Reptiles

Iguanas are found elsewhere in the Bahamas (see map), but those on San Salvador are unique. They have no other home in the world. Sadly, their decline has been staggering. At present, fewer than 600 iguanas likely remain, and these are now restricted to a mere fraction (0.2%) of their former range. They are essentially confined to the most remote and inaccessible places available: four tiny offshore cays and two small islets within the hypersaline lakes (31.5 ha total). A few individuals are still encountered rarely on the main island (163 km²), but no viable population remains. Three populations have become extirpated in recent decades (Barn Cay in the 1970's, and High Cay and Gaulin Cay in the 1990's). Since 1993, when we first began to study these populations, we have documented declines on other cays as well (see Table).

Distribution of Cyclura in the Bahamas, including the three subspecies of C. cychlura (Andros, northern Exumas, southern Exumas) and the three subspecies of C. rileyi (southern Exumas, San Salvador Island, Acklins Bight). Cyclura carinata bartschi exists only on Booby Cay off of Mayaguana Island, Bahamas; the second subspecies of C. carinata occurs in the Turks and Caicos Islands to the south. Map: William K. Hayes.

A number of threats make continued survival of the iguanas tenuous. They are especially vulnerable to feral animals, including cats, dogs, and rats. For this reason, the iguanas may never be able to re-colonize the main island. Some of the remaining populations coexist with rats, and others have suffered vegetation damage from recent catastrophic storms and the larvae of an introduced, cactus-eating moth (Cactoblastis cactorum). Rising sea levels threaten to inundate the lower-elevation cays. Disease could be catastrophic because of the small populations and limited genetic diversity. In spite of strict protection by CITES (Convention on the International Trade in Endangered Species) and Bahamian law, humans still remove some of the iguanas. Two smugglers are presently in a United States jail for having done so!

Population estimates (N) for San Salvador Island iguanas (Cyclura rileyi rileyi), with their present status and identified threats (based on data spanning 1993-2003; Hayes, 2004).
	*Cay*	N	*Status & Identified Threats*
	Goulding	116-174	Stable; no known threats
	Green	130-195	Declining; hurricane damage, cactus die-off, smuggling by humans
	Guana	30-45	Increasing; recovery from mortality event in 1994, rats present
	Low	42-63	Declining; low survival of juveniles to adults, cactus die-off, rats present
	Manhead	38-57	Stable or declining; cactus die-off
	Pigeon	70-105	Stable or declining; hurricane damage, rising water levels, rats present
	*Total*	426-639	Decline continues

These unique and majestic lizards still have a chance to survive. Based on more than a decade of research, we have a much clearer picture of their ecological requirements. Though our time and funds are severely constrained, we are working to safeguard and improve remaining habitats. We hope to eventually create new populations. Through an outreach program, we have brought their fragile existence to the attention of San Salvadorans, who are eager to see the iguanas thrive and hopefully increase in numbers. However, we are greatly concerned by the threat of further development. Increased visitation by humans, their pets, or unintended stowaways (e.g., rats, fire ants, non-native plants) will spell certain doom.

The most critical populations to protect include Green Cay (Graham’s Harbor) and Goulding Cay (Green’s Bay); collectively, these islands harbor nearly two-thirds of the remaining iguanas. Because the iguanas on Low Cay attain the largest size and produce the largest clutches of eggs, they warrant protection as well. Unfortunately, only two populations (Green Cay and Pigeon Cay) appear to be on Crown Land; these would be the easiest to protect from future development.

Five additional lizards occur on San Salvador, four of which are native and one is introduced. Although iguanas can lose a portion of their tail, such loss generally requires severe injury, such as a bite from another iguana. The other lizards described below, in contrast, can sever (autotomize) their tails very readily when attacked by a predator or picked up by a human, especially when the tail is grabbed. This amazing anti-predatory strategy allows the lizard to escape unharmed as the tail continues to wriggle for a period of time, distracting the predator’s attention. In time, the lizard will grow back its tail.

This small lizard (body 2-2.5 inches or 50-65 mm, excluding tail) can be easily identified by the lighter-colored markings on its back (often with a central stripe) which contrast with darker chevrons on its side. The overall color varies from tan to brownish or grayish.

