Male Morphs, Uta stansburiana

Synopsis of the behaviors seen among male morphs


Yellow-throated Sneaker Male Behavior

Yellow males are “sneakers” in that they mimic the throat color of receptive females, and yellows also mimic female behavior. When a yellow male meets a dominant male, he pretends he is a female — a female that is not interested in the act. The head bobs (“vibrations”) involved in actual female rejection behaviors are of very high frequency compared to the low frequency aggressive challenge displays shown by aggressive males. In many cases, females will nip at the male and drive him off. By co-opting the female rejection display, yellow males use a dishonest signal to fool some territory holding males. The ruse of yellows works only on orange-throated males.

Blue-Throated Male Behavior

Blues are not fooled by yellows. Blue males root out yellow males that enter the territory of the blue male. Blue males are a little more circumspect when they engage another blue male during territory contests. Blue males spend a lot of time challenging and displaying, presumably allowing males to assess one another. Attack may or may not follow as blue males very often back down against other blue males. Indeed, Neighboring males use a series of bobs to communicate their identity, and the neighbors usually part without battle.

Orange-Throated Male Behavior

Orange males are ultradominant and very aggressive owing to high levels of testosterone, and attack intruding blue males that typically have more modest levels of testosterone. Attacks by orange males on blue males do not involve the ritualized head bobs that are seen when blue males engage blue males — orange males just attack with little advanced warning. When an orange male encounters a more equally matched orange male, they are both a little more circumspect, and they will not necessarily attack one another (as is seen when blue meets blue).


Thus, each strategy has a strength and a weakness and there are strong assymetries in contests between morphs. Trespassing yellows, with their female mimcry, can fool oranges. However, trespassing yellows are hunted down by blue males and attacked. While oranges with their high testosterone and high stamina can handily defeat blues, they are susceptible to the charms of yellows. In contrast, contests between like morphs (e.g., blue vs blue, orange vs orange or yellow vs yellow) are usually more symmetric.