Natural History

Two subspecies of Spiny Tailed Monitors are generally known to captive collections, V.acanthurus acanthurus (the Red Spiny Tailed Monitor) from the west and V.acanthurus brachyurus (the Yellow Spiny Tailed Monitor) from the east. (Although there has been some debate about this).  A third sub sp V.a.insulanicus is known from Groote Eylandt and Machinbar Island, off the Northern Territory. There is much speculation by various authors that there may be many other ssp of acanthurus in existence.

Of the two, Red Ackies grow the largest with a field specimen near Wyndham being recorded at an enormous 34”! (Jeff Lemm 2008)

Due to the extent of their range, differences have been noted in colour and size. Ecological differences have also been noted, with tropical localities spending time in trees, and arid locality specimens being found in rock out crops and burrows. For the most part, Ackies are associated with more arid areas, normally in rocky outcrops, boulder formations and burrows where they can hide from predators, and thermoregulate in the differing range of temps that the rock stacks provide. I have witnessed this around Mt Isa with Yellow Ackies. Interestingly, Ackies along with some of the other Dwarf’s, live in groups with social structures, unlike their larger counterparts.

Captive Husbandry

It has been proven by many keepers that temperature is the key to successfully maintaining Ackies. A temperature gradient in the vivarium should range from around 100F at the warm end, down to low 80sF in the cool end. A method developed by Frank Retes utilises a stack of plywood boards with spacers in between, just wide enough for the animals to squeeze into, piled high under the basking lamp. This will provide a habitat similar to rock piles or boulder formations, and give them security and most importantly, they can use the “Retes Stack” to thermoregulate. You will note that the surface temps on these “stacks” will get very high, possibly in excess of 150F.

In order to achieve safe gradients a vivarium of not less than 100x50x50cm will be required. Temperatures should be monitored with max/min thermometers and controlled with a thermostat (eg: Microclimate). 

A full spectrum tube is important.  Aside the importance of UVA and the psychological benefits, these animals occur in areas of highly concentrated sunlight and will be able to access UVB.  UVB is important to help synthesise vitamin D3 which in turn, aids the metabolism of calcium. In the wild it is likely that Ackies eat small rodents, baby birds and lizards that would provide a direct source of metabolised calcium. In captivity, diets tend to be more insectivorous based and need supplementation (eg:Naturerep Vitarep and Calcimax) and UVB (via Zoomed Reptisun 5.0 tube, for example), to achieve good calcium absorbsion. 

Diet should include locusts, crickets, morio mealworms and feeder roaches. A small amount of meat in the form of ground, raw turkey mince can also be offered. Some keepers feed pinky mice, but if over fed, this can lead to obesity and possibly renal gout. Certainly no more than 2-3 pinks should be fed per animal per week.

Due to the high temp requirements, Ackies have very high metabolisms and must be fed insects, preferably several times a day, and in good quantity.

Water should be provided at all times in a shallow bowl. Areas of higher humidity can also be created by spraying areas under hides etc..

Substrates can be sand, soil or a mix of the two.

Although Ackies can be kept in groups, it is very difficult to introduce new animals into an established group.  Fighting can occur resulting in injury or even death. Even “alpha” females of a group will attack newly introduced subordinate males, if an alpha male is already established in the group. In order to set up a small group it is preferable to obtain several babies and grow them up together as a social group.

Ackies can be sexually mature at as little as 5-6 months of age, producing 6 months of the year, multiple clutches with up to a total of 60 eggs per female per year! Average clutch size is said to be 10 eggs up to around 18.

Links:

Naturerep Vitarep BUY

Natuerep Calcimax BUY