In all instances, rivals responded to this posturing, with nonterritorial males fleeing and established males showing aggression.
Lawrence, Kansas (PRWEB) December 04, 2013
Herpetologica – Many lizard species rely on a conspicuous color to warn other males trespassing on their territory. Male Eastern Water Dragons in Australia are known for their orange-red to reddish-black abdomen and chest, but this area of the body is normally hidden as the semi-aquatic lizards go about their daily activities. Previous research has not recorded the water dragons using this coloration when showing sexual dominance or interest. Instead, overall body size has seemed to be the determining factor for which lizards control territory in preferred habitats.
The authors of an article in the current issue of Herpetologica tested those previous theories. They studied whether or not male water dragons use their colorful bellies in the same social dominance and intimidation tactics as have been observed among other lizard species.
The authors recorded both normal and aggressive behavior of free-ranging male water dragons toward other males, and toward courtship attempts by other males. They also recorded similar behavior to an oversized model lizard for which the belly colors could be adjusted from brown to red.
The researchers found that when confronted by neighboring males, the water dragons displayed their red bellies in three ways: stretching to show their entire colorful torso, charging on their hind legs, and running sideways on all legs. In all instances, rivals responded to this posturing, with nonterritorial males fleeing and established males showing aggression. Though some interactions ended in fights, most behavioral displays by these lizards involved less intense head bobbing and throat extension, but not likely to lead to physical conflict. Rivals were also more likely to confront the brown-bellied model than the red-bellied model, indicating that red bellies may be more intimidating than brown.
Although same-sex interactions prompted color displays by Eastern Water Dragons, such posturing did not occur when males interacted with females. This suggests that a red belly is not necessarily attractive to potential water dragon mates.
The full text of the article “Showing red: Male coloration signals same-sex rivals in an Australian Water Dragon,” Herpetologica, Vol. 69, No. 4, 2013, is now available.
Herpetologica is a quarterly journal of The Herpetologists' League, containing original research articles on the biology of amphibians and reptiles. The journal serves herpetologists, biologists, ecologists, conservationists, researchers, and others interested in furthering knowledge of the biology of amphibians and reptiles. To learn more about the society, please visit: http://www.herpetologistsleague.org.