




































Iguana 10.1


A
mong the jagged limestone rock and dry
forest vegetation, I spot one of the
world’s most endangered lizards
sprawled on a fallen palm frond and

basking in the sun. This magnificent creature, with
dramatic red eyes and nearly four feet of bright
blue scales, is the endemic Grand Cayman Blue
Iguana, Cyclura nubila lewisi. Hoping for a closer
glance, I hold my breath and creep slowly forward
until I am only a few feet away. No reaction yet...
Step by step, I stealthily approach until — how’s

this? — I am only inches away from this apparently
bored iguana?! Though free to flee, Old Yeller, as
one yellow bead in this iguana’s crest identifies
him, calmly lies there like a log as numerous staff
and visitors to his home pass by on a regular basis.

Old Yellow is one of about twenty free-
roaming Blue Iguanas at the Queen Elizabeth II
Botanic Park (QEIIBP) on Grand Cayman. These
animals were bred onsite and released at 2–3 years
of age. The iguanas in this population are few,
young (the oldest is eight years old), live in an

Studying the World’s Most Endangered
Rock Iguana, Cyclura nubila lewisi

Rachel M. Goodman
University of Tennessee, Knoxville

15IguanaMarch 2003

Female Grand Cayman Blue Iguana (Cyclura nubila lewisi) named Carley. This animal was hatched in the wild and captured
by a local Caymanian who kept her until he recently donated her to the breeding facility at Queen Elizabeth II Botanic Park.
Photograph by Fred Burton

Iguana 10.1  3/2/03  11:11 AM  Page 15



unnatural setting, and are, for the most part,
highly habituated to humans. Despite these oddi-
ties, the study of these iguanas is critical for the
survival of C. n. lewisi. The released QEIIBP
iguanas are the only Blue Iguanas left living out-
side of captivity other than an estimated 7–25
iguanas remaining in the wild.

While working on a master’s degree at the
University of Tennessee, Knoxville, I collaborated
with the National Trust for the Cayman Islands
(NTCI) in studying the released population in
QEIIBP during the fall of 2001 and the summer
and fall of 2002. At the IUCN/SSC Iguana
Specialist Group meeting held on Grand Cayman
in 2001, I participated in a workshop to develop a
Species Survival Plan for the Blue Iguana. One
component of this plan, addressed by my current
research, was a detailed field study of the released
animals, including an analysis of spatial distribu-
tion, to estimate the carrying capacity of QEIIBP
and the required area for a proposed iguana
reserve. Additionally, I identified habitats and spe-
cific resources which are important to the iguanas
in order to improve living and breeding conditions
for the released and captive iguanas within the park
and to assess potential sites for the proposed
iguana reserve.

My project focused on determining the spatial
distribution and habitat utilization of the released
iguanas by radiotracking and conducting focal ani-
mal observations of 12 individuals. Because of the
low density of iguanas, I followed each iguana
continuously for one day at a time to conduct

observations. While watching iguanas sleep
motionless for hours on end and trying to remain
similarly motionless but alert, I repeated to myself
my mantra (borrowed from Beverly Dugan):
“Iguanas are not dull; they are just very subtle.” 
I often recorded tens of park visitors and staff pass-
ing or driving within three meters of an iguana
without so much as a lift of the head from the
happy blue basker. For iguana enthusiasts who
have patience and luck with weather, up-close
experiences and photographs of Blue Iguanas at

16 Iguana Volume 10, Number 1

Old Yeller rests on a man-made pile of rocks next to a
favorite food item, Asystasia gangetica. Photograph by
Rachel Goodman

An iguana’s head pokes out from the manicured lawn of
the Colour Garden in the Queen Elizabeth II Botanic Park.
Biter basks on top of a pile of discarded wooden beams
which also serve as her usual retreat. These are decidedly
unnatural habitats. In stark contrast is some of the natural
shrubland which iguanas inhabit in the mostly undisturbed
portion of the park. Photographs by Rachel Goodman

Iguana 10.1  3/2/03  11:11 AM  Page 16



the park are guaranteed. The habituation of the
released iguanas also proved to be a real asset for
my research, as I was able to follow iguanas at a
very close range without interfering with their
behavior. One exception to this was Pink (also
identified by a bead), who, accustomed to being
fed by park staff, followed me and begged for food
if I approached too closely.

