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122 IGUANA  •  VOLUME 12, NUMBER 2  •  JUNE 2005 POWELL

References
General Guides
Numerous guidebooks address the logistics of travel to what has become one of
the Western Hemisphere’s major tourist destinations. All provide some basic
background on the archaeological sites buried among recommendations for lodg-
ing, dining, and experiencing the apparently abundant nightlife. All are totally
devoid of any meaningful discussions of the region’s natural resources (except
those that have themselves been converted to tourist destinations). Two guides
that we found particularly useful, primarily because they went farther beyond the
mundane than most of the alternatives, were: Yucatán (Lonely Planet) by Ben
Greensfelder and Hidden Cancún & the Yucatán by Richard Harris.

Reptiles and Amphibians
The Amphibians and Reptiles of the Yucatan Peninsula by Julian C. Lee.

Phenomenally comprehensive, a reference rather than a guide. Highly rec-
ommended, but expensive and not for carrying into the field.

A Field Guide to the Amphibians and Reptiles of the Maya World: The Lowlands
of Mexico, Northern Guatemala, and Belize by Julian C. Lee. A field guide
based on the more authoritative coffee table book by the same author.
Highly recommended.

Amphibians and Reptiles of Northern Guatemala, the Yucatán, and Belize by
Jonathan A. Campbell. A nice guide enlivened by tales of the author’s per-

sonal experiences in the region. Recommended.

Reptiles of Central America by Gunther Köhler. Nicely illustrated, but broader
coverage than the other books listed results in less detail than in the other
recommended guides. Recommended, but expensive.

Birds
A Guide to the Birds of Mexico and Northern Central America by Steven N. G.

Howell and Sophie Webb. The most comprehensive guide to the region,
but large and heavy. Highly recommended.

Birder’s Mexico (Louise Lindsey Merrick Natural Environment Series, 12) by
Roland H. Wauer. Not so much a traditional guide as an introduction to
birding in México; definitely nice to have and great for preparation prior
to a trip. Recommended.

A Field Guide to Mexican Birds: Mexico, Guatemala, Belize, El Salvador (Peterson
Field Guides) by Roger Tory Peterson (Series Editor) and Edward L.
Chalif. Not up to the standards of the Peterson Field Guides for the U.S.
and useful only with both U.S. guides in hand. Definitely a third choice
among those listed.

Field Guide to the Birds of Mexico and Adjacent Areas: Belize, Guatemala, and El
Salvador by Ernest Preston Edwards and Edward Murrell Butler (illus-
trator). Nice pictures, but disorganized and difficult to use. Not recom-
mended.

The long slender bodies of Blunt-headed Tree Snakes (Imantodes 
cenchoa) allow them to span considerable distance as they move from
branch to branch.

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

Blunt-headed Tree Snake
Imantodes cenchoa

Snakes in the genus Imantodes are among several Central American
species to effectively exploit arboreal prey. Like many other species

that spend most of their lives in vegetation, these snakes are very slen-
der and elongate and have very long tails. Compressing their sides and
forming their bodies into a semblance of an I-beam, they can span
remarkable distances as they move from branch to branch. Although
they can and do occasionally venture onto the ground, most individ-
uals probably never leave the trees and bushes on which they’re usually
encountered. Active at dusk and well into the night, these snakes take
refuge during the day, occasionally hiding in bromeliads or other epi-
phytic vegetation.

As do many Neotropical snakes in the Family Colubridae (which
includes most common snakes throughout the world), Blunt-headed
Tree Snakes have enlarged, grooved teeth near the back of each upper
jaw with which they can inject venom. However, the location of the
fangs renders the delivery of venom difficult unless the prey item has
been taken well into the mouth. Also, the venom appears to be most
effective on their usual prey of lizards and frogs. They are not danger-
ous to humans and very rarely bite, even when handled.

Unlike Vine Snakes in the genus Oxybelis, which fill a compara-
ble arboreal, lizard- and frog-eating niche during the daytime,
Imantodes cenchoa has a vertically elliptical pupil that allows for con-
siderable enlargement in order to trap sparse light at night. Like most
snakes, however, Blunt-headed Tree Snakes rely primarily on chemical
cues to find lizards sleeping on branches and leaves, nocturnally active
frogs, clutches of frog eggs suspended over water, or lizard and snake
eggs hidden under bark or in nooks and crannies above the ground.
Their blunt heads allow them to consume larger prey than their slen-
der bodies would seem to be able to accommodate.




