What to Expect When You’re Expecting: Egg Care – July 2013

By Erin Lane

What to Expect

In the May issue of the Reptile Times we discussed maternal care of gravid bearded dragons, from conception to laying.  With any luck, your breeding endeavors have so far been fruitful, and you are preparing for a clutch of eggs.  While incubation requires the least amount of action on your part, it can in some ways be the most nail-biting aspect of breeding reptiles.  In this issue, we’ll try and relieve some of those worries by going over some tips and techniques that will help those of you first time dragon breeders.  Luckily, incubating beardie eggs is about as easy as using an Easy Bake Oven.  If you follow a few simple instructions, you should be on your way to whipping up a batch of dragons.

Egg Deposition

Cupping the clutch

A simple, yet important, aspect of incubation is what to put the eggs in.  A lot of it depends on the size of the clutch and the size of the incubator.  If you only have one dragon’s eggs to worry about, a smaller incubator and smaller containers are probably the easiest.  Deli cups—those with pre-punched holes—are readily available, and easy to use.  The 8 oz cups that come in the incubator specials (described later) are perfect for dragon eggs.  I have found that you can easily fit 5-6 into each deli cup.

Larger deli cups or other ventilated containers can also be used if you prefer to put all of your eggs in one container.  This is sometimes helpful if you have more than one female.  You can then put each clutch in its own container without having to worry about keeping track of multiple smaller cups.  Regardless of which type of receptacle you choose, remember that proper labeling is important.  It’s easy to forget the lay date even when you only have one dragon’s eggs to keep track of.  I always label the container (either with a makeshift sticky tag, or directly on the lid) as soon as I get done cupping the eggs. 

Happy medium

Last time we talked about preferred medium for egg laying.  If your female is getting ready to drop eggs, having the lay box set up ahead of time is a good idea.  Anything from vermiculite to organic potting soil can be used as a substrate for egg deposition.  However, what you put the eggs in after they are laid is a little more important.  Luckily, there are a few good and easy to use options.  If you are looking for a ‘no brainer’, Hatchrite is a great option.  This incubation bedding looks a lot like perlite, but has the advantage of being ready to go right out of the bag.  Unlike other egg incubation media, Hatchrite does not require you to add water, taking out a sometimes tricky step for a new breeder.  Simply add a couple of inches of Hatchrite to your egg container, place your eggs, and leave alone until they hatch.  I have had good results with this product, and would recommend it to anyone who is a little daunted by figuring out just how much water to add to a traditional egg substrate. 

 

Perlite will clump, but not drip, when water to media ratio is correct.  Make finger sized impressions in the medium.

Although Hatchrite is easy to use and reasonably priced, many breeders opt for more traditional media, such as vermiculite, perlite, or a mix of the two.  I have used both, and have found that they both work well.  Let’s start with vermiculite, as it is the established go to.  I have found that it works well when the water to vermiculite ratio is done right.  The usual advice is to combine 1 part water to 2 parts vermiculite.  However, I don’t think that this is always helpful, as a lot depends on the moisture content of your particular bag of vermiculite, as well as the size of the granules.  A good way to do it is to start by adding a small amount of water, mixing it in, and testing the result by seeing how well it sticks together.  Keep adding water in small quantities and mixing until you don’t have any dry sections that won’t clump.  You can then take a handful of the moist mix and squeeze it.  If more than a few drop come out, then it is probably too wet.  If you can’t squeeze any water out, you can probably add just a little bit more. 

The problem that I have run into with vermiculite is that the size of the granules can vary from batch to batch.  I have found that the more coarse, or larger, grains work better.  The finer grains tend to either get too wet or too dry.  A good egg substrate will hold onto moisture for a long period of time without being ‘wet.’  Too much water can ‘drown’ eggs and encourage mold growth, whereas too little water can lead to your eggs desiccating.  The larger grain vermiculite seems to absorb water better, and can then provide moisture for a longer period of time without being too wet. 

This year I went with perlite, and that has seemed to work well so far.  Yes, you still have to add water, but it seems to keep the humidity at a consistent level throughout incubation.  Mix it the same way you would vermiculite, keeping in mind that though it may not feel very wet or release much excess moisture when squeezed, it probably holds onto to more than the vermiculite does.  You can buy perlite at any plant nursery or garden center. 

