat. Keep the room completely dark (close blinds and drapes, don't use any white light) for three days. When you take the iguana out after the three days, make sure you stick to a rigidly diurnal schedule for several weeks.

Diurnal Schedule
Some owners are, by choice or happenstance, nocturnal by nature. While this may be fine for humans, it is not for a diurnal animal. Iguanas need to sleep at night. They need to eat during the day. They need a length dark period at night when they sleep. If you work at night or get up late in the day and stay up till the wee hours of the morning, that's fine - just don't force your ig to the same schedule. It will affect his or her overall growth, health and, with males, can lead to more and prolonged periods of breeding aggression.

A Note on "Suddenly" Aggressive or Strange Behavior...
"My iguana is six years old and has always been real sweet and friendly. All of a sudden he is going nuts! He's gotten very aggressive, chases me, and oh, yeah, I must be feeding him too much squash because he's turning orange!"

"My female is suddenly acting weird! She's five years old, and has always been pretty inactive. Suddenly, she is pacing her tank, digging at the floor and substrate. What should I do? What's wrong with her?!"

It isn't strange and sudden - it's quite predictable, accruing same time every year, once they hit sexual maturity. They should reach sexual maturity at 1.5 years of age if they have been fed and housed properly, anywhere from age 3-6 if not. The sad thing is that the only reason so many owners think that these behaviors are "strange" and "sudden" is that, to date, most igs have died before attaining sexual maturity. Now that we are getting better diet information out there and better veterinary care, igs are finally living a bit longer and attaining maturity, albeit late in still too many cases...

Iguanas need space to roam - males to 'protect' their territory, females to find nesting place. Most enclosures sold or built for igs are way too small. This results in increased aggression from increasingly frustrated males (often compounded by more than 10-12 hours/day exposure to UV A or UVA/UVB, with this supplemental lighting being kept on until late at night), and may cause injury as they bash their face against the enclosure wall, rip their toes trying to claw out, and trash their tail whipping it in such confined quarters. I find that giving most males as much time as they want in front of a mirror each day, and freedom to roam around, dragging their thighs to their heart's content, results in an uninjured, well-balanced healthy male. Yes, I still have to watch my colors with a couple of them, and it is rather cute to see them 'act like gentlemen' and stand up when I enter the room (actually, presenting to me, collapsing like puppies when I stop to pet them, as long as I keep my hand carefully away from their open mouth!). But I am always aware of what is going on, and who is in an aggressive breeding mode, and mitigate my behavior accordingly if necessary, depending on the individual.

Some vets recommend castration/neutering as a way to end the aggression...the only problem is that this doesn't work very well - often not at all. Noted reptile veterinarian Douglas Mader recently went back and talked to ig owners about their neutered igs and found that results were less than gratifying. Dealing with them behaviorally, reducing photoperiods, being very conscious of their environmental set up and your own behaviors, and carefully and thoughtfully observing your males will help make breeding season less stressful for all of you.


If You Get Bitten
If you do get bitten, don't jerk your hand away (if you can!), and absolutely do not put him down! If you do you will have reinforced that behavior. Just get someplace where the blood won't ruin anything, go through your "Baaaad lizard!" routine, and keep holding him for at least a minute or two before putting him down. This tends to freak out friends who may be around when this happens, but you can deal with them (after you take care of the ig and yourself! This may all sound facetious but it works like a charm on most iguanas who have decided to try a bite to dissuade you.


A Note on Breeding Season Females...
Females in the wild often travel miles to their preferred nesting spot, and then may spend days digging and defending their sites from other females. Restricting them from doing so not only results in the injuries described above for males, but increases the risk of egg retention; coupled with the fact that the too-small enclosures do not allow for proper exercise, it is no wonder that egg retention/binding is the number one problem with sexually mature females. To find out more about egg-binding (dystocia), please check out my article on this subject.

Gravid females often become more receptive to handling and petting. This can help increase the level of taming and socialization if your female has been more distant or less receptive to interactions prior to the onset of her first breeding season with you.

The techniques and suggestions above represent what I have used successfully for years in dealing with breeding season males. They also work, in conjunction with the information in the Psychosocialization section of my ICFS article, to deal with obnoxious, often aggressive, dominant males. These techniques and ways of working with such iguanas have also worked for thousands of other iguana owners through the years.

There are some people who do things differently. Some sequester a breeding season male completely, interacting with him only for purposes of cleaning and feeding. Some leave an untamed iguana alone in the hopes that it will eventually become tame on his own. Based on the number of iguanas who have been treated this way who are given away to others or to rescues, or dumped at animal shelters or abandoned at vets, it appears to be a way that has less success in the long run than a more proactive approach.

Related Articles

Male Iguanas in Breeding Season and Human Females

Tough Love, or Attigtude Adjustment

Introducing and Housing Multiple Iguanas Together

Lizard Tough Guys

LuvSocks for Male Green Iguanas

Neutering Green Iguanas

Signs of Illness & Injury

Testosterone, Aggression and Green Iguanas

Testosterone Rules

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