The skull tree iguana is active during the day (7) (8) (9), with most activity occurring on warm, sunny days (7). This species is less active during the winter (8) (9). The skull tree iguana feeds mainly on insects, which it hunts using a ‘sit and wait’ strategy, lying in wait to ambush passing prey (4) (10).
If threatened, the skull tree iguana typically flees into vegetation or buries itself in the sand (2) (7) (8), and if caught by a predator it may shed its tail to escape (8). This species also constructs burrows in which to shelter at night or during the hottest part of the day. The burrow is usually built next to sand dunes with patches of vegetation, and can measure around 20 to 30 centimetres in length (2) (7). Skull tree iguanas may also use the burrows of other animals (2).
During the breeding season, a male and female skull tree iguana can sometimes be found within the same burrow (2), but males are aggressive towards each other and may fight (3) (8) (10). Individuals in captivity have been shown to use signalling behaviour, such as flexing the feet and shaking the head, to mark the territory or court mates (10). The skull tree iguana usually breeds between September and December (11), although some populations may have a longer breeding season, with high numbers of juveniles appearing between March and April (6). Males reach sexual maturity at a snout-vent length of around 5 centimetres, and females at about 4.5 centimetres (4) (11).