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Connectivity and Interpond
Movements of Painted Turtles

Because of the importance of facilitating
movement of plants and animals
between habitats, protecting the connec-
tivity of isolated habitat patches has
become an essential component of con-
servation biology. For a corridor to be
successful, it must allow for increased
movement, compared to the uncon-
nected state. BOWNE ET AL. (2006.
Conservation Biology 20: 780–789) stud-
ied the relationship between connectivity
and population density in Painted Turtles
(Chrysemys picta) in northern Virginia.
They examined movement rates and
movement probabilities in an agricultural
landscape in order to determine persist-
ence over a four-year period. The study
area consisted of nine ponds, with inter-
vening distances ranging from 110–2300
m. On occasion, more distant surround-
ing ponds were sampled to check for
emigrants from the focal area. Turtles
were categorized into five classes: Adult
male, adult female, subadult male,
subadult female, and juvenile. Of those,
adult females were the most sensitive to
habitat quality, and would move to more
distant ponds. Habitat patch quality was
influenced by interpatch distance and
patch size and shape. The authors found
that connectivity is a function of the
behavior of individuals in relation to
landscape features and habitat quality.
Thus, if the ecology of a species is not
taken into account, structural connectiv-
ity by itself has little worth. For proper
conservation planning, connectivity must
consider known behavior of the target
species as well as the quality of habitat.

Rat Eradications
Using New Zealand as a case study,
TOWNS ET AL. (2006. Biological Invasions
8:863–891) examined the effects of inva-
sive Pacific Rats (Rattus exulans), a small
South-East Asian species spread by
Polynesians throughout the Pacific, and
more recently introduced Norway Rats
(R. norvegicus) and Ship (Roof) Rats (R.
rattus) on native species. Rats suppress
some forest plants, and are associated
with extinctions or declines of flightless
invertebrates, ground-dwelling reptiles,
land birds, and burrowing seabirds.
Globally, Ship Rats were associated with
declines or extinctions of the largest
number of indigenous vertebrate species.
Effects of rats on forest trees and seabird
populations are sufficiently pervasive to
affect ecosystem structure and function.
However, data are patchy, and deficien-
cies would be reduced by documenting
distribution and abundance of indige-
nous species before and after eradications
of rats on islands.

Conservation Implications of Sea
Turtle Nesting Beach Loss

Historically, Green (Chelonia mydas) and
Hawksbill (Eretmochelys imbricata) turtles
nested in high densities throughout the
Caribbean. Because of hunting by
humans, turtle populations have been
decimated and populations continue to
decline. Population declines and ecolog-
ical changes have occurred over many
centuries and historical and archeological
data provide information that can be
used to estimate early geographic ranges
and population sizes of sea turtles.
MCCLENACHAN ET AL. (2006. Frontiers

in Ecology and the Environment
4:290–296) used historical data on use of
nesting beaches to determine changes in
population sizes for both species in 20
regions of the Caribbean. Historic data
show that nesting sites supported large
populations in the past, but that those
are now extremely depleted. Current
Green and Hawksbill populations are
0.33% and 0.27% of their respective his-
toric values, 20% of the historic nesting
sites have been lost, and 50% of the
remaining sites support very low popula-
tions. Because historic data have not been
used previously, the magnitude of popu-
lation declines has been underestimated.
Protection efforts have resulted in
increases in a few turtle populations, but
long-term data are sparse. For successful
conservation to occur, short-term data
should not be used to infer long-term
change. Without proper protection, the
remaining nesting beaches could soon be
lost. Protection and scientific research
funding must be implemented in as
many beaches as possible to help recover
lost nesting beaches.

Invasion and Displacement in 
Pacific Island Geckos 

Growing international travel and trade
have amplified the spread of invasive
species, which causes significant ecologi-
cal and economic damage. Invasives can
alter successional patterns, mutualistic
relationships, community dynamics,
ecosystem function, and resource distri-
butions. The Common House Gecko
(Hemidactylus frenatus) continues to
expand its range and is displacing many

54 IGUANA  •  VOLUME 14, NUMBER 1  •  MARCH 2007 CONSERVATION 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

Adult female Painted Turtles (Chrysemys
picta) were more sensitive than adult males or
subadults of either sex to habitat quality.

JI
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Introduced rats (Rattus spp.) suppress some
forest plants, and are associated with extinc-
tions or declines of flightless invertebrates,
ground-dwelling reptiles, land birds, and
burrowing seabirds.

