Natural Sunlight

[empire3569]

I have heard that natural sunlight is one of the best things for a bearded dragon? I have a large outdoor enclosure for mine (it has a the necessities like climbing and a place to get out of direct sunlight) that they stay in for about 6 hours a day. My question is if they are outside for this long and getting natural sunlight do I need a UVB bulb for them when they are inside? Thank you for any input!

 

[MAK]

They need uvb for 10-14 hrs a day, so I would say yes you still need a uvb inside.

 

[empire3569]

Even in direct sunlight? I thought I remembered someone saying on a different thread that just an hour outside in direct sunlight would be enough UVB exposure for an entire day. These are my first bearded dragons I don't want to sound annoying just curious

 

[BadCon]

Even in direct sunlight? I thought I remembered someone saying on a different thread that just an hour outside in direct sunlight would be enough UVB exposure for an entire day. These are my first bearded dragons I don't want to sound annoying just curious

You are correct. UVB exposure, like most radiation exposure, is cumulative, so a few hours of high UVB exposure is roughly equal to 10hrs+ of low UVB exposure. Under a low output fluorescent tube they'll need almost constant exposure throughout the day. Outside however, they need far less exposure. Depending on your location and the levels of UVB, that exposure could be as little as an hour a day.
This is also why a fluorescent tube needs to be roughly 3/4ths the size of the tank, while an MVB can make do with just providing UVB to a small area. The overall levels are much higher with an MVB, so the dragon needs less time underneath it, which is not the case with a fluorescent tube. Mind you, this doesn't take into account the reliability and safety among certain bulbs...and I don't say this to imply that an MVB is a better alternative (recent history has shown they are not).
Here are some numbers to chew on. At typical basking distances, a Reptisun 10.0 will provide roughly 25-50 uW/cm2 of UVB. A sunny summer day in much of the southern United States may see levels creep over 250 uW/cm2 (around noon). If your dragon was outside basking during this time, he'll be exposed to more UVB in 1hr then he would get in roughly 4-8hrs under the Reptisun (depending on the levels in the enclosure of course). So you can see how just a few hours outside can easily equal a full days worth of exposure under a linear fluorescent UVB tube. This is also the reason why vitamin D3 is supplemented for dragons raised under such lights indoors, whilst D3 is not recommended for those living outdoors or even under MVB's.

Now, outside UVB exposure varies with location and season, but its usually always the case that if its warm enough to leave your dragon outside then its a good bet that the UVB levels are higher then anything a reptisun would emit at the 6-8" recommended basking distances. Anyone looking to really learn all they can about their lighting setup, I recommend they get a UV Index meter and a UV-B meter. With these two meters you'll be able to determine precisely whats needed for your dragon (inside or out).