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IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 125BOOK REVIEW

Biology of the Boas and Pythons. 2007. Edited by Robert W.
Henderson and Robert Powell. Eagle Mountain Publishing, LC,
Eagle Mountain, Utah. x + 438 pp. Hardback – ISBN: 978-0-
9720154-3-4. $100.00.

This sumptuous book is the result of a symposium entitled
Biology of Boas, Pythons, and Related Taxa conducted at the

2005 joint meetings in Tampa, Florida, USA, and sponsored by
the Society for the Study of Amphibians and Reptiles. This sym-
posium represented the first effort to assemble researchers work-
ing on some aspect of the biology of boas and pythons.

An impressive and exquisitely produced volume, Biology of
the Boas and Pythons (BBP) contains 29 chapters authored by 79
contributors. These chapters follow a Foreword by Richard
Shine, in which he notes the paradoxical situation in which
many laypeople envision a large boa or python when the word
“snake” is mentioned, yet herpetologists have generally ignored
these “spectacular” animals — until the present volume.

The main portion of the book is organized into five sec-
tions. The first section is the introduction, and the remaining
four sections deal with “Ecology, Natural History, and
Evolution,” “Behavior,” “Physiology, Neurology, and
Reproductive Biology,” and “Conservation.” Thirty-four taxa of
boas and pythons are addressed, with many chapters dealing
largely with members of the genera Python (three chapters), Boa
(six), and Eunectes (five).

The book’s editors, the two Bobs, Henderson and Powell,
wrote the book’s masterful introduction, which provides a short
summary of the book’s contents, but mostly serves as a review
of the literature on these basal macrostomatans prior to the 2005
symposium. This review is divided into a series of sections deal-
ing with early publications on pythonid biology, various
overviews of boid and pythonid biology, checklists of taxa, stud-
ies of basal macrostomatan phylogeny, and works on ecology
and behavior, on morphology, physiology, and reproductive
biology, and on conservation. Two tables and one appendix, all
very useful, summarize the taxa of basal macrostomatans and the
conservation status of a number of species. This chapter is graced
with photographs of several herpetologists who study these crea-
tures. The literature cited section is expectedly lengthy, contain-
ing 196 entries, five from 2006.

Instead of following the sections of the book, we have cho-
sen to review the bulk of this volume from a taxonomic stand-
point, grouping chapters dealing with the same taxon, which
leaves us with a group of six chapters dealing with more than a
single taxon. Five deal will multiple higher-level macrostomatan
taxa. The first of these, by Nicolas Vidal and coauthors, addresses
higher-level alethinophidian relationships, splitting this clade into
two new entities, the Amerophidia, of hypothesized South
American origin, which includes the families Aniliidae and
Tropidophiidae, and the Afrophidia, of presumed African origin,

which contains the remaining alethinophidians. They further
hypothesize that this deep split is the result of the separation of
South America from Africa in the mid-Cretaceous, which infers
that the clade that contains almost all snakes, save for the
amerophidians and the scolecophidians, had its origin on the
emerging African continent. The authors acknowledge that the
“phylogenetic status of ‘Henophidia’ (all Afrophidia, excluding
Caenophidia) remains uncertain.” A second such chapter, by
Pizzatto and coauthors, addresses the evolution of ecomorphol-
ogy in boine snakes, primarily of South America. By comparing
morphological features (body size and shape) and macrohabitat
use (arboreal to terrestrial to aquatic) to the two most complete
boine phylogenies of Kluge and Burbrink, the authors hypothe-
size that the ancestral boine was a stout, short-tailed snake of
moderate head length, but note that further characterizations dif-
fer between character optimizations based on morphology and
those based on molecular data. Grace and Matsushita examine
the interplay between vision and infrared imaging in guiding
complex behavior in boas and pythons and concluded that
infrared-imaging systems can be used alone to target prey, but
almost certainly function in conjunction with vision when visi-
ble light is available. Other possible uses of infrared imaging in
boas and pythons, such as predator avoidance, defense, and loca-

A Bonanza of Boas and Pythons

B O O K  R E V I E W



tion of refugia, are almost completely unstudied in these snakes.
Goris et al. begin their summary of current knowledge of the
anatomy and physiology of infrared imaging in snakes with a
frank discussion of the stumbling blocks involved in their
research. Their summary indicates that facial pits in snakes
“appear to represent an ideal form of infrared eye.” Finally, Ott
and Secor studied the specific dynamic action (SDA), the
amount of energy involved in the processing of a meal, in four
species of boas and fours species of pythons. They demonstrated
that SDA responses vary according to differences in meal size,
meal type, body temperature, body size, and, perhaps, with type
of foraging behavior, i.e., ambush foraging versus active foraging.

