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Wildlife: Racer, Ground Snake


Racer, Ground Snake – Alsophis cantherigerus caymanus
(Grand Cayman)

  Size: 500 to 860 mm SVL* As is usual with most snakes, females are larger than males. The record size for a female so far is 1190 mm SVL* and weighing 1.25 kg. Basic colour is grey with a series of small dark blotches along the sides with larger adults sometimes showing a rosy pink wash. When upset this snake will expand its throat to each side to make its head appear larger as a defence. It is active during daylight hours. Its habitat encompasses all strata. In other words, it is both ground-dwelling and arboreal. This adaptation enables this snake to be most successful given the limited resources of a small island. This snake is well known as being the primary predator of Cuban Tree Frogs. It also takes the nestlings of birds, causing alarm calls from the adult birds which will often gather to mob the snake. This snake has been seen to drop from a tree, while yet holding a prey species in its jaws. It will then seem to go into a temporary catatonic state or “plays dead”, following which it will rapidly slither away with its prey. One of the benefits of our local racer is that it feeds on baby rats.
* Key:
SVL Snout to Vent Length

Total Length (including tail)



For those worried about the following images, be reassured that there is no danger to people or pets posed by native Cayman snakes. Since these are the only photos known of this event, we wonder if the snake was actually successful in swallowing the iguana. It appears to be a pretty ambitious meal! Since these photos are being circulated by email, to calm the alarm in some quarters, here is a response from Dr. Mat DaCosta-Cottam, Senior Research Officer at the Cayman Islands Department of the Environment: 

"These pictures show a (local) Cayman Racer snake (Alsophis cantherigerus caymanus) eating an (invasive) Green Iguana (Iguana iguana).

The Racer is endemic to the Cayman Islands, and is found no-where else in the world, in fact, unique subspecies of the Racer are present on each of the three islands.

Adults can reach a length of 4-5ft an look quite formidable. The one pictured looks to be as large as any I have seen - maybe larger. Racers are to be found throughout the islands, however, we usually see them much smaller than this, maybe 2ft in length. Many are killed by cats and dogs, and run over when they are still young, so very few survive to reach this large size.

Racers can flatten their heads as a defense response, and this sometimes leads to their being confused for cobras.

The good news is that they are non-venomous, and pose no threat to people what-so-ever."

(sorry about image quality - shots were taken with a cell phone)

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