by Mark Chapple

Warning – some mathematics ahead – but don’t worry - it's easy in the end.

This is not a simple question to answer. In the wild some snakes move about frequently and hunt. Others are quite inactive for much of the year. Snakes from warmer cliomates will eat more as they can eat all year round; snakes from cooler climates will have long periods of brumation and not feeding. For example the Chappell Island Tiger snake only feeds fro two months of the year, when the mutton birds are nesting.

What is known is that temperate zone snakes generally consume about two to four times their body weight per annum, depending on their level of activity.

Snakes in captivity would generally considered to be not as active as a wild snake and would therefore be expected to be at the lower end of the consumption spectrum, meaning they would require around twice their body weight per year.

Thus a 1 pound snake would eat about two pounds of mice per year. Using the weight of an average mouse at 50 grams (0.11 pounds) we can work out that a one pound snake would need about 18 mice per year (2 pounds ÷ 0.11).

If we assume that the snake is active for about 8 months of the year and inactive for 4 months, then those 18 mice are spread over about 32 weeks. That is, 1 mouse every two weeks for a 1 pound snake. This takes no account of breeding activity or the extra energy required for growth for a younger snake.

There is a formula you can use to calculate the amount of energy a snake needs in Kcal (Kilo Calories)

Weight of snake 1lb = 0.45kg

Now a 50g mouse has 85 Kcal of energy.
So
Number of days one 50g mouse would last a 1 pound snake       = 85 ÷ 5.5
                                                                                                    = 15 days

This is approximately two weeks, the same as the other calculation.

Using the above formula you can calculate the amount of energy required for a snake of a certain value. If you know the weight of the rats you are feeding it is easy enough to change the formula for rats as well. The average weight of a rat is between 250g and 400g and a sub adult rat weighs about 100g.

Many owners feed their snakes too much. The end result is often an overweight snake and hence potentially serious health risks, such as heart disease, lower fertility, tumors, metabolic and musculoskeletal problems. Your snake may not even survive in captivity as long compared to a more controlled diet.

Breeding snakes, especially females, will require more than this, as they will require the higher energy needed for reproduction. This may two or three times more during the breeding period.

Signs that your snake is overweight include

• Inability to coil properly
• Skin showing between scales
• “Fat’ lines, which are vertical lines of folds in the scales that remain after a snake has been coiled for a long period of time.

If you suspect your snake is overweight you can place it on a weight loss diet. You will need to decrease the amount of food gradually. You should reduce the feeding amount by about a ¼ each month over several months, until you reach the maintenance amount.

I have made an excel spreadsheet that you can download (right click and select Save Target As..) and use to calculate your snakes ideal feeding amounts. You can alter the default weights of the mice or rats you are feeding and the weight of your snake within the speadsheet.

Reference:

"What's wrong with my Snake?", J. Rossi & R. Rossi, AVS, 1996

by Bert Langerwerf of AgamaInternational with additions by Mark Chapple

Physignathus lesueurii

I decided to do an article on Eastern Water Dragons after spotting a couple in wild while fishing along the Snowy River in Gippsland Victoria. I had caught one as a boy nearby to my home which is much further south but have not seen one in that area for many years. I did not even know what it was at the time. I suspect they have been driven out of the area by development now.

The local herp store had a large Gippsland Water dragon (a sub-species Physignathus lesueurii howittii) for a few years. I was impressed by this spectacular lizard, with its spines running down the back and colorful head and throat. I would always be sitting majestically atop his rock, eyeing off those who came by. None of the photos I have seen would do this fellow justice.

When fishing, we often saw them early in the day, basking or lying in the water. The water we were fishing in was estuarine, meaning it was salty, not fresh, but they also could be found further upstream in the fresher water.

Australian Water Dragons live in the Eastern part of Australia from Cairns down to Southern Victoria, though they avoid the northern part of Australia. They occur only in regions where there is enough winter to trigger their reproduction. In many parts of their range there is nightfrost in winter, particularly in southern NSW and Victoria. Their range has decreased somewhat with expanding urban areas anad decreasing habitat but they are still relatively common in many areas that are not built out and can often be seen by rivers, either basking in the sun or semi-submerged in the cool water. Australian Water Dragons will survive temperatures till 32 F.

They will hide in burrows during winter, so that it is rather easy to keep them outdoors in unheated terraria in the southern USA. Adult lizards are quite spectacular and pre-historic looking animals. They are more tolerant of temperature ranges than Asian Water Dragons, are not green and have a less 'jumpy' personality.

