Red-Eyed Crocodile Skink (Tribolonotus gracilis) Caresheet
by Casandra McKee
Adult Male Tribolonotus
© Casandra McKee
Red-Eyed Crocodile SkinkAliases:
The Red-Eyed Crocodile Skink has a number of aliases and may be called an Orange-Eyed Crocodile Skink, Red-Eyed Bush Crocodile Skink, Armored Skink or Helmeted Skink.
The Red-Eyed Crocodile Skink is a species of terrestrial, semi-aquatic skink native to New Guinea and the surrounding islands of Indonesia and Solomon Islands. There are eight recognized sub-species in the genus, however, Tribolonotus gracilis are the most common sub-species found in captivity. This type is often found in lush, tropical forests and humid, wooded areas near water. A shy, crepuscular species, they are most active at dawn and dusk, and spend the rest of their time burrowed or well-hidden under leaf litter or in hides. Tribolonotus (“Tribbies”) are one of the few species of lizards that vocalize when in distress, and when startled, are known to freeze and/or play dead. Unknown in captive collections until about 1994, there is still much to be discovered about this mysterious little skink.
Crocodile skinks are about 2.5 inches long at birth, and average about 8 to 10 inches in length (or 20 to 25cm) from nose to tip of the tail as adults. They have an average adult weight of 38-45g. Hatchlings and juveniles are a dark brownish-black with variable amounts of yellow or cream on their heads and scales, and as they mature, they darken, and develop the trademark bright orange or red ring around the eye and a creamy appearance to their underbelly. Crocodile skinks have large, triangular heads and are distinguished by four rows of pointy, ridged, bony scales (vertebral spines) along their back and tail, and textured, leathery skin, all of which are reminiscent of a crocodilian and lead to the skink’s name.
Unknown, although there have been reports of Tribolonotus living 12 to 15 years and longer in captivity.
Maturity - Sexing
Crocodile skinks are slow to mature, reaching sexual maturity at around 3 to 4 years of age. Mature specimens can be identified by distinctive orange-colored markings on the underside of the chin, however, this coloration can fade in and out in younger skinks so its appearance alone should not be used to determine a skink’s maturity. There are three ways to sex a Tribolonotus. The first is on the basis of size, with adult males being larger and stockier overall than females. The second difference is that male skinks have small, light-colored (white, grey, or blue) raised pores or pads on the third, fourth, and sometimes fifth toes on the underside of their back feet (these pores are absent in females). Their purpose is unknown; although it’s speculated that they may produce a scent used for territorial marking. The third method of differentiating the sexes is by the appearance of enlarged abdominal scales in a square-shaped pattern which are present in males, but absent in females.
Ease Of Care
Crocodile skinks do well housed alone or in male-female pairs. Males should not be kept together as they are territorial and will fight. I have found that a 20 gallon enclosure is suitable for a single or pair of skinks. The enclosure should offer plenty of foliage and cover, especially in the event of housing a pair as they do require separate spaces in which to retreat. Cork bark, logs/wood, pre-made hides, and plants (real or artificial) work well to provide the skink with adequate cover. A large, shallow pool is also imperative as this species spends much of its time swimming, and will utilize the water to aid in shedding. Rocks can be added to deeper pools to allow the skink to easily climb in and out and prevent drowning. Ensure the water is checked daily as they will often defecate in their pool. Crocodile skinks require higher humidity (60-100%) so a substrate such as Coco fiber or peat moss is suggested to aid in humidity as well as to allow for burrowing. I have found that 4-6 inches or more of substrate works well for this species. Daily misting is important, and adding a source of running water, a misting system, or live plants to the enclosure are also suitable means of maintaining proper humidity. Do ensure the skink always has both moist and dry places to take cover.
There are some discrepancies as to what is considered appropriate temperatures for this species, but it is agreed that a thermal gradient is important. Some Crocodile skinks will utilize basking areas if available, so a basking temperature of up to 86F is considered acceptable. Higher temperatures should be avoided as they can stress out and ultimately kill the skink. A daytime range of 70-75F (on the cool end) up to 80-85F (on the warm end) with a nighttime drop to 65F is the general consensus on the appropriate temperature range. The use of a heat pad or supplemental lights can be used to achieve the higher temperatures if necessary, although I have found that housed at room temperature (70-75F), a UVB light provides enough heat to achieve the required temperature gradient and render the use of supplemental heat sources unnecessary.
A UVB full spectrum light on a 12-14 hour light cycle is highly recommended for maintaining the health and longevity of the Crocodile skink. Being crepuscular, they are most active at dawn (around 6-7am) and at dusk (6-7pm) so they will benefit most from a light cycle that accommodates this.
Crocodile skinks are insectivores, and do well offered a variety of appropriate-sized, gutloaded prey items such as crickets, mealworms, mealworm beetles (darkling beetle), worm larvae, waxworms, earthworms, and silkworms. Some skinks may prefer only one or two food items, whereas others benefit from a larger variety. Prey should be dusted with calcium with vitamin D3 supplements at every feeding for hatchlings and juveniles, and every other feeding for adults. A multivitamin supplement containing D3 should be used at least once a week for both. Young skinks can be fed every other day, whereas adults only need to be fed every 3 or 4 days. Keep in mind that being shy, you will likely very rarely see them eat, so it’s best just to monitor their food consumption and defecation to ensure they are eating and leave them to their own devices.
Crocodile skinks are a shy species, and although they rarely bite (may do so if restrained), frequent handling is not recommended. Some skinks will become very nervous, and will attempt to dart for cover or jump, vocalize, freeze, or play dead. In some instances, they may even drop their tail. As such, until accustomed to handling (some tolerate it better than others), it is recommended that you start off by handling in the enclosure or close to the ground in a secure location, and tailor your handling to what the skink can tolerate. It is important to note that the tail can break off if handled roughly, and although it will eventually regenerate, it won’t look the same as before and can result in health complications stemming from the stress and possible infection from the wound.
A healthy skink is a hardy skink, but they can quickly succumb to their ailments if not dealt with appropriately or subjected to improper conditions long-term. The majority of crocodile skinks available for purchase are wild caught, so it is important that a fecal exam is conducted by a vet as early as possible to rule out any underlying conditions. Stress of a new environment combined with previous ailments such as parasites is most often implicated in deaths of new acquisitions. Ongoing maintenance and proper husbandry is also essential for ensuring the health of your skink. Enclosures should be spot-cleaned at least once a week, unless a biological agent such as springtails or isopods are added to the substrate to maintain cleanliness, in which case a once a month cleaning is usually sufficient. Water should be changed frequently, especially if the skink utilizes it for defecation. Maintaining proper humidity is important both for shedding purposes and respiratory health, however, ensure the skink has both moist and dry places to retreat to as they can develop skin/fungal infections such as blister/scale rot if subjected to constantly damp conditions.
When Purchasing A Crocodile Skink
It’s important to distinguish between healthy and unhealthy specimens. A healthy skink will have clear nostrils and mouth, bright eyes, a firm, plump body, all scales intact with no scars or missing appendages, and will appear alert. There should be no retained shed, gasping, clicking or wheezing noises when breathing, and they should be able to walk without difficulty or apparent problems. Skinks which appear to have skeletal issues, unhealed wounds or lacerations, or are thin or dehydrated should be avoided as they may carry a heavy parasite burden or other chronic underlying illnesses.