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THIS MONTH IT’S: BIAZA

The British and Irish Association of Zoos and Aquariums (BIAZA) is the professional body representing the best zoos and aquariums in the UK and Ireland. They have more than 100 zoo and aquarium members whom they support in their commitment to be at the forefront of conservation, education and research. www.biaza.org.uk

BLUE OR FALSE?

Identifying and caring for Indonesian blue-tongue skinks.

Blue-tongue skinks have been popular pets for decades. Seven separate species make up the Tiliqua genus, which includes the shingleback lizards (T. rugosa) and the pygmy blue-tongue (T. adelaidensis) of Australia. However, this genus is most characterised by the bulky, smooth-skinned and perpetually “chill” blue-tongue skinks of Australia and Indonesia. Historically, Australian blue-tongue varieties were very popular and morph breeding in the US opened an entire subculture of keepers dedicating their time to producing these impressive animals. Now, in the UK the most dominant pet species is T. gigas, commonly known as the Indonesian or “giant” blue-tongue skink. This species inhabits the tropical forests of Indonesia, Papua New Guinea and the surrounding islands. Not only are these animals different to their Aussie cousins, but speciation has led to three distinct subspecies, with several ‘locales’ regularly exported to the UK over the last 40+ years. Over that time, crossbreeding between locales has likely happened, but a better understanding of the distinctions between each population will undoubtedly improve the husbandry of these loveable lizards.

Indonesian blue-tongue skink

Tiliqua gigas gigas is the nominate form of this species. However, due to its distribution, island ‘locales’ have evolved in isolation from one another for millions of years. This means that although the Indonesian blue tongue skink is a distinct species, further studies into each population have described several subspecies. There are bound to be more identified as taxonomists continue to study these populations, but for now, these unique animals are referred to as ‘locales’. Some of these locales are already widely available in captivity and are as follows…

Halmahera: The Halmahera blue tongue skink is a subspecies of T. gigas that is found only on the Halmahera Island in North Indonesia. Distinguishable by their red/ grey colouration and thin dark markings as well as a different scale structure around the eye, this is a unique variation on the nominate form. Caring for Halmahera blue-tongues should be identical to other island forms of T. gigas. Although many animals with black banding are listed as ‘Halmahera’ regardless of their lineage, in the wild this species would be exposed to the highest levels of humidity of any blue tongue species. Keepers should average around 70% RH, with daily spikes up to 100%. This contrasts with other T. gigas found on more southernly islands which tend to thrive at 50% with spikes of 80% humidity.

Irian Jaya: Irian Jaya is the name given to the Indonesian (Western) side of Papua and adjacent islands. It is a huge landmass with a vast spectrum of biotopes and climates. Although the ‘Irian Jaya’ blue-tongue is taxonomically incomplete, it is widely believed this species thrives in lower-humidity environments when compared to other island forms. They are variable in their patterning and not always easy to distinguish from other subspecies or locales. This has led some people to believe it is a cross between the Tiliqua gigas species of Indonesia and the Tiliqua scincoides (Eastern) species of Australia, from when there was a land bridge between the two countries.

The Kei Island blue-tongue skink

Tiliqua gigas keiensis

The ‘Kei Island’ blue tongue originates (unsurprisingly) from the Kei Islands of Maluku in Indonesia and perhaps the neighbouring Aru Islands. These islands are part of Wallacea and sit at a Northernly position in the bluetongue skinks range, suggesting that high humidity and a tropical environment will provide optimal care. They are a very robust subspecies of T. gigas and are characterised by their orange base with speckled patterns that stretches from their head and down their torso. Juveniles will develop these patterns at around 3-6 months of age. Their unique appearance prompted the distinction of this subspecies back in 1894 and since then the islands changed their name from “Key” to the colloquial “Kei” spelling, with the scientific name ‘keyensis’ following suit. They are reported to be one of the more aggressive subspecies of blue-tongue though this could be because most of the animals in the hobby are wild-caught. Captive breeding of this species has been successful in the US, but as blue-tongues are not prolific breeders, they are still reasonably rare in the UK and Europe.

