






































Iguana b&w text


Physiology and Sociality: Why
Banded Geckos Band

Aggregation may have important repro-
ductive, ecological, and fitness implica-
tions. Although studies of aggregating
behavior have been conducted for many
species, few have measured the benefits
of lizard aggregation. LANCASTER ET AL.
(2006. Animal Behaviour 72:199–207)
conducted a study to determine the ben-
efit of aggregation in the desert-dwelling
Banded Gecko (Coleonyx variegatus).
Geckos from Borrego Springs, San Diego
County, California were housed in
groups of five and offered a surplus of
retreats in an effort to test the hypothesis
that geckos benefit from grouping by
lowering rates of evaporative water loss.
The authors also tested effects of humid-
ity and scents of conspecifics and preda-
tors. Geckos avoided predator-scented
areas, supporting past work on other
species, but did not band together to
avoid predators. Nor did lizards use con-
specific scents to choose retreat sites, and
no social or mating benefits were found.
Instead, the study showed that Banded
Geckos benefit from aggregation by low-
ering rates of evaporative water loss.
Thus, aggregation provides physiological
but no evident social benefits for
Coleonyx variegatus.

Foraging Ecology of 
Tokay Geckos

Although individuals exhibited varied
foraging behavior, AOWPHOL ET AL.
(2006. Amphibia-Reptilia 27:491–503)

found no significant differences in forag-
ing parameters (foraging period, time
spent moving, foraging attempts, forag-
ing success, prey size consumed, and for-
aging distance) among male, female, or
juvenile Tokay Geckos (Gekko gecko) in
Thailand. Foraging occurred from
1800–0900 h, peak emergence was from
1800–2000 h, and peak retreat time
from 0400–0700 h. Food items were
insects, most in the orders Lepidoptera,
Orthoptera, and Coleoptera. The lack of
size differences in prey taken by geckos of
different sizes reflected no prey size selec-
tion, possibly attributable to low insect
availability. Geckos mostly used a sit-
and-wait strategy, but foraged more
widely when prey was relatively abun-
dant.

Are Snakes with Narrow
Distributions More Specialized?

The Italian Aesculapian Snake (Zamenis
lineatus) has a narrow distribution in
southern Italy and on Sicily. CAPULA ET

AL. (2006. Amphibia-Reptilia 27:531–
537) examined the diet of this snake to
test the hypothesis that species with nar-
row distributions will be more ecologi-
cally specialized than wide-ranging rela-
tives. The diet of adult Z. lineatus
consisted of small mammals and birds,
whereas that of juveniles was composed
mainly of lizards. Diets of males and
females did not differ. The authors con-
cluded that the feeding ecology of Z. 
lineatus was very similar to that of the
widespread ecological generalist, Z.
longissimus, indicating that the assump-

56 IGUANA  •  VOLUME 14, NUMBER 1  •  MARCH 2007 NATURAL HISTORY RESEARCH REPORTS

N A T U R A L  H I S T O R Y  R E S E A R C H  R E P O R T S

Desert-dwelling Banded Geckos (Coleonyx variegatus) benefit from aggregating in groups because
that lowers rates of evaporative water loss.

JE
FF

 L
EM

M

Tokay Geckos (Gekko gecko) are native to southeastern Asia, but have been widely introduced in
tropical and subtropical areas. A study in Thailand indicated that adults of both sexes and juve-
niles were active at comparable times, used essentially similar foraging strategies, and ate the same
types of prey.

JE
FF

 L
EM

M

The feeding ecology of the Italian
Aesculapian Snake (Zamenis lineatus) was
very similar to that of the widespread ecolog-
ical generalist, Z. longissimus, indicating that
narrowly distributed Mediterranean snakes
are not more specialized than their widely
distributed counterparts.

ST
EF

A
N

 M
O

EL
LE

R
, W

W
W

.E
LA

PH
E.

IN
FO

Iguana 14.1 b&w text.QX6  2/25/07  10:46 PM  Page 56



IGUANA  •  VOLUME 14, NUMBER 1  •  MARCH 2007 57NATURAL HISTORY RESEARCH REPORTS

tion that narrowly distributed
Mediterranean snakes are more special-
ized than their widely distributed coun-
terparts does not apply to the dietary
ecology of these snakes.

