Red-bellied racer (Alsophis rufiventris)

GenusAlsophis (1)
SizeMaximum snout-vent length: 92 cm (2)

The red-bellied racer is classified as Endangered (EN) on the IUCN Red List (1).

The red-bellied racer (Alsophis rufiventris) is a small snake found only on the islands of St Eustatius and Saba (1) (3). Its upperside ranges from dark brown to relatively light shades of grey, and the male and female red-bellied racer have different patterns along the body. Black-bordered blotches run along the male’s back, merging into a dark line towards the end of its body. The female has an attractive series of streaks and smudges on its back, which fade near the tail (2).

Historically, the red-bellied racer’s distribution included several small islands in the Lesser Antilles. Healthy populations can still be found on the small islands of Saba and St Eustatius. However, the red-bellied racer is now thought to be completely absent from St Kitts and Nevis, where it was once widespread (1) (4).

The red-bellied racer favours rocky environments offering plenty of refuge. Rocky areas are also the preferred habitat of Anolis spp., lizards which the red-bellied racer preys upon (5).

On St Eustatius, the red-bellied racer is most active during the morning and late afternoon, with a lull around midday to avoid the high temperatures (6).

The red-bellied racer is known to predate upon young rats and small lizards (3), particularly Anolis spp., with which it is closely associated (5). It is an active hunter during the day, sliding between rocks and through leaf litter, using tongue-flicking to detect potential victims. The red-bellied racer will occasionally venture into burrows in search of prey (5).

Racers of the Alsophis genus are rear-fanged and are known to use venom to subdue their prey (7). Individuals have also been observed consuming lizard eggs, probably belonging to the same Anolis lizards which they prey upon (8).

There has been little research into the breeding habits of the red-bellied racer, but other racers are known to give birth to live young (2).

The red-bellied racer now occupies only 11 percent of its original range (5), largely due to the deliberate introduction of the mongoose (Herpestes auropunctatus) to control rat populations in the 19th century. The two islands where the racer persists are mongoose-free, but additional threats include other introduced animals, such as cats, dogs and rats (9), as well as negative local attitudes towards the snake (4).

Racers are particularly vulnerable to habitat destruction, as they only exist in very small island communities; this is becoming more of an issue due to increasing development for tourism (10).

Fortunately, there are some systems in place to conserve the red-bellied racer. For example, on St Eustatius the Quill-Boven National Park is a protected area which provides suitable habitat for red-bellied racers, with plenty of rocky terrain (4) (11).

It is crucial to educate local people about the red-bellied racer, to ensure they are aware it is a harmless species. Further introduction of alien species must also be prevented at all costs (4).

More information on the red-bellied racer:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. IUCN Red List (January, 2012)
  2. Schwartz, A. and Henderson, R.W. (1991) Amphibians and Reptiles of the West Indies: Descriptions, Distributions, and Natural History. University Press of Florida, Florida.
  3. St. Eustatius, Dutch Caribbean
    http://www.comitekoninkrijksrelaties/ (January, 2012)
  4. Barun, A., Perry, G., Henderson, R.W. and Powell, R. (2007) Alsophis portoricensis anegadae (Squamata: Colubridae): Morphometric characteristics, activity patterns, and habitat use. Copeia, 1: 93-100.
  5. Savit, A.Z., Maley, A.J., Heinz, H.M., Henderson, R.W. and Powell, R. (2005) Distribution and activity periods of Alsophis rufiventris (Colubridae) on The Quill, St. Eustatius, Netherlands Antilles. Amphibia-Reptilia, 26(3): 418-421.
  6. Heinz, H.M., Maley, A.J., Savit, A.Z., Henderson, R.W. and Powell, R. (2009) Behaviour and time allotment in the West Indian snake Alsophis rufiventris (Colubridae). Herpetological Bulletin, 89: 22-25.
  7. Weldon, C.L. and Mackessy, S.P. (2009) Biological and proteomic analysis of venom from the Puerto Rican Racer (Alsophis portoricensis: Dipsadidae). Toxicon, 55(2-3): 558-569.
  8. Heinz, H.M., Savit, A.Z., Maley, A.J., Henderson, R.W. and Powell, R. (2005) Alsophis rufiventris (Red-bellied racer). Foraging and diet. Herpetological Review, 36(2): 186-187.
  9. Henderson, R.W. (1992) Consequences of predator introductions and habitat destruction on amphibians and reptiles in the Post-Columbus West Indies. Caribbean Journal of Science, 28(1-2): 1-10.
  10. Sajdak, R.A. and Henderson, R.W. (1991) Status of West Indian racers in the Lesser Antilles. Oryx, 25(7): 33-38.
  11. BirdLife International (January, 2012)