The faded blue-tongue skink

Tiliqua gigas merauke

Pronounced mer-oo-kee, T. g. Merauke (sometimes referred to as the ‘faded’ blue-tongue) is the longest subspecies of the Indonesian blue-tongue skinks. They inhabit transitional coastal plains of Irian Jaya, suggesting they require a reasonably low humidity (around 60%) and may benefit from drier elements in the composition of their substrate. These huge lizards can reach up to 70cm in length and often have extremely good temperaments, making them one of the more popular subspecies available. They are routinely captive-bred across the world.

However, these animals may not be true Merauke’s as this species shares its distribution with other locales of the nominate form and can be extremely variable in colour. In fact, the concept of a ‘true Merauke’ is hotly contested across herpetologist circles, with many researchers believing this is just another colour form of the Indonesian blue tongue, T. gigas.

The ‘other’ blue-tongues

There are several other species of blue-tongue found across Australia which have their own subspecies, colour morphs and locales. The Eastern (Tiliqua scincoides) and Northern (T. s. intermedia) blue-tongues are most commonly seen in the pet industry, but due to export restrictions are generally less widespread in the hobby than their Indonesian counterparts. However, there is one subspecies of the Eastern blue-tongue which inhabits the Tanimbar Islands of Maluku, Indonesia. Tiliqua scincoides chimaerea, the Tanimbar blue-tongue skink has an incredibly glossy appearance, small body and fierce attitude. Tanimbars have very firm bodies compared with other blue-tongue species with faded streaks down their back. Their name comes from Chimera, a mythical firebreathing dragon. Herpetologists are still unsure why the blue-tongues on this island have evolved such firm bodies and feisty attitudes, predicting that there may be a specific predator or higher density of predators on the island that this species needs to contend with.

Keepers should be extremely vigilant in understanding exactly what species of blue-tongue skink they are caring for. Although these animals are not readily available in the UK, the blotched alpine locality of the Eastern blue-tongue (Tiliqua scincoides) can tolerate extremely cold conditions and inhabit areas that are frequented by snow. The Central blue-tongue, on the other hand, thrives in the heart of Australia where temperatures can reach upwards of 40°C. As these are completely distinct species (as opposed to the subspecies and island localities of T. gigas), they are easily distinguishable. It would be very difficult for someone to source a Centralian blue-tongue for a similar price as a ‘Northern’. Yet, it would not be out of the realms of possibility for an animal to be rehomed under the ‘bluetongue’ banner and a novice keeper to believe all species are synonymous. Naturally, these specialist species require entirely different environmental parameters to T. gigas sp.

Indonesian blue-tongue care

Blue-tongue skinks often have docile personalities and have made excellent pets for decades now. They are routinely bred in captivity but continue to be imported from the wild in small numbers, which supports bloodlines with sturdy genetics and healthy animals. As females are viviparous and produce just a few large, stocky offspring once a year, the availability of this species can be sporadic. It has also meant that prices for T. gigas have risen sharply in the last 10/15 years now their appeal as pets have become well-established.

Another appeal of this species in captivity is its omnivorous feeding habits. Juveniles will tend to eat a larger ratio of meat to vegetables, but this should even out to around 50:50 as the animal reaches sexual maturity around two years old. Dedicated ‘blue-tongue’ diets exist, but eggs, rodents, mince/dog food and a wide variety of insects can be used. Blue-tongues are known for enjoying soft-bodied prey, but keepers should be wary that they can become picky-feeders if they are constantly fed a single, rich food source.

blue-tongues in, we’ve given them a brilliant high-energy diet to ensure they’re fit and healthy before they’re sold on. This consists usually of raw or scrambled eggs, with crushed crickets and locusts and some berries too. We’ve also found that they love Repashy Blue-tongue Buffet and this tends to support their health over time too. We also frequently provide snails, which they love! People often make the mistake of just throwing a few crickets into a bluetongue enclosure and that doesn’t work long-term. They need a varied diet, this is extremely important to them.”

Blue-tongues, like all other reptiles and amphibians, should have access to UV but their cryptic behaviours can make this difficult to assess. They are diurnal and hail from the tropics suggesting they need high UVI, but they are also terrestrial, living amongst high grasses or the forest floor and probably receive much lower exposure than other animals in the same biotope. Some island forms will inhabit coastal plains (mimicking the grassland environments of their Australian cousins), while others will thrive in dense rainforest. Although Tiliqua scincoides is considered a Ferguson Zone 2-3 animal, T. gigas is yet to be officially categorised. Applying this logic, whilst also providing plenty of hides and foliage would be recommended.