 

Eggs can quickly go bad if kept too moist.

Regardless of the type of medium you use, remember that checking the substrate about once a week or every two weeks is probably a good idea, especially with your first clutch of the year.  Eggs can and do dry out, so too little moisture can be just as big of a problem as too much.  To avoid the too-wet-or-too-dry issue, I mix my substrate a little on the dry side, and then add small amounts of water to the substrate a few times throughout incubation.  I determine whether or not to add water by sticking my finger down into the corner of the substrate. 

If it feels bone dry, I gently add water with a pressure sprayer to the corners (if in a larger container) or around the edge and in between the eggs.  Avoid spraying the eggs directly, as you really don’t want them to be wet, but don’t stress if a little water does get on them.  You can always gently wipe it off with the corner of a rag or a paper towel.  Remember, it is easier to add water than it is to take it out.

Eggs that have gone bad can and will attract bugs quickly.

Placement parameters

The number of eggs you fit into your container is obviously dependent on the size of the cup or box.  As stated previously, you can decide what will work best for you.  However, how to actually go about placing the eggs in the medium can be a little confusing; different sources will tell you different things.  In my experience, whether you cover your eggs completely, or you rest them on top, they will probably all come out okay.  The easiest way, I have found, is to make an indentation of about ¾” with your index finger or thumb into the egg substrate, about ¾” apart from each other.  Place the eggs on their sides into each indentation, and leave them alone until they hatch.  Don’t worry about covering them up; just keep them about ½ way buried.  As the media dries and the eggs enlarge, they will often seem to unbury themselves.  You can go with this, or make new indentations when you add a little more water to the container. 

Many people will tell you that you need to be careful about how you place your eggs.  Many sources will say that you must place them in the same orientation that the mom laid them, and to not turn them over or you will kill the embryo—or it will drown, or die, or break it’s eventual yolk stalk.  From my experience with this species, this is relatively unimportant when moving newly laid eggs.  Eggs can be moved about and placed with little care as to up or down early on.  Because I now candle all of my eggs after being laid, I usually try and place each egg with the ‘pink spot’ up.  This pink or red spot is seen as a faint pink ring around a red dot, usually found on one of the long sides of the egg.  If you can’t see the pink circle through the shell, it can easily be seen when candled (as described below).  My advice would be to not worry so much about which side is up when they are first laid, but to be more gentle with them as they start to develop. 

After one week of incubation you can see veins beginning to develop.

Easy bake

There are a variety of incubators available, from the simple Hovabator to the advanced Exo Terra Reptile Incubator.  The incubator you choose should be dependent on a few things.  The first is size.  How many eggs are you expecting?  Do you have one lizard, or 5?  The smaller Hovabator incubator is fine for holding a few clutches at the same time, but if you are planning on more than that, it would be worth it to get a bigger incubator.  One advantage to the Hovabator is that you can order it as part of the incubator special, which gives you 5 deli cups and a bag of Hatchrite for a great price, meaning you don’t have to look around for what you need—it all comes together in one package. 

After three weeks, you can see the embryo and the network of veins in the egg.

The second consideration is the ambient temperature in your house.  Where you put your incubator becomes important here. Most incubators will only heat, not cool, meaning that your eggs can overheat more easily if kept in a room that gets hot.  If you put your incubator in the garage where the temperature can soar in the summer months, then you should probably go for the Exo Terra Reptile Incubator, which can both heat and cool to maintain the desired temp.

The third thing to think about when purchasing an incubator is ease of operation.  How much monitoring do you want to do to maintain the proper temperature?  If you plan on placing your incubator in a room where the temperature doesn’t fluctuate much, and it stays in the 70’s most of the time, then you won’t have much to worry about regardless of which one you choose.  However, if you don’t have that luxury, a higher end incubator is probably going to make the process a little easier.  While the Hovabators are effective and easy to use, you have to monitor the temperature and adjust the thermostat accordingly.  The Zoo Med ReptiBator Digital Incubator and the Exo Terra Reptile Incubator are both programmable, meaning that you set the temperature, and they will adjust to keep it stable, even when the room temperature drops or rises.  The Zoo Med ReptiBator is a good middle ground for ease of use.  While it doesn’t have a cooling mechanism to keep things from getting too warm, it otherwise gives more temperature control and also comes equipped with a humidity gauge. 

