Heating
Coming from an arid, hot environment where temperatures frequently exceed 35C in the spring and summer, one might assume this snake and others from the region require high temperatures in the terrarium. Furthermore with the advent of the internet it has become vogue to refer to climate and annual temperature charts when deciding on how to heat reptiles - and this is informative to an extent. However a climate data mapper six feet off the ground will not be recording the exact microclimate that reptiles will be exposing themselves to, nor will points on a graph tell us anything about how a reptile is using its time in the wild - so it is wise to appreciate that very few reptiles are going to be exposing themselves to the extremes of heat in the desert, and instead their lives revolve around being active in the cooler periods also.
Diadem snakes forage mainly at night and, while they do enjoy basking and are frequently seen doing it in the morning and early evening, avoid the heat of the day. So we can safely ignore the extremes of heat found in the desert in favour of not cooking our poor snakes in their terrarium!
During the day, I provide my Diadem snakes with an ambient temperature of around 22C at the cool end to 25C at the warm end. This is facilitated by having long terraria with plenty of ventilation points. Further, a basking zone is provided using low wattage (20w) halogen bulbs at the warm end, shining down onto a flat stone or tile to create a warm surface that can reach 35-40C. As long as this temperature is localised only to the surface under the basking lights and the snakes can easily move on and off it, this is fine. In fact the snakes will usually bask for some time in the morning and then move away from the very warmest area.
Halogen lights are eminently suitable for this task as they heat the surface beneath them more than the air around them and their provision of near infra-red radiation (IR-a), which is not provided by other types of heating element, penetrates the flesh of the animals more deeply and activates the mitochondria in their cells. This is particularly important for reptiles as they only have around half as many mitochondria as warm-blooded animals and may serve to explain why they often seem so much more active under true sunlight or light that includes IR-a.
Where one 20w light does not provide enough heat, or a basking area large enough for the snake, I prefer to use a second 20w bulb rather than upping the wattage. This keeps the heat relatively gentle and expands the size of the basking zone.
Ceramic Heat Emitters (CHEs) and reptile radiators do a better job of heating the air around them but I find them of more limited use in the relatively small terraria likely to be used for snakes like this, and it becomes much harder to provide a good thermal gradient across the enclosure. In my opinion such heaters are better served as space heating in larger enclosures for tropical animals that require more constant temperatures, rather than small desert reptiles where temperatures will fluctuate considerably during a 24 hr period.
During the spring and summer periods, I leave the heaters on for 14 hours a day, from 07.00 to 21.00, in synch with the fluorescent lights. In the autumn I begin cycling down the heat until it is 12 hours on, 12 hours off in preparation for cooling.
A small heat mat set to about 25C with a thermostat can be provided which can stay on throughout the night if required, to simulate residual heat on rocks and roads. My reptile room remains at 22-23C at night and so I rarely use this. Otherwise, I switch off all heating and lighting at night and this is sufficient - temperature drops quite considerably at night in the desert. Night temperatures can drop drastically, especially in inland areas of the snake’s range, although I would suggest providing a gentle heat mat if temperatures in the home drop below 20C at night during the spring and summer at least.