St. Lucia Racer, World’s Rarest Snake (Population 11) is Rediscovered

The St. Lucia Racer or Ornate Ground Snake, Liophis ornatus, has the unenviable distinctions of being both the world’s rarest snake and the species with the smallest range…it may even be the rarest creature on the planet.  The entire population – 11 individuals at last count – is confined to a 30 acre Caribbean island off St. Lucia.

Ever since reading Archie Carr’s wonderful books as a child, I’ve been drawn to the Caribbean’s islands and coastlines.  As luck would have it, I eventually found myself working at Tortuguero, Costa Rica – the very site where much of his ground-breaking Green Turtle research was done.  There I became hooked on the region’s fantastic array of creatures, and endeavored to become familiar with as many as possible.  In time, I tagged Leatherback Sea Turtles on St. Croix, collected Bahaman Brown Racers, Alsophis vudii, on several islands, and vowed to find again a large, flying Mole Cricket that once stopped me in my tracks on St. Lucia.  Unfortunately, Caribbean animals suffer some of the world’s highest extinction rates.  In fact, the St. Lucia racer was “officially extinct” for nearly 40 years.  Happily, we now know that it still holds on…but just barely.

“Hello Mongooses…Goodbye Snakes”

The St Lucia Racer, known locally as the Kouwes, was once quite common.  That changed in the late 1800’s, when Asian Mongooses were imported from India to battle the Black and Norway Rats that were ravaging the cane fields (a naturalist’s journal from that time recounts that the British officer responsible, unsure of the proper plural form of “mongoose”, wrote his superior with this request: “Please send a mongoose” – and while you’re at it, please send several more”!).

The diurnal mongooses rarely encountered the nocturnal rats, but they made short work of many of the island’s reptiles, including the racer.  Also facing threats from habitat loss due to goat grazing and development, racer populations plummeted, and the species was declared extinct in 1936.

Intelligent and adaptable, the Asian Mongoose has devastated amphibians, reptiles, invertebrates, birds and small mammals throughout the West Indies.  I saw them frequently on St. Croix, where they have even learned to locate the deep-set nests of Leatherback Turtles.  Two St. Lucian snakes, the endemic St. Lucia Fer-de-Lance and the St. Lucia Boa (Boa constrictor orophias), exact revenge by occasionally indulging in a mongoose dinner, but this has no real effect on their numbers.

A Species Resurfaces

The St. Lucia Racer remained “extinct” until 1973, when a single specimen was found on Maria Major, a tiny, mongoose-free island off St. Lucia.  But joy over the species’ rediscovery was short-lived, and after years without further sightings it was again feared to be extinct.  In 2011, however, biologists from the Durrell Wildlife Trust and other organizations made a detailed survey of the island, and in the process they turned up 11 St. Lucia Racers.  The snakes were outfitted with transponders and released back on Maria Major, which is now protected as a wildlife reserve.

St. Lucia Racers spend much of their time in lizard burrows among rocky thorn scrub and cactus thickets, and hence are difficult to locate.  Most researchers put the total population at no more than 18, but only 11 have actually been confirmed.

Very little is known about the St. Lucia Racer’s natural history, and nothing of its reproductive biology, so captive breeding is not considered an option.  There is some evidence the eggs of lizards such as the St. Lucia Whiptail (Cnemidophorus vanzoi, please see photo) make up much of its diet, but it likely takes lizards, frogs, small mammals and birds as well.

St. Lucia’s Other Reptiles and Amphibians

St. Lucia is home to approximately 28 reptile and amphibian species, only 19 of which are native.  Seven of these, including the St Lucia Fer-de-Lance, Bothrops caribbaeus, the St. Lucia Thread Snake, Leptotyphus bruilei, the Cribo, Clelia errabunda, and the St. Lucia Racer, are endemic.  At six inches in length and a mere 1/8th inch in width, the St. Lucia Thread Snake is the world’s second smallest serpent (another Caribbean island, Barbados, is home to the world’s smallest snake, L. carlae; please see photo and article linked below).

Unfortunately, six of St. Lucia’s native species are likely extinct, but detailed surveys are needed to confirm this.  Those believed to have vanished from St. Lucia are the Antillean Skink, Maybuya maybouya, the Antiguan Pygmy Gecko, Sphaerodactylus elegantulius, the Lesser Antillean Pygmy Gecko, S. vincenti, the Mountain Chicken (a relative of the Smoky Jungle Frog), Leptodactylus fallax, the Martinique Whistling Frog, Eleutherodactylus martinicensis, and the Cribo.  In addition, 5 subspecies unique to the St. Lucia are threatened with extinction.

Another Caribbean Rarity

Until being displaced by the St. Lucia Racer, the Antiguan Racer, Alsophis antigua, was considered to be the world’s rarest snake (please see photo of related Antilles Racer).   Driven to the brink by mongooses, goats and rats, only 50 remained by 1999, and the species was declared extinct 1936 (and again in 2005).  Fortunately, a small population was recently found on mongoose-free Great Bird Island.  Predator control and relocation programs have increased the total number of Antiguan Racers to 500+ individuals on four islands.

 

Further Reading

World’s Smallest Snake is Discovered on Barbados (2008)