The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 28, Number 4; April, 2001

Iguana Banished to Fend for Itself

by Lauren Roark, Brush, Colorado

Reprinted from Notes from NOAH, the newsletter of the Northern Ohio Association of Herpetologists, Vol.28, No.5, February 2001.

What do you do when the overbearing aggressiveness of an adult male iguana becomes more than you are willing to tolerate? There are not usually many options for this situation. I came up with an idea that was a little risky for the animal, but none the less, worked successfully last summer.

I raised four hatchling green iguanas to adulthood. One of these, a male, was acquired two years later than the other three. This male began breeding at about twenty months of age, and fathered babies for three consecutive years. There were no problems with the males behavior through the first two mating seasons.

However, in the year 2000 the male developed quite an attitude. In February he began giving threatening displays whenever I came into the immediate vicinity of his cage. Upon seeing me he would spread his dewlap and raise and flatten his body. When out of the cage he would rise up on extended legs, flatten his body, and with his tail flicking side to side circle around me and eventually try to climb up my legs. On a couple of occasions I was taken by surprise when he leaped at me from his basking perch when I opened the cage door. Fortunately, both times I saw him coming in time to dodge his charge by quickly stepping backward causing him to land harmlessly on the floor.

There was another time when this iguana gave me quite an education on exactly how serious his intentions were. While seated in a chair, I let him climb onto my lap. When within reach of my hands he bit my thumb and held on. I have a pair of heavy leather welder's gloves that I often use for routine handling of the iguanas for protection from their claws, Luckily I was wearing these gloves when the iguana clamped down. He managed to get a great hold. My thumb was inside his mouth with the base of the nail near the jaw hinge, giving him maximum biting power. The pressure exerted was terrific and eye-watering, and he was not about to let go. Working frantically I managed to slip my thumb out of the glove and the iguanas vice-like grip, and then I pushed him to the floor. While continuing to hold the glove in his teeth, the iguana made about six rapid rolls across the floor. This was identical to the roll that crocodilians employ when attempting to dismember a large animal carcass, sometimes called the "death roll." For weeks following the event, my thumbnail looked like it had been hit by a hammer, though the lizard's tiny teeth did not penetrate through the leather. My thumb is lucky that this was only a seven pound animal and not a twenty pound brute like some males become.

The death roll was demonstrated on a few other occasions when the iguana seemingly attempted to kill a glove. All I had to do was simply toss a leather glove into the cage near the male. Biting and holding the glove, he would immediately begin rolling. Falling to the cage floor, the fury would continue for as many as eight rolls. I have read in books and articles numerous accounts addressing male iguana aggression during mating season, and of cases cited where someone was seriously bitten. Knowing this, I was still not fully prepared for the surprising amount of violence that this individual seemed capable of. Though he was by no means my favorite, he had not previously been a biter or tail whipper.

It does not take long to tire of an animal that is so relentless in its endeavor to cause you physical injury. In order to clean the cage I had to throw a towel over him. Or, he was let out of the cage and then I could go inside, closing the door between us.

Several times I thought about tossing him out of the house to let him fend for himself. This was a serious consideration that, out of frustration, I was truly wanting to do. Of course, here in northeastern Colorado he would not have survived outdoors at that time (February through April) because subfreezing nightly temperatures were prevalent, and I was not one hundred percent ready to kill him.

My iguanas are not strangers to the outdoors. Since they were hatchlings, several times a week in the summer, I put them in an outside pen for basking. Also, iguanas seem to be animals of habit. After a basking session, I'd open the pen and they'd usually walk across the yard and enter the house on their own. Another male iguana of mine escaped from the basking pen two years earlier and was gone for two weeks. This individual was finally discovered in our kitchen after he had entered the house on his own.

I had thought that the mating spirit in male iguanas only lasted about two months. Whether it was his hormones at work during this entire period or something else which had come into play, this male continued his aggressive streak from February until late May. In late May the chance for frost had passed when he challenged me for what I decided was going to be the last time. I grabbed the male iguana behind the neck and with my other hand firmly around the base of his tail, we went outside. I would not have done this with a valued specimen, but I had become extremely weary of the continuous belligerent behavior. I did have a strong feeling in my mind, based on previous experiences, that the iguana would not stray far from home. Anyway, this animal seemed the perfect guinea pig to help me gain more insight about iguana behavior.

I released him in a medium size birch tree near the house in the backyard. Two of my other iguanas, when placed in that tree, come down in an hour or less and usually proceed to the house. This male remained in the tree for five days and appeared to adjust quite well. I attached a food platter to the tree and on it was offered the usual greens and veggies which he would come down to get. In the new environment he seemed to immediately mellow out and accepted food from my hand without any more threatening gestures.

On the sixth day, the iguana was not in the birch tree. He moved to a slightly larger maple tree. The day following that he was back in the birch tree. Then after eight days in our yard we saw no more of him for a week. It was a relief when we finally sighted him again back in the yard, browsing in the vegetable garden. Several varieties of greens were planted to feed the iguanas and they were growing well. It seemed this food supply, which he couldn't have found anywhere else in the neighborhood might help to keep him close by. A couple of times I noticed him on a neighbor's grape arbor eating the leaves. He was not unapproachable and could be lured close enough to touch by offering pieces of whole wheat bread, his favorite food treat.

Throughout the summer we usually managed to see the iguana a couple of times a week foraging in our garden. Squash leaves seemed to be eaten more than collard or mustard greens, and he was especially hard on the leaves of our bell pepper plants. When he left the yard it was usually over the fence to the south. Where he spent most of his time was never learned, except, that it was not in our yard. I have wondered if he might have preferred the security which could have been afforded by the thick branches of the blue spruce tree two doors to the south.

In the adjacent yard to the north reside two miniature dachshunds. Once, when finished browsing, the iguana climbed over the fence into the north yard and ambled across the rear of the lawn. I looked and saw the two dogs near the house and they were not aware of the lizard. He was about three-fourths of the way across the lawn when the dogs finally noticed him. Immediately they pursued the intruder on the run and I was amused as the lizard, now running, dove into a large bush to elude the dogs.

A fierce July thunderstorm with much hail raised concern for the iguanas well being. Two days after the storm the male was again spotted browsing contentedly in the garden and looking very well. Also, there were a couple of early summer nights when the temperature got down to the forties, and the lizard seemed to handle this fine.

I chanced to find someone interested in having this iguana. Near the end of August the lizard had come into the yard to feed. We still had a couple more weeks of guaranteed warm weather left in the season and I would have preferred to let him have freedom that much longer. Considering that he was often not seen for days at a time, I decided not to pass up the opportunity to capture him. An offering of bread brought him within reach and his twelve weeks of freedom ended.

For the few days that I kept him after capture he was not aggressive. It is also interesting to me that with the iguana on the loose for that many weeks, I heard no reports of anyone in the neighborhood having seen it.