This book also has something for those interested in aspects
of the anatomy, mechanics, and physiology of feeding and con-
striction in boas and pythons. Cundall and coworkers studied
aspects of the biomechanics of feeding in 15 species of boas and
pythons in nine genera through a series of recorded feeding tri-
als. In this exemplary study, the authors identify three patterns
of strike kinematics evident in boids, which can be preliminar-
ily associated with the phylogenetic patterns evident at the sub-
familial level. Secor and Ott explore the adaptive regulation of
digestive function and intestinal physiology in boas and pythons,
and the correlation between feeding habits and digestive per-
formance. In a chapter measuring and comparing the constric-
tion strength in 12 species of snakes, including eight boas and
pythons and one tropidophiid, Moon and Mehta demonstrate
that snake diameter and the number of coils employed in con-
striction strongly influence the pressure exerted during constric-
tion, and that the crushing power employed by many species is
enough to kill many prey items by crushing the spinal cord or
stopping the heart, rather than by suffocation alone.

No single species is as well represented in this volume as Boa
constrictor, with six chapters devoted entirely or almost entirely to
this widespread Neotropical boa. While Boa constrictor is cur-
rently considered a single widespread species, the variation
demonstrated by this large snake across its range is apparent in
the breadth of its coverage in the volume. Two chapters are
devoted to insular populations of Boa in Central America, includ-
ing Boback and Carpenter’s study of the ecomorphology of boas
from islands off Belize. While insular Boa populations are well
known for generally being much smaller than their mainland
conspecifics, Belizean island boas also have longer heads and
larger eyes, traits apparently inherited in this population. Reed
and coworkers provide an assessment of the microhabitat, distri-
bution, and conservation of another dwarf island race of Boa,
from Cayos Cochinos, Honduras, and indicate that initial pop-
ulation size estimates for these small islands are alarmingly low.
These boas, called “Hog Island Boas” in the live animal trade,
have been and continue to be heavily exploited since at least
1979, yet this volume presents the first detailed study of this
species in its natural habitat. This is one of the strengths of BBP,
providing well-researched data on wild populations of species that
are among the most heavily exploited snakes in the pet trade and
simultaneously among the most poorly known snakes in their
native environs. Two complementary chapters deal with the
Argentine Boa Constrictor (Boa constrictor occidentalis):
Chiaraviglio and Bertona’s contribution examines factors influ-
encing the ecological distribution of this subspecies, whereas

Cardozo and coworkers use landscape modeling and population-
level genetic markers to elucidate the effects of habitat loss and
fragmentation on gene flow. These studies have important impli-
cations for the conservation of Boa constrictor in the wild, as does
Holtzman and coworkers’ chapter on the movement patterns and
microhabitat selection of experimentally displaced boas in
Nicaragua, which were shown to move more frequently and over
greater distances than resident boas.

The widespread popularity of Boa constrictor and other
large snakes in the pet trade has had negative impacts other than
overexploitation of wild populations, as exemplified by the final
chapter in the book, by Snow and coworkers. In this chapter, the
distribution and ecological impact (existing and potential) of
introduced populations of Boa and the Burmese Python (Python
molurus bivittatus) in southern Florida are revealed. While the
established Boa population seems restricted to a relatively small
natural area along Biscayne Bay that is surrounded by suburban
development, Python molurus bivittatus, which can readily
exceed 4 m in length, is now well-established and reproducing
throughout Everglades National Park. The impact of such a large
predator in the Everglades is demonstrated by interactions
between pythons and native alligators (Alligator mississippiensis),
illustrated in three dramatic color photographs.

Two other chapters deal with species of Python, and both
serve to further enlighten us about the natural history of heav-
ily exploited pet-trade species. Perhaps the most popular of all
pet boas or pythons is the Ball or Royal Python (Python regius),
and a comprehensive ecological study of this species and the syn-
topic Central African Rock Python (Python sebae) in the Niger
Delta, Nigeria, is provided by Luiselli and coworkers, and rep-
resents one of the most complete studies on wild populations of
these two species. A chapter on the thermal biology of the
Southern Rock Python (Python natalensis), formerly considered
a subspecies of Python sebae, by Alexander is another data-rich
and detailed analysis of a poorly known taxon, this time using
modeling and field studies to evaluate the distribution of P.
natalensis in relation to its thermal requirements.

A couple of contributions deal with habitat utilization of
Caribbean boids in the genera Corallus and Epicrates. Sylvia

126 IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 BOOK REVIEW

Epicrates monensis occurs on the Puerto Rico Bank and on Isla Mona.
This small, largely arboreal boid is listed in Appendix I of CITES.
Epicrates m. monensis, such as this subadult emerging from a bromeliad
(Tillandsia utriculata), is endemic to Isla Mona.

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IGUANA  •  VOLUME 14, NUMBER 2  •  JUNE 2007 127BOOK REVIEW

Powell and coworkers examine habitat utilization of two
Caribbean treeboas, Corallus cookii and C. grenadensis, and indi-
cate that treeboas are more commonly encountered in orchards
and other disturbed habitats that contained edge microhabitats
than in higher elevation “pristine” habitats that had few or no
edges. Tolson and coworkers provide our first look at habitat use
and natural history in one of the most poorly known extant
members of the genus Epicrates, E. monensis monensis, which is
endemic to the small limestone island of Mona in the strait
between Hispaniola and Puerto Rico. These boas appear to be
habitat generalists on their xeric island, but larger individuals
tend to be found only among limestone boulders or high in the
canopy. All three of these Caribbean boids are under threat from
habitat disturbance and destruction, as well as introduced species
like the mongoose, feral goats, and feral pigs. These contribu-
tions represent important additions to the body of data available
to influence the conservation and management of remaining
critical habitat.

