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Anegada Island Iguana (Cyclura pinguis)
In order to determine the genetic suitability of the San Diego
Zoo’s six adult (3.3) Anegada Iguanas for a captive breeding pro-
gram, relatedness within the captive population was examined by
comparing their microsatellite variation to that observed for two
groups of wild Anegada Iguanas, one known to be closely related
(clutchmates from marked nests) and one presumed to be ran-
domly related (haphazardly captured adults and juveniles).

A Cyclura pinguis DNA microsatellite library was con-
structed using 23 of 48 candidate loci screened for polymorphism
and found to be useful for analysis. DNA was extracted from a
total of 178 Anegada Iguanas: 12 captives at the San Diego Zoo
(the six adult founders and their six offspring) and 166 wild indi-
viduals (68 haphazardly captured animals assumed to be ran-
domly related, and 98 hatchlings from eight nests assumed to
represent eight sibling groups). Genotypes were obtained for all
individuals and the average number of alleles observed across the
23 loci in the captive and wild populations was 2.8 and 4.3
respectively, with observed heterozygosity determined to be 0.61
in the captive group and 0.53 in the wild population.

A maximum likelihood statistical approach, using the six
captive founders and most of the wild individuals sampled, was
used to infer relatedness among the captive adults. Results of this

analysis suggest the six captive adults contain three related pairs
(one pair of males, one pair of females, and one male and female
pair) and that each related pair is unrelated to the other pairs.
The statistical approach used requires more markers to estimate
specific relationships, such as determining whether two iguanas
are likely to be siblings, half-siblings, parent-offspring, etc. For
this reason, we can only generally state whether each pair is likely
to be related or not.

The molecular data compiled to infer relatedness of the six
adult founders was also used to correctly assign parents to a cap-
tive offspring with a questionable pedigree. The adults that were
believed to be the parents of the offspring were excluded at 7 out
of 23 loci. Of the four other possible adult candidates,
microsatellite allele data revealed that only one male and female
qualified as parents of the offspring at all 23 loci.

The microsatellite data have also provided important infor-
mation about the genetic diversity of the wild population on
Anegada. Although population estimates suggest that the wild
population contains fewer than 300 individuals, the microsatel-

West Indian Iguanas: An Update1

278 IGUANA  •  VOLUME 13, NUMBER 4  •  DECEMBER 2006 GERBER, HINES, IVERSON, AND KNAPP

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To determine the genetic suitability of the San Diego Zoo’s adult Anegada Iguanas (Cyclura pinguis) for a captive breeding program, relatedness in
the captive population was compared to that observed for two groups of wild iguanas.

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1 Reprinted with permission from the IUCN Iguana Specialist Group
Newsletter 9(1), Summer 2006.



IGUANA  •  VOLUME 13, NUMBER 4  •  DECEMBER 2006 279WEST INDIAN IGUANAS

lite data suggest that the population is genetically healthy
(observed heterozygosity is 0.53) and that subpopulations are
not significantly subdivided (FST is 0.153).

The genetic data also support the presence of partial sibling
relationships across multiple field seasons for hatchlings captured
on the tiny islet of Windberg Cay (0.26 ha) in Red Pond, suggest-
ing that females return to this cay year after year to lay their eggs.

This work was jointly undertaken by the Genetics and
Applied Conservation Divisions of CRES and was funded by a
grant from the Institute for Museum and Library Services and
with a Van Ness Research Fellowship at CRES.

Glenn Gerber
San Diego Zoo

ggerber@sandiegozoo.org

Allen Cays Iguana (Cyclura cychlura inornata)
Two separate research trips were made to the Allen Cays area in
the northern Exumas, Bahamas, one from 18–26 March 2006
and one from 16–21 July 2006. The March trip consisted of an
alumni team that surveyed cays in and around the Allens
Harbour for potential migrant iguanas and for the collection of
blood samples. This expedition replaced the normal May trip
for current Earlham College students that involves intensive
mark-recapture work on Leaf and U cays. The July trip focused
on nesting activity on Flat Rock Reef Cay (FRRC) just north-
east of Leaf Cay. We hoped to compare nesting parameters in
this rapidly growing population with those observed in 2001
and 2002 on Leaf and U cays, where populations are presumed
to be at or near carrying capacity.

March Survey Trip.—As early as 1995, JBI (author) began hear-
ing reports that iguanas were seen on islands around Leaf and U
cays, where they had not been previously observed. By 2001,
populations had been confirmed on Allen Cay and FRRC (ca.
1 km NE of Leaf Cay), both of which contained individuals pre-

viously marked on Leaf or U cays. Our assumption was that
people were relocating iguanas. In 2005, two iguanas and a car-
cass, none of which were marked, were discovered on a tiny islet
just north of Leaf Cay that had yielded no sign of iguanas when
surveyed in 2001. In order to better understand the issue, 13
Earlham alumni and associates spent six days in March 2006 in
the Allen Cays area to survey islands and to collect blood sam-
ples for future DNA work.