Jump Dispersal in Introduced
Mediterranean Geckos

From 1962–1997, Mediterranean
Geckos (Hemidactylus turcicus) were
intentionally introduced multiple times
into a science building at the University

of Central Oklahoma in Edmond. In
2005, LOCEY AND STONE (2006. Journal
of Herpetology 40:526–530) recorded 365
captures of 305 individuals and estimated
the population size to be 1005 geckos
with at density of 478 lizards/ha. The
population had dispersed a maximum of
200 m from the point of introduction, a
diffusion dispersal rate of 20 m/yr. The
wide distribution of this species across the
southern United States since their intro-
duction in Key West, Florida was
recorded in 1910 suggests that expansion
of the species’ range occurred as a conse-
quence of multiple jump dispersal events
instead of slow diffusion dispersal.

Population Structure and Density 
of Leopard Tortoises

Leopard Tortoises (Geochelone pardalis)
are the largest tortoises in southern
Africa, where they are widely distributed
in a variety of habitats. MCMASTER AND

DOWNS (2006. Journal of Herpetology 40:
495–502) studied Leopard Tortoises in
semi-arid farmland in Nama-Karoo, cen-
tral South Africa. The sex ratio of 92 tor-

toises did not differ significantly from
1:1. Adult females were larger than adult
males, and adults were larger than con-
specifics studied in more mesic habitats.
A population estimate of 57.6 ± 4.0 tor-
toises translated to a very low density of
0.017 tortoises/ha, much lower than in
more mesic situations.

Slow rates of diffusion dispersal in introduced
Mediterranean Geckos (Hemidactylus turcicus)
suggest that the wide distribution of this species
across the southern United States is a conse-
quence of multiple jump dispersal events.

D
A

W
SO

N
/W

IK
IP

ED
IA

.O
R

G

The population density of Leopard Tortoises
(Geochelone pardalis) was lower in dry South
African habitat than in more mesic situa-
tions, but adults were larger.

A
N

D
ER

S 
G

.J
. R

H
O

D
IN

, C
H

EL
O

N
IA

N
 R

ES
EA

R
C

H
 F

O
U

N
D

A
TI

O
N

Butler’s Garter Snake Will Remain 
on Protected List

A legislative committee in Wisconsin
that this summer had threatened to
remove Butler’s Garter Snake
(Thamnophis butleri) from a protected
list that stops developers from killing it,
reversed course and decided to allow the
snake to remain on a list of threatened
species. The decision was praised by state
Department of Natural Resources execu-
tive assistant Mary Schlaefer, who said
protecting the endangered snake was vital
to the overall health of the environment.
Critical steps need to be taken when
there is a species like this snake that is in
danger of disappearing, she said.

With their habitat shrinking, the
reptiles were placed on the threatened list
in 1997 by the DNR, meaning that in
most cases the snakes cannot be killed.
The protected area encompasses about
405,000 acres in southeastern Wisconsin.
Known for its colorful yellow stripes, the
1- to 2-foot-long snake is generally found

in marshes, prairies and fields, as well as
in roadside grassy areas and in vacant lots.
In addition to southeastern Wisconsin, it
can be found in Ohio, Indiana,
Michigan, and in southern Canada.

The Republican-controlled Joint
Committee for Review of Administrative
Rules decided in July to remove the
snake from the DNR’s threatened list if
the agency didn’t soften its regulations.

The agency on Tuesday outlined a num-
ber of changes it had made and was in
the process of implementing, including
reducing the time of review of proposed
projects from 27 to seven days and com-
ing up with more funding to reduce costs
for homeowners to get needed surveys.
Those surveys can cost up to $10,000,
said Andy Galvin, a consultation special-
ist in the DNR’s bureau of endangered
resources. The agency also reduced the
number of acres in the protected area by
500. It is working to identify as many as
65 protected sites for the snake. Once
those are established and stabilized, regu-
lations on private landowners can be
ended more quickly, Schlaefer said. “Our
goal is to manage based on science, but
in a way that minimizes impact on
homeowners,” she said.

The committee voted 7-2 not to
take the snake off the protected list. One
of the two no votes, state Rep. Debi
Towns, R-Janesville, said she was con-
cerned that the DNR was not setting a

N E W S B R I E F S

A legislative committee in Wisconsin that
this summer had threatened to remove
Butler’s Garter Snake (Thamnophis butleri)
from a protected list that stops developers
from killing it, reversed course and decided
to allow the snake to remain on a list of
threatened species.

G
A

R
Y

 C
A

SP
ER

Iguana 14.1 b&w text.QX6  2/25/07  10:46 PM  Page 57


