214 
Greenberg 
PfRCHING 
BASKING 
ventral 
lateral 
Figure 9. Basking and perching postures in the blue spiny lizard have been operationally defined. When 
basking, the profile of the body is expanded and the legs are out; in perching, the limbs are closer to the 
body in a way that suggests readiness for rapid action. 
animals (Kavanau, 1967). in my present 
studies, lizards in colonies are initially fed a 
variety of prey. Tenebrio larvae, pupae, and 
adults, crickets, sweep-net contents, and an 
occasional neonatal mouse are provided on 
an irregular schedule in order to provide a 
variety of prey types (and prey behaviors) 
to induce lizards to explore their habitats in 
a natural way. 
SceUyporus cyanogenys are more likely to 
feed or forage during perching than basking 
(Greenberg, 19736, 1976a). Feeding epi- 
sodes that are initiated from the perch occur 
when a lizard perceives prey (or another 
lizard) moving in its surveillance area. At 
times, in the absence of moving prey, a blue 
spiny lizard will spontaneously begin a foray, 
alerting it to prey that would otherwise be 
ignored. For example, nonmoving Tenebrio 
pupae would be nudged until they twitched, 
and then quickly eaten (Greenberg, 1977a). 
A foraging lizard will always attack prey. 
Another consideration in the interpreta- 
tion of predatory aggression is social feeding 
(Greenberg, 19766). In some situations, 
perching lizards, watching each other as 
well as looking for prey, will be guided to a 
feeding site by the activity of congeners, or 
be stimulated to search their habitual feed- 
ing sites by the sight of a feeding congener. 
Food stealing is a common social interaction 
at feeding sites and may be a source of infor- 
mation about novel prey. Large prey will be 
shared when attempted stealing results in a 
pulling contest that rends the prey. 
Deference to dominants at a feeding site, 
or an apparent reluctance to be active near 
a dominant, can compromise the activity of 
