Male headbob display structure in a neotropical lizard, Liolaemus pacha (Iguania: Liolaemidae): relation to social context

Visual communication is important in many lizard species. One conspicuous visual signal is the headbob display, which consists of a stereotyped up and down movement of the head and/or torso. We analysed male headbob displays in the neotropical lizard, Liolaemus pacha, in its natural environment. Our objectives were to describe and analyse the structure and form of these headbob displays and to relate these to two social contexts: male without an apparent receiver (MA context) and male responding to another male (MM context). We measured duration of each headbob bout, its maximum amplitude, duration of intervals, number of headbob bouts and presence or absence of three modifiers (gular inflation, back arching and lateral compression). We found two types of triple headbob displays, corresponding to what has been previously reported as the challenge headbob and the broadcast headbob display. Duration and maximum amplitude were significantly greater in headbob displays in the MM context compared to the MA context. We did not observe modifiers when a male was in the MA context but there was at least one modifier present in the MM context.