A total of 12 cays were visited during this trip. U Cay and
Leaf Cay were visited long enough to collect blood samples, but
no other work was conducted on either cay. Allen Cay and
FRRC were extensively sampled and blood was collected at each
location. Total population estimates for each now stand at 20
(total marked) and 100 (based on 38 captures this trip that
included five recaptures and a total of 45 marked for the island),
respectively. To date, neither juveniles nor adequate nesting sites
have been observed on Allen Cay.

FRRC, which had no evidence of iguanas in 1994, now has
a thriving, growing population and the estimate of 100 iguanas
includes a subjective count of 30 elusive juveniles. Eight other
cays between the Allen Cays and Robert’s Cay just south of Ship
Channel Cay, most of which had never been surveyed before,
were also visited during this trip. A total of seven iguanas was
seen on three of these islands and a fourth island had iguana scat
and tail drags. Of the observed iguanas, two were captured and
blood was collected from each. One of these iguanas was
unmarked and the other was a female originally from U Cay
that had clearly been relocated sometime after 2001, when it had
been included in our nesting study on U Cay.

July Nesting Study.—JBI and KNH returned to FRRC for five
days after the presumed nesting season (mid-June to mid-July
on Leaf and U cays). A total of ten potential nest sites were iden-
tified based on mound presence, soil and vegetation disturbance
patterns, and female attendance. All ten sites were excavated and
egg clutches were uncovered at seven of the sites. Unlike on Leaf

An adult female Allen Cays Iguana (Cyclura cychlura inornata) in the northern Exumas, Bahamas.

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and U cays, female nest defense was minimal and it took some
time to determine which nests had associated females.
Nonetheless, seven nesting females were identified and six were
matched with precise clutches. One female was associated with
a potential nest site, but the eggs were never uncovered. At one
nest where eggs were found, no female was observed. Two of the
identified sites yielded no eggs nor associated females, indicat-
ing that our initial nest identification may have been incorrect
for those sites.

In addition to a lack of strong nest defense, the most
important differences between the young population on FRRC
and the older populations on Leaf and U cays tentatively appear
to be a higher clutch frequency (40–50% on FRRC; ~33% on
Leaf and U cays) and more rapid growth rate (32 cm SVL = 10
years on FRRC; 32 cm SVL = 18–23 years on Leaf and U cays)
on FRRC. The latter apparently results in female sexual matu-
rity being attained in less than a decade on FRRC rather than
the 12 or more years necessary on the other cays. Other nesting
parameters, including clutch size, egg size, and distance between
closest nests, do not appear to differ significantly between FRRC
and Leaf and U cays.

As a follow-up to the March survey, JBI and KNH revis-
ited one of the cays where four iguanas had been observed and
the previously unmarked individual had been captured. We
observed a total of five individuals and captured two. As with
the March capture, these were unmarked, adult females. The
captured females demonstrated site fidelity suggestive of nesting,
and digging was observed, but soil appeared to be too sparse for

actual nest construction. No juveniles were observed, reinforc-
ing the notion that these individuals may be unable to nest on
this island.

Conclusions.—Our research this year leads us to wonder whether
this might be an optimal time for the Bahamian government to
formally protect the Allen Cays Iguana area. The discovery of a
U Cay female as far away as Robert’s Cay (6 km to the north)
verifies that unauthorized persons are relocating iguanas from
Leaf and U cays. The presence of unmarked adult iguanas on at
least two new cays also suggests a wider natural distribution than
previously known. For example, at least three of the five iguanas
on the newly surveyed cay appear to be long-term natural inhab-
itants. Aside from Leaf, U, and FRR Cays, however, the other
cays appear to lack nesting habitat, potentially rendering the
iguana populations there biologically dead.

Results of DNA analyses from collected blood and future
survey work should help clarify relationships among these
island-separated populations. In the meantime, preliminary
nesting results from FRRC verify that populations can establish
quickly given appropriate nesting habitat. In addition, the island
with five iguanas offers a potential experimental site to study the
demographic effects of adding nesting soils to an island.

Launching an educational campaign that includes informa-
tional kiosks on Leaf and U cays is essential to the long-term
well-being of the Allen Cays Iguana. Leaf Cay and its iguanas
support a booming tourist industry, but the latter depends on a
vulnerable species that is made even more so by increased

280 IGUANA  •  VOLUME 13, NUMBER 4  •  DECEMBER 2006 GERBER, HINES, IVERSON, AND KNAPP

John Iverson exhumes an Allen Cays Iguana (Cyclura cychlura inornata) nest in the northern Exumas, Bahamas.

