MATING BEHAVIOUR OF THE SIDE-BLOTCHFD LIZARDS OF THF GENUS UTA (SAURIA: IGUANDIDAE)

few investigators have studied the courtship of lizards in detail (see Milstead 1967 for literature reviews). To my knowledge no one has described quantitatively the courtship of any lizard species and attempted to analyse geographic variation. Ferguson (1966) described the general court-ship procedure of the side-blotched lizard Uta stansburiana from West Texas. My major goals were: (1) to describe more quantitatively various features of the mating behaviour of lizards of this genus; (2) to include in the analysis individ-uals from several geographic localities; (3) to evaluate the behavioural features as taxonomic characters; (4) to obtain insight into the adaptive significance of these features; (5) to obtain in-sight into the factors reponsible for evolutionary divergence of the features between populations. Methods In August 1966, and the summer of 1967, I photographed in slow motion the mating be-haviour of forty-one pairs of U. stansburiana from four localities and eight pairs of Uta squamata from a single locality, Santa Catalina Island. I used a Bolex-H-16 mm movie camera with a Vario Zweiter 80 mm zoom lens. The camera speed averaged thirty-eight frames per s and the speed was checked periodically by photographing a running stop watch. I photo-graphed most of the matings in the field, but I maintained the U. squamata singly in small terraria and photographed them in the labor-atory. Although female utas occasionally per-formed stereotyped behaviour that seemed to indicate non-receptivity, their response to a courting male was usually passive. I did not analyse the behaviour of females in this study. I photographed in mid-morning or late after-noon during the peak activity of the lizards. After photographing the behaviour, I recorded the cloacal temperature of most individuals with a Schultheis thermometer. The maximum differ-ence in mean temperature between any two populations was 1-1'C. All temperature mean