Western Mexico Whiptail

Fascinating facts about the Western Mexico Whiptail

• A 4-inch snout-to-vent lizard can stretch to almost a foot long because its tail can be more than twice its body length, giving the illusion of a much larger animal; this tail length also fuels dramatic whipping displays during territorial fights.
• When startled, the whiptail can sprint at 18 mph (29 km/h), keeping its tail straight behind like a galloping crocodile, a speed that lets it dash across open ground to the safety of dense shrubs in a heartbeat.
• These lizards keep moving almost nonstop, probing leaf litter and rocks with jerky start-stop steps that rustle dry leaves into a distinctive crunch, a sound that signals their constant foraging activity.
• Living from temperate savannas to tropical low-deciduous forests and even dense urban areas, the species shows a remarkable ability to adapt to human-altered landscapes, a flexibility that may help it survive shifting climate zones.
• Unlike many of its relatives, the western Mexico whiptail reproduces sexually; males and females meet in a cloacal kiss where a single hemipenis everts to transfer sperm, highlighting a rare break from the parthenogenic trend seen in other whiptails.

At a glance

About the Western Mexico Whiptail

The western Mexico whiptail (Aspidoscelis costatus) is a diminutive yet striking lizard, barely 4 inches from snout to vent, but boasting a whip-like tail that can exceed twice its body length, giving the animal a total reach of nearly a foot. Its skin is a tapestry of straight dorsal stripes, grey, brown or black, interrupted by pale spots or bars, while the belly ranges from cream to light blue and the throat may flash pink to red. Males shift through a kaleidoscope of dorsal patterns as they mature, becoming increasingly colorful, whereas females retain their striping throughout life. These lizards inhabit a mosaic of environments across Guerrero, Morelos, Puebla and other western and southwestern Mexican states, from dry savannas and shrublands to tropical low-deciduous and thorn forests, and even the bustling streets of densely populated cities where the subspecies A. c. costatus has adapted to urban life. Active, diurnal foragers, they spend daylight probing leaf litter, rocks and debris, their jerky movements producing a distinctive crunch as dry leaves are disturbed. When threatened, they sprint at up to 18 mph (29 km/h), tail held straight like a galloping crocodile, and can shed their tail in a flash of autotomy to distract predators.

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