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all available space. This is not possible for ground-dwelling species. In fact, whilst many people would argue that terrestrial animals are easier to house, this can be another challenge that the keeper must consider. They should not be housed in anything shorter than five feet in length, with six feet being more appropriate. Height is less of an issue, but installing light fixtures may be easier in a taller vivarium and will make room for various hides and artificial or growing plants.

Breeding blue-tongues

There are seven distinct species of blue-tongue skink. Five are endemic to Australia, while two occupy the islands of Wallacea.

In 2020, researchers discovered the most Westernly occurring population of Indonesian blue-tongue skink (Tiliqua gigas gigas) in Sulawesi. It is thought that there is still much to learn about this species and perhaps many more species and subspecies to be described to science.

Blue-tongue skinks

sneeze. In the wild, they will use their noses to push through dirt and sand to search for prey. They use this sneezing to clear out any loose particles that get stuck in their nasal cavities. Keepers should be careful this is not combined with a mucus build-up, which could be a sign of infection.

Blue-tongue skinks are routinely bred by many hobbyists and lots of pet shops will keep a breeding pair as they are usually quite straightforward to breed. However, there are a few notable challenges when embarking on a blue tongue breeding project. Firstly, sexing blue tongue skinks is incredibly difficult. In fact, before the age of around two years old, all species and subspecies are practically impossible to sex without veterinary intervention. Northern blue tongue skinks (T. scincoides) can sometimes be sexed based on their head size and bone structure as they get older. However, the breeder would need to select from a good number of animals to create a ‘best guess’ as a straight comparison between two animals is unlikely to be conclusive. Unfortunately, this method of identification does not work with Indonesian subspecies as both males and females can differ greatly in size and shape.

One method of sexing that applies to all species, including the Indonesian varieties is by identifying the colour of the iris. Males are more likely to have red irises, whereas females are more likely to have yellow irises. This is completely unreliable, as there are many reports of females with red irises and males with yellow. However, it can be used in conjunction with other identifiers to help the breeder make an informed guess.

James Wilson is an expert blue-tongue breeder in the USA. Writing to bluetongueskinks.org he claims: “The presence of, or lack of, seminal plugs has proven to be one of the most reliable indicators that I have used in determining the sex of my blue-tongued skinks. Most hobbyists overlook this dead giveaway because they keep their skinks on dirt, bark, gravel, or aspen bedding. The seminal plugs simply get lost in the substrate, never to be discovered by the skink's owner. I have found that when I keep my skinks on artificial turf, at least during brumation and the breeding season, the males will "drop" seminal plugs daily. These plugs are small (about the size of a bb) clearish-white slimy little blobs with tails that give them a total length of about 1-inch. They resemble small tadpoles and are usually found in pairs. They are quite obvious on the turf but will dry up by the end of the day, turning a yellowbrown colour and withering into thin brittle twigs. At this point, they are very easy to mistake for a small piece of aspen bedding or a dried up piece of cut grass. Some people confuse seminal plugs with the urates that skinks produce along with their faeces. Urates are the white chalky portion of a skinks waste matter. During brumation, they are produced in the absence of faecal matter, because the skink has not taken in any food, but was still given access to water. This can be misleading, and it is important to know exactly what you are observing. Remember that urates are chalky, and they will crumble up quite easily in your fingers, while seminal plugs come in pairs and look like very small albino tadpoles.”

There are other, more invasive methods of sexing blue tongues. Some breeders will expose their animals’ hemipenes but this can risk damage and future health complications. Finally, an MRI scan will sex a blue-tongue skink with confidence. For breeders dealing with many animals or high-end morphs, this might be a worthwhile investment. For most hobbyists, however, it is a very expensive procedure that is often unviable.

Brumation should be encouraged in Australian species, but it is much less important for Indonesian subspecies. All T. gigas species experience a ‘wet’ and a ‘dry’ season in the wild and therefore do not require a brumation period to breed. This being said, many hobbyists will choose to semi-brumate their animals in anticipation of breeding. Dropping temperatures just a little bit and reducing the photoperiod will mimic wild seasonality. The animals will lose their appetite and become less active. Keepers of gigas sp. should not drop temperatures below 21°C (as opposed to the Australian subspecies which will happily tolerate 15°C for several months). Not all blue tongue skinks will want to brumate. Even those that experience the harshest conditions in the wild might find that their captive environment does not warrant the need to brumate. Therefore, the keeper should be extra vigilant around winter and observe their animals’ behaviour. If the animal is becoming extremely inactive, brumation is encouraged. If the animal is simply reducing the amount of food they eat during winter, this is perfectly normal and does not necessitate drastic temperature drops.

Once both animals are receptive (females will reportedly react to a little back scratch by raising or wiggling her tail, whilst males are noticeably more active), pairing can commence. The breeding process is anything but romantic. It can be very daunting for a new breeder to watch their animal's mate. Males will be very aggressive and bite the flanks of the female. She will also be pushing back, testing the male’s strength, in what can appear to be a rather vicious struggle. Although males can be introduced to a female’s enclosure, using a separate tub will allow the keeper to observe the process and break up the wrestling if, for example, the male begins biting the females’ feet and toes. Eventually, he will stroke the top of the female’s tail with his hind legs and, if he is successful, she will lift her tail and allow him to copulate. If they are unsuccessful, they should be separated and paired again a few days later. The female will be receptive for around one month and should not be paired with males more than 3-4 times during this period.

Blue-tongue skinks will generally give birth to between five and 15 young after a gestation period of around 100 days. The young are fully formed, independent lizards that should be introduced to their new enclosures as soon as possible.

The importance of reputable breeders

Anyone who is looking to source an animal should have a keen desire to know where that animal came from. With many shops breeding their own blue-tongue skinks, a few simple questions about the lineage of the animal should help the keeper identify the exact species/locale. Networking with breeders who produce specific varieties is also a great way of picking up unique tips for that locale/subspecies. Hardy species that have occupied herpetoculture for decades often make excellent pets. Sometimes, however, it is the longest-kept species that require the most effort and research to update their husbandry practices.