Egg in the final days before hatching

Tools of the trade

Even when using a higher end incubator, it never hurts to have a second thermometer on board.  I use the Zoo Med Digital Thermometer (with probe) in my incubator to watch the temperature.  This is especially useful if you have an Hovabator, so that you don’t have to open the lid to check the temp.  You just insert the probe into one of the ventilation holes, and keep the unit resting on top of the incubator.

Another consideration is to use an external thermostat in your incubator.  If you already have an Hovabator or equivalent, which lacks the more precise temperature control of the higher end models, you can always set up an external thermostat to control the temp.  This is really more of a safe guard as the Hovabators usually work well as is, assuming that you keep them in a room with a moderately stable temperature.  This isn’t necessarily more beneficial from a cost perspective, but simply another way to go about regulating the temperature for your eggs.

Egg just beginning to dimple before hatching

Temps and times

Dragon eggs are fairly easy to incubate in that they can withstand a fair amount of range when it comes to temperature.  I always shoot for 84 F throughout incubation, but slightly lower or higher temps have resulted in perfectly healthy hatchlings.  There is some anecdotal evidence that eggs incubated at room temperature and those incubated hot (let’s say around 90 F and above) result in lower hatch rates and, sometimes, weak babies.  I have always incubated mine in the low to mid 80s with success, so have not strayed from that recipe yet. 

Clutch of eggs hatchinh

Just like when you are baking a cake, the temperature of your oven will determine how long you need to keep it in.  If your incubator is set to 85 F, your eggs will likely hatch faster than those set at 81 F.  A few degrees can make a difference of a week or more in some cases.  If you are incubating in the mid 80s, you can probably expect your eggs to hatch between 60 and 70 days, plus or minus a week.  Last year, at a relatively steady 84 F, my clutches went an average of 72 days before hatching.  A good idea is to start checking for hatchlings every day starting at around day 50 or 55.  While babies can stay in the incubator (and is often a good practice) for a day or two, you will want to be on top of it, and keep track of when they hatch.

Proof in the pudding

All of this information is helpful only if you have a healthy clutch of fertilized eggs.  It is possible for unmated females to lay unfertilized eggs, just as it is possible for seemingly healthy mated females to lay bad ones.  You never know until they are laid, and even then, you might have to wait and see.  I have incubated fresh, seemingly good eggs only to have them go bad sometime during the incubation process.  It can be heartbreaking, but these things do unfortunately happen.  Even when you have done everything right, you can still wind up with eggs that don’t make it.  Remember, in the wild, hatch rates are likely significantly lower than in captivity—not all eggs (or hatchlings) are destined to make it.  That’s why females lay multiple eggs, and usually multiple clutches. 

There are a few things that you can do to determine if your eggs are good, and even worth incubating.  Let me start by saying that I am incredibly optimistic when it comes to bad eggs.  Even when I suspect an egg will not make it, I will give it a chance until it is extremely evident that it’s no good.  This is especially true for newly laid eggs.  You will often times have one or two that aren’t plump and seem to be lacking filling.  Bearded dragon eggs, like those of manyreptiles, have a soft shell, which is designed to swell as the egg absorbs moisture from its surroundings, and as the embryo grows.  A ‘squishy’ egg will sometimes plump up after a day or two in moist incubation bedding, so I would always give it a chance—you might be surprised.  

Egg that has just pipped

Shell texture can also tell you a lot about whether or not an egg is good.  A good egg will typically not only feel plump between your fingers, but will have a relatively smooth dry feel to it (a reasonable time after being laid, that is).  If the egg feels slimy or slick more than an hour after being laid, chances are it’s not good.  The exact reason for this is unclear to me, but it probably has to do with the calcification process.  Females often expel underdeveloped eggs when conditions aren’t right (e.g. they are not fertilized, the female has an underlying infection, or she is young).  It is sometimes unclear what causes this to happen, but when it does, it never hurts to give the eggs a chance. 

