Iguana 12.4 b&w text


Conserving an Amazonian River
Turtle Using a Community-based

Sustainable Harvest of Eggs
The exploitation of South American river
turtles as a food source has long been con-
sidered the main factor contributing to
the decline of populations. Along a
stretch of the Aguarico River (Ecuador),
CAPUTO ET AL. (2005. Biological
Conservation 126:84–92) investigated the
spatial and temporal distribution of
Terecay (Podocnemis unifilis) nests, factors
affecting nest success, and the effect of
offering a reward for each hatchling cap-
tured on the pattern of egg consumption
by the local human community. Flooding
appears to be particularly important in
this Amazonian region, destroying 63.1%
of all nests, which is in excess of the num-
ber of nests needed to satisfy the local
community’s consumption needs
(28.2%). The proposed reward for each
hatchling ensured the voluntary partici-
pation of the Cofan people in the Terecay
conservation project, leading to: (i) nests
being harvested only from sites where
hatching possibilities were very low, (ii)
efficient management and protection of
nesting beaches with abolition of poach-
ing of nests and adult females, and (iii)
transplantation of nests from sites that
would be flooded (and whose yield
exceeds human consumption). Therefore,
we argue that in this area of Aguarico
River both biological and social condi-
tions favor the establishment of a sustain-
able harvest of Terecay eggs.

Genetic Diversity of 
Amazonian Crocodilians

FARIAS ET AL. (2004. Animal
Conservation 7:265–272) used the mito-
chondrial cytochrome b gene to study
the population genetic structure of
Melanosuchus niger (Brazil: Negro and
Purus Rivers, Lake Janauacá; French
Guiana: Kaw River swamps), and
Caiman crocodilus (Brazil: Purus River,
Lake Janauacá; French Guiana: Kaw
River swamps). Analyses indicated that
isolation-by-distance was an important
population dynamic in M. niger, but
were unable to differentiate between iso-
lation-by-distance, historical fragmenta-
tion or range expansion in C. crocodilus.
Hypotheses of demographic expansions
were supported in one out of four and
two out of three sampled localities of 
M. niger and C. crocodilus, respectively.
Populations of M. niger in central
Amazonia also appeared to show differ-

entiation that was correlated with water
type. These results are compatible with
the life-style of these two crocodilians; 
C. crocodilus is a habitat generalist and
appears to disperse rapidly to newly avail-
able habitats, whereas M. niger is a more
sedentary habitat specialist. Both species
appear to be recovering from unregulated
over-harvesting; however, their responses
are life-history- and, potentially, ecologi-
cally dependent.

Home Range and Habitat
Associations of a Bahamian Iguana:

Implications for Conservation
The Andros Iguana (Cyclura cychlura
cychlura) is an endangered lizard threat-
ened by habitat loss, illegal hunting,
impacts from historic large-scale logging
practices, and predation by feral animals
(e.g., cats, dogs, and hogs). Local and
national conservation organizations are
interested in demarcating protected areas
for the iguana in the southern portion of
its range. However, no life history infor-
mation is available. In order to provide

data that can be applied in a science-
based management strategy for the
Andros Iguana, KNAPP AND OWENS

(2005. Animal Conservation 8:269–278)
investigated seasonal variation in home-
range size and habitat selection using

IGUANA  •  VOLUME 12, NUMBER 4  •  DECEMBER 2005 275CONSERVATION RESEARCH REPORTS

C O N S E R V A T I O N  R E S E A R C H  R E P O R T S

Black Caimans (Melanosuchus niger) are rela-
tively sedentary habitat specialists. Genetic
studies indicated that more geographically
distant populations and those associated with
different water types are more genetically dis-
tinctive.

JO
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 T

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JA
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Populations of Terecays (Podocnemis unifilis), a South American river turtle, may be able to sus-
tain a controlled harvest of eggs in at least one part of the Aguarico River system.

SA
N

D
Y

 B
A

R
N

ET
T

Large home-range sizes and associations with
open pine forest and shrublands must be
considered when establishing protected areas
for the Andros Iguana (Cyclura cychlura cych-
lura).

C
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PP



276 IGUANA  •  VOLUME 12, NUMBER 4  •  DECEMBER 2005 CONSERVATION RESEARCH REPORTS

radio telemetry. Home ranges were the
largest reported to date for free-ranging
Cyclura (30.6 ha for males, 5.6 ha for
females). Open pine was the only habitat
type out of four where iguanas occurred
more than expected by chance. However,
the pair-wise comparisons of habitat
types reveal that iguanas were found sig-
nificantly closer to open pine and shrub-
land than to closed pine. Conservation
implications of the dynamic seasonal
home-range fluctuations and habitat
usage are discussed and recommenda-
tions are offered for establishing pro-
tected areas.

Spatial Ecology of Endangered 
Grand Cayman Blue Iguanas

West Indian Rock Iguanas (Cyclura spp.)
are among the most endangered lizards
in the world and many populations will
need to occupy human-modified habitats
to escape extinction. Fewer than 25
Grand Cayman Blue Iguanas (C. lewisi)
remain in the wild. GOODMAN ET AL.
(2005. Journal of Herpetology 39:402–
408) examined spatial ecology of
released, captive-bred iguanas in a
botanic park on Grand Cayman. Males
used larger areas and moved greater dis-
tances than females in the summer but
not in the fall and overall male home
range sizes were greater than those of
females. A few home range estimates
were greater than any previously reported
for Cyclura. Especially males during the

breeding season used areas outside the
park, where they are vulnerable to preda-
tion, vehicular death, and hunting by
humans. Reserves for C. lewisi must be
large and surrounded by buffer zones or
fenced.

Displacement of 
Native Geckos by 

Introduced House Geckos
How introduced reptiles cause the loss of
endemic reptiles is poorly understood.
COLE ET AL. (2005. Biological
Conservation 125:467–474) investigated
the role of the introduced House Gecko
(Hemidactylus frenatus) in causing a cata-
strophic decline and extinction of the
endemic night gecko (Nactus spp.) pop-
ulations in the Mascarene Islands.
Competition for enemy-free space was
tested in experimental enclosures and
showed that H. frenatus displace endemic
Nactus coindemirensis and Nactus durrelli
from favored positions in and near refu-

gia, thus increasing the risk of predation
and exposure to stochastic events. The
ability of H. frenatus to grip substrates
with their pad-bearing toes was exam-
ined, and the data indicated that natu-
rally occurring substrates with a greater
amount of loose surface material of a
higher particulate concentration and size
excludes H. frenatus, but not Nactus.
These findings support the hypothesis
that H. frenatus led to the fragmentation
and extinction of endemic Nactus popu-
lations and demonstrate that artificial
refugia made of a crumbly substrate may
be used to limit future disturbances by
this gecko and others like it in the
Mascarene Islands and elsewhere.

Introduced House Geckos (Hemidactylus frenatus, top left) are displacing endemic Night Geckos
(Nactus coindemirensis, top right, and N. durrelli, bottom) from favored positions in and near
refugia in the Mascarene Islands.

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Released, captive-bred male Grand Cayman
Blue Iguanas (Cyclura lewisi) in a botanic
park used larger areas and moved greater dis-
tances than females in the summer but not in
the fall.

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