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IGUANA  •  VOLUME 13, NUMBER 4  •  DECEMBER 2006 281WEST INDIAN IGUANAS

human involvement. Well-meaning tourists may be creating
some of these biologically dead populations. Too many islands
support only single sex individuals or may not have sufficient
nesting soil. Furthermore, preliminary observations suggest that
tourist feeding has dramatic effects on a subset of the popula-
tions. We have yet to understand the implications this may have
on the health of individuals and the population as a whole.
Education, combined with a cooperative agreement among the
owners of Leaf and U cays and the Bahamian government,
could go far in ensuring the long-term existence of the Allen
Cays Iguana, the indigenous endangered Audubon’s Shearwater,
and other flora and fauna in that area of the Exumas.

Kirsten N. Hines
The Institute for Regional Conservation

hines@regionalconservation.org
and

John B. Iverson
Earlham College

johni@earlham.edu

Exuma Island Iguana (Cyclura cychlura figginsi)
Surveys in the Exuma Island chain were conducted from 6–11
April 2006. The surveys were part of the John G. Shedd
Aquarium’s citizen-scientist iguana research program and
included the islands of Leaf (northeast of Normans Pond),
White Bay, North Adderly, Noddy, and Pasture cays. Objectives
for 2006 were to: (1) survey iguana populations in the south-

central Exuma chain because they have not been visited since
1998, (2) translocate iguanas from Leaf Cay (northeast of
Normans Pond) to Pasture Cay in the Exuma Cays Land and
Sea Park to augment the initial colony that was translocated in
2002, and (3) collect preliminary diet and body condition data
for comparative studies of iguana populations inhabiting Exuma
cays visited by tourists versus un-visited cays.

In addition to the April surveys, Gaulin, Bitter Guana, and
Pasture cays were visited by CK (author) between 26 May and 4
June 2006. The surveys were part of a Bahamas Ecology course
that included undergraduate students to help collect data from
each cay (Gaulin: 27, 28 May and 4 June; Bitter Guana: 27 May;
Pasture: 26 May and 2, 3 June). Research on Gaulin and Bitter
Guana cays is part of an annual monitoring project initiated in
1998. Approximately 2.5 days were spent on Gaulin Cay, one
day on Pasture Cay, and three hours on Bitter Guana Cay.

General Surveys and Morphometrics.—During the April surveys,
we captured and processed 123 iguanas from five cays (Leaf, n
= 19; North Adderly, n = 33; Noddy, n = 14; White Bay, n = 51,
Pasture, n = 6). This was the first year that iguanas were all
marked with PIT tags on these cays (except Pasture Cay) for
long-term identification. During the May/June surveys, we cap-
tured an additional two founder iguanas from Pasture Cay, one
iguana from Bitter Guana, and 51 iguanas from Gaulin Cay. Of
the 51 Gaulin captures, 27 were recaptures dating back as long
ago as 1998. No differences existed in body mass, snout-vent
length, or ectoparasite load between the North Adderly, White

Exuma Island Iguanas (Cyclura cychlura figginsi) populations in the south-central Exumas were surveyed for the first time since 1998.

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Bay, and Gaulin cay iguana populations (all P > 0.05). Leaf and
Pasture cays were excluded from statistical analyses because they
represent translocated populations with low densities and thus
exceptional large body sizes. Noddy and Bitter Guana cays also
were excluded from analyses because of small sample sizes. The
southern end of Bitter Guana Cay was surveyed by CK and L.
Roth on 27 May. Twelve iguanas representing multiple age
classes were observed, but only one large male was captured
because of the extreme wariness of the iguanas and our short
time on the island. Additionally, while at anchor on 26 May off
of Bitter Guana Cay, four iguanas were observed foraging on the
north beach. These observations represent an increase in
recorded iguanas over the past nine years. Although speculative,
annual increases in observations coincide with the
informative/protective signs posted on the island in 1998.

On 10 April, we set Sherman live rat traps on White Bay
(n = 28 traps) and Leaf Cays (n = 30 traps). We trapped six rats
from White Bay and none from Leaf Cay. To date, rats have
been confirmed from White Bay, Gaulin, Bitter Guana, and
Pasture cays. North Adderly, Noddy, and Guana cays (not vis-
ited in 2006) still need to be surveyed for rats.