Egg color can also be a giveaway that something isn’t quite right.  Eggs that appear very yellow usually aren’t good.  This can also be a sign that they have dried out.  Mold can also  be a sign that the egg is bad, though not in all cases.  Although I am loathe to throw out an otherwise good looking egg just because of a little mildew spot, an egg that is covered in it probably has something wrong with it.  I would recommend not throwing the egg out unless it starts to collapse.  While eggs will start to dimple just prior to hatching, or collapse when too dry, a bad egg will often collapse when others around it look fine.  Mold is usually the first sign that there is a problem with the egg, but it may also be that you are keeping the substrate too wet.  If this happens, try drying things out a bit, and see if it clears up.  If it doesn’t, but it otherwise looks okay, leave it alone—it might come out just fine.  That being said, the shell of a healthy egg should be mostly white.  You can sometimes see a pink spot or circle where the egg is beginning to vascularize, and the embryo is developing.  Healthy eggs will also usually have a soft pink glow when a light is placed next to them. 

The same egg a few minutes later – you can see the slit where the baby will emerge! 

If you have given a bad egg a shot, or a good egg has gone bad, it is best to remove it from the incubator sooner rather than later.  They can go from a little ugly to really bad in a hurry, which will attract insects or provide an opportunity for mold to grow.  Although a bad egg will usually not impact the healthy eggs around it, it is better not to let it go.  If you have an egg that you suspect isn’t going to make it, check on it every couple of days, or move it to its own container.

Hold a candle up

I have found that candling the eggs is a fun and fascinating way to pass the time until they hatch.  While I don’t recommend doing this every day, candling an egg or two from the clutch once a week doesn’t seem to cause any harm.  Again, you will read that doing so can kill the embryo, and to not candle any egg that is within a few weeks of hatching.  I disagree with this, though I will say to be gentle and proceed with caution in the later stages of incubation. 

The baby beardie emerging.

When candling, any small flashlight should do.  LED lights might be a better option since they put out bright light without much heat.  Gently hold the egg by its ends, and hold over the flashlight.  Early in development you will see the egg begin to vascularize, and the tiny embryo begin to grow.  As the embryo develops it will be harder to see what is going on in there since its body will obscure much of the light.  A few weeks out from hatching, you can often see the shadow of a tail along the side if the egg, and notice small movements.  When handling eggs this far along, I would here say that placing it back in the same position may be more important.  Will it kill the embryo to place it upside down? Probably not, but sometimes it’s best to be a little cautious. 

Time’s up

When your eggs finally get ready to hatch, you may notice a few things start to change in their appearance and turgidity.  Eggs will often start to dimple when hatching is imminent, so don’t be too concerned if this happens.  However, they do not always dimple.  I have found that when kept a little more humid, dragon eggs will often not dimple at all.  You may also notice that the eggs start to ‘sweat.’  If this is happening before you are expecting your first hatchlings, then you may need to dry things out a little by keeping the lid off of the egg container for a day.  However, if you notice this on late-term eggs, you can probably expect them to pip within a day.

Eggs that are about to hatch will also get a little softer feeling, almost as if they are full of water.  Again, be gentle with eggs that are about to hatch.  While beardies are pretty sturdy, it is probably better to be careful.  Once the egg has pipped, the egg will look deflated.  If you wait a few minutes, you might even see a little snout poke out of the end!  Once they start to hatch, leave them alone, and let them do the work.  You aren’t doing the hatchling any favors by pulling it out of the egg the rest of the way.  It will come out when it’s ready.  Neonates can stay partially in the egg for up to 24 hours as they finish absorbing the last bit of yolk.  Leave them alone, and only take them out of the incubator when they are moving around on their own. 

The next phase

Breeding reptiles can be fun, though there are often unforeseeable challenges.  Bearded dragons are an extremely rewarding pet, and have the added advantage of being easy to breed in captivity.  Whether you planned on eggs, or had a surprise, incubation can be a simple process with the right tools and a little patience.  In many ways, it is like baking a cake.  When you start with healthy, fertilized eggs, and follow the basic recipe, you will usually end up with a rewarding end product.  In other words, when set up properly, there is every reason to look forward to a good hatch rate and lots of mouths to feed in the near future.  Next month we will go over tricks and tips to taking care of those little mouths, from feeding and watering to lighting and housing. 

