Uvb and D3

[Diver]

Thanks Elly! The first frog is the Waxy Monkey Frog (Phyllomedusa sauvagii), a nocturnal species well known for basking all day in the hot sun. I actually emailed John Courteney-Smith from Arcadia in the UK (a man who does a huge amount of research on the subject of UVB!) to ask him his opinion on the correct light to provide to simulate what this species receives in the wild. He has kindly allowed me to share his very detailed response below. The figures concerned are of course specific to this frog, but the methods used are appropriate to all species denied natural sunlight in captivity and of course reinforces the need to provide UVB to our captive frogs. This is to be published formally later this year:

Hi, A great question and one that has a rather simplistic answer but requires some study and implementation to really get things right.

Basically as with every aspect of exotic animal care we have to look to the actual evolved (core) needs of a species, per species and subspecies! We need to look intricately at the needs and actions of the species including the actual everyday patterns of behaviour per season.

We have to look to the wild environment, the average weather patterns and seasonal cycles and of course the average solar index of the given locality per season and over as long a period of time as records allow. this is research gold to the exotic animal keeper.

We look at rainfall, the quantity and longevity of the rainy season or seasons, we look at wind factor and the given elevation above sea level per species(the higher a species is found the higher the available index will potentially be). We look the wild diet and method of water ingestion whether it is lapped directly from pools or if it is obtained from rain rivulets running down a tree or from capillary action collected across the body or even from the simple opening of the mouth in the rain. We should also factor in the 'nutritional content' of wild water, it is far from 'pure'! No it will contain Ca and many other minerals. This can and does play an active roll in nutritional provision.

In short we look at every aspect of the habits and environment of the wild species or subspecies and make good notes. From these we will see just how the seasons can effect a species. In the case of P sauvagii we can see a direct link between the changing of the seasons of the rather harsh environments in which they live and their resting and breeding cycles.

We can see that they obtain a vast solar index in the wild and can see how they have adapted to life in this rather hot, quite dry and windy place by evolving a level of protection against and a subsequent use for the sun. This of course comes from the waxy secretion that is wiped over the body. This does not just stop the frog from drying out as was once thought but it also acts a functioning sunblock, however this important evolutionary change is not an indication to the species lack of solar requirement! No, rather this clever adaption has in a similar way to the thick skins of arid lizard species allowed the frog to take what it needs from the sun in the safest method possible. It really is a case of 'six and two threes'. Either you have a thin skin and develop a crepuscular tendency and pop out and energise quickly or you have a thick skin and spend a much longer period of time in the sun or in the case of this group, you develop the ability to use 'sunscreen'. The biological changes after exposure are still largely the same, these are just differing ways of obtaining the required dose of energy. Remember, just because an animal is found asleep by day does not mean that it has evolved to live in the dark! No just as humans burn when asleep in the sun the core biological processes still play out in terms of UVB to D3. You do not have to be awake to benefit in full from the energy of the sun.

So how do we implement this knowledge into our at home enclosures? Well it really is very simple indeed. We use the knowledge that we have of the wild animal proactively. This is always our 'base' point. This is the place where we can start to build our tech around the animal in ITS enclosure as this is of course the actual evolved and as such actual 'need' of the species. For instance, if a species has evolved to thrive in full exposure under a solar index of 7-8 for 10 months of the year and at a thermal daily peak of say 34-36 and obtain hydration via mist and capillary action then this is its biological need. No matter what we do as keepers this will always be their biological need and we must provide for it.

So if we supplied that species with an index of 2-3 for 6 hours a day and ran the viv at 30 and left a bowl of water on the floor for it to drink from we could not possibly be catering for its wild evolved biological needs. The animal would be in a real sense 'under run' or under provided for. This is where nutritional disease starts its long and chronic progression, whether this disease manifests from a lack of minerals and as such poor organ and bone health or a lack of water soluble vitamins or even poor organ function from the lack of hydration. The clues to great captive care really are hidden in the wild.