Five chapters are concerned with features of the biology of
two of the four species of Eunectes. Two chapters deal with E.
murinus and three with E. notaeus. Rivas et al. examined the nat-
ural history of E. murinus in the Venezuelan Llanos. In what is
one of the significant chapters in this volume, these authors note
the need to consider natural history to be “good science,” espe-
cially for the purposes of conservation and sustainable manage-
ment, but that funding agencies may not support work that does
not involve easily formulated and quickly testable questions.
They also note that funding support may depend on such non-
biological features as the degree of “charisma” of the research
subject. Four of these authors also studied sexual size dimor-
phism and the mating system of this species, demonstrating that
females are more than 4.5 times the size of the males, one of the
largest sexual size differences known, and that prolonged breed-
ing-ball polyandry is the principal mating system. Young
demonstrated that E. notaeus responds to aquatic acoustic stim-
uli, allowing snakes to locate prey swimming on the surface.
Waller et al. studied the conservation biology of E. notaeus in
northeastern Argentina, in an area where this snake is heavily
exploited for the skin trade. They concluded that due to biolog-
ical trait plasticity, habitat inaccessibility, and rudimentary local
hunting methods, this species is capable of being sustainably
managed. Finally, Mendez et al. investigated the management
implications of the genetic population structure of E. notaeus,
concluding that demonstrated genetic isolation of Yellow
Anaconda populations in northern Argentina require these pop-
ulations to be treated as distinct management units.

One chapter each deals with some aspects of the biology of
Charina, Liasis, and Ungaliophis and two chapters deal with
species of Morelia. Dorcas and Peterson tested the coadaptive
relationship between thermoregulatory behavior and thermal
physiology in Charina bottae, and found that a tight relationship
between the two cannot be applied to this snake. Carmichael et
al. examined geographic variation in pheromone-trailing behav-
iors among island populations of Liasis mackloti, concluding that
pheromone-trailing discrimination parallels the relationships
demonstrated by morphological and genetic means, and sup-
ports the recognition of three clades. Burger and Ford examined
aspects of the reproductive biology of poorly-known Ungaliophis

continentalis, finding that males use two distinct types of
courtship behavior, one passive and the other assertive. The lat-
ter, which involves continuous tail-biting, is unique to the
species. When combined with coiling, it allows males to adjust
their behavior for successful copulation through sexual coercion.
Wilson investigated the foraging ecology and diet of M. viridis,
a sit-and-wait ambush predator. This species is largely arboreal
and adopts either a feeding or resting posture in sites that can be
maintained for up to 14 days, making it possible to time-lapse
videotape radiotelemetered individuals. Wilson determined that
this species’ foraging behavior and diet are affected by both
ontogeny and sexual differences. As such, they demonstrate “an
ontogenetic change in their diet from invertebrates and diurnal
skinks to primarily nocturnal mammals as they increase in size.
This dietary change happens in conjunction with a change in
hunting time from primarily diurnal to nocturnal and an onto-
genetic color change from yellow to green.” Freeman and Bruce
studied habitat use in two species of Morelia (M. kinghorni and
M. spilota) in North Queensland, Australia, using data derived
largely from roadkills. By this means, they demonstrated that M.
kinghorni is primarily restricted to closed rainforest habitats,
where they use large epiphytic ferns for basking, and is no longer
found in cleared rainforest locales. In contrast, M. spilota is com-
monly found in cleared/mosaic areas, including agricultural and
urban areas. For differing reasons, neither of these snakes is con-
sidered currently in danger of extirpation.

This book is a hugely important contribution to our bur-
geoning knowledge of the biology of this fascinating group of
diverse, beautiful, and phylogenetically significant basal snakes.
It takes its rightful place alongside the earlier compendia on the
biology of pitvipers and vipers in general, also available through
Eagle Mountain Publishing. In a number of ways, this volume
actually stands ahead of its brethren. It is full-color throughout
(with more than 200 color images) and the layout and produc-
tion values are impressive, attesting to the skills of its editors and
publisher. This book is a classic out of the gate. This is also a
book that cries out for a sequel, so we can hope the editors and
publisher will consider such for the near future. Any herpetolo-
gist will be seriously embarrassed if this book is not on the
shelves of his or her library. Instead of filling up the gas tank two
or three times, we recommend buying this book, curling up
under a reading lamp in your favorite chair, accompanied by
something soothing, and learning about the biology of some of
these really nice animals. Better options may exist, but we have
forgotten how … and why.

Larry David Wilson
Department of Biology

Miami Dade College
Kendall Campus

Miami, Florida 33176

and

Josiah H. Townsend
School of Natural Resources and Environment 

and Florida Museum of Natural History
University of Florida

Gainesville, Florida 32601