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36 IGUANA Volume 10, Number 2

In addition to an already remarkable three native
iguanas, tiny Utila (only 41 km2) supports a phenome-
nal reptilian diversity: 15 lizards (including the three
iguanas), 11 snakes, a freshwater turtle, and a croco-
dilian. Most are representatives of widely ranging
Central American species, but two are endemic to Utila
(Anolis utilensis and Ctenosaura bakeri) and three oth-
ers are found only on the Bay Islands (Anolis bicaorum,
Phyllodactylus palmeus, Sphaerodactylus rosaurae).

The American Crocodile (Crocodylus acutus) pop-
ulation on Utila may be extirpated already and the tur-
tle, a Slider (Trachemys sp.), is known to occur in only
very small numbers in a single, largely freshwater
pond in the undeveloped western half of the island.

The snakes range in size from the Boa constric-
tor and Indigo Snake (Drymarchon corais), which may
exceed 2 m in length, to the tiny Thread Snake
(Leptotyphlops goudotii), a termite- and ant-eating
specialist that reaches a maximum known total
length of 18.5 cm. Swamp Snakes (Tretanorhinus

nigroluteus) are highly aquatic and the very slender
Vine (Oxybelis aeneus and O. fulgidus) and Tree
snakes (Imantodes cenchoa) are adapted for a largely
arboreal existence. The remaining snakes tend to be
habitat and prey generalists of moderate size. These
include the Tropical Ratsnake (Pseudelaphe flavirufa)
and three “racers” (Coniophanes imperialis,
Dryadophis melanolomus, and Leptophis mexicanus).

The lizards include a beach-dwelling racerunner
(Cnemidophorus lemniscatus), a skink (Mabuya uni-
marginata), the Common or Brown Basilisk (Basiliscus
vittatus), three anoles (Anolis bicaorum, A. sericeus,
and A. utilensis, all of which are sometimes assigned
to the genus Norops), and six geckos (Coleonyx
mitratus, Hemidactylus frenatus, Phyllodactylus
palmeus, Sphaerodactylus millepunctatus, 
S. rosaurae, and Thecadactylus rapicauda).

SPECIES PROFILE: UTILA’S REPTILES
Robert Powell

The Boa constrictor usually is considered a predator of
mammals, but it will readily hunt and consume iguanas
and is relatively common in the mangroves, where
Ctenosaura bakeri would seem to be the primary prey.
Photograph by Robert Powell.

The Green-headed Parrot Snake (Leptophis mexicanus) is
a habitat generalist that is equally at home on the
ground or in trees and bushes. Although it will feed on
birds and small mammals, its preferred prey is lizards. This
may be the most common snake on Utila. Photograph by
Robert Powell.

Like most skinks, the local species (Mabuya
unimarginata) has smooth scales well-adapted to
foraging in leaf litter. They are most frequently encoun-
tered when they climb vegetation to bask. Photograph
by Robert Powell.

Tiny Dwarf Geckos (Sphaerodactylus millepunctatus) are
abundant inside rotten logs and in surface debris, where
they feed on a variety of small arthropods. Photograph
by Joe Burgess.



37IGUANAJune 2003

Anolis bicaorum is the most
common anole on Utila, but
is abundant only in the
forest-mangrove interfaces,
where pairs occupy most of
the larger trees. This male is
responding to an intruder in
its territory. Photograph by
Joe Burgess.

Basilisks (Basiliscus vittatus) are
known best for their ability to run
quickly on their hindlegs, to the
extent of being able to run on
water. However, they are abundant
in a variety of habitats, many of
which are not associated with
streams or ponds. Photograph by
Robert Powell.

This brightly colored
racerunner
(Cnemidophorus
lemniscatus) is some-
times referred to as the
Rainbow Lizard. Because
of a tendency to twitch
an elevated forelimb
when it pauses in its
search for food (as this
individual is doing), this
lizard is known locally as
the “Shaky-paw.” They
are locally abundant on
sandy beaches.
Photograph by Robert
Powell.

The Tropical Rat Snake (Pseudelaphe
flavirufa) is a capable climber. In
addition to rodents and other
mammals, this species, like all rat
snakes, also will consume birds and
lizards. Photograph by Robert
Powell.

The very tiny Striped Thread Snakes (Leptotyphlops
goudotii) are most frequently encountered in association
with termite and ant nests, where they feed preferentially
on eggs, larvae, and pupae. This specimen, however, was
discovered in the open on a sandy beach. Photograph by
Robert Powell.



38 IGUANA Volume 10, Number 2

The Turnip-tailed Gecko
(Thecadactylus rapicauda) is named
for the shape of its regenerated tail
(the original is more typically
tapered). These large geckos are
abundant on trees and, more rarely,
buildings. They are unusual among
lizards in that they can retract their
claws into “sheaths” when not in
use. Photograph by Robert Powell.

This Leaf-toed Gecko
(Phyllodactylus palmeus) is
abundant on trees and
buildings, but is being
displaced on the latter by
the recently introduced
House Gecko (Hemidactylus
frenatus). Photograph by
Robert Powell.

Coleonyx mitratus is an unusual gecko in that it lacks
adhesive lamellar scales on the undersides of its digits
and doesn’t climb. These lizards are common in and
around surface debris and trash. Photograph by Robert
Powell.

Anolis utilensis, like the other Utila endemic, Ctenosaura
bakeri, is a mangrove specialist. Common only in the
Black Mangroves of the Big Bight, these well-camou-
flaged lizards behave in a very gecko-like fashion,
crawling on the tree trunks and adpressing themselves
tightly against the bark when threatened. Photograph by
Robert Powell.


