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IGUANA  •  VOLUME 12, NUMBER 2  •  JUNE 2005 131CONSERVATION RESEARCH REPORTS

Road Mortality Altering 
Sex Ratios in Turtles

With an increase in turtle road mortality
accompanying the expansion of the road
network throughout the United States,
affecting mostly females searching for
suitable nest sites, GIBBS AND STEEN

(2005. Conservation Biology 19:552–556)
predicted that historical trends in sex
ratios of turtle populations would be
increasingly male-biased. Using 165 esti-
mates of population-level sex ratios for 36
species (published from 1928–2003), the
authors demonstrated that the proportion
of males in populations had increased lin-
early. Populations have become more
male-biased in aquatic species, in which
movement differentials between males
and females are greatest, and are least
biased in semiaquatic and terrestrial
species, in which overland movements are
more comparable between sexes. Their
results suggest an ongoing depletion of
breeding females from wild turtle popu-
lations over the last century.

Commercial Trade in 
Amphibians and Reptiles

Amphibians and reptiles are taken from
the wild and sold commercially as food,
pets, and traditional medicines. Because
some species have been over-collected
and the United States, unlike most coun-
tries, tracks imports and exports of all
amphibians and reptiles, SCHLAEPFER ET

AL. (2005. BioScience 55:256–263)
examined records from 1998–2002. This
revealed a US trade of several million
wild-caught amphibians and reptiles each
year, although many shipments were not
recorded at the species level. Because

accurate trade and biological information
for most species are not available, estab-
lishing whether current take levels are
sustainable is difficult. The void of infor-
mation also implies that population
declines due to over-collecting could be
going undetected.

Decline in a Population of 
Wood Turtles in Southern Québec

Wood Turtle (Glyptemys insculpta) popu-
lations have been declining throughout
the species’ range and some populations
have been extirpated. DAIGLE AND

JUTRAS (2005. Journal of Herpetology
39:130–132) used mark-recapture meth-
ods to document a 50% reduction over
seven years in an agricultural area in
southern Québec. Emigration from the
area is not likely; instead, increased mor-
tality and poor recruitment probably are
responsible for the decline in the turtle
population. Increased mortality may be
related to increased incidence of roadkills,
deaths attributable to farm machinery,
burial or crushing by heavy machinery
during stream bank stabilization, higher
predation pressure, and even poaching.
Because of success in finding juveniles in
other Wood Turtle populations, the
authors did not think the low numbers of
young individuals was due to either secre-
tive habits or use of habitats that were not
sampled. Thus, the best explanation is
poor recruitment. Since apparently suit-

able nesting sites are available, low nesting
success, attributable to increased preda-
tion, especially by Racoons (Procyon
lotor), appears to be responsible.

Conservation Status of the 
Komodo Dragon

Information on population size and dis-
tribution of the Komodo Monitor
(Varanus komodoensis) is largely restricted
to surveys conducted on only part of the
species’ range, the most recent of which
was conducted in 1971. CIOFI AND DE

BOER (2004. The Herpetological Journal
14:99–107) noted that populations
occur on only four islands in Komodo
National Park and on the island of Flores
in southeastern Indonesia. Population
density estimates for Flores were more
than 60% lower than those for islands in
Komodo National Park. Habitat frag-
mentation and poaching of prey species
currently represent the main threats to V.
komodoensis. Protection of monsoon
forests in western and northern Flores is
crucial for the long-term conservation of
the species.

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

Road-killed Common Snapping Turtle
(Chelydra serpentina) from Hickory County,
Missouri. Populations have become more
male-biased in aquatic species, because
females may wander far in search of nesting
sites, whereas males rarely leave the immedi-
ate vicinity of water.

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Detailed and accurate data are not available
for most imported species. Establishing
whether or not current take levels are sus-
tainable is impossible. Complicating matters
is high mortality in many shipments. These
flat, stacked boxes, nailed together for ship-
ping, are barely high enough to accommo-
date animals, which are packed tightly. The
“tegues” (= tegus, Tupinambis sp.) in this
shipment, photographed in the mid-1990s at
John F. Kennedy International Airport in
New York, did not survive.