Translocation.—The original translocation from Leaf Cay [north-
east of Normans Pond] to Pasture Cay in the Exuma Cays Land
and Sea Park was conducted as a necessity because of a land sale
dispute that required the removal of as many lizards as possible
in two days. The translocated colony was heavily male-biased
(11.5) resulting in an initial loss of large males. Since December
2002, three male iguana carcasses have been recovered, while the
fate of four (2.2) iguanas remains uncertain. One of the male car-
casses was discovered in December 2002 washed up on Compass
Cay located approximately 5 km south of Pasture Cay.
Interestingly, two large iguanas have been spotted this year on the
north beach of a private cay (Little Halls Pond) located 1.5 km
north of Pasture Cay (Tom Barbernitz, personal communica-
tion). We were not granted permission to land on the island, so
we were unable to determine if those iguanas came from Pasture
Cay. However, no iguana-inhabited islands are in the area, so, if
the iguanas did not originate from Pasture Cay, they were pur-
posely put on the island from a distant iguana-inhabited cay.

Seven (5.2) of the founder iguanas remaining were recap-
tured on Pasture Cay and all appeared healthy and had gained
body mass since last capture. Two additional founder iguanas
(1.1) were observed but not captured. One subadult that
hatched on the island was recaptured and increased its body
mass by 302 g and SVL by 5.9 cm (BM = 420 g; SVL = 19.6
cm) since it was last captured in 2004. Two other subadults were
observed but not captured.

Evidence of exploratory dig activity was observed on the
north beach, and two iguanas appeared to have nested. One
female was aggressive toward male and female conspecifics in her
nesting area and chased iguanas away from the area if they
approached too closely. A snake (Alsophis vudii) was captured on
the island in April. High predation rates of iguana hatchings by
these snakes on Andros Island warrant future investigations con-
cerning predation effects on Pasture Cay.

Dietary Comparisons.—Visitor traffic in the Exuma Cays has
been increasing significantly over the past decade. Many of these
tourists land on cays inhabited by iguanas. For example, the
Allen Cays in the northern Exumas experience up to 600 peo-
ple each week from one-day Nassau excursions. The islands in
the southern Exumas also receive high-impact visitors from
Great Exuma aboard one-day excursion tourist trips. Previously
undisturbed populations in the more remote central Exumas
also are becoming subjected to more frequent visits by tourists
due to increased traffic from the Staniel Cay Yacht Club.
Consequently, few iguana populations remaining in the Exumas
are free from visitor impact. Visitors purposely feed the iguanas,
thus altering their natural behavior and potentially their health.
In order to assess the impact of tourist feeding on populations
of Rock Iguanas in the Exumas, general dietary data were col-
lected for comparative analyses between disturbed and undis-
turbed islands. We collected 131 scat samples from six cays in
the central and southern Exumas (White Bay, North Adderly,
Pasture, Noddy, Leaf [northeast of Normans Pond] and Guana).
In March 2006, KH (with John Iverson) collected 84 scat sam-
ples of C. c. inornata from seven cays in northern Exumas (Leaf
[east of Allens], Southwest Allens, Flat Rock Reef, Roberts, and
three unnamed cays just north of Allens). Scat samples were col-
lected in different habitats and areas that included wooded inte-
rior, rocky areas, and beach habitat. Preliminary results indicate
that prolonged, high rates of feeding do alter iguana diets. Of
the islands sampled, Leaf Cay (Allens) has by far the longest his-
tory and greatest rate of food provisioning by tourists. Scat sam-
ples from the main tourist beach on Leaf Cay contained high
levels of ooid sand grains (six of 19 samples), remnants of grapes
(seven of 19), and fresh samples with more of a loose/liquid con-
sistency than fresh samples found on other parts of the island
(sand in two of 17 samples; grapes in one of 17; no loose/liquid
samples). To a much lesser extent, other sampled iguana popu-
lations experience food provisioning by tourists (e.g., White Bay
Cay, Southwest Allens Cay), but no distinct differences were evi-
dent between samples from these islands and samples from pop-
ulations with minimal or no food provisioning by tourists. More
data are needed to make meaningful conclusions, but we now
have a working hypothesis for future studies. Future work will
also focus on blood chemistry and behavioral comparisons.

Further reinforcing the timeliness of this work, we docu-
mented an increase this year in tourists visiting Gaulin and
Pasture cays, thereby stressing the need for signs advertising the
protected status of the iguanas. Additionally, dialogue needs to
be initiated to prohibit the feeding of iguanas on selected cays
to prevent potential perturbations or preserve selected “natural”
populations.

Charles Knapp
San Diego Zoo and John G. Shedd Aquarium

cknapp@ufl.edu
and

Kirsten Hines
The Institute for Regional Conservation

hines@regionalconservation.org

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