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IGUANA  •  VOLUME 11, NUMBER 2  •  JUNE 2004 107IGUANAS OF ISLA MONA

In addition to the Mona Island Iguana, the island supports one
endemic frog (Eleutherodactylus monensis), four other lizards,

and three snakes. Of the lizards, one is a widely distributed exotic
species (Hemidactylus mabouia), a second also is widely distrib-
uted in the West Indies, but probably native to the region
(Mabuya sloanii complex), and the other two are endemic to the
island (Sphaerodactylus monensis, Ameiva alboguttata). Of the
snakes, one is an endemic species (Typhlops monensis) and the
other two are endemic subspecies (Epicrates monensis monensis,
Alsophis portoricensis variegatus), although, as for the iguana, some
authorities consider the Isla Mona populations to be full species
(see also article on facing page).

Until recently, Ameiva alboguttata was considered to be a
subspecies of A. exsul, a species that is widely distributed on the
Puerto Rico Bank. However, the two species differ consistently
in color and pattern and are precluded from any gene exchange
by the insular distribution of the Isla Mona form.

As for many of its relatives throughout the Neotropics, sur-
face activity of A. alboguttata often is restricted to the period from
mid-morning to early afternoon, although some individuals may
reappear during the late afternoon. This activity period allows
these lizards to avoid cooler mornings and evenings and to avoid
the very hot mid-afternoons when temperatures frequently
exceed even the tolerance of these heat-loving animals. At first
glance, Mona Ground Lizards appear to move constantly, but
closer observations will reveal short pauses in direct sunlight or

shade. These allow the relatively precise thermoregulation
designed to maintain optimal temperatures approaching 40 °C.

Also like other species of Ameiva, A. alboguttata is an active
forager. Rather than sitting on an elevated perch looking for
movement by potential prey (a “sit-and-wait” strategy), Ground
Lizards actively search for food, often rooting vigorously in leaves
and other debris. Prey consists largely of small arthropods, and
otherwise inactive life stages (pupae and larvae) are sometimes
excavated during the search. Although not documented on Isla
Mona, larger individuals of other species of Ameiva are known to
consume vertebrates, including smaller lizards, and may occa-
sionally eat carrion. Ground Lizards also may consume plant
material, especially seasonally abundant fruits or flowers.

As the common name implies, Ground Lizards are essen-
tially terrestrial, foraging on the surface and retreating into self-
excavated burrows. However, one documented observation
described a subadult A. alboguttata following a trail of ants high
on the trunk of a large tree. Although obviously capable of climb-
ing, such arboreal activity has been observed only very rarely.

References
Powell, R. and E.J. Censky. 2002. Ameiva alboguttata. Arboreal activity.

Herpetological Review 33:50.

Rivero, J.A. 1998. Los Anfibios y Reptiles de Puerto Rico. The Amphibians
and Reptiles of Puerto Rico. 2nd rev. ed. Editorial de la Universidad
de Puerto Rico, San Juan.

S P E C I E S  P R O F I L E

The Ground Lizards of Isla Mona: Ameiva alboguttata
Robert Powell

Avila University, Kansas City, Missouri

Adult and juvenile (lower right) Ameiva alboguttata foraging in leaf litter on Isla Mona. Photographs by Robert Powell.