How many hours of natural sunlight does my tortoise need daily...?

[theelectraco]

I live in Southern California and the weather has been pretty nice lately, staying in the mid 70s most of the earlier part of the day. I have been keeping my red foot tortoise outside in its temporary outdoor enclosure for 3 hours a day, and with the weather suppose to be staying pretty nice since its spring, I'm wondering if 3 hours a day in sunlight is enough for me to discontinue using my UVB bulb in its indoor enclosure. I think it is, but I would like others opinions.

 

[Madkins007]

As best we can tell, an hour or so a week of good quality sunlight, spread over about a week, is enough for proper vitamin D3 metabolism. In the wild, tortoises get plenty of UVB without getting too much heat or exposure to enemies and spending most of the day in some sort of shelters without actually basking- although this species basks in the wild, usually after a cool spell or period of clouds or rain.

 

[Tom]

I have found 15 minutes, twice a week is enough to prevent MDB in any reptile, including tortoises. I think more is better, but this is the base line I use. Its not quite so simple though. In winter my reptiles will often go 2-4 weeks with zero sunshine and no indoor artificial UV producing devices. They are all fine and this causes no issues. Most of the year hatchlings get an hour or two and older ones are out all day most days.

I would think a red foot would need even less.

 

[theelectraco]

Thank you!

 

[Levi the Leopard]

In winter my reptiles will often go 2-4 weeks with zero sunshine and no indoor artificial UV producing devices. They are all fine and this causes no issues. Most of the year hatchlings get an hour or two and older ones are out all day most days.

I'm the same... a few hours outside daily on average, but longer spells during winter where my leopard is indoors, no artificial UV lighting.

 

[theelectraco]

What I am curious about is in the winter, if they are not exposed to any UVB, are they able to absorb calcium?

 

[DeanS]

What I am curious about is in the winter, if they are not exposed to any UVB, are they able to absorb calcium?

That's the key...I don't care how cold it is...if there's sunlight...they're out for at least a 1/2 hour...I can't remember a day they didn't catch at least an hour...except for days of NO sun. The answer is NO...they need some UV to utilize calcium...and powdered D3 is crap!

 

[Tom]

What I am curious about is in the winter, if they are not exposed to any UVB, are they able to absorb calcium?

On the days where they get sunshine, vitamin D3 is manufactured in the skin and then stored in fatty tissue and some organs. Then on cloudy days the tortoises body will pull D3 from the tissues as needed.

The trick is: How much D3 does a tortoise need on any given day and how much is stored in the blood and other tissues? At some point every tortoise will run out of stored D3 and will need to make more. One of our moderators keep her tortoises outside all summer long and then as the weather gets too cold, she moves them all indoors. She goes all winter long with no artificial UV and then puts her tortoises back out in the sun when spring arrives. She's done it this way for years and her babies grow up smooth and healthy. Mine only go for a week or two at a time over winter between sunning sessions, and I see no discernible ill effects.

Unlike my friend Dean, I do not put my babies outside when the temps are cold. My standard is "t shirt" weather. I'd go lower than that with temperate species like a Russian or a Hermanns, but not for a leopard or sulcata.

There is debate about whether or not tortoises or other reptiles can actually use dietary D3. I have seen nothing that convinces me they can, and one study that showed that green iguanas can't.

 

[GeoTerraTestudo]

and powdered D3 is crap!

Really? My Russians get plenty of sun in the summer here in Colorado, and some in spring and fall, too. But of course, they are never outdoors in the winter. Their indoor enclosures do have UVB and heat, so hopefully that helps them synthesize some vitamin D3. But I supplement their diet with calcium and D3 about 3x per week. Is that not helpful?

As for redfoots, being forest tortoises, they don't bask as much as open-land tortoises, and therefore get much of their D3 from food.

BTW - The nice thing about D3 is that it's fat-soluble, meaning that you can store up on it during the warm season, and then use your reserves during the winter. Of course, it's better to keep producing and consuming it. Also, the fat solubility of D3 is why it is possible to overdose on it - not from basking, but from ingestion.

 

[pspryu101]

I usually leave mines nowadays with these nice weather outside all day till about an hour before dawn then i take them back inside in their indoor enclosure