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Wood Turtle (Glyptemys insculpta) popula-
tions are declining throughout the species’
range.

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A solitary male Komodo Monitor (Varanus
komodoensis) on the island of Komodo.
Often called “dragons,” these largest living
lizards are threatened by habitat fragmenta-
tion and poaching of prey species.

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Impact of Humans on 
Savanna Lizard Assemblages

Habitat degradation through over-graz-
ing and wood collection is prevalent in
South Africa. Although protected areas
have been designated for conservation,
little is known about diversity outside
these areas. SMART ET AL. (2005.
Biological Conservation 122:23–31)
assessed the impact of land use on lizard
assemblages in communal rangelands by
comparing abundance, species richness,
and species diversity in degraded com-
munal lands and a protected area.
Communal lands had fewer large trees
and less ground cover, but the authors
found no evidence that any species of
lizard was negatively affected by habitat
disturbance. Some species were more
common in communal lands, and
species richness and diversity were also
higher when using certain sampling tech-
niques. This may have been attributable
to the preference of many terrestrial
lizards for open, sparsely grassed areas,
but reduced numbers of predators and
competitors may also have played a role.
However, species commonly used by tra-
ditional healers were not encountered in
field surveys, and local residents indi-
cated that they appeared to be declining.

Declining Population 
or Always Rare?

Species that are rare when discovered pres-
ent a practical management problem
because we may not be able to determine
whether a taxon is in the final stages of an
anthropogenic decline or is naturally
uncommon. BERRY AND GLEESON (2005.
Biological Conservation 123:197–210)

analyzed mitochondrial and microsatellite
DNA data to distinguish between these
possibilities in a rare lizard from southern
New Zealand. Grand Skinks (Oligosoma
grande) are large, rock-dwelling lizards
with a fragmented distribution consisting
of a western and eastern cluster of popula-
tions separated by about 120 km. This
distribution could result from human dis-
turbance, pre-human climatic and vegeta-
tion changes, or both. The current situa-
tion is likely to have both historical and
recent anthropogenic elements. Two east-
ern populations showed evidence of being
historically large, although they are now
small, supporting anecdotal data that
Grand Skinks have declined in historical
times. However, reciprocal monophyly
suggests long independent evolutionary
histories of eastern and western popula-
tions that predate the arrival of humans.
Eastern and western populations fulfill
many criteria necessary for consideration
as evolutionarily significant units (effec-
tively, species), but such a classification
must be balanced against addressing more
immediate threats to the species’ survival,
such as introduced predators.

Blanding’s Turtle in Nova Scotia
Nova Scotia populations of Blanding’s
Turtle (Emydoidea blandingii) are small and
disjunct. What was previously thought to
be a single panmictic population consists
of three discrete groups in two different
watersheds. MOCKFORD ET AL. (2005.
Biological Conservation 123:373–380)
identified significant genetic differences in
pairwise comparisons between groups.
Distance rather than watershed seemed to
be the principal determinant. Population
simulations suggested that this differentia-
tion likely pre-dated human influence on
the local landscape. In the face of rapid
environmental changes, understanding

132 IGUANA  •  VOLUME 12, NUMBER 2  •  JUNE 2005 CONSERVATION RESEARCH REPORTS

The lacertid, Pedioplanis lineoocellata, was
more abundant in disturbed areas than in a
protected area. The species is reasonably
common in sparsely vegetated areas through-
out much of southern Africa. This specimen
is from southern Namibia, near Aus.

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The Grand Skink, Oligosoma grande, is restricted to 8% of its former range in Otago, New Zealand
due to agricultural development and predator pressure. These endangered skinks live on schist rock
outcroppings in the harsh environments of the high country.

