Jamaican Lizards Work Out at Dusk and Dawn
It seems that Jamacian lizards are just as concerned about their physical fitness as some humans.
Jamacian anole lizards start and finish each day with a wonderful visual display of push-ups, head bobs, and prancing around on a brach or tree.
They are the first known animals to start and end their day this way, instead of making noise and chirping away.
"Up until this study, dawn and dusk choruses have only been documented for acoustic signals," Terry Ord, who conducted the study, told Discovery News.
Ord, a postdoctoral researcher at the University of California at Davis and at Harvard University's Museum of Comparative Zoology, explained that birds, frogs, geckos, primates and other animals sound off at such hours, but the Jamaican anole lizard proves that "the same phenomenon occurs for visual signals."
He studied four different species of Anolis lizards at various sites on the island of Jamaica. Adult males were the primary focus of his research, since previous studies had found that the lizards' mating system relies on males establishing and defending territories.
When he spotted a lizard, Ord would set up a camcorder near the reptile's perch to record its behavior. The findings are published in the October issue of American Naturalist.
Both females and males were observed performing calisthenic-like displays, but the males "exercised" more frequently and with greater predictability. Many females also lack the colorful neck flap, technically called a dewlap.
Each species of lizard actually has its own routine, like various aerobic classes. Sceintists think they are performed to mark territory, and keeps them from fighting with each other.
Plus, stronger males can advertise their strength, so a younger, smaller lizard won't fight them.
Judy Stamps, a professor in the Department of Ecology and Evolution at UC Davis, told Discovery News that she "was delighted to see this article, because it confirms a vague impression I had years ago when watching lizards in the West Indies, that territorial males were most likely to display the first thing in the morning, and the last thing at night."
She agrees with Ord's theories behind the dawn and dusk displays, and added that the lizards might also choose such hours "because these times of day are less favorable for other important activities, such as foraging, or chatting up the females."