Reversely this wild need will show the upper limits of the species evolved solar protection method. As such if we know a species basks at an index of 5 and we provide 15 we will be over providing for the species, pushing through the animals solar protection and we will risk just as with humans skin cancers and other biological problems. By over providing we do nothing other than put the animal at risk.


In the case of this highly evolved frog we already know that they like it hot and dry for most of the year and have a regimented breeding cycle that is weather specific. We can see that they are opportunistic feeders and will take food of many differing forms, all adding into their core nutritional provision over their lifespan (we should seek to mimic this also). We can see that temps are rather prone to change in the wild but lets take an average of 28 degrees as a generally safe basking temp. This can of course be increased just before cycling right up to 34-36 depending on the locality of the frog to be kept. We can see that UV Indexes for most of the year are shown as 'extreme' that means 9-11. However we should not seek to irradiate the poor thing to this level in the confines of captivity. This is where a very fine line is drawn.

If 9-11 is the wild need then surely we should provide 9-11 in captivity? Well the answer is of course in a sense yes and no. A frog in the wild has a vast space to move around and to find areas of strong sunshine and of course reversely to find good gradients into shade. We must also remember that light and as such UV is not simply on or off, no, it has billions of gradients in-between, each one usable in an intricate way by the animal. Light reflects off of everything so solar energy is made available in a myriad of graduations and angles. UV bouncing up from a wet leaf or light stone and hitting the flanks and undersides of a species is just as important and active as the light that hits it back!

What about the frogs waxy secretion does this indicate that the frog is protecting itself against the sun and therefore has no use for it? To this we have to say an emphatic no. The level of protection against the sun is there so that the animal can bask safely and still be able to obtain essential solar energy and all of the biological processes that this causes. If we underprovide for this index the level of energy will not be able to penetrate through the secretion and go on to have the positive interaction that the frog has evolved to utilise. This is exactly the same for the green igg or the bearded dragon or any other solar reliant species. In the case of the green iguana of course they have evolved a need for and a level of protection against the sun via the thick almost armour like skin. If the evolved total index is not provided for correctly we cannot push through this level of protection and there will be a potential shortfall in UVB exposure to D3 production (D3 cycle).

Ok, so we take an average, unless you have a room sized enclosure for your frogs it will always be hard to provide a safe graduation from the vast wild power into cool and shade, as such we use an average and try our best to cause this usable sense of the wild in the enclosure size that we have. As we know UVB is a weak wavelength that decreases in power as light travels forward. It is also impeded by plastics, glass and of course reduced in potency or index by a mesh. So we have to decide upon a basking index, match that with a basking area in the viv and then choose a lamp that will provide for that index at that basking area or in your case 'perch'.


This of course has to be measurable. So we use a solarmeter 6.5 to check the actual index and monitor this over the year. Lets say that due to the level of protection against and the requirement for a specific index and coupled with daily activity patterns and or course foliage cover etc that we should seek to provide an upper index basking zone of 5-6. That sounds about right to me. You would therefore choose a lamp that projects that index towards your basking area and then light the area of projection accordingly by using broadleaf live plants and branches. We choose a lamp or lamps that are shorter than the viv and as such create 'light and shade' in which the frog can accurately self regulate. Then we sit back and watch. If the frog is constantly hiding after the settling in period and skulking about in the shadows then the index could be too high for its needs, reversely if it is sitting up as high as it can right under the lamp, then move the perch up half an inch at a time until it stops reaching forward but never exceed the 'safe' index, lets say 8.

As with all of these things it is never a single simple answer that suits all, we can have a rough guess as to what is needed but we need tools to take measurements to become accurate with regard to provision.

In most cases a stat controlled halogen heat source fitted alongside a D3 linear or UVFLOOD is indeed required to provide the wild re-created index. Jungle Dawn can be used alongside this lamp to increase further visible light, increase the CRI an of course cause live plants to flourish.

Then of course you can manipulate heat, light and lighting periods to cause the seasonal changes that are required for breeding. Certainly with this group if you are lucky enough to have your breeding plans coincide with a local drop in barometric pressure and a storm it would be a great aid to the rain chamber!

John Courteney-Smith, Arcadia Reptile