What to Expect When You’re Expecting: Care of Gravid Bearded Dragons – May 2013

By Erin Lane

What to expect

While there are a plethora of guide books for expecting parents, there are a scant few that give detailed information on how to care for your gravid reptile pet.  Although many are quite happy never delving into the world of breeding, others find themselves, sometimes unexpectedly, prepping for eggs and babies.  Many care books have a short chapter on breeding, but few give up many secrets that can help you to figure things out when they don’t go according to plan.  Over the next few issues we will be discussing the ins and outs of breeding bearded dragons, from conception to hatchling care. My hope is to provide some tips and information that I have picked up over the years, and would have found helpful my first time out with my own breeding endeavors.  In this issue we will start with the basics: how to prepare your female for breeding season, and how to care for her once she becomes gravid.

Female Translucent Bearded Dragon Basking

Being responsible

Any discussion on breeding should at some point address the importance of being a responsible pet owner.   My assumption is that anyone reading this article is not in need of this section, but it never hurts to review the basics.  So, let’s quickly cover the bases!  An obvious point to make here is that the health of the female is the most important aspect in the breeding equation.  If your female beardie is underweight, lacks proper lighting, nutrition, or supplementation, breeding should be out of the question.  Make sure that you are providing optimal care for your animal before you consider breeding.

Dragons are hardy animals, and will often trudge along for years with suboptimal care.  Just because your animal eats when offered food, basks under its heat lamp, or sits calmly on your shoulder doesn’t mean that it is in good breeding condition.  Before introducing a male, make sure that your enclosure is an adequate size, you have ample visual barriers and basking space, and that your female has good body weight.  We sometimes have the tendency to overfeed our animals, often creating numerous health issues in the process that can greatly shorten the life of our pets.  A little thin isn’t always a bad thing when it comes to beardies.  However, I think it better in some cases to have a little extra body weight than not quite enough.  The best way to check is by looking at the base of the tail.  If the pelvic girdle, or hips, are showing, your animal is probably underweight for breeding.

Female Bearded Dragons enjoying some calcium dusted mealworms!

Counting the calories

Preparing your healthy female bearded dragon for breeding season can mean little more than a few extra feedings a week and more attention to calcium.  While some species require a realbrumation, beardies do not seem to need a cooling off period in order to breed.  From personal experience, females can be kept awake all winter and go on to produce multiple fertile clutches the next season.  In this case, preparing her for gravidity (reptile version of pregnancy) can start as early as late winter.

When it comes to nutrition, the more varied the diet, the better.  A beardie can do just fine on a diet of gut loaded crickets and greens, but I have found that my animals do best when supplied with one that includes a wide variety of protein and vegetable sources.  Some authors will warn against feeding rodents to dragons, as those that get a diet high in fatty pinky mice tend to become obese.  In moderation, mouse pups can be an extremely nutritious addition to your lizard’s menu.  As my females gear up for breeding, I generally increase the number of rodents in the diet to between 2 and 3 fuzzy mice a week.  Though this may be too much protein and fat for a bearded dragon during most of the year, a breeding female will need all the calories she can get before long.  A heavier feeding routine should start as early as 4-6 weeks prior to pairing her with a male.  I continue to provide a relatively heavy offering of mouse pups until the end of breeding season, especially right after the female lays.

Adding rodents to the diet is a good way to add a lot of calories to a meal, but don’t neglect insects.  Dubia roaches are becoming increasingly popular these days as they are easy to breed and offer a great ‘flesh’ to exoskeleton ration in comparison to crickets.  If you can get over any lingering fears of cockroaches, I highly recommend them as a staple.  Superwormsand mealworms are also great sources of protein, with the former being a real favorite among my pets.  Superworms also offer a lot of meat, and I have found that, unlike mealworms, you can generally feed them in small quantities to young dragons.  But remember—regardless of the type of feeder, you MUST gutload.  Neglecting the feeders is a rookie mistake that can have a big impact on your animal, and subsequently, your breeding success.

