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IGUANA  •  VOLUME 14, NUMBER 1  •  MARCH 2007 45HISTORICAL PERSPECTIVE

Numerous attempts are made by zoological gardens to dis-
play resident populations of iguanids and varanids, but

often these meet with little success. Many species of the two
families are imported annually; yet surprisingly, few exhibit the
characteristic alertness and activity associated with wild speci-
mens. After a few months in captivity, their lethargy and obvi-
ous lack of health is depressing even to the casual zoo visitor.

Since November 1966, we have maintained an exhibit cen-
tred around these two families. Rhinoceros Iguanas Cyclura cor-
nuta, Andros Island Iguanas Cyclura b. baealopha [Cyclura cych-
lura cychlura], Exuma Island Iguanas Cyclura b. figginsi [Cyclura
cychlura figginsi], Cayman Island Iguanas Cyclura macleayi cay-
manensis [Cyclura nubila caymanensis], Green Iguanas Iguana i.
iguana2, and the Mexican False Iguana Ctenosaura hemilopha live
in complete harmony with a large Water Monitor Varanus sal-
vator and a Lace Monitor Varanus varius. They are exhibited in
a large glass-fronted display area, measuring 4.6 x 2.4 x 3 m, the
top being screened with wire. A concrete pool, 2.4 x 1.2 m, is in
the centre of the cage. The monitors are often seen swimming
or resting in the water.

Because the natural temperature of the area is only 27 °C
(80 °F), an auxiliary heat source is needed so that normal meta-
bolic functions can proceed. A bank of six 250-W/11O-V Infra-
red Heat Lamps (Ken-Rad) and two 275-W/11O-V ‘Sun
Lamps’ (Ken-Rad) are directed to a ‘hot spot’ at the front of the
cage where the temperature reaches 41 °C (106 °F). The value
of these lamps cannot be underestimated, for the lizards are most

healthy when they are in operation. Common or Green Iguanas
Iguana iguana with paralysed hindlimbs and in generally poor
health are often brought in as donations. In many cases, their
condition has improved after a few months under the sun lamps.

For a natural effect, plastic foliage, rocks, and tree limbs are
used. The plants must be chosen carefully to withstand the con-
stant prowling and climbing of the lizards. The limbs are
arranged at an angle one meter from the ground, so the lizards
may retire to them during the heat of the day. Gravel that will
pass through a 1-cm screen is used for the substratum, as this
tends to hold the warmth well. It also gives a firm footing for the
constantly scurrying lizards, which seem to feel insecure if placed
on material that gives way under their weight.

To ensure the health of the saurians, a proper diet must be
offered and they are fed three times a week. Two large alu-
minium trays are filled with diced fruits and vegetables.
Oranges, apples, bananas, grapes, lettuce, spinach, kale, toma-
toes, beets, carrots, papaya, and cantaloupe are used according
to season. Once a week, strips of lean horsemeat and freshly
killed mice are included in the tray. A multiple vitamin prepa-
ration (Pervinal) and steamed bone meal or oyster shell flour are
the only additives. Care is taken to avoid overfeeding, and we
judge this by observing the girth of the hind limbs and proximal
portion of the tail.

The photoperiod and temperature remain relatively con-
stant day by day and the relative humidity is about 40%. The
lights are turned on at 0800 hours, and the lizards begin to
emerge almost immediately. Usually, after basking in the heat
for the first 30 minutes or so, they begin to leave the ‘hot spot’
and return only periodically to maintain their temperature level.
They are fed between 1500 and 1600 hours. After the meal they
return to the ‘hot spot’ and remain there for some time. This
apparently aids digestion. The lights are turned off at 1700
hours, and this is the period of greatest activity. Flattening them-
selves dorsoventrally, they remain on the ‘hot spot’ area until it
cools. During this time, the sunlight that shines through the sky-

H I S T O R I C A L  P E R S P E C T I V E

Notes on Iguanids and Varanids in a 
Mixed Exhibit at Dallas Zoo1

James B. Murphy

Supervisor of Reptiles, Dallas Zoo, Dallas, Texas, USA

1 This article is adapted with the kind permission of the International
Zoo Yearbook (International Zoo Yearbook 9: 39–41; 1969), which
is published by the Zoological Society of London. Additional infor-
mation about the IZY can be found at http://www.blackwellpub-
lishing.com/journal.asp?ref=0074-9664&site=1.

