Ferguson Zone


We want to change the way the reptile industry looks at the provision of UVB and UVA for our reptiles. This is the brave idea that we wanted to implement for a while, and the launch of our new generation of T8 and T5 fluorescent lamps has given us the opportunity to take our vision over onto the packaging for our UV products. This way of thinking has evolved because Reptile Systems, although quite a relatively new brand, has allowed us to start afresh with our approach to the way we display the amount of ultraviolet (UV) on our packaging. Packaging for UV lamps, so far, has been straight forward, and normally has the word daylight, forest or desert followed with a percentage.

Reptile keepers have been purchasing lamps, based on this quoted percentage, for many years, with less than 2.5% being daylight, 5% or 6%forest and 10% or 12% desert. What does this percentage mean? It relates to the amount of UVB phosphors in the lamps, so typically quoted values would be 10% UVB, 30% UVA and the rest would be made up of a blend of visible light.

The percentage that we see depicted on reptile and bird fluorescent UV lamps packaging, although may have been correct many years ago, definitely is not now, due to today’s higher output lamps.

The way we keep our reptiles has changed dramatically in the last decade, with more importance being placed on the provision of correct environmental needs. Enclosure size and shape, temperature, light, and the correct amount of UV have all played a big part in this revolution.

What species benefit from having access to UV?

The simple answer is - all animals that live outside and have some access to direct or indirect sunlight exposure. Unless they live in a dark cave, or spend all but the darkest hours in a deep burrow, they will be exposed to the sun’s life-giving rays to some degree or another. Birds, reptiles, insects and mammals all benefit, in some way, from having interaction with the sun. This interaction is on many different levels, but we mainly want to focus on ultraviolet, for now.

The animals that we keep in captivity need to have different levels of UV depending on where they originated from and their basking habits that have evolved.

Until recently reptile keepers have been concentrating on how much UVB an animal needs rather than how much sunlight we can artificially reproduce, within a micro habitat, to mimic naturalistic activity.

Although all the components of sunlight are essential for habitat replication, reptile health and wellbeing, we will be focusing on the 290nm-400nm section. All the wavelengths below this are extra-terrestrial in nature and are filtered out by the earth’s atmosphere. UVC has a wavelength of 100–280nm and is harmful to all living cells and used to sterilise equipment and surfaces. UVC should be considered dangerous and unnatural and should not be present in any reptile lighting products.

The sun’s spectral wavelengths are measured in nanometres (nm) and are divided into two groups: long or short wavelengths. Interestingly, the gap in the wave length is measured in nm which is a billionth of a meter. The short wavelength section is UVB (290-320nm) with the longer part being UVA (320-400nm). Beyond this we have visible light with the human eye seeing between 400-700nm and after that we move into infrared ranges which are the wavelengths that keep us warm.

What makes up sunlight?

UVA is, now, often found in most good quality lighting products on the reptile market, to one degree or another, but always check with specialist retailers to ensure the correct levels for your animal. Reptile, bird, insect and amphibian vision starts before the visible light spectrum, at around 350nm, and is used in conjunction with this to help locate food, stimulate appetite, select mates and evaluate other important situations and seasonal changes. By not providing UVA you are robbing your animals of part of their vison.

UVB is quite possibly the most important light level to get right in your enclosure and often the hardest to achieve. It should also be taken into consideration that most standard glass and plastics do not allow UVB to pass through them. So, household windows and the side of your glass vivariums will not allow transmission of this vital part of the spectrum. This means that the only way to sufficiently provide for the needs of your animal must be supplied artificially. It is your duty to provide this and will require specialised products as it cannot be supplied by general household lighting equipment.

UVB has many beneficial effects for reptiles, many of these applying to people as well. It increases pigment production and strengthens the skins barrier function removing fungus, bacteria and viruses on the surface, giving you that feeling of general well-being due to the release of endorphins.

Reptiles convert the components found in sunlight, mainly heat and UVB, through a series of chemical events which produce vitamin D3 in their skin when exposed to UVB light. This is then processed by the liver and kidneys, regulating calcium absorption, along with many other vital bodily functions. These include growth and maintaining a healthy immune system with sunlight or correct lighting. This process is self-regulating and limits the amount of pre-vitamin and D3 being produced. This process is essential to enable calcium to be absorbed from their diet.