Greens are also important as they offer moisture, vitamins, and minerals into the diet. Supplementing is always stressed, and you should do so for a number of reasons.  However, a nutrient found in a whole food is better than a nutrient you get in a jar in almost all circumstances.  A diet that includes a wide variety of veggies (mostly dark leafy greens) is best.  I try and provide a wide range of greens for my dragons, but I am careful to also include a good general supplement, such as Repashy Calcium Plus.  This has worked great for my dragons, which are housed indoors during the winter.

Bearded Dragon getting a drink in the shower

A quick note on hydration

When your dragon is gravid, don’t neglect hydration.  Bearded dragons can go a long time without drinking, but usually take advantage of a good soak when offered.  I try and water my dragons once a week as a rule, but this is especially important for expecting moms.  Make sure to provide water once a week, and perhaps even every other day when she is getting ready to lay.

Although she may not need it, it won’t hurt to offer.  I have seen gravid beardies go from looking a little heavy in the belly to looking full of marbles in less than a day after getting a much needed soak.  This is especially important once she is finished laying.  As soon as one of my females is done in the lay box, I put her in the shower, and leave the water on until she stops drinking.  She will be surprisingly thirsty—and no wonder!

You may be wondering about a water bowl… Though I have seen some dragons drink from a water bowl, many beardies will simply ignore it.   A great way to hydrate your pet is to set them in the tub in shallow luke warm water, or to turn the shower on.  Try to avoid water levels that force your animal to float or swim.  While they can do it, they don’t seem to enjoy it.  Either a shower or shallow water is best.

The lay box

There are some really easy ways to set up a lay box for your beardie.  As long as you have (only) slightly moist substrate, deep enough for her to dig in, placed in a warm private spot, you should be good to go.  There are some that will insist that you set up a lay box outside of her enclosure.  While that works for the majority of dragons, don’t be afraid to set up one inside of the tank if she seems reluctant to lay in a new environment.  Though I typically use a separate lay box, I have had no issues arise from making up an area inside of the cage.  Just keep in mind that you will want to collect the eggs pretty quickly to avoid desiccation or disturbance.  Either way, the principles are the same.

Laying Box with organic potting soil

I like to use organic potting soil as a laying substrate, though a coconut husk product, such asExo Terra Plantation Soil or Zoo Med Eco Earth work well.  Vermiculite can also be used, and is very easy to wipe off of the eggs once you retrieve them.  While any of these substrates works well, it’s important to make sure that it is not bone dry or too wet.  If too dry, it’s harder for her to dig a tunnel.  If too wet, the eggs will be ruined by sitting in water at the bottom of the box.  Add water in small quantities, mixing it into the substrate, until you can make a hole about the size of your hand without it falling in on itself. Make sure to check the temp in the box.  Too hot or too cold can cause problems.  You don’t need to provide a hot basking spot, but upper 70’s or mid 80’s ambient is probably good.

As stated above, you can really set this up anywhere.  I use a large plastic tub, filled with about 16-18” of substrate.  Although they can work with less, I would recommend at least a foot of substrate.  She will probably scratch at the bottom of the tub for a while, trying to dig deeper.  Eventually, she will leave off, turn around, and deposit her eggs.

Bearded Dragon in the middle of laying eggs.

Knowing when

It is sometimes hard to time things out, as you rarely see the actual copulation.  A good guideline is to start looking for signs that your female is gravid between 5 and 6 weeks after pairing her with the male.  A month and a half is generally what I have found to be the time between mating and laying in this species.  Best practices would be to observe her behavior and body condition on a daily basis, and be prepared with a lay box ahead of time.

With some females, it is easy to tell when they are going to lay.  They spend a few days digging or scratching in the substrate, they seem antsy, undeterrable.  They are also chocked full of eggs, which make it look like they’ve swallowed a bag of marbles.  At this point, you can start introducing her to the lay box.  Leave her alone, and check on her after an hour or so.  If she hasn’t started to dig, place her back in her home cage—she probably isn’t ready yet.probably isn’t ready yet. An important note: not all females are visibly
gravid!  Although uncommon, some females will have no palpable eggs, and go on the next day to lay a normal clutch. If your female has been with a male, and she is showing other signs, treat her as if she is gravid.

