Male Anole lizards start their day with push-ups and other visual displays to announce to their rivals, “I survived the night, I’m still here so stay off my territory,” according to Terry Ord, a postdoctoral researcher at UC Davis and Harvard University.
Male Anoles spend much of the day sitting on tree branches defending their territories from rivals. The lizards display visually, by bobbing their heads and inflating their throat pouches. Sometimes, they have to contend with a “noisy” visual background of waving branches and shadows, and in a previous paper Ord showed that they deal with that by “shouting:” making their motions bigger and more vigorous.
In the current study, Ord got out in the Jamaican forest with a video camera well before dawn until after dusk. He found that the lizards showed a peak of display activity just around dawn and again at dusk.
It’s the first example of a “dawn chorus” of purely visual signals, Ord says. It lends support to the idea that when birds sing at dawn, they are defending territory.
The push-ups also show that the lizard is in good shape and capable of handling any other male foolish enough to wander into its territory.
The study is published online in the journal American Naturalist.