Breeding Season Issues
So - you've visited our Sexing
Iguanas page
and you've figured out your iguana's gender. Now you are
wondering what to expect from your iguana during the
breeding season. Most healthy iguanas go &into
season& at some point each year once they've reached
sexual maturity, regardless of whether an iguana of the opposite sex is with them, or whether you plan to breed them (visit
for more information). The exact time of year varies among
individuals, perhaps due to what region of Central/South
America they originally came from. A prepared iguana
owner knows the signs of breeding season and is prepared
to deal with it on a yearly basis. Males and female
iguanas both present their owners with their own set of
challenges during this time. Read on to learn what you
can expect.Males During Breeding
Season: Physical Changes - Physical signs that a male iguana
is in breeding season are an increase in orange coloring
in the skin, an enlargement of the waxy protrusions from
the femoral pores (see photo below), and the presence of
sperm plugs seen either protruding from the vent or found
in the enclosure or habitat area. Sperm plugs are dried
packets of semen that often appear as long, translucent
orange or cream colored objects. Males in season may also
leave fresh semen around too, which is sometimes compared
in color and consistency to melted mozzarella cheese.
photo of Jake, a mature male, was taken when he
was in breeding season. Notice the large waxy
plugs protruding from his femoral pores. Compare
this to the photo of Jake's pores when he is not
in season, which is located on the Sexing Iguanas page.
Males During Breeding
Season: Behavioral Changes - Many owners get quite
exasperated with their males during breeding season.
Owners of male iguanas should be prepared for possible
difficulties when their iguana matures. Since mature
iguanas go into breeding season for a period of several
weeks, or even months, every year, this is something
owners must deal with on a yearly basis. Many male
iguanas exhibit behavioral changes during breeding season
that can make them very difficult to handle or interact
with. Some males can even be dangerous during this time.
Behavioral changes may include an increase in head
bobbing and display behaviors, an increase in territory
patrolling and an increase in territorial defensive
behavior. Problems occur when male iguanas defend their
territories, which may range from their enclosure, to one
room, to an entire house, with violent attacks. These
attacks may be initiated by a normally docile male
against the owner he usually trusts and has bonded with.
These attacks can be unpredictable and severe. Iguanas
can deliver serious bites, especially when their owner is
caught off-guard. It is imperative that owners of male
iguanas be on the lookout for this type of territorial
aggression during breeding season. Not all males exhibit
this type of behavioral change. Many remain their normal,
docile selves. However, the very real possibility exists
for this type of behavior, so all owners of mature male
iguanas should be prepared for it.
question that often comes up is whether or not aggressive
males can be neutered to lessen the impact of breeding
season hormones on their behavior. The answer to this is
still unclear. There are some vets who will do this
procedure, but it is quite difficult and can be risky if
the vet is not knowledgeable. In addition, there is little
evidence to support the idea that such a procedure
actually lowers aggression in males with this behavioral
pattern. At the present time, the better way to go is to
be prepared to deal with possible behavioral problems
rather than relying on a potentially risky and uncertain
surgery to solve the problem.
addition to territorial behavior, there are other
behavioral signs that a male is in season. He may
experience a decrease in appetite. In the wild, male
iguanas spend the breeding season courting females and
defending territories. They spend little time eating
during this period. It is important to keep your iguana
hydrated during this time, since he may become dehydrated
from a lack of moist foods. Frequent baths, an increase
in room humidity and daily spritzing can help. Feeding
small amounts of high-water treat foods (peeled grapes,
watermelon) can also help.
may also &forget& their proper toilet habits as
they get distracted by the breeding instincts they are
experiencing. Owners may find themselves cleaning up more
messes than usual. For this reason, it may be necessary
to confine your male to his enclosure more than usual
during this time. Good toilet habits will often return
when the breeding season is over.
behavior that males often exhibit during breeding season
is, reasonably enough, mating behavior. Many males will
stalk their owners not to attack with aggression, but to
attempt to mate with an unsuspecting foot or leg.
Menstruating human female owners should be particularly
aware and on the lookout for such amorous behavior in
their male iguanas, because males often seem to be
especially interested in their female owners during that
time of the month. Although such mating attempts sound
humorous, they can be dangerous, because during mating the
male grasps the back of the female's neck with his teeth.
Her tough skin can withstand these &love
bites&. Human skin cannot.
Below are photos of iguanas mating. Notice how the males have a grasp on the females' necks. This helps the male maneuver the female into position and hold her still.
In the top photo, male Bumpy (right) mates with female Hopper (left).
In the bottom photo, Jake (on top) mates with Donnie.
Notice how their tails are entwined.
Be on the lookout for such mating
behavior in your male. If you see it, try offering him a
green towel, sweatshirt or stuffed toy. Males will often
&mate& with such substitute objects, and will
deflect their attentions from you to the &love
toy&. Watch your male carefully to be sure he does
not accidentally ingest any pieces of the toy while he
&mates& with it.
Below are photos of Hal, a
mature male, as he &mates& with his
&love toy& - a stuffed grasshopper.
Notice how he has a grip on the toy with his
teeth, as he would a female during mating.
this mating behavior, you will likely see your male evert
his hemipenes from his vent. This is natural behavior,
and is nothing to be worried about. It can, however, be
quite alarming to see the first time.
This is a photo of male iguana hemipenes.
This photo was taken just after mating occurred
between Bumpy and Hopper (see above photo).
During Breeding Season: Physical Changes - Like males, female
iguanas undergo physical changes during breeding season.
