Types of racers

Pseudalsophis is a genus of colubrid snakes, members of the huge family Colubridae that accounts for most of the world's snake species. Within that family they sit among the New World racer-type colubrids, slim and quick ground hunters rather than heavy ambush predators. Our database lists 10 species in the genus. The best known of these are the Galapagos racers, a cluster of species found only on the Galapagos archipelago, alongside a handful of mainland South American relatives such as the Painted Racer and the South American Elegant Racer.

The genus is centered on western South America and the Galapagos Islands. On the Galapagos, individual species are often tied to single islands or island groups, including forms like the Fernandina Racer and the Santa Cruz Racer, where long isolation has produced distinct local populations. They live in dry and arid habitats: lava fields, rocky coastal zones, scrub, and open ground where they can move and bask in the open. Mainland species occupy comparable dry to semi-arid country in parts of Peru, Ecuador, and Chile.

In general terms these are typical racers. They are slender, with a fairly long body, a head only modestly distinct from the neck, and relatively large eyes with round pupils that fit a daytime, sight-driven hunting style. Coloration tends toward browns, grays, and tans, frequently with stripes, spots, or a mottled pattern that breaks up the outline against rock and soil. They are alert and quick to flee, which is the usual racer behavior when approached.

Pseudalsophis are rear-fanged colubrids. They have enlarged teeth toward the back of the upper jaw and produce a mild venom used to subdue small prey, not a front-fanged, medically significant venom system like that of vipers or elapids. For people they are considered harmless and are not regarded as dangerous, since the venom is weak and the fangs are positioned to work on small animals rather than to deliver a serious defensive bite. Even so, no wild snake should be handled. If any wild snake bites someone and the species is uncertain, treat it as a medical matter and contact US Poison Control at 1-800-222-1222 or local emergency services.

Ecologically these racers are active diurnal predators of small vertebrates and invertebrates, including lizards, small rodents, insects, and the young of other animals. The Galapagos racers are famous for hunting marine iguana hatchlings on the beaches, sometimes in coordinated-looking groups as the young iguanas race for the rocks, a behavior widely filmed in nature documentaries. Like most colubrids in this lineage they are egg-laying. Several Galapagos species have small, island-bound ranges, which makes them vulnerable to introduced predators and habitat change and a conservation concern on the islands.