The males grow to 2 1/2 to 3 ft and females 2 to 2 1/2 ft in length.

Eastern Water Dragon (Physignathus lesueurii)

Eastern Water Dragon submerged in watrer, Snowy River, Gippsland, Victoria

Eastern Water Dragon

Food:
Newly arrived water dragons will normally start eating after 3-4 days as they need some time to adjust to their new surroundings. If you have recently arrived water dragons, it is important to have the temperature inside the terrarium high enough (80F) if you want them to start eating soon. As in Australia they will stop eating when days get shorter and cooler; they may do the same in your terrarium if temperatures and light periods decrease.

At Agama International, Inc. we feed them mainly superworms as they can be fed from a feeding dish. This allows for very easy checking on their feeding habits. They also eat crickets. The drawback with gray- or house-crickets is that they are nocturnal and hide during the day, while the lizards are diurnal, meaning they are active during the day. So it can happen that there are more crickets in the terrarium then needed, and that the crickets disturb the lizards at night.

Of the cockroaches you should never feed German or American ones for obvious reasons (they will escape and become a true pest in the house). Hissing cockroaches, and deadhead cockroaches (Blaperus cranifer) can be fed easily from a container with smooth sides.

Cat food and all kinds of sweet and soft fruits (banana, peach, watermelon, etc.) can also be offered to your Australian water dragons. Although some will never touch it while others may eat it with fruition. Adults may also eat pinkie rats and pinkie mice.
As always, it is important to "gut load" your feeding insects first. This means you have to feed the insects before they are fed to the reptiles. This way the reptiles get extra nutrients which they may otherwise not be able to get. Sweet potato or carrots are very good choices for "gut loading" your insects.

You can also increase the food value of the feeder insects by dusting them first with a powder specifically made for that purpose, like for example Miner-All. These powders are easily available at all pet stores.

Terrarium:

The terrarium size for one pair of adult water dragons should be about 4 feet long by 3 feet high by 2 feet wide. In the terrarium you can place a tree branch or tree trunk on which they can climb and sit. A warm basking spot is also needed. They also like a small box or place into which they can both sleep and hide. The water bowl needs to be situated so that it can be cleaned easily. The lizards should to be able to get in and, also, out off the water easily. Although not very elegant, we often use paint-roller dishes as they have a sloped "beach" area.

A larger pond, with water plants such as lotus, should get a filtering system. Another possibility is to use a water bowl with a drain, which can be cleaned and replenished without opening the terrarium.

Lighting:

It is always important to place the lamp at the correct height (as listed on the lamp's instructions) above the lizard basking spot. Just 2 inches higher or lower will greatly change the amount of ultraviolet radiation that the lizard will absorb.

If you keep your water dragon indoors you need a UVB lamp to provide ultraviolet radiation for the reptile. You should only purchase Zoomed Reptisun 5.0 fluorescent bulbs as they are the only fluorescent bulbs that we know of which produce enough UVB light for proper calcium metabolization (there is not much quality control in the reptile supplies industry). Incandescent bulbs don't produce UVB, though they may produce UVA, which is good for the animal's psychological health, but does nothing for calcium absorbtion. On the other hand, mercury vapor bulbs produce quite a lot of UVB, but are more expensive and are more work than fluorescent since they run hot enough to badly burn the animal if they come into contact with it.

Please read and follow the instructions that accompany the lamp. It is always important to place the lamp at the correct height (as listed on the lamp's instructions) above the lizard basking spot. Just 2 inches higher or lower will greatly change the amount of ultraviolet radiation that the lizard will absorb. Also, it is important to replace the bulb every six months or so as the amount of UVB that it produces decreases with time and it eventually becomes worthless. Even when it is not producing useful amounts of UVB it will still be quite bright, so you won't be able to tell whether it is burnt out simply by looking at the light.

Conversely, if you have other fluorscent lamps, bulbs older than 6 months make good general purpose bulbs as they typically look more like natural sunlight than the yellowish bulbs which are commonly used in fixtures for humans (or fish tanks, etc.). You don't have to throw out bulbs older than 6 months, you just can't use them as the primary UVB source for your reptile.

Article reproduced with permission. Bert Langerwerf breeds and sells a wide variety of animals including Australian Eastern Water Dragons, Tegus, Bearded Dragons, Shinisaurus crocodilurus, Uromastyx.

Bert's website is www.agamainternational.com. Bert has Water Dragons for sale year round.

New discovery - Cobra

Old discovery - Yet another dinosaur

New Invention - Snakebot

Stupid Invention - Copperhead Collar (not really an invention)

Great article on a snake catcher

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