Category: lighting

UV myth #6: Windows block all UV light

UV myth #6: Windows block all UV light

There is disagreement about what effect windows have on UV light. However, this is something that can be easily measured with UV meters. The end result is that windows only partially block UVA light, while completely blocking UVB light.

Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm.

Ultraviolet—Wikipedia

Below 330 nm (UV-B and UV-C), almost 100% is blocked by normal glass

UV FAQs—International Ultraviolet Association

Note: If your windows have a special UV coating applied to them, then you should check with the manufacturer to see how it would affect UV light.

The conclusions from this:

  • UVA, the type of light known for enhancing bird vision significantly, is only partially blocked by glass. This means that putting a bird in a room with abundant light coming through windows could have a great impact on their lives.
  • UVB light is blocked by glass, so there is no Vitamin D benefit from being in a sunlight filled room with closed windows.
… READ THE REST
Case study of “How do I know who to trust?”

Case study of “How do I know who to trust?”

I wanted to provide an example to back up what I wrote about in How do I know who to trust? I wish I could say it’s easy to spot misinformation, but it does get easier over time.

I could’ve picked any number of articles, but I chose this one to illustrate how I determine a trustworthy source.

Proper lighting to support avian vision

On the plus side

  • It comes from a seemingly credible source, one of the largest bird rescue organizations in the US
  • Clearly a lot of effort was put into writing a very wide-reaching article that is presented and formatted nicely and with images

On the minus side

This article has a number of obvious red flags to start off with:

  • No author is listed as well as no contact information
  • No sources are cited for an article that is highly technical and critically important to bird health

Analysis

Now I’m going to go through the article and quote some bits of it and explain the concerns that I find.… READ THE REST

UV myth #5: Diet is better than sun for Vitamin D

UV myth #5: Diet is better than sun for Vitamin D

It’s commonly thought that diet is the optimal way to ensure that birds get the right amount of Vitamin D. It turns out that you can end up with too much or too little Vitamin D with diet alone and adding sunlight or UVB lighting is your best option.

Note: The research for this post mostly come from one article in a scientific journal, but it collects research from 69 sources so it’s pretty comprehensive.

There are two ways to get Vitamin D:

  • Supplementation, typically in food
  • UVB from sunlight or artificial lighting

Hypovitaminosis (low Vitamin D)

Low Vitamin D can lead to all sorts of problems. Birds can even get rickets!

Although vitamin D is critical to calcium/phosphorus homeostasis, bone formation and remodeling, there is evolution-based variation between species in vitamin D metabolism and susceptibility to rickets and osteomalacia.

The pathology of vitamin D deficiency in domesticated animals: An evolutionary and comparative overview—International Journal of Paleopathology—December 2018

And here it’s noted that sunlight or UVB supplemention are in some cases required to have adequate Vitamin D levels.… READ THE REST

UV myth #4: Full spectrum bulbs contain UV light

UV myth #4: Full spectrum bulbs contain UV light

When recommending avian lighting, the suggestion is often that you should buy a full-spectrum bulb. However, if you are wanting UV light, a bulb labelled as full-spectrum is unlikely to put out any UV light at all.

The term “full spectrum” doesn’t have a strict definition when it applies to light bulbs. Wikipedia clearly explains the difference between full spectrum and full-spectrum lighting.

Full-spectrum light is light that covers the electromagnetic spectrum from infrared to near-ultraviolet, or all wavelengths that are useful to plant or animal life; in particular, sunlight is considered full spectrum […]

“Full-spectrum” is not a technical term when applied to an electrical light bulb. Rather, it implies that the product emulates some important quality of natural light.

Full-spectrum light—Wikipedia

More importantly, use of the term is not regulated nor is there any kind of certification organization. So, when you see full-spectrum on the box for a light bulb, it is typically one of four options:

  • The manufacturer is misusing the term for marketing purposes when the bulb has no full spectrum qualities at all
  • It’s a bulb that only spans the visible spectrum
  • It’s a bulb that includes visible spectrum and UV-A
  • It’s a bulb that includes visible spectrum, UV-A, and UV-B

Sadly, the term is meaningless.… READ THE REST

UV myth #3: UVB light will lead to cataracts

UV myth #3: UVB light will lead to cataracts

There is a lot of misinformation out there about UV light and how it affects birds. Here’s one of them.

UVB light will cause cataracts

Let’s look at the different sounces of light.

Natural light

As with almost anything, even water, too much of a good thing can become a bad thing. There is pretty solid agreement that exposing a bird to 5-10 minutes of direct sun is beneficial to them. Here is one source that indicates that the risk for cataracts requires more exposure.

[…] It has been surmised that in July at noon at 40° latitude […] lens damage due to UVB exposure would take 245 hours, but the cornea could potentially be damaged in 23 minutes of direct exposure.

Vitamin D and Ultraviolet B Radiation Considerations for Exotic Pets—Journal of Exotic Pet Medicine—’Oct 2014

Note that it says potentially. Like many things, you may need to weigh the health benefits of sunshine and fresh air against a very low to zero chance of a problem.… READ THE REST

UV myth #2: Exposed skin needed to synthesize Vitamin D

UV myth #2: Exposed skin needed to synthesize Vitamin D

There is a lot of misinformation out there about UV light and how it affects birds. Here’s one of them.

Only bird species with exposed skin can synthesize Vitamin D from the sun

Vitamin D synthesis in humans begins when UVB rays from the sun are absorbed by the skin. Some people make the argument that birds don’t have exposed skin (some have a little), therefore they get no Vitamin D benefit from the sun.

It’s kind of an amazing trick, but when your bird preens, s/he may be kicking off a process that ends with producing Vitamin D.

The secretion of the tail gland contains 7-dehydrocholesterol. After the secretion has been spread over the feathers by the beak, this compound is converted by ultraviolet light to provitamin D3, which is in chemical equilibrium with vitamin D3. Hence if exposed to sunlight, birds are able to synthesize vitamin D3.

… READ THE REST
UV myth #1: Any UV light can stimulate Vitamin D

UV myth #1: Any UV light can stimulate Vitamin D

There is a lot of misinformation out there about UV light and how it affects birds. Here’s one of them.

Any ultraviolet light can cause a bird to synthesize Vitamin D

There are actually two relevant types of UV light: UVA and UVB. Most articles about birds and lighting don’t specify with type and just say “ultraviolet” light.

So, first let’s establish that it’s UVB light that is required for Vitamin D synthesis.

During exposure to sunlight 7-dehydrocholesterol in the skin absorbs UVB radiation and is converted to previtamin D3 which in turn isomerizes into vitamin D3.

Sunlight and Vitamin D: A Global Perspective on Health—Dermato-Endocrinology—’Jan 2013

UV light causes the body to produce vitamin D (specifically, UVB), which is essential for life.

Ultraviolet—Wikipedia

In humans, both UVA and UVB are responsible for secondary effects on the skin such as erythema (sunburn) or tanning, but UVB is the only range associated with the photobiochemical synthesis of vitamin D3.

… READ THE REST