Some limitations and quirks of the QEIIBP
population were frustrating for me as a researcher,
but emphasize the critical need for research and
monitoring of this population. For example,
iguanas who were supplementally fed moved
shorter distances to forage, leading to a confound-
ing variable in my analysis of home range size
which my small sample size cannot address.
However, the suggestion that iguanas may center
their home ranges around supplemental foods is
strong enough for management plans to include a
consideration of feeding sites as a tool for encour-
aging settlement of newly released iguanas, which
otherwise might disperse into unprotected areas.
The presence of feeding sites also may lead to a

17IguanaMarch 2003

The author monitoring
movement of iguanas
with telemetry
equipment.
Photograph by 
Sandy Echternacht

Slugger models his radio transmitter.  Photograph by Rachel
Goodman

Slugger regularly sunbathes on the road near the staff
office, refusing to budge even when cars pass at less than 
3 m away.  Photograph by Rachel Goodman

Park staffer John Lawrus laughs at the common sight of
Pink, a released iguana, begging for handouts on the porch
of the staff office. Iguanas have gone so far as to run into
this office or attempt to jump into cars or onto people in
the park. Photograph by Rachel Goodman

Iguana 10.1  3/2/03  11:11 AM  Page 17



18 Iguana Volume 10, Number 1

decrease in the size of existing home ranges,
thereby increasing the number of iguanas that can
be packed into the park.

Another quirk of my study was the constant
human disturbance of iguanas and researcher alike.
I often interrupted my observation sessions, dur-
ing which I strived to minimize disturbance, to
jump in front of a car threatening to run over my
subject or to prevent an iguana from eating a plas-
tic bag or a tourist’s berry-colored toenails! Also,
convincing park visitors and staff to ignore and not
talk with me while I
conducted behavioral
observations was a
constant challenge.
Visitors were satisfied
receiving a small infor-
mative pamphlet I
wrote up, but some
staff could never accept
the fact that I was on
duty while watching a
motionless iguana and
not interested in join-
ing their smoking
break.

In addition to my
study of spatial distrib-
ution and habitat use
in the park, I collected
data on the diet and
demographics of the
released iguanas. The
first successful repro-
duction in the released
population had been
confirmed in 2000 by
the appearance of year-
lings the following
spring. In fall 2001,
Fred Burton, director
of the Blue Iguana cap-
tive breeding and
release program, and I
built enclosures around
five nests of released
females to examine
nest structure and suc-
cess. Two nests were
successful and an evalu-

ation of a third was inconclusive. These findings
and the recensusing of the wild population in sum-
mer 2002 indicated a need for headstarting juve-
niles produced by the released QEIIBP iguanas. In
2002, I monitored nesting of released females.
Fred subsequently excavated clutches for incuba-
tion, resulting in a total of 25 hatchlings for head-
starting in the captive facility.

Fred and I collected and identified plants that
Blue Iguanas were observed eating and examined
a limited number of freshly collected scats. We

found that the released iguanas
eat the leaves, seedlings, fruits,
and flowers of many species of
exotic plants in the park’s color-
ful gardens in addition to native
species in the park’s natural habi-
tats. They also occasionally take
some animal matter in the form
of slugs and invertebrate larvae.
One six-year old male, Slugger,

Cagerat, who was released near the captive breeding
compound in the spring of 2002, found a hole in an empty
cage shortly thereafter, and has remained resident ever
since. He rarely ventures far outside of the compound, but
often climbs on top of the cages to bask and display at the
captives. Photograph by Rachel Goodman

The author holds Cagerat
(three years old when this
photo was taken), who
has grown nearly twice as
fast as the other released
iguanas, presumably
because of his double-life
as both a well-fed pseudo-
captive and a free-roaming
forager and basker.
Photograph by Fred Burton

Iguana 10.1  3/2/03  11:11 AM  Page 18



acquired his nickname by searching for and con-
suming at least six live slugs during one spree.

