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IGUANA  •  VOLUME 11, NUMBER 2  •  JUNE 2004 119SAUROMALUS ATER

Some iguanas, such as Chuckwallas, inhabit arid climatic zones
and are well-adapted to scarcity. Feeding these animals only

three times per week is probably adequate. However, as a reptile
rescuer and rehabilitator, I am loathe to publish any iguana feed-
ing schedule that suggests anything less than fresh food and water
being provided on a daily basis. “Three times a week” is far too eas-
ily misinterpreted by the all-too-many pet owners who devote less
than the appropriate amount of attention to their animals’ needs.
“Three times a week” too easily segues into “twice a week” or “once
a week” or “I fed it last week; I don’t have any food handy so I’ll
feed it again next week.” As implausible as this may seem to those
of us who strive to provide our captive animals with the best pos-
sible care, my experience has, unfortunately, taught me otherwise.

A case in point: a male Green Iguana and a male Spiny-tailed
Iguana (Ctenosaura similis) were each kept for 12 years in a large
(150 gal), tidy enclosure with cypress mulch substrate and branches
for climbing. Ceramic heat emitters were used to provide heat and
Reptisun 5.0 UVB fluorescent tubes provided light. Both animals
received the same diet: once a week they were fed an unknown
amount of kale and organic spinach, with mango, melon, and
occasionally other fruit. I was told they were always fed on Sunday
and would have polished off all their food by Tuesday. Once a
month, they would receive an unknown quantity of kitten chow.
The effect of this highly questionable diet proved to be very dif-
ferent for these two animals in different genera.

“Ctolstoy” is a large, impressive, Spiny-tailed Iguana that
appears to be in good health. His body is a bit slim, even for a
species known to be lanky, but, compared to two other male C.
similis that have been with me for several years, his size seems rea-
sonable and his temperament is remarkably calm.

“Schiller,” on the other hand, is smaller than healthy 12–18
month-old Green Iguanas. He has no obvious deformities and,
superficially, has the appearance of a juvenile female (with the
exception of hemipenial bulges). Personality? This little guy has
what is currently referred to as “attitude,” but, after a few short
weeks of being provided with food on a daily basis, he is much
calmer and quite easy to handle.

I see far too many stunted Green Iguanas. However, most of
them come to me with no history, making it impossible to tease
out what factors might have led to that state. Given their identical
histories of long-term deprivation, I was curious as to why Ctolstoy
and Schiller had fared so differently.

I posed my query to Dr. Gunther Köhler, who is both a
trained veterinarian and a biologist whose research has focused
primarily on ctenosaurs, and Dr. John Iverson, who has investi-
gated the digestive physiology of various species of iguanas. Both
provided me with insightful responses, which served to raise fur-
ther questions.

Dr. Iverson pointed out that a sample size of 2 was insuffi-
cient for any definitive determination and that a host of reasons
(unrelated to digestive physiology) might be responsible for why
one animal might prosper and the other not. Factors such as par-
asites, diet as a juvenile, stored fat at the beginning of study, and
incubation temperature of the original eggs, among other things,
might have come into play. He also suggested that Schiller might
have had a developmental problem since hatching (or even before).

In my experience (with a limited sample size), iguanas with
developmental disorders also tend to have anatomical anomalies
that are visible externally (e.g., twisted vertebral columns, mis-

shapen or malproportioned heads, extra or missing digits). In my
experience with stunted iguanas, which, unfortunately, is much
more extensive, I find that when they are provided with a nutri-
tious diet on a regular basis, they grow to a variable extent.

Dr. Köhler pointed out that ctenosaurs usually inhabit arid
regions that experience a distinct (sometimes severe) dry season
during which food is scarce. Green Iguanas usually live in the for-
est (at least gallery forest along rivers) that tend to provide food
more regularly. Therefore, ctenosaurs might be better adapted for
irregular food-intake.

Fascinating information to ponder, but what does this prove?
Chuckwallas, like ctenosaurs, can probably survive (and even
thrive) on an intermittent feeding schedule — if they are cared for
by professional zoo personnel or responsible pet owners. Even so,
approximating the seasonal availability of foods in an animals’ nat-
ural environment remains difficult. Also, given the sheer number
of animals that come past my door that have been nutritionally
deprived, I strenuously advocate daily feeding. Although individ-
uals may not always feed, if given the opportunity each day, they
are much more likely to remain healthy and grow to their geneti-
cally determined potential.

In any case, I am pleased to report that both Schiller and
Ctolstoy have both been eating ravenously on a regular basis and
both are gaining weight.

F E E D I N G  F R E Q U E N C Y
AJ Gutman

West Hartford, Connecticut

“Schiller,” a 12-year-old male Green Iguana, is smaller than
healthy 12–18 month-old iguanas. He lacks obvious deformities,
but has the superficial appearance of a juvenile female.
Photograph by Carole Saucier.


