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Lizards may scale back head bobbing to avoid predators

Mating signals get smaller with carnivores around

By
3:04pm, May 19, 2014

NOT SO SHOWY  With predators nearby, male brown anole lizards, Anolis sagrei, dial back the jerky head bobs used to pick up females and scare off males. A more subtle show may help the lizards blend in and avoid predators.

Predators can really mess up a lizard’s mojo.

Male brown anoles, Anolis sagrei, tone down the swaggering head bob that says “come hither” to females and “get lost” to other males when threatening foes come along, reports biologist David Steinberg of Duke University and colleagues May 19 in the Proceedings of the National Academy of Sciences.

Steinberg’s team measured the height of anoles’ head bobs, sharp up-and-down jerks of the head, on nine tiny Bahamian islands. On five of the islands, researchers introduced carnivorous curly-tailed lizards, Leiocephalus carinatus.

On these predator-infested islands, the lanky reptiles bob their heads a lot less emphatically: a hearty nod became a timid wobble. These lizards’ biggest bobs were as little as 40 percent of those of males on non-threatened islands.

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