[8] It is believed that these iguanas may have ended up on the Baja peninsula and the islands because early Seri Indian inhabitants transported them there from the mainland as a food source thousands of years ago.

[5][9] This theory is based on the fact that the coastal distribution on the mainland ends 115 km south of Isla San Esteban.

[5][9] The cape spinytail iguana makes its den in old woodpecker nests in giant columnar cacti and in other tree cavities.

[11] The cape spinytail iguana has a green or yellow coloring when young and turns whitish gray with age.

[5] Like most iguanids, the cape spinytail iguana is primarily herbivorous, eating flowers, leaves, stems, fruit, and cactus, such as the bushy Jatropha cuneata and the taller, spindly Solanum hindsianum.