A healthy, mature female iguana will develop eggs in her
ovaries during breeding season, even if she hasn't mated with a male. This condition is
referred to as gravidity, and females carrying eggs are
said to be gravid. Some females turn a bit orange on the
legs and/or belly during this time, but many exhibit no
color change. As the eggs develop, females often stop
eating and get thin in the legs and tail. Their bellies,
however, may bulge with eggs, giving them a round
appearance. As the eggs near the end of their
development, the shells develop and the eggs can be felt
by gently palpating the belly. Be careful while doing
this, though, as the eggs can break inside the female,
which is deadly. This pattern of egg development and
eventual laying will occur every year, regardless of
whether the female has mated.
Below are two X-Rays taken of Vega$. The X-ray on the left was taken when Vega$ was gravid, and her abdomen was full of eggs. The X-ray on the right was taken after Vega$ laid her eggs. It is a good idea to have your vet take a pre-laying and post-laying X-ray, to be sure that all eggs have been laid. Eggs that are retained in the body of the female will cause serious problems.
Although most times you can
clearly see the signs of gravidity if you know what to
look for, some females may not clearly appear to be
gravid. However, there are some behavioral changes that
can clue the observant owner to the fact that their
female is gravid.
During Breeding Season: Behavioral Changes - Many females will
exhibit a much decreased appetite as their abdomens fill
with eggs. As with males, dehydration is always a
potential problem during this time. In addition, gravid
females need more calcium, which is used to build the
shells of the eggs.
(MBD) may develop in
gravid females, and extra calcium is recommended during
this time. Owners should offer their female iguanas small
amounts of salad with extra calcium and water-rich foods.
Another possibility is to offer a slurry of Ensure™ shakes mixed with fruit, veggies,
greens and extra calcium in a blender.
behavioral clue that a female is gravid is an increased
activity level and digging behavior. In the wild, females
build nests by digging tunnels and chambers in the soil,
in which they lay their eggs. Pet female iguanas will
often spend hours searching the house for a
&good& nesting spot, and will often dig at
walls, carpets, the floor, windows, and in potted plants.
Owners may facilitate the female's nesting desire by
providing a nesting box of some sort. There are many
designs for nesting boxes, ranging from simple to
complex, but a sturdy plastic box or laid-down garbage
can filled with sandbox sand and/or potting soil will
often do the trick. Be prepared to clean up a lot of dirt
as the female spends hours digging it out repeatedly onto
the floor! Some females will ignore nesting boxes, or dig
in them only to lay their eggs elsewhere, much to their
owners' frustration. It is probably a good idea to
provide one, just in case. The lack of a good nesting
spot can cause some females to withhold egg laying, with
dangerous consequences.
During Breeding Season: Egg-Laying Problems - Eventually, the time
will come for the female to lay her eggs. Below is a
photo of Hopper laying an egg (left) and a batch of
iguana eggs after laying (right). For more neat photos of egg laying, visit Vegas$' web site, listed at the bottom of this page.
all has gone well, female iguanas will lay their eggs
continuously one after the other all at one time until
they are done. If you see one or a few eggs scattered
around throughout a period of hours or days, your female
may be egg-bound, which means that her eggs are not able
to properly exit her body. Other signs that a female is
egg-bound include lethargy and straining. If you suspect
that your female is egg-bound, get her to the vet
immediately. This condition is fatal if not treated. The
treatment for egg-binding is to spay the female, which
involves the removal of both the ovaries and any eggs
present. Some owners of female iguanas chose to have
their healthy females spayed to avoid later
complications. Although this procedure is easier and more
common than neutering males, it should only be done by a
vet that is skilled and experienced in this procedure.
Spaying a female will eliminate the yearly gravid period,
although some spayed females exhibit behavioral signs of
&false pregnancies& during breeding season.
Below are some spay photos. The photo on the left is of Primrose.
After her period of gravidity, she experienced difficulties, and was spayed. Here you see the incision and stitches on her belly. She recovered well from her surgery.
The photo on the right shows developing eggs and ovaries removed from another female, Donnie, during her spay. (See photo of mating iguanas, above, to see Donnie pre-spay.)
This clutch, about 30 eggs, is rather small.
Females have been known to carry many more eggs than this.
The following photo shows eggs removed from Vega$ during her spay. If you look closely, you can see the membranes that hold the eggs together in the ovaries.
Some females will develop eggs,
exhibit decreased appetite and digging/searching
behavior, but then resorb the eggs into their bodies
before the egg shells develop. Owners of mature female
iguanas must be aware of the signs of gravidity and must
be on the lookout for such signs in their females. Gravid
females should be carefully monitored for any signs of
MBD or egg-binding.
For even more information on spaying iguanas, please read
Conclusion - As you can see, in
iguanas, neither sex is &easy care& - not only
in terms of reproductive behavior, but overall. Since
baby and juvenile iguanas are very hard to accurately
sex, new iguana owners must educate themselves about the
challenges presented by both sexes, so that they are
prepared when their iguana finally reaches maturity. If
you prefer one sex over the other, you may consider
adopting a mature iguana from your local shelter. There
are many out there that need good homes, and at least you
will know what to expect!
Vega$ - A Beachy Kind of Ig
by Desiree Wong, contains great photos of egg laying.
by Henry Lizardlover is an excellent article on iguana aggression, including some very good photos of what kind of damage an aggressive iguana can do to a person.
Breeding and Reproduction section of Melissa Kaplan's web site
- great information here.
- An excellent article written by Doug Mader, DVM, for Reptiles Magazine.}