Years ago I discovered that 365 nm light caused fresh eggs to fluoresce. The fresher eggs were a bright red which dulled as the eggs aged. I suspect this is due to oxidtion or it could be the natural UV light in sunlight although many eggs are laid in dark places.
I picked up this very fresh peacock egg last night and took cell phone pictures with while and UV light. The colors with UV were actually much more brilliant that the photo shows but I didn't correct the photo to try to show the true color.
I first discovered this by wandering around in the woods with a UV light to see what glowed, and saw a red glow under a cove of brush. I now use this method when examining a found nest of guinea eggs to gather the freshest for incubation while leaving the older eggs to encourage the hens to keep laying in the same spot. Brown eggs tend to fluoresce as well but not as brightly.
Interesting. Never though to try an egg under the light. I bought one of the little Chