Lizards are among the most curious reptiles in the animal kingdom, and their behavioral traits and communication methods spark the interest of both scientists and regular people alike. Male lizards are able to perform many complex movements and gestures to indicate anything from a desire for showing sexual interest in members of another sex, to showing aggression and exhibiting territorial behavior in the presence of other males. The famous head bobbing movement that humans are quick to notice is one such behavior, and it can have one of many different meanings, depending on the species and the specific circumstances the lizard finds itself in.
The main purpose of the head bobbing movement is to communicate. Head bobbing is primarily observed in males of the species, and especially in species such as anoles and iguanas. Since acoustic communication is less common in reptiles, lizards often communicate through visual cues, such as changing color, expanding their dewlaps, doing push-ups or head bobbing. The movement can signify any number of things, depending on the speed and frequency of the bob. Mostly it has to do with communication regarding territory; however, many lizards may also indicate an interest in a new sexual partner through a jerky head bobbing movement that often extends to their entire bodies.
A slow head bob is normally used to indicate that a male accepts territorial dominance from another lead male. At a medium speed, individual lizards may also elect to greet their peers upon entering their territory. Fast head bobbing indicates territorial dominance. Sometimes, the bobbing movement might be accompanied by a waving movement, especially when the goal is to indicate the acceptance of territorial loss. Gecko females also use head bobbing quite frequently in order to resolve territorial disputes or warn rivals.
Push-ups and head bobs often go together when it comes to certain species of lizards. The idea behind both movements is to create a visual cue that communicates to other lizards some type of territorial status. Typically, the lizard that is able to do more push-ups or head bobs than the other is considered to be in better physical condition, and is crowned the winner of the territory in question. These displays of strength will actually aim to avoid aggression between geckos, iguanas, anoles or other lizards belonging to the same species and gender. Experts have found that anoles in particular are highly visual and are able to respond very well to these visual cues.