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Significant genetic differences exist between
isolated populations of Blanding’s Turtles in
Nova Scotia.

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IGUANA  •  VOLUME 12, NUMBER 2  •  JUNE 2005 133CONSERVATION RESEARCH REPORTS

spatial structure in this population com-
plex is essential for matching management
strategies to ecological realities in this long-
lived, late-maturing species.

Artificial Lights and 
Hatchling Sea Turtles

Artificial lighting disrupts the nocturnal
orientation of sea turtle hatchlings as they
crawl from their nest to the ocean.
TUXBURY AND SALMON (2005. Biological
Conservation 121:311–316) used labora-
tory experiments in an arena to simulta-
neously present artificial light (that
attracted the turtles toward “land”) and
natural cues (a dark silhouette of the dune
behind the beach) that promoted “sea-
ward” orientation. Artificial lighting dis-
rupted seaward crawling in the presence of
low silhouettes, but not high silhouettes.
Low silhouettes provided adequate cues
for seaward crawling when the brightness
of artificial light was reduced. Based on
these results, the authors postulated that
artificial light disrupts orientation by com-
peting with natural cues. Current restora-
tion practices at nesting beaches empha-
size light reduction. However, at many
sites, some lights cannot be modified. The
study suggests that pairing dune restora-
tion (to enhance natural cues) with light
reduction (to the extent possible) should
significantly improve hatchling orienta-
tion, even at nesting beaches where light-
ing cannot be entirely eliminated.

Green Bridges
TEUFERT ET AL. (2005. Zeitschrift für
Feldherpetologie 12:101–109) examined
use of the “green bridge” across Autobahn
4 near Bischofswerda (Germany). They
documented use of the bridge by three
species of amphibians (European
Common Toad, Bufo bufo; Common
Eurasian Spadefoot Toad, Pelobates fuscus;
European Common Frog, Rana tempo-
raria) and three species of reptiles
(Viviparous Lizard, Zootoca vivipara; Slow
Worm, Anguis fragilis; Grass Snake, Natrix
natrix). Most crossings were by B. bufo and
Z. vivipara. The latter especially demon-
strated a very high fidelity to appropriate
microhabitats, suggesting that the efficacy
of green bridges is dependent on main-
taining appropriate habitat structure on the
bridge and in areas to either side.

Buffer Zones
The preservation of riparian taxa often
requires the preservation and manage-

ment of buffer zones around riparian
areas. ROTH (2005. Copeia 2005:
399–402) tested this assumption using
radio-telemetry to examine the spatial
distribution of male, gravid female, and
non-gravid female Cottonmouths
(Agkistrodon piscivorus) in a stream/ripar-
ian habitat in Texas. Over 80% of all
observations were within 10 m of the
stream. However, gravid females were
most frequently found farther away, up
to 94 m from the shoreline. The author
concluded that disturbances to the ter-
restrial areas surrounding the riparian
habitat would have a disproportionate
effect on gravid females, potentially
affecting the reproductive capacity of the
population. This study reinforces the
importance of buffer zones and consider-
ation of spatial use differences between
population subunits when developing
management plans.

Cottonmouths (Agkistrodon piscivorus) usu-
ally are associated with streams. However,
especially gravid females may move some dis-
tance from the stream, indicating a need to
maintain sufficient buffer zones when con-
serving riparian habitats. Adult in defensive
posture (top), showing the white oral lining
from which the common name is derived;
juveniles (bottom) are much more distinctly
patterned and retain a yellow tail through
several sheds.

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Species that are known to use the “green
bridge” near Bischofswerda: The Viviparous
Lizard (Zootoca vivipara, male and female)
and the Slow Worm (Anguis fragilis).

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These hatchling Leatherback Sea Turtles
(Dermochelys coriacea) were photographed
using light from a flashlight with a red filter
over the lens in order not to disrupt their ori-
entation. Photograph courtesy of the St.
Eustatius National Parks Foundation (STE-
NAPA).




