Breeder's Spotlight: Breeding Fire Skinks
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Breeding the Fire Skink
By Jennifer Greene
Step one: Breeding
In writing this article, I will be making the basic assumption that you, the fire skink keeper, are already familiar with the care and husbandry of successfully maintaining your fire skinks. Breeding is the natural next step in husbandry once you have successfully established your pair or group of skinks. Sexing Fire Skinks is at best an exercise in educated guesswork, especially if you have young or lean skinks. Most skinks available at pet stores are not old enough or established enough to develop the very subtle characteristics that allow for an attempt to be made at sexing them. For this reason, I highly recommend feeding your skinks well for at least a month before attempting to guess at the gender of your pets, as all fire skinks generally look like females when they are first acquired. Females are slightly more slender in the head and body than males, and lack in anything resembling hemipenal bulges. Males have a slightly broader head and are built a little more “beefy” than females of a similar size and age, and develop very slight jowls with age. When mature, breeding adults are compared side by side, a careful eye can distinguish the genders, but even an experienced keeper can find it difficult to accurately sex fire skinks.
Feeding your skinks well will result in a healthy, robust pair that breed easily and often. My adults feed on large crickets, superworms, giant mealworms, dubia roaches, hissing cockroaches, and pinky mice once the female has laid eggs. They also eat canned insects with gusto, with canned caterpillars being a particular favorite of my pair. I emphasize again that a good diet is a major part of successfully breeding your skinks and getting multiple, fertile clutches. Healthy, well fed skinks can and will lay between 3 and 5 clutches of eggs a year without any problems whatsoever. However, a malnourished or underfed skink may experience egg binding, parasite blooms, or crash from lack of calcium or other nutrients used to make her eggs.
Alright, so your skinks are eating a varied diet and are as fat and chunky as the ones you see pictured here. Great! They will take care of the rest. You may not see actual copulation, but it will take place without any encouragement from you as long as temperatures are warm enough. Fire skinks tend to breed whenever ambient temperatures stay above 75, and daylight hours last longer than 12 hours. This means their breeding season starts in the early spring, and can last until mid-autumn. Females are capable of retaining sperm, although they do not seem to lay more than one clutch when they do so.
Step Two: The Gravid Female
Once your skinks are breeding, and your female is starting to look even plumper than before, it’s time to make sure you are diligent about keeping up on a nice, varied diet and providing her with adequate supplementation. Your female skink may appreciate a slightly warmer basking area if yours is typically only about 85 to 90 degrees. When my skinks are breeding, I offer them a basking zone with the warmest area reaching temperatures of about 95 degrees. The female will seek out the warmer temperatures to grow and develop the eggs within her, and this also helps to ensure her appetite stays up – she’ll need lots of food to grow all the eggs she’ll be laying!
Fortunately for the fire skink keeper, care for gravid females is not much more difficult or different than for non-gravid females. More care needs to be given to ensuring that she is eating a rich diet that is well supplemented, but for the most part she will take care of her needs on her own.
Part Three: Egg Deposition and Incubation
After about 30 days, the female will look fat enough to burst, and at this point her appetite is likely to be next to nothing. She’ll start digging and exploring throughout her cage for a suitable place to lay her eggs, and it’s at this time that you need to pay close attention to the cage to make sure you catch when she lays her eggs. You’re extremely unlikely to actually see her laying the eggs, as they are very secretive about it, but you should be able to notice when she has suddenly lost a significant amount of weight.
Once you notice that the female seems to have abruptly lost half her body weight, carefully dig through the cage to find the eggs. They have excellent taste in nesting sites, and will select a nice moist (but not wet) area to lay their eggs in. Most often, mine laid their eggs under their water bowl or under cork rounds on the humid side of the cage.
Clutches range in size from 3 to 6 eggs on average, with clutches of up to 9 eggs not being uncommon. If you maintain your cage well with bioactive substrate (see The Art of Snake Keeping for information about bioactive substrates), you can actually leave the eggs in the cage until they hatch. I did this the first time entirely by accident, not realizing my skinks had already begun laying eggs – the first set of babies were a very pleasant surprise! Adults can and will cannibalize the offspring, so do not leave them in the cage once they hatch.
To incubate your eggs in a somewhat more professional manner, remove them carefully from the substrate once you have found them. Marking a dot on them with a permanent marker can help you ensure you keep them oriented upright in the position they were laid. From there, place them in your preferred incubation medium. I use Hatchrite, as it’s a nice, clean looking material that holds moisture well, comes pre-mixed, and I’ve had good success with it. I keep my clutches in the incubator in 4.5” deli cups with lids, and write the date I found the clutch on the lid. Bury them about halfway into the incubation material, and then leave them for as long as it takes to hatch!
When incubated at 84 degrees, most clutches hatch at 55 to 65 days after being laid. I leave the babies in the cup until they’ve all hatched. While I have not seen a study on fire skinks in particular, I know for other species of lizards it has been shown that the activity of the first babies to hatch climbing over the eggs of their unhatched siblings encourages the babies still within their eggs to hatch. It does not hurt them to remain in the incubation cup for a day or two while their siblings hatch, so leave them in the cup and let them do their thing!
Part Four: Caring for Neonates
Set up the new hatchlings in a cage similar to the adults, just on a smaller scale. My adults are in a 36” x 18” x 24” terrarium, and I raise babies in a 36” x 12” x 12” terrarium. I provide my babies with a 100 watt powersun to bask under, which results in healthy, fast growing and chunky little babies. Humidity is important for babies, and I highly recommend providing them with a thick layer of substrate you can easily add moisture to. I often pour water directly into the substrate, especially directly under the heat light, to ensure that the babies are able to burrow at the moisture level they prefer.
Diet for babies is simple to start with, as there are not many prey items small enough for hatchling fire skinks. Small crickets 1/8” of an inch to ¼” of an inch are small enough for them, and once they are a couple weeks old they are usually big enough to start eating regular sized mealworms as well. Waxworms can also be added to their diet, which can help keep them full if you notice your babies are nipping at each other’s tails. Hungry babies will consume the tails of their clutchmates, and the easiest way to prevent tail nipping is to simply keep them fed! I always leave a dish of regular mealworms out for my hatchlings, and offer 5 to 10 small crickets per baby every other day. On this regime, your hatchlings will be large enough to go to a new home within the first month!