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Gila monsters are
adapted to eating large meals infrequently. In
fact, an adult male Gila can consume its entire
yearly energy budget in three or four meals!
This is because of the large meals they can
consume as well as their limited
food requirements.
This allows them to consume most of their food
during the limited Spring activity period. Their
food requirements are reduced by a low metabolic
rate, as well as the relatively cool body
temperatures they maintain for most of the year.
Gila
monsters specialize in feeding on the young and
eggs in vertebrate
nests.
The Gila monster’s main activity period
coincides with the availability of their main
food source. For example, Gambel’s quail nest in
April and May, and the peak of desert cottontail
nesting is also in April and May.
Foraging for such
nests requires a search over a relatively large
area. Since they are able to consume large
quantities of
food (up to 1/3rd
of their body weight) and their resting
metabolic rate is so low, the energy expenditure
for such
foraging activities
are more than offset by their long periods of
inactivity.
Gila monsters also
have unique physiology to assist them in storing
food for their long periods of
inactivity.
Immediately after eating, large quantities of a
hormone-like molecule called
exendin-4 circulate
in the Gila’s blood. With this unique mechanism
of metabolic control, the act of eating primes
the organism to receive the incoming nutrients,
by, for example, stimulating
insulin secretion.
A synthetic version of this protein is currently
being developed as a treatment for human
diabetes.
Gilas have specially adapted
tails that allow them to store
fat
away for future needs. A well-nourished Gila
will have a thick, robust tail. The ability to
store fat in the tail is particularly apparent
in a reproductively active female. As she
converts stored fat into
yolk in the developing ovarian follicles, her
tail will change from thick and round to thin
and bony.
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In many parts of their range, a large part of a
Gila monster's diet consists of the eggs and
nestlings of the Gambel's Quail.
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