This natural limiting effect cannot be achieved if using artificial oil based D3 supplements, normally Cholecalciferol, as excess cannot be excreted by the body as it can with water soluble vitamins. D3 over-supplementation is almost unheard of, using most of the wellknown branded supplements. Artificial D3 levels are difficult to regulate and certain diurnal species cannot utilize them efficiently and will do much better using a UVB lighting system to synthesize their own.

Reptiles need vitamin D3 in order to absorb and use calcium. Without adequate supplies of both nutrients, a condition commonly known as Metabolic Bone Disease (MBD) will develop. Because the feeder insects we use, our animals rarely achieve the digestive goal of calcium to phosphorus ratio of 2:1. This is why we dust our animal’s food with a good quality calcium supplement. Large crickets for example, have a Ca:P ratio of 1:9, which means that if you do not dust your crickets at every feed it can creates a calcium deficit. So, to make up the ratio for digestion, calcium is pulled from the bones making them weak and, in the process, suffering growth deformities and difficulties in movement, feeding and eventual death.

So, we have clearly established that recreating the ultraviolet part of sunlight is very important to reptile health and well-being and to ensure the correct level for our reptiles. How do we measure it, with what and how much do we need for our animals?

We need a device that measures the UV range we are looking for and the Solarmeter 6.5 does just that, measuring from 280-400nm. This hand-,held device has been developed to measure the strength of UV from the sun to help people protect themselves from sunburn, however, this spectrum is very close to the D3 synthesis range, making it suitable for our use. The scale starts a 0 and goes upwards. This has been used in weather forecasting, when sunny, and is expressed as the UV Index (UVI). The higher the UVI the greater the power of the sun, which changes over the course of the day reaching its peak at midday.

As reptile keepers we can use this index to measure wavelengths that let our reptiles produce their own vitamin D3. As our pet reptiles originated from different countries, with many different habitats, they have morphologically evolved to take advantage of environmental niches for the optimal benefit to their species. This means that two different types of reptiles, even from the same area, may still have completely different UV requirements. To help make sense of this, a renowned herpetologist, Dr Gary Ferguson measured different reptile’s daily basking sites and exposure times which gave him a good indication to their natural UV requirements. These species were divided up into four different sun exposure groups, which are now referred to as Ferguson zones. Each zone was allocated a range of figures, calculated from the readings, that were taken from the animals basking UVI. Other researchers have added more data to this study to help create a list of animals that fit into these four zones.

To replicate a natural behavioural pattern, each enclosure should provide a photo gradient with one end using your maximum chosen zone based for your animal’s requirements and the other end of the gradient going down to zero. This will allow for photo regulation, prolonged or partial basking, depending on the habits of your reptile. This gradient and access to full UVI limits should be taken into consideration when building and designing the layout for your enclosure. Also allow for other factors such as mesh top screens or lamp guards, which can reduce light levels between 30-50%, and reflectors which can double the light output, and perhaps, even more in some cases. Using more than one light source you can also add a more natural photoperiod to stimulate more naturalistic activity.,

So now, all you need to do is locate your animal on the chart, or one that closely resembles its behaviour; this will be the zone you need. Taking into consideration the size and shape of your enclosure, set it up around the Ferguson zone, for your basking sites, remembering that the gradient must allow provision to go down to zero, enabling your pet areas to retreat from the light.

You are now armed with all the information you need to provide your pet with suitable UV lighting for a rich and rewarding life. Fuelled with this information you could now go to your local reptile store looking for suitable UV lighting products for your garter snake, for example, which you know is a zone 2 animal and falls into the occasional basker and thermoregulator category.

You are now confronted with words like “high output” or “2.4,5,6,10,12%”! None of this really relates to what you or your animals need! There are no charts or diagrams to show how much UVI will be delivered at certain distances or even which zone to choose. It all very confusing! We, as hobbyists, understand these issues and recognise that it is time things changed.

Reptile Systems, known for their fresh approach, constant research, testing and development, have redesigned all their UV product packing to conform to this enlightened approach to UV provision. It will now be easy to choose, with confidence, the correct values, at given distances including use with or without reflectors, making life easier and better for your pet. We have even added distances that are considered “not safe” either due to very high ultraviolet, heat or visible light volumes. We also recommend a minimum distance of 30cm to prevent ocular damage, unless otherwise stated by your advising reptile care specialist. The question of “which lamp do I need?” has now been answered with our no-nonsense approach, in clearly defined packaging as ‘we create your best solutions’.