Historically, Green (Chelonia mydas; above)
and Hawksbill (Eretmochelys imbricata) tur-
tles nested in high densities throughout the
Caribbean. Because of hunting by humans,
turtle populations have been decimated and
populations continue to decline.

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IGUANA  •  VOLUME 14, NUMBER 1  •  MARCH 2007 55

other species, such as the ecologically
similar but all-female Indo-Pacific Gecko
(H. garnotii) on a global scale. DAME

AND PETREN (2006. Animal Behaviour
71:1165–1173) predicted that the pres-
ence of H. frenatus will cause H. garnotii
to consume fewer resources and tested
whether H. frenatus would respond to H.
garnotii as they would to conspecific
males or to conspecific females. The
hypothesis that resource competition is
the mechanism of displacement of H.
garnotii received no support from the
experiments. Although geckos consumed
fewer resources when they were in pairs,
resource consumption of H. garnotii was
not negatively affected by H. frenatus.
The hypothesis that male aggression
toward H. garnotii is the primary mech-
anism of invasion of H. frenatus was also
rejected. Male H. frenatus responded to
H. garnotii as they did to conspecific
females, and courted and copulated with
them. However, male H. frenatus showed
a preference for larger female H. garnotii,
which suggested that sexual interference
could be a mechanism for displacement
of H. garnotii.

Tiger Salamanders 
Disappear in Maryland:

Is This the Fate of Other Non-game
Species of Conservation Concern?

LEE (2006. Bulletin of the Chicago
Herpetological Society 41:217–224) docu-
mented the demise of the last Maryland
population of Eastern Tiger Salamanders
(Ambystoma tigrinum) from a site that is
owned and managed by the Maryland
DNR. This site was purchased by The
Nature Conservancy specifically to pro-
tect this species and was sold to the state

with the stipulation that this salamander
be managed in perpetuity. The last breed-
ing pond was not monitored, and, over
time, silted in, pH and water depth
changed, surrounding vegetation shaded
the pond, and Bluegills were introduced.
Despite warnings from people familiar
with the needs of these salamanders and
a decline documented by a private indi-
vidual, the state refused to take action or
listen to advice from local herpetologists.

An agency boasting “everything we
do is based on the best available science”
failed to maintain a viable population
under their stewardship since the early
1970s. An agency with a forestry divi-
sion, wetland specialists, wetland restora-
tion teams, a legal mandate to protect
state endangered species, and a state her-
petologist, was unable to oversee the

wellbeing of a forest-dwelling creature on
lands it owns and manages. One can
only imagine how well other locally rare
and endangered reptiles, turtles, and
amphibians are doing under their care.
The article raises the obvious question as
to how other states oversee non-game
species of conservation concern.

Survival and Growth of Artificially
Incubated American Alligators

TEMSIRIPONG ET AL. (2006. Journal of
Herpetology 40:415–423) compared arti-
ficially incubated and repatriated
American Alligator (Alligator mississippi-
ensis) hatchlings released within and out-
side the maternal alligator’s home range
with naturally incubated hatchlings
released within and outside the maternal
alligator’s home range at three lakes in
central Florida. Artificially incubated
hatchlings released outside the maternal
alligator’s home range had lower recapture
probabilities than all other treatments,
none of which differed significantly.
Artificially incubated hatchlings were
about 6% shorter than naturally incu-
bated hatchlings at about nine months of
age. The authors concluded that repatria-
tion of hatchlings might be an economi-
cal alternative to repatriation of older
juveniles in efforts to restore populations,
but that location of release may affect
subsequent survival and growth.

CONSERVATION RESEARCH REPORTS

The Common House Gecko (Hemidactylus
frenatus; above) continues to expand its range
and is displacing many other species, such as
the ecologically similar but all-female Indo-
Pacific Gecko (H. garnotii) on a global scale.

R
O

B
ER

T 
PO

W
EL

L

The last known Maryland population of
Eastern Tiger Salamanders (Ambystoma
tigrinum) has disappeared from a site that is
owned and managed by the Maryland
Department of Natural Resources.

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E 
L.

 C
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LL
IN

S,
 C

N
A

H

Repatriation of American Alligator (Alligator mississippiensis) hatchlings might be an economi-
cal alternative to repatriation of older juveniles in efforts to restore populations, but the location
of release may affect subsequent survival and growth.

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