Male Lizards Do Push-Ups to Get Attention

Nov. 25, 2008 -- Grabbing someone's attention from a distance is a challenge, particularly under noisy conditions but, according to a new study, anole lizards have devised a successful "look at me" technique: They perform multiple full body, four-legged push-ups to get their fellow lizards to turn their heads.

The exhausting ritual supports the theory that many animals sometimes precede vocal and visual communications with an otherwise meaningless alert signal. It's been suspected that birds, frogs, dogs, coyotes and numerous other animals, including humans, do this.

"The example I give is tapping on glass to get everybody's attention at a dinner before making an announcement, or perhaps whistling loudly to get the attention of somebody at a distance," lead author Terry Ord told Discovery News.

"Another nice example is the emergency radio broadcasts I used to hear when I lived in the Midwest where we would have tornado warnings all of the time," added Ord, a research associate in the Section of Evolution and Ecology at the University of California, Davis (now at Harvard University).He explained that the emergency broadcasts begin with ultra loud tones or beeps followed by the official announcement.

For the study, he and coauthor Judith Stamps observed and videotaped 38 male yellow-chinned anole lizards in the deep-shade forests of Luquillo Mountains in northeastern Puerto Rico.

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Earlier this year, the researchers determined that, at dusk and dawn, males of this species plant themselves on elevated perches within their territory to broadcast visual displays to audiences of neighboring males and females up to 29 feet away.

The main signal consists of rhythmic head bobs and flashy displays of their colorful neck flaps, called dewlaps. The underlying message is sort of like a bodybuilder flexing his muscles in front of another bodybuilder. If one male is clearly stronger and fitter than the other, the scrawnier fellow is unlikely to challenge the first individual in a fight, saving a lot of injuries and deaths. The lizard routine also communicates territory ownership.

The scientists noticed that sometimes -- but not always -- the males would add the exaggerated full body push-up sequence before their usual routine.

To see if the push-ups conveyed any meaningful information, they designed a remarkably realistic-looking anole lizard robot that was programmed to perform the usual head bob display with either the push-ups or a novel dewlap extension intro. Each introductory move got the attention of other lizards, indicating that the push-ups indeed function as an alert.