Dappled light for small amphibians
I have recently started keeping small frogs – both dartfrog and mantella species – in their own 45x45x60cm (18x18x24in) enclosures. I wish to provide my animals with a set-up that is as close to their natural environment as I can. One particular aspect that is confusing me is how to establish leaf scatter illumination in the best way for them?
Your approach really helps to reconnect with the way that these animals live naturally, and gives a much better understanding of their lifestyles. A few years of captive breeding can simply never override millions of years during which these amphibians have existed in a wild state. What you have to do, therefore, is to research and copy the ecosystems for the species that you have chosen.
Having said that, both dart frogs and mantellas are surprisingly easy to care for, if their basic requirements with regard to heat, humidity and diet are met. Light will then help the animals to live in a way that is natural to them. They will also be able to take any energy from the light that they require in a way that is best suited for them.
Both the groups of amphibians that you keep are noted for their tendency to live in the undergrowth and leaf litter. This in itself does not in any way stop them from using solar energy in the form of infrared heat or UVA/UVB. Nature is a wonderful thing. If a species has developed to utilise the rich feeding ground and safety provided by undergrowth, nature will have equipped that species to utilise energy from light in a very sensitive and effective way.
This is generally achieved by adjustments to the thickness and therefore the level of protection afforded by the skin. Diurnal, desert animals have relatively hard, thick and therefore protective skins, as they are active during the daytime when the sun is at its hottest. In contrast, crepuscular species which emerge as the sun sets have thinner and therefore more absorbent skins.
This simply means that they can use lower light levels more effectively, over shorter periods of time, in order to achieve exactly the same results as occurs in desert species exposed to more intense sunlight.
How amphibians have adapted
Amphibians have taken this a step further of course, as some species including the waxy monkey frogs (Phyllomedusa sauvagii) found in South America will actively bask in very strong sunlight. They do, however, produce this special waxy secretion that is wiped over the body as “sunscreen”.
Does this mean that these frogs do not use the power of the sun? No, it simply reveals that they have developed a way of protecting themselves from very intense periods of exposure and that they allow themselves to benefit from this in a safe and measured way. It is all very clever indeed!
Light also reflects back off the water.
When setting up your enclosures, decorate them in a way that is re-creating the typical habitat used by that particular species. For instance, the golden mantella is often found in deep leaf litter, only becoming visible when the leaves are overturned. In contrast, the bronze mantella is found out in grass and sandy areas and is frequently exposed to full sunlight in its native Madagascar.
The starting point therefore, when it comes to creating a natural environment, is to match the habitat to the particular species that you are keeping at the outset. A simple online search will therefore be required, helping to reveal the local habitat. You will be also able to see average temperatures and humidity levels. As far as lighting is concerned, you can determine the average UVI (UV index) and this can then be used as a benchmark for setting up a measured and safe lighting system.
It is also a great idea to create different levels in your enclosure. This can be easy achieved, as the frogs will climb over plants, rocks and wooden ledges. I aim to have at least three areas of this type. The inclusion of living plants is very useful as they allow you to maintain good levels of humidity and to use their inherent reflective properties that in turn provide a more natural form of light provision.
Plants require light of particular wavelengths (within the red and blue parts of the spectrum) to grow properly, and although it is not widely known, UV lamps will burn and may even kill off plants growing in their vicinity. The plants’ needs for light of specific wavelengths can be met by the inclusion of a second lamp that caters for them.
This can be achieved by a standard output T8, a high output T5 or an LED in the form of a very special new plant growth system called “Jungle Dawn”. Providing suitable lighting of this type for plants, at the right wavelengths, means that this will not only reduce the risk of UV burns, but also maximises their rate of growth.
Begin to decorate your enclosures in a way that allows plenty of areas of shade and where you can see that the plants will grow up into the “canopy” of your vivarium. This will then allow them to act as a series of reflectors from the light source placed above their accommodation.
An approach of this type recreates the type of lighting that many amphibians, reptiles and other forest creatures utilise in wild, which is of course “leaf scatter illumination”. This is a natural process that occurs as light enters the emergent layer of a forest. Much of its energy is reflected back upwards at this stage and also in many different directions by the top layer of trees.
The light then penetrates the canopy where it is again reflected and bounced around. These shafts of light then travel downwards into the understory where again, they are reflected down onto the forest floor. This in itself results in a pattern of lighting, almost like a “disco ball effect”, involving millions of shafts of light of differing power. The animals can then use these shafts of light to energise their bodies for their health and well-being.
This is why it is so important to include areas of total shade and areas of solar power at differing levels. Through the power of tetrachromacy – being able to see UV light, which is something that we cannot do – the amphibians are able to detect these shafts of light and the power associated with them. This helps them to move back and forth as required, assisting them to select the power zone that they require, as and when needed.
The waxy monkey frog uses its own sunblock.
A practical approach
For many keepers using 60cm (2ft) wide enclosures, a simple twin 24 watt T5 system, comprised of one D3 6% UVB lamp and one plant growth lamp with reflectors will provide all of the light and energy from light that both the frogs and plants require. Unfortunately, there really is not a “one stop” lamp that provides every wavelength required in one tube as yet. Jungle Dawn is useful as it can be easily fitted into a lighting canopy and combined with compact lamps, being an E27 screw fit.
In a newly established set-up, it will take time for the plants to grow sufficiently to generate the desired light and shade effect. Ideally therefore, it is worth running the vivarium but without the animals added, while everything settles down and the plants grow to the level that you require.
It is also recommended to “seed” your floor media with a bioactive culture of invertebrates. Springtails and tropical woodlice are quite easy to purchase now and they will work tirelessly in your enclosure to keep things clean. These small inverts act as a terrestrial clean-up crew, digesting waste material produced by the vivarium occupants – plants or animals. They keep the soil fresh and of course, provide a welcome addition to the diet of vivarium occupants such as dart frogs.
As such, it is a good idea to refresh your culture by adding in new starter cultures a few times a year. In addition, use supplements such as Vetark’s Calci-Dust and Nutrobal so as to make up for any nutritional shortfall in their food. It may even be a good idea to use calcium-rich rocks such as chalk in the enclosure, or to mix a source of natural calcium into the growing medium. This is then likely to be ingested by the frogs as they prey on these invertebrates.
Calcium is one of the most plentiful minerals on earth. In fact, a species would have to work very hard indeed not to ingest it, either from its food or drinking water. As such, adding it into floor coverings and water sources is very natural indeed.
I would also include a small, very shallow pool of water for most species. This will not just act as a source of humidity or direct hydration but the water will also act to reflect light back upwards in a natural way.