# Question about sunlight absorption in birds...



## Pigeonpal2002 (Jul 27, 2002)

Hello everyone, 

I have a question that's been bugging me for a long time now but I couldn't find the "appropriate or easy" answer to this question, even when I looked on google.

My question is, how do birds absorb UV light from the sun and synthesize it into Vitamin D(3) like they do? Humans have large areas of skin that allows us to gain positive effects from natural sunlight, but what about birds and furry creatures...how do they "absorb" natural sunlight and turn that into usable vitamin D? I've read that there are special and specific light sensitive "receptors" located on the eyelids of birds that "tell" their brain when they are benefiting from the sun and therefore are able to produce vitamin D(3) specifically. To me, and otherwise though, sunlight would be "lost" in their feathers. How can an essentially dead organ collect, store and reproduce vitamin D? The feather follicle is "dead" and only if not a blood feather, these modified scales cover the entire bird in most species. Do the feathers and even though they are "dead" tissues still absorb the UV rays of the sun and metabolize the vitamin D(3) through the shaft and into the skin????

I hope someone can enlighten this clued out, but very curious bird lover.


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## pdpbison (Mar 15, 2005)

Hi Brad,



...primarily through their Eyes if memory serve...

Ceres and Nares might play roles also...


Too, one sees them lay on their sides and hold a Wing up so the inderside of the Wing is getting Sunshine, or they lay in other positions for Sunning themselves, and I have wondered why they do this?



Phil
Las Vegas


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## Reti (Jul 20, 2003)

Brad, I am glad you brought this up cause I have been wondering about the same thing for a long time now. I tried too to search in books and on the web.
The eyes don't seem enough for sunlight absorbtion, maybe the feet? But what about the birds with feathers on the feet?
I know rabbits and nocturnal animals do not need sunlight.
My vet specifically told me about the rabbits and my hamster, but didn't know about birds.
Hope someone knows.

Reti


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## pdpbison (Mar 15, 2005)

Hi Brad, Reti, all...



Most Mammals are just as covered by Furr, as Birds are by Feathers...

People are the exception in Mammalhood, as for being only very thinly hair-covered in very very 'fine' thin hairs which make us ( most of us anyway, ) appear more or less hairless/furrless/depilitate but for some certain areas...

Probably a Bird's exposed Legs and Feet and Toes, Nares and Ceres, Eyelids and Eyes themselves, however exposed they are for any individual, play the absorption roles for Vitamine D making, when allowed to be exposed to direct Sunshine...


But overall, almost no one Mammal wise or Avian wise, has anything much BUT their Eyes, Lips, Eye lids, or whatever other small areas which allow for exposed 'skin' or specialized skin, even if in areas of 'thin' covering, for direct Sunshine to encounter.

Most Mammal Noses and Lips are darkly pigmented also, possibly as a defence against too much Sunshine effecting them adversely.


Darkly pigmented skin, in blocking the UV and ancillary wavelengths of Light, does not figure into Vitamine D making as effeciently as does lightly pigmented skin.

'Black' people in Northen climes are laible to be Vitamine D defficient when getting the same amounts of direct Sunshine as 'White' people...while no one swo far as I know in any clime tends to make too much Vitamine D, even pale people working out doors in decidely Sunny climes of the Tropics or deserts.


The 'Eye', ultimately, is a highly specialized grouping of 'Skin' Cells.


Evidently, no one actually needs a great deal of such direct Sunshine for their Vitamine D making, but they will need whatever for them is 'enough'...species-wise, or individual wise.


And all the various Creatures seem to manage well with only their very small areas of exposed skin, for doing so.


Phil
Las Vegas


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## Pigeonpal2002 (Jul 27, 2002)

Thanks Phil and Reti, 

I guess it would seem that it's the eye lids and other small areas where birds are not feathered that allows them to make use of the sunlight. I know when my birds are outside sunning that they tend to squat a lot so their feet are covered...this isn't make things easier.  

I really wish there was more literature and information about this topic though that one could research.


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## Maggie-NC (Jun 22, 2005)

You know, Brad, I kinda think they do get sunlight through the feathers. If you notice birds sunbathing, they spread their wings out. Just a thought.


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## pdpbison (Mar 15, 2005)

Lady Tarheel said:


> You know, Brad, I kinda think they do get sunlight through the feathers. If you notice birds sunbathing, they spread their wings out. Just a thought.



Hi Maggie,


They might do this because it simply feels good, or, maybe, because the UV or Actinic wavelengths will adversely effect Feather Lice or other small exoparisites...but I would not think that this would be a gesture related to Vitamine D making...or that the Sunlight penetrates very much into or through the Feathers...unless their Feathers are poofed-out and the Sunshine enters in-between the spaces to somehow shine on their Skin...


Phil
Las Vegas


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## Flying_Pidgy (Apr 26, 2006)

I would like to add that they dont only open their wings, they also spread their tails. here is a picture of one of my IHF tumbler sunbathing.


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## george simon (Feb 28, 2006)

*Hector F DeLUCA*

Hi Brad, First I check one of my books "PIGEON HEALTH AND DISEASE" by David C Tudor. In his writings on vitamin D he named DeLuca as having done some work on vitamin D in animals so I googled DeLuca over 300,000 refrences to DeLuca.after rooting around for over an hour is what I found. VITAMIN TOLERANCE OF AMINALS a work by DeLuca.the thing that I found intresting is that mammals absored vitamin D by using their lymphatic system while birds and fish use their portal circulation system(I have no idea what the portal system is) BUT I FEEL THIS JUST MIGHT BE THE KEY. I will see what I can find out about the portal circulation system. .GEORGE


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## Pigeonpal2002 (Jul 27, 2002)

Thanks George for the information....if you find any more information, please let us know. Thanks for your input Maggie and Flying Pidgy....who knows how they do it really. This is why I asked the question.


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## NitaS (May 26, 2007)

You're birds are absolutely beautiful!!!


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