Readers’ Questions Answered: Breeding Basics

It’s that time of year again for most geckos –breeding season.  Each season brings geckos new to the breeding experience as well as keepers new to breeding them.   This month’s Readers’ Questions Answered features some basic questions about aspects of the breeding process.  Although the first question is specific to leopard geckos, the other question could apply to any gecko species.

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Question 1:

What is the right weight and time to breed Leo’s?

Vanessa Lane responds: The general rule of thumb for breeding leopard geckos is to wait until your geckos are at least a year old and above 60 grams.  (Some people use a 50 gram minimum, but I prefer to play it safe with 60 grams). However, 60 grams may be underweight for a big female.  For example, some of the giant line females can get to be over 100 grams, and giant geckos at 60 grams are definitely not breeding material.  No rule of thumb can trump your own knowledge of  your gecko’s health.  Weigh your geckos frequently from when you hatch or purchase them, and learn what the right weight is for your gecko.  Not only will this help you determine if your geckos are in good condition for breeding, but you can also monitor weight loss during egg laying so you know how much weight your female needs to gain before you can breed her again.
Breeding females too young or underweight can cause a variety of problems for the geckos themselves, including calcium imbalances, extreme loss of weight, and shortened life spans.  But those aren’t the only problems you could encounter.  Female geckos that are physiologically stressed due to poor body condition or young age will have fewer clutches, more single egg clutches, and any fertile eggs that are actually laid may not go full term.  Egg production is the most energetically demanding part of a reptile’s life, so it’s critical that your gecko is in peak condition before you breed it.   One of the worst things you can do to your gecko is make it breed prematurely.  If in doubt, wait until next year.  Remember that good things come to those who wait.

Melissa Borden responds: From my recent experiece 55-60 grams is a good weight. My Leo seemed to lose about 5-10 grams during the laying process once she got off food, but she still looked good after the eggs were laid.

Aliza Arzt responds:  Although in general it’s best to breed a heavier, older gecko, at a minimum I will breed a leopard gecko who is at least 9 months old and at least 50 grams.  All male and female breeders should be in good health with fat tails.  You also ask about the right “time” for breeding.  Leopard geckos in captivity can ovulate at any time of the year, but most leopard geckos in the northern hemisphere ovulate from early spring throught late summer.

 Question 2:

What are the best ways you can tell for sure if your leopard gecko is gravid besides trying to decipher what’s fecal material or eggs?

Vanessa Lane responds: Identifying a gravid leopard gecko is very easy.  Leopard geckos have very thin belly skin, and it’s possible to see ovulations, eggs, fat deposits, and even organs if you know what you’re looking at.
Learning how to hold your gecko so you can see her belly is a very important skill.  Handle your females frequently before the breeding season to get them accustomed to your touch.  The best way to check their bellies is to gently lift the geckos by the base of the tail.  Although leopard geckos can drop their tails if you’re not careful, a habituated gecko will tolerate this as long as her front legs are still touching the ground.  Carefully lift the gecko’s back legs up so you can see her belly.  Alternatively, you can hold your gecko over your head to peek through your fingers, or you can use your bathroom mirror to reflect the image of your gecko’s belly back to you.
Ovulations are easily recognizable as bright pink circles, occasionally outlined in white, around the mid- to back-section of your gecko’s belly.  Ovulations almost always occur in pairs, with one ovulation typically being bigger than the other.  In some heavily ovulating individuals, you can see up to 6 individual ovulations at the same time!  Ovulations do not imply that you will get eggs.  If not introduced to a male, most females will reabsorb the ovulations and not lay any eggs.
Eggs are even easier to identify.  They will appear as slowly growing white blobs on either side of your gecko’s midline.  The females will almost always be developing two eggs at once, although sometimes you may only see one egg.  Fecal material, on the other hand, will be smaller and darker, and almost always closer to the cloaca.

Melissa Borden responds: I find one way to  determine if the area in question is an egg or something else is to look for a pinkish color that surrounds the white area.  The pinkish color indicates that it is an egg.

Aliza Arzt responds: Eggs generally appear in any gecko as white spheres on either side of the middle abdomen.  However, the eggs are harder to visualize on some geckos.  I have never been able to see fecal matter while still in the gecko, but have gotten eggs confused with follicles from ovulation and fat pads.  The best advice to help determine whether or not the gecko is gravid is for the breeder to become familiar with the gecko’s appearance and behavior just before it lays eggs.  This can include digging, restlessness and in leopard geckos, a weight drop of as much as 10 grams just after laying.

Question 3:

I’m incubating eggs and some are starting to deflate.  How do I know whether or not they are any good?

Vanessa Lane responds: If in doubt, don’t take them out!  Eggs deflate for a variety of reasons, and the very first question you need to ask yourself is “how old are the eggs?”
Eggs that are deflating within 40 days of laying are probably dehydrated.  Add water to the bottom of your incubator to increase the relative humidity.  If the eggs still appear dimpled after 24 hours, lightly mist the incubation medium around the eggs, then seal them up in a small plastic container.  A common misconception is that eggs need constant ventilation.  In reality, eggs do not require daily ventilation if kept in a large enough container (~3” in diameter for a single clutch), and constant ventilation dries out the incubation medium faster.   Opening the container once a week allows fresh air in while preserving the humidity.
Sit back and wait.  You’ve done all you can. If the egg continues to deflate, try to add a little more water, but after that it’s up to the little hatchling to decide if it’s going to make it.  Sometimes eggs just don’t go full term.  If the egg starts to look really bad, place it in a separate container from the healthy egg, and keep it in the incubator.  Sometimes eggs I’m convinced are dead end up hatching just fine!  I generally don’t throw out bad eggs until well past their due date.
If the egg is older than 40 days, mist it lightly, then step back and wait.  Eggs that are about to hatch often become dimpled, and adding a little bit of moisture will ensure the shell doesn’t stick to your baby gecko.  With any luck, you’ll be a new gecko mom or dad in a few days!

Melissa Borden responds: You can always attempt to candle the eggs looking fora reddish or pinkish glow, or if the egg was further on in the incubation I would just leave the egg in the incubator until it starts to get icky and stinky (or until it hatches), just to be safe.

Aliza Arzt responds: I can’t add much more to what’s already been said.  I usually suggest incubating until it either “hatches or stinks”.  In general, it’s best to take a “whatever happens, happens” attitude about eggs in the incubator and to resist the temptation to handle or repeatedly candle them once they have been placed there. 

Authors

Melissa Borden is a Registered Nurse from Milwaukee WI.  She got her first Leos last summer and aquired an instant addiction to these beautiful and interesting reptiles.  This late winter is her first, and so far successful attempt at breeding.  She also is loved by 2 Long Coat Chihuahua’s, and is one of many people in the show breeding world who love to show off and educate the public on the misconceptions of this wonderful dog breed!
 
Vanessa Lane  is a PhD student in forestry at the University of Georgia.  
Although she primarily works with birds in her professional career,
reptiles and amphibians were her original love.  She began breeding
leopard geckos in 1999 and has since acquired a fascination with the
eyelid gecko group.