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

Green Iguana Head Bobbing

©1995 Melissa Kaplan

There are many reasons why green iguanas bob their heads.

Males bob:

• when greeting the owner (owned) good morning.

• to instruct the owner (owned) to leave alone now, thank you, and get breakfast ready. Now.

• when getting into bath.

• after scaling to rim of tub when done with bath.

• upon reaching floor after climbing down from rim of tub.

• After walking out of bathroom door way.

• Upon walking into to iguana room after bath.

• Upon attaining the top of the first roosting place on climb towards top shelf.

• when the owner (owned) pays attention to other igs without first paying proper obeisance to bobber.

• When surveying one's domain - the visual equivalent of scent marking.

Females bob to say:

• "Enough is enough, buster. Get a life."

• "Outta my face. This is MY space."

• "I will get this shed off myself. Get. Out. Of. Here."

• "Watch it, girl/boy, I was here first."

• "Hey, little boy, go find someone your own size." (Hey, if you were chewed on and dragged around and put up with rutting males, then carry eggs around for two months, eggs which got so big that your internal organs were all squished up and you couldn't eat or drink very much and had to go to the bathroom all the time, and then had to dig around in the dirt and spend a day getting rid of the darn things, you wouldn't be real sociable either!)

Contrary to popular belief, females as well as males bob their heads. Males do it more frequently than do females, but bobbing itself cannot be used as a gender determinant. Bobbing can start at any age. As it is typically used in an aggressive way or to assert dominance, and it is generally executed by iguanas who are secure in their surroundings. Females generally bob in a rather jerky, erratic manner - it almost looks as if they are practicing, just learning how to bob. Females bob when irritated (generally at another iguana, less frequently at humans), such as when annoyed by the attentions of a male, or when warning another iguana away from their basking area.

Males have several different bobs. Male bobs are generally fluid, executed smoothly. Bobs are usually straight up and down; some may include side-to-side movement. The shudder-bob is a warning: the head is vibrated quickly in the up-down-sideways mode, the head kept raised upwards after the last movement. This is held for a moment or two, followed by an up-and-down bob. This bob is often addressed to the owner the first time the iguana sees the owner during the day or after a long separation and is delivered from a relaxed, laying down position rather than the raised and laterally compressed body position that typically accompanies the aggressive bobs.

Subordinate iguanas tend to bob more like females than males. Males who have been raised alone and who have not had access to their own reflection also often bob like females. After time, however, in the presence of other males or after several hours in front of a mirror, their bobs are executed in the male mode. Subordinate male iguanas, however, may maintain a low profile in the presence of dominant males by appearing as females, hence the quasi-female bobbing.

Rapid bobbing is usually be a warning or assertion ("This is MY area") to another iguana, a human, or the cat spied sitting on the fence across the yard. Slow bobbing may be a restrained statement of annoyance or warning by a subordinate iguana to a dominant iguana (or human or other creature). Some slow, deliberate bobs may be done when two iguanas encounter each other when they haven't yet had a chance to assess the other. In this case, it is a sort of guarded greeting and assertion ("I'll say 'Hello', but don't get any ideas about messing with me"). If this bob is accompanied by a raised laterally compressed body, there is more warning or defensiveness in the greeting than there is greeting.

Bobs, dewlap extensions, and posture provide the iguanas with a highly varied, often subtle vocabulary with which they communicate. It is up to us to learn to recognize the various combinations and analyze the context in which they are given in be able to begin to understand just what our iguanas are saying.