Photogradient

From UroWiki

Similar to the temperature gradient, in which the ambient air or basking surface temperature ranges from hot to cold at opposite ends of the enclosure or on a basking platform, your uromastyx also requires a photogradient. This is where the lizard is able to reach different gradients of UVB from the UVB-producing bulb(s)and non UVB-producing heat sources, which it can move into and out of at will, in order to take in the desired amount of UVB radiation for D3 synthesis and still be able to get up to temperature. You should set up your basking spots and position your UVB and non-UVB heat sources accordingly to allow for this layout. UVB/UVI meters such as Solarmeter 6.2 or 6.5 are recommended. You must ensure that your uromastyx can reach sufficient UVB gradients throughout most of the photoperiod.

Enclosure layout

Many will use self-ballasted Mega Rays and halogen floods or reptile basking bulbs. It may be stressful if the lizard has no other choice but to bask under strong UVB/UVA-producing bulbs, particularly mercury vapour bulbs. If using a self-ballasted MVB as the sole source for UV and heat, a large low dark hide (made from slate and bricks) directly under the bulb that reaches basking temperatures inside is a must, and may alleviate stress. The uromastyx will be able to get out of UV exposure and still reach basking temperatures to digest its food under the hot hide (thermometers and infra-red temperature guns are a must). A cool hide in the same fashion is also a must to allow the lizard to cool down; this hide and a large area around the hide should be 80-85'F (27-30'C). Secondary basking sites without UV or with much lower UV are recommended.

These secondary non-UVB light/heat sources do not have to be completely separate from the UVB bulb for the animal to benefit. Typically, this can only be done in larger enclosures where space permits. Just as a mammal thermoregulates its body, lizards also photoregulate themselves - if the lizard has enough D3 produced in its skin and in its body through adequate UVB exposure, it can still get up to basking temperatures under halogen flood(s) and/or incandescent heat lights.

Avoiding the photogradient

If you notice your uromastyx hiding for extended periods of time and/or will not bask under the UVB-producing bulb, it could be for a variety of reasons including:

• basking area or hot end ambient temperature is too hot
• basking area or hot end ambient temperature is too cool
• UV bulb is too strong/too close
• the lizard could be suffering from parasitic infection or illness
• brumation
• dehydration

Psychological considerations

CHEs and heat projectors are not recommended as the sole basking spot heat sources, as uromastyx also require high lux levels for their psychological well-being, and heat-only sources should only be used to boost the temperature if the heat bulbs are not hot enough. Thermostats are also recommended to keep basking and/or ambient temperatures stable. As uromastyx like to bask under high lux full sunshine, keepers should try and mimic this with lighting from above as heat sources.