2 Note that subspecies of Green or Common Iguanas (Iguana
iguana) are, for the most part, not currently recognized. Extensive
studies of genetic relationships among populations from different
regions are underway (e.g., see “ISG Reports” in Iguana 13(2):
127–128).

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light above the cage gradually fades. The only variation in this
routine is during the introduction of new animals when, if they
are shy and feeding diffidently, the lights will be left burning
after visiting hours so they will emerge and feed.

Newly acquired animals are quarantined in fibreglass hold-
ing cages for at least 30 days. Upon arrival, they are washed in a
prophylactic solution of oxytetracycline hydrochloride (Cosa-
terramycin) for 24 hours. Food is presented daily until a pattern
of feeding can be determined.

Maintenance of the exhibit is remarkably uncomplicated
considering the number of reptiles involved. Daily, the keeper
enters the cage before the lights are turned on, drains the pool
and scrubs it with a disinfectant (Roccal), cleans faecal matter
from the gravel, and polishes the glass. The cage is completely
dismantled bi-monthly and the gravel and walls are thoroughly
disinfected. The plastic plants, rocks, and gravel are also cleaned
and disinfected.

Rudimentary ‘grooming’ by the Exuma Island Iguana has
been observed. As the lizards shed their superficial epidermis in
fragments, pieces adhere to the body. Individuals of the same
species will investigate the body of the shedding lizard and con-
sume the skin whenever possible. Not only are the dorsal and
lateral areas checked, but the shedding iguana will lift its leg and
allow the others to pull the skin from beneath the leg.
Occasionally, more than one ‘grooming’ lizard will be involved
in this process.

Hopes for future successful breeding with this arrangement
are based on the numerous copulations we have observed;
although, unfortunately, the only eggs discovered were broken.
The male iguanas display vigorously in typical head bobbing
fashion and territories are rigorously defended. For such a large
and varied population, the mortality in the cage has been
remarkably low. Since its inception, only one Nile Monitor
Varanus niloticus has died.

46 IGUANA  •  VOLUME 14, NUMBER 1  •  MARCH 2007 MURPHY

Editor’s Remarks
This is the complete, edited text (e.g., capitalized formal common names, insertion of current scientific names when they
differ from the original) of the first major publication by James Murphy of the Dallas Zoo, whose profile appears elsewhere
in this issue. Although relatively recent compared to other studies we have highlighted in this section, this article was an
important milestone.

Zoos used to be dismal places. They began as places of entertainment, and animal welfare, conservation, and research
were not a part of their missions. That eventually began changing, but reptile departments were not at the forefront of this
process. The 9th issue of the International Zoo Yearbook (IZY), in which this article appeared, was the first to have a her-
petological focus. Other articles examined thermal requirements of captive reptiles (following on the work of Cowles and
Bogert, which we featured in Iguana 13(1): 53–61), reported on lighting and humidity, and described captive reproduc-
tion and incubation techniques. Species covered were primarily large: crocodilians, tortoises, constrictors, iguanas, and
monitor lizards. Most articles were shorter than Murphy’s, and few had references. Zoos were beginning to emphasize schol-
arship, and Murphy was a leader in applying this to herpetological collections.

Things have changed dramatically over the ensuing decades. The IZY has had a number of herpetologically themed
issues over the years, and these reflect the increasing sophistication of zoo research. Some leading zoos (including the Dallas
Zoo, whose herpetological publications can be seen at http://www.dallaszoo.com/oth/oth.asp?page=spubs#reptiles), now
include studies of natural habitats and their conservation in their mission. This modest paper led that change.

Gad Perry
Texas Tech University

Products mentioned in the text: Ken-Rad, Owensboro,
Kentucky, USA; Pervinal, US Vitamin and
Pharmaceutical Corporation, Veterinary Products
Division, New York, USA; Cosa-terramycin, Charles
Pfizer and Company Inc., New York, USA; Roccal,
Winthrop Laboratories, New York, USA.

Readers should recognize that combining different species

in one enclosure is a risky proposition. Behavioral triggers

that cannot be anticipated may result in aggression lead-

ing to injury or death of some animals. With very few

exceptions, such practices are not recommended.

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