More than 120 species of anoles have been described in the West Indies region, with about half-a-dozen occurring in the Bahamas. This particular anole is widespread in the Bahamas, occurring on virtually every island. It can also be found on Cuba, Jamaica, the Cayman Islands, and on the Atlantic coast of Mexico and Belize. It has been introduced to Florida, where it has become abundant and has spread throughout the state. The subspecies on San Salvador also occurs on the Little and Great Bahama Banks, the Crooked-Acklins Bank, Rum Cay, and Cay Sal Bank.

This anole can be easily seen on San Salvador, as it is abundant in diverse habitats, particularly near or in vegetation. It prefers areas with sun exposure and avoids heavily shaded forest. It generally stays near or on the ground, where it can be seen sun-bathing or running short distances. It usually perches with its head pointed down, making frequent forays to snap up insects and, occasionally, smaller individuals of their own species. It becomes most active at midday and retires at night beneath rocks and other objects. Where electric lights are present, it may continue to feed for several hours after dark. These lizards live for only one or two years.

Social behaviors are particularly amusing to watch in these lizards. Their behavioral displays consist of frequent head bobs, push ups, vertical tail wags, and dewlap extensions. The dewlap is the loose fold of throat skin that, when extended, reveals vivid coloration that is often bright orange or red. During territorial encounters, the resident (of either sex) becomes dark, even black, whereas the invader remains lighter in color. The resident male fights off an invading male but tries to court an invading female, even though the resident female may attack the invading female. Breeding occurs during the summer, when females lay eggs that hatch in about six weeks.

Similar in size (body up to 2 inches or 50 mm, excluding tail) to the preceding species, the Bark Anole can be distinguished by its much more even coloration (gray, brownish, greenish, or yellowish) with (on this island) virtually no chevrons or blotches on the back. If you look very closely at the belly (try looking backwards through your binoculars, which creates a microscope), you will see smooth scales, in contrast to the keeled scales (with a crease in the center) of the Brown Anole’s belly. There is sexual dimorphism, with males looking a bit different than females.

The bark anole occurs widely in the Bahamas and on Hispaniola. This particular subspecies, however, is restricted to San Salvador Island and Rum Cay. This anole appears to be less abundant than Brown Anole on the main island of San Salvador, but it may be more numerous in the deeper forests, as the Brown Anole prefers sunny habitats. It occurs on some offshore cays and on islets within Great Lake where the Brown Anole may or may not be present.

Bark anoles are most often seen on tree trunks, but can also be seen on the ground or on rocks. Having a restless nature, this lizard seldom remains in one place for more than a few minutes, snapping tiny insects off the bark and then moving a few inches further and resting briefly again. If you watch this anole for any length of time, you may some interesting behavior, as this species has an unusually large repertoire of displays. At night, it sleeps on leaves, twigs, or small limbs up to 12 feet above the ground.

Like other geckos of the genus Sphaerodactylus, this lizard is very tiny (1-1.5 inches or 25-35 mm in this species, excluding the tail). It can be recognized by its relatively short legs and thick tail, pointed snout, and brownish body with variable amounts of flecking or dotting. Whereas anoles have a leathery feel when one touches them, the Dwarf Gecko has a very soft, velvet-like texture.

Sphaerodactylus corticola occurs only in the Bahamas, with populations elsewhere on the Crooked-Acklins Bank, Rum Cay, East Plana Cay, Samana Cay, and possibly Conception Island. This particular subspecies appears to be endemic to San Salvador. It also occurs on most, if not all offshore cays and islets within Great Lake.

This tiny lizard hides by day beneath rocks, palm fronds, leaf litter, and anthropogenic (human-related) objects, emerging at dusk to feed on small insects during the night. It occasionally enters buildings but seldom crawls about on walls. Instead, it generally remains close to or on the ground.

Breeding has been reported from June through December, but like other members of the genus elsewhere, it probably breeds year-round. It presumably lays one to two eggs at a time under rocks, in leaf litter, or in crevices formed by loose bark or other objects. Multiple individuals may lay eggs in the same nest; thus, they are communal ovipositors.

This gecko is much larger (4-7 inches, including the tail) than the Dwarf Gecko. You can easily recognize it by the pale white or tan body (individuals can change color somewhat), with dark chevrons on the back extending to and being most visible on the tail. This gecko will be found almost exclusively around buildings, where at night it can be seen scampering across the walls (sometimes inside the building), often near lights that attract insects. The Dwarf Gecko, in contrast, seldom climbs buildings.

