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UVB for Crepuscular and Shade-Dwelling Species


Before anything else, I wanted to take a moment to thank everyone for what is now over 4 years of support for this blog. I cannot believe that the little pet project I thought no one would ever read has become a blog that receives a quarter million views a year and that generates an inbox full of emailed questions, comments, and grateful messages of encouragement. Last year I did not write very much due to work and other priorities but this year I am pushing myself to get back into blogging, which I so enjoy. And all the encouragement reminds me that I don’t just write into the void. Thank you again and here’s to another 4 years! Cheers!

Now, I wanted to give an example of how relevant something like proper lighting is to reptiles in general and what an impact it can have on health, even those that traditionally aren’t given regular UVB access. I’ve explained in other posts how important UV lighting is, so in this post I just want to tell you a cautionary tale, as it were, from my time as an intern at the herpetology department of a major zoo here in Florida. This department had several major faults that I will not go into, primarily because this isn’t supposed to be an exposé on what is essentially a department of well-meaning but stifled zoo keepers mismanaged by a barely competent administration, but also because only one story is relevant here; the story of why the dart frogs were mysteriously ill.

It is not apparent to the public, but in this department there were hundreds of dart frogs in little terrariums lining the walls of all the back rooms, the ones not visible to anyone but employees. And among these, there were dozens of Golden poison frogs, Phyllobates terribilis, in various cages across these rooms. Small, adorable, and indeed golden in color, these frogs were an important breeding project for the department. However, over the span of a few weeks some of the frogs had started developing sores on the palms of their hands, on their noses, and on their thighs. The zoo veterinarian was doing everything she could think of; she had them change the substrate in their cages to a more sterile one, and she had them apply an ointment to the sores as well as a topical antibiotic. But none of this worked, the frogs were not improving. The sores stayed exactly the same for weeks at a time.

One morning I was handed a Solarmeter and told to perform the monthly check on all the UV lamps in the entire department, to ensure that UV levels were still appropriate for everyone. Shockingly, many were not. Many lamps read 0, regardless of the distance to the lamp. The lamps had completely burned out. I even checked the terribilis UVB lamps and those read 0 as well. I flipped back through the cage logs to the last time the readings were taken and even a month ago then were practically useless; hovering in the single digits. I immediately changed the lamps. Within a couple weeks the sores were looking much better, and knowing all we do about how UVB and vitamin D assist the immune system this improvement didn’t seem accidental. Management half-heartedly listened when I reported how many lights were outputting nothing at all and why this was bad for immune systems and over-all health, but I am unsure if any moves were made to ensure this never happened again either.

I recently contributed to an article for Swell Reptiles regarding UV access for all species, including those that traditionally have not been given UVB lamps. In the series of articles they discuss Ferguson Zones, four different zones that categorize reptiles and amphibians from those needing the least UV exposure (Zone 1, crepuscular or shade-dwelling animals) to those that bask in the mid-day sun and have the highest requirements (Zone 4). It is argued that even species like dart frogs, which traditionally are heavy shade-dwellers, need and receive low levels of ambient UVB exposure throughout the day and as such should be provided the option to bask under a gentle UVB light in part of the enclosure. I myself have observed some dart frog species basking in speckles of sunlight on the rainforest floor in Costa Rica. The appropriate level of UVB is such an easy thing to provide and it can have such a powerful effect on the immune system and overall well-being of the animal in question, even for animals that appear to be doing fine with their current set-up.


Check out the article and the series on UVB exposure here:

Consider adding UVB to species that have traditionally been able to “get away” without having it and see what the health benefits might be. And for species we know need UVB, such as chameleons, always stay on top of the age of your UVB bulbs, replace them often, and (with the assistance of someone experienced, if needed) make sure you buy the strongest bulb possible with the appropriate UVB output for your specific species. If natural sunshine time is possible periodically, then excellent! Provide different areas of shade and open exposure so that your pet can regulate their own heat and UVB needs appropriately. Don’t be like the zoo above and let the lights deteriorate beyond the point of being useful or look into all husbandry parameters when a health issue pops up.

I myself will be adding low-level UVB lights to my crepuscular/nocturnal geckos (crested geckos and leachianus geckos) to observe for myself what Dr. Gary Ferguson has said in his zone research; that even species that traditionally have not been provided UVB can benefit from access to it. I will write more on the subject once I have everything set up and allow the geckos to live with access to this new light source for a few months and see if I see any improvements in health, growth, and breeding habits. What do you think about this idea to provide crepuscular species with UVB? Have you tried this? I would love to hear what others think about this, either in theory or from practice. 

My adult male Nuu Ana Rhacodactylus leachianus gecko, or Leachie for short. 

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