Blood plasma
Blood plasma testosterone levels play an important role in the creation of the three male morphs both during and after development. Orange-throated males have 46-48% higher plasma testosterone levels compared to their yellow- or blue-throated counterparts. Experimental elevation of plasma testosterone levels in the other two male morphs led to increases in endurance, aggressiveness, and territory size to the degree expressed by normal orange-throated males. In addition, the transformation of yellow-throated males to blue-throated males is accompanied by an increase in their plasma testosterone levels.