I also often served as an informal monitor of
the captive and released populations at QEIIBP,
alerting and aiding when a captive iguana escaped
from its cage or when a released iguana’s favored
retreat was in danger of being destroyed (poten-
tially with the iguana in it). Before my arrival at the
park, the general assumption was that released
iguanas were not fed heavily by humans, as park
staff were explicitly instructed not to feed them. I
discovered that nearly all of the released iguanas
were supplementally fed, either directly or indi-
rectly — and most commonly by the staff. In fact,
several iguanas regularly traveled to the staff office
just before lunch to wait on the front steps for
their regular meal of fruits, fish, meats, and, most
commonly, rice and beans. Besides the obvious
potential for nutritional problems, uncontrolled
supplemental feeding has led to decreased wariness
of and increased aggression toward people. If
iguana attacks on park visitors, which currently
occur, though infrequently, are to be eliminated,
direct feeding by humans must be stopped and
signs warning visitors not to approach or pet the
iguanas must be erected. The latter will be accom-
plished this year, thanks to IIS-member John
Bendon’s donations of two signs for the park.

After wrapping up my last field season in
December 2002, I found that I did not want to
leave the botanic park, where the Blue Iguanas are
still in need of much help and greater understand-

ing. Formerly, Fred Burton, park staff, and volun-
teers organized through the NTCI fed and cared
for the captive iguanas, and I was often the only
daily monitor, particularly of the released popula-
tion. This year, a part-time employee has been
hired by the Blue Iguana Conservation Program
to feed and care for the released and especially the
captive iguanas at QEIIBP. Although I’m sure
they are in good hands, I had a hard time saying
goodbye to those funny blue lizards: Cagerat, who
was released but refused to leave the captive com-
pound; Biter, named for splitting open a finger;
Slugger, who thankfully survived vehicular crush-
ing; and Pink, infamous for his assaults on cars and
women. Each iguana has a unique personality, and
all became my dear friends. I have hope that the
Grand Cayman Blue Iguana will survive its current
brush with near-extinction and flourish, so that
future generations will have the chance to experi-
ence this iguana’s unique beauty and charms. 

19IguanaMarch 2003

Biter, here five years old, rests for a moment after digging
her nesting burrow in a pile of discarded potting soil.
Photograph by Rachel Goodman

Fred Burton and the author built enclosures in 2001 to
catch hatchlings as they emerged from nests of released
female iguanas in QEIIBP.  Photograph by Sandy
Echternacht

Iguana 10.1  3/2/03  11:11 AM  Page 19



Acknowledgments
My research has been supported by advisors

Sandy Echternacht and Fred Burton. Funding and
housing were provided by the Blumenthal and
Bumgarner families, National Trust for the
Cayman Islands, University of Tennessee, includ-
ing the Department of Ecology and Evolutionary
Biology, Chicago Zoological Society, Chicago
Herpetological Society, Explorers Club, the stu-
dents of Watkinson School in Connecticut, and
John and Sandy Binns.

Pertinent Literature
Burton, F.J. 2002. Grand Cayman Blue Iguanas in the wild: 

A survey of the population status of Cyclura nubila lewisi
(working report).

Dugan, B. 1982. Overview of Section V, Social Organization, pp.
301–302. In G.M. Burghardt and A.S. Rand (eds.), Iguanas of
the World: Their Behavior, Ecology, and Conservation. Noyes
Publications, Park Ridge, New Jersey.

20 Iguana Volume 10, Number 1

An iguana stands in front of one of the park’s golf carts and
contemplates crawling under for some refuge from the hot
midday sun. To date, two released iguanas have been run
over after doing just that, though luckily one survived.
Photograph by Rachel Goodman

Billy, a member of the captive breeding program, opens
wide for a big yawn. Photograph by Rachel Goodman

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