Once she has deposited her eggs, she will begin to bury them.  I have found, through trial and error, that it is probably best to let her finish burying the eggs before you take her out of the box.  At that point, they are running on a program that won’t let them stop until they have dug, laid, and buried.  If you remove a female too soon, she will often continue to pace and scratch.  Leave her in the box until she seems to have stopped—which usually means there is no sign of where she made her burrow.  After, throw her right into the shower for a good soak, and then back to her quiet home cage. If at all possible, house her by herself for at least a week to give her a chance to rest and recover.  If she must go back to group housing, make sure to check on her daily, and provide extra food just for her.

After she has laid, don’t be surprised if another clutch is on its heels in 4-6 weeks.  Even if you have separated the male at this point, a female can, and usually does, continue to lay throughout the season.  Like many other animals, bearded dragons can store sperm in their reproductive tract that can be used to fertilize multiple clutches throughout a season.  My first female laid three consecutive clutches one summer after being bred one time by my male.  So, if you have one clutch, be prepared for more.

Bearded Dragon depositing a healthy clutch of eggs!

The Language of Love: Breeding Behavior in Reptiles and Amphibians – April 2013

By Erin Lane

Part III: Visual Virtuosos

It is finally that time of year—the days are getting longer, the weather is milder, and your herps are just starting to wake up from brumation.  Spring is in the air, and reptiles and amphibians are responding accordingly.  This is perhaps the most exciting time for reptile and amphibian keepers as it is when many of our pets begin to show the most interesting and diverse behaviors.  For some species, breeding season is well underway.  Over the past couple of months we have discussed how herps use auditory and chemical communication to find and attract mates.  This month we will be wrapping up our talks with perhaps the most evident form of reptile behavior—visual communication.

Visual communication is perhaps one of the most interesting forms as it takes advantage of our own primary sensory system. What makes it particularly enjoyable to watch is that it is an extremely diverse mode, which can range from push ups and head bobs to flashes of intense color.  Previously we discussed how many frogs and toads use auditory communication to attract mates, and that others take advantage of chemical cues to sniff out a good mate.  When it comes to visual communication, lizards reign supreme.

The unique eyes of a young male Jackson’s Chameleon!

The right kind of attention

The way to get attention for most lizards is to be visible to conspecifics (animals of the same species).  Unlike anurans (frogs and toads), very few lizards vocalize, and most that do typically reserve it for when they are threatened.  And, while some lizards also use chemical signals to communicate, these appear to be secondary to visual signals.  For a lizard, it’s all about the show!

Almost every reptile enthusiast can conjure a picture of a lizard doing pushups on a rock, or a bearded dragon head bobbing.  Lizard visual displays are often eye catching and rhythmic in nature.  One problem that lizards run into is one that most small animals have to worry about—when you make yourself visible, you run the risk of predation.  There is often a fine line between being visible enough to attract attention from conspecifics without drawing attention from predators.  In many cases, caution is thrown to the wind in favor of attracting a mate.

An agama in the wild displaying brilliant colors intending to attract a mate!

Peacocks are a perfect example of this phenomenon.  While these birds have been bred in captivity for centuries, their true wild form is not much different from those you might see at a park.  With their overly long tail feathers, bright colors, and larger than life display, they stand out in almost any environment.  In addition, those beautiful tails also make quick movement and flying more cumbersome.  While peafowl may be good enough at escaping a human, they are a much easier target for their wild predators.  However, it is exactly these traits that make males so attractive to females.  A number of studies have shown that females (peahens) are more likely to breed with makes whose trains have certain qualities, such as those that are longer or have more eye spots1.  Sometimes safety is sacrificed in order to gain access to reproductive partners, and in many cases it pays off.  After all, the success of an animal is not measured in its longevity, health, or looks, except how these relate to the number of offspring they produce, that in turn live long enough to reproduce themselves.

Capitalizing on calisthenics

Reptiles are no exception to the rule.  Attracting a mate is of upmost importance, but you still have to be careful about not attracting predators.  One way around this dilemma is to produce signals that are only visible to conspecifics.  For lizards, this usually means signals that are highly visible to other animals on the same horizontal plane, but less visible to aerial predators a primary concern for most small lizards).  The push up is a great example of this.

