Department of Planning and Naturia Resources
Division of Fish and Wildlife
U.S.V.I. Animal Fact Sheet #20
Virgin Islands Tree boa
Epicrates monensis grant
There are two subspecies of the boa
Epicrates monensis. The Mona boa (Epicrates
monensis monensis), is only found on Mona
Island west of Puerto Rico, and the Virgin
Islands tree boa (Epicrates monensis granti),
which is found on Puerto Rico and the U.S. and
British Virgin Islands. The VI tree boa, worm
snake, racer, and the garden snake are the only
snakes found in the territory.
In 1979 the VI tree boa was listed as an
endangered species by the U.S. Fish and
Wildlife Service. It is also listed on Appendix I
of the Convention on the Trade in Endangered
Species (CITES), which lists the world's most
critically imperiled species.
Tree boas may live longer than 25 years.
Like most boas, the tree boa is nocturnal-
although occasionally they may be found
basking in the sun during the day. In daytime
they are usually found under rocks or logs.
They may grow to become 41 inches in length.
The VI tree boa is easily identified within its
entire range, as it is the only native snake with
blotches. The body in adults is a light brown,
with chestnut blotches edged in black. A newly
shed boa will have a blue-purple iridescence as
well. The juveniles are a light grey with black
blotches, and change to the adult coloration as
The VI tree boa is a reptile, like all snakes. It
belongs to the family Boidae, in the order
Squamata, suborder Serpentes. All boas are
constrictors; they suffocate their prey by
squeezing it and are not venomous.
Distribution & Habitat
Tree boas are found on the east end of St.
Thomas and on a few offshore cays. They
generally live in xeric (dry) habitat, which is
characterized by poor rocky soils, in scrub-
woodland or subtropical dry forest. Although
the VI Tree boa has been found on Virgin
Gorda, Tortola, and other low profile cays on
the Puerto Rico Bank none have been found on
C 1 2
The tree boa is also called the "Culebr6n de la
Sabana", by Spanish speakers, because of the
dry savannah-like habitats they live in.
Location of VI Tree boa habitat on the east
end of St. Thomas, USVI.
Anoles are the preferred food item for the tree
boa, although they may also eat hatchling
iguanas, nestling birds, or mice. From limited
observations of snakes hunting they seem to
glide along tree branches looking for sleeping
lizards. The lizards and other prey are
constricted before being swallowed headfirst
The VI tree boa, like most boas, is
viviparous. There is a primitive placental
attachment from the mother to the young.
Gravid adult females thermoregulate during
gestation, or pregnancy, which lasts about 150
days. The young are born alive in litters of 2-10
depending on the size of the mother. They
usually produce young biennially, or every other
year, but if food is scarce it may only be every
third or fourth year. The young are usually born
in late August through October. Baby tree boas
are self-sufficient at birth and must hunt food
successfully within three weeks if they are to
stay alive. There is no maternal care.
Status in the VI
To help ensure the long-term survival of the
VI tree boa, the Division of Fish and Wildlife
has reintroduced this species to offshore cays
that are free of rats and mongooses by relocating
boas brought in by the public and releasing
captive born animals from the Toledo Zoo.
In the absence of these predators, the tree
boa has the potential to achieve high population
densities, sometimes greater than 50 snakes per
acre. A recent survey of the VI tree boa
population has determined that the snakes are
successfully breeding and thriving on some of
the offshore cays.
What you can do to HELP
1. Please call the Division of Fish and Wildlife,
340-775-6762 St. Thomas if you see any VI
tree boas in danger of being injured or
2. Leave tree boas alone if they are not in
danger. They are not venomous and they
pose no threat to humans. The boa is
nocturnal and hides whenever there are
lights shining. It is illegal to capture them
and they do not make good pets.
3. Reduce the amount of pesticides and
chemicals used to control pests. This will
help the VI tree boa.
4. If you find a VI tree boa in danger, for
example in the middle of a construction site,
or a dead boa, please place it in a container
(so that if it is alive it can breathe), and
bring it to the Division of Fish and Wildlife
at Red Hook.
5. Remember, it is illegal to take, catch,
possess, injure, harass, or kill any
indigenous or endangered species. The only
exceptions are for people holding valid
permits from the Division of Fish and
7. For more information on this and other
animals in the Virgin Islands please visit out
Written by William Coles, Peter Tolson 2003.
THIS PUBLICATION WAS PRODUCED WITH
FUNDS FROM THE WILDLIFE
CONSERVATION AND RESTORATION
FOR MORE INFORMATION ON
OUR NATIVE ANIMALS CONTACT
DIVISION OF FISH AND WILDLIFE
6291 ESTATE NAZARETH, 101,
ST. THOMAS, VI 00802
PHONE 340-775-6762 FAX 340-775-3972
45 MARS HILL, ST. CROIX, VI 00840
PHONE 340-772-1955 FAX 340-772-3227