This introduced species was first detected on San Salvador in 1998 by a child (Krista Hayes), who captured a juvenile inside the Lucayan Indian Museum at its former location (the pink building) in Cockburntown. Subsequently, it has spread to other townships and can now be seen abundantly on the walls of buildings after dark. Native to Africa and South America, this lizard and others of its genus have been introduced to many parts of the world, including Florida and the Bahamas. It can thrive beyond areas of human habitation, and therefore could compete with the native Dwarf Gecko. At least 14 non-native gecko species have become established in Florida, underscoring the considerable potential for more species becoming established in San Salvador. Unfortunately, they can get a free ride on nursery plants that are shipped from all over the world.

Like the Dwarf Gecko, the House Gecko lays its eggs singly or in pairs under rocks, in leaf litter, or in crevices formed by loose bark or other objects. In Florida, multiple individuals of up to four different gecko species (including Sphaerodactylus and Hemidactylus) may lay their eggs in the same nest! In Florida and presumably elsewhere, this gecko breeds year-round, helping it to rapidly establish new populations.

Curly-tailed lizards can be readily identified by the manner in which they curl their tail. However, this medium-sized species (2-3.5 inches or 50-85 mm, excluding tail) actually does not curl its tail! The black and white longitudinal stripes, however, are distinctive (but be aware that juvenile iguanas can also show a faintly striped pattern.)

Curly-tails of several species are widespread in the Bahamas. This particular species, however, is confined to Rum Cay (L. l. loxogrammus) and San Salvador (L. l. parnelli); hence, the subspecies on San Salvador is endemic, occurring nowhere else. It occurs commonly on the main island and, although possibly declining, can be seen on High Cay.

This lizard frequents sandy and vegetated areas behind and near beaches, under and among rocks in sunny areas, and less often in scrub and shrubby growth. Food includes flowers and other plant parts, insects (including ants), and occasional Anolis lizards.

As in the anoles, social behaviors are fascinating to watch. Mating probably peaks in mid-summer, with females laying eggs that require two months or more to hatch.

This diminutive (5-7 inches or 125-175 mm), highly-secretive snake is the only serpent that occurs on San Salvador. It is harmless and essentially incapable of biting a human. It has a very slender, wiry appearance with rudimentary eyes. It spends much of its time underground, and is generally encountered only by lifting rocks or by seeing them above ground during or shortly after rainstorms. In either case, you are very lucky to see this reptile.

Although blind snakes occur in many parts of the world, this species is endemic to San Salvador. That is, it occurs nowhere else in the world. (However, this snake may have been lumped recently with one or more other species; we could use some help locating this paper…)

Blind snakes feed on the larvae and pupae of ants. Rather than use side-to-side (bilateral) jaw movements for ingesting prey, blind snakes are unique among lizards and snakes in that the lower jaw moves vertically (unilaterally), like a shovel, to rake or scoop prey into the mouth. This adaptation permits more rapid feeding, which appears to be adaptive since the snake is vulnerable to attack when raiding ant nests and may need to make a hasty exit following a quick meal. Unfortunately, fire ants from South America have been introduced to San Salvador and other Bahama islands. These are highly aggressive predators with powerful stings and they could threaten the small amphibians and reptiles that call San Salvador their home.

Carter, R. L., and W. K. Hayes. 2004. Conservation of an endangered Bahamian iguana. II. Morphological variation and conservation recommendations. Pp. 258-273 in: A. C. Alberts, R. L. Carter, W. K. Hayes, and E. P. Martins (Eds.), Iguanas: Biology and Conservation. University of California Press, Berkeley. PDF reprint (450 K)

Hayes, W. K., R. L. Carter, S. Cyril, and B. Thornton. 2004. Conservation of an endangered Bahamian iguana. I. Population assessments, habitat restoration, and behavioral ecology. Pp. 232-257 in: A. C. Alberts, R. L. Carter, W. K. Hayes, and E. P. Martins (Eds.), Iguanas: Biology and Conservation. University of California Press, Berkeley. PDF reprint (437 K)

Hayes, W. K. 2003. Can San Salvador's iguanas and seabirds be saved? Bahamas J. Sci. 11(1):2-8. PDF reprint (420 K)