Many lizards, such as sceloporus species (e.g. fence lizards and spiny lizards), common out here in Southern California, can be seen doing pushup displays on any high point in the terrain (usually a rock or boulder).  The movement is easily seen by us human onlookers, and is also visible to other nearby lizards that are likely keeping an eye on their neighbors.  However, if seen from above, this is not a display that creates a lot of visual commotion.  While movement of any kind is a risk, the type of movement can make all the difference.  A display that is highly visible to conspecifics, but not particularly visible to predators is a great form of communication.

But back to the point—how do visual signals, such as a push up, relate to breeding behavior?  Like the peacock, it’s all about getting attention.  Many signals can communicate the same thing to both sexes, but with very different outcomes.  For example, a male bearded dragon that performs a lot of head bobs may be communicating his dominance, ownership of a territory, his energy reserves, or a combination of all three.  To other males, this may be sign that they should stay away.  After all, if the displaying male is confident enough to display himself prominently, he has likely had to fight for that position, and may be a formidable opponent.  He must also have lots of energy reserves to continually display, meaning that he may also have lots of energy for fighting as well.

Lateral Compression in a Fence Lizard

While a push up might signal health and dominance to an onlooker, this may have a very different effect on females.  To a female, these traits communicate that a particular male has good genes to pass on to his offspring.  And remember—at its most basic level, life is about reproduction.  Signals that show off a male’s ability to survive, thrive, and produce hardy offspring may have the dual purpose of reinforcing a male’s status while also attracting females.

Color me pretty

While displays of physical ability are common forms of communication among lizards, it is perhaps overshadowed by the incredible array of color exhibited by these squamates.

Unlike most mammals, many lizards see in wide range of colors.  As humans, we have three different color receptors in our eyes that through combination (and your brain’s interpretation) give us the standard rainbow colors, and all those in between.  Most other mammals see the world with comparably limited color.  Your dog and cat, for example, can see blue, but lack the receptors to see red and green.  Some animals see in shades of black, white, and gray.  While it is impossible to make a blanket statement about reptile color vision, we can say that some species possess a highly evolved visual system that allows them to see color the same way, and in some cases even better than, the way we humans do.

From the black beard of a bearded dragon to the myriad colors exhibited by chameleons, color display is perhaps visual communication at its most interesting.  Like physical displays, color is usually an excellent communicator of health and good genetics.  More or more vibrant color has been linked to a number of other fitness indicators across different species, including an animal’s size2, fighting ability3, the amount of courtship a male performs4, body condition5, and even parasite load6, 7.  All of these qualities can contribute to a healthy individual that is bothnot worth fighting, and probably worth mating with.  Color is a way to communicate fitness without putting much physical effort into it.

Male Beardie with dark beard

Color is also used to enhance other displays, making them more visible to conspecifics.  Think of a male bearded dragon head bobbing on his perch.  The dark black beard makes that head and the motion more visible, further emphasizing the overall display.  A fence lizard’s defensive and aggressive displays also utilize color and position.  When the body is laterally compressed (sides pressed flat), it emphasizes the blue ventral (tummy) color that gives them the colloquial name of “blue belly” lizard.  Flashing some color when you need to may help dissuade an aggressor.

Although many males exploit color for communication, they are not the only ones.  Females of many species also use color to communicate.  One example is the color changes that some female lizards undergo when gravid.  What is the first sign that a female chameleon is gravid?  Her color changes—and it is not limited to chameleons.  Many female lizards change color to indicate that they are no longer receptive to a male’s advances.  This saves the male wastedtime courting a female he cannot impregnate, and the female is saved the hassle of prolonged male harassment.

In conclusion

Animals have a number of ways that they communicate with one another.  For some, auditory communication is preferred, for others, chemical cues are of upmost importance.  For many lizards, visual communication is perhaps the most widely used.  From pushups to head bobs, flashy agamas to gravid chameleons, visual signals are some of the most interesting.  They can often communicate incredibly important information to conspecifics, sometimes with no immediate effort at all.  So next time your anole flashes his dewlap, your bearded dragon head bobs, or your chameleon changes color, give ‘em a nod back.

REFERENCES
1) Loyau et al. (2005)
2) Vásquez & Pfennig (2007)
3) McElroy et al. (2007)
4) Sorenson & Derrickson (1994)
5) Elder & Friedl (2010)
6) Mougeot et al. (2009)
7) Václav et al. (2007)