Jamaican Lizards Mark Territory at Dawn and Dusk

At dawn and dusk, Jamaican lizards engage in a lively display of strength to mark their territories. They bob their heads, they perform rigorous push-ups, and they extend their dewlap (a colorful flap of skin under their neck). The lizards' behavior has been likened to dawn and dusk declarations in a variety of other animal groups—the chirping of birds, the croaking of frogs, and the howling of primates. But the lizards' daily displays are unique in one important manner—it turns out they are the first animal known to use visual displays of territory instead of auditory ones.

The research was conducted by Terry Ord, a postdoctoral researcher from Harvard University's Museum of Comparative Zoology and the University of California, Davis. During the study, Ord examined four species of Jamaican forest lizards (Anolis lineatopus, Anolis sagrei, Anolis grahami, and Anolis opalinus). Ord video-taped males at various times throughout the day and found that the Anolis species studied were most active in their displays for about two hours after daybreak and again at dusk.

Although it is a topic of debate as to why birds sing at dawn and dusk (some experts believe it is more an expression of circadian rhythms than one of territorial declaration), Ord feels in the case of the lizards' displays, it is more straightforward:

"All of these behaviors [head bobbing, push-ups, and dewlap extension] are displays of physical vigor. As in humans, if an anole can do many of these push-ups it shows that he is in prime physical condition. These displays of strength help avert actual physical confrontations between male lizards, which can be very fierce and destructive."

Ord's findings provide new insights into dawn and dusk signalling and pave the way for additional study in the way animals mark the start and finish of each day.

Find out more: Jamaican Lizards' Shows of Strength Mark Territory at Dawn, Dusk (Eurekalert)

Photo © Terry J. Ord / Harvard University and University of California, Davis. Anolis opalinus: The opal-bellied anole was observed in the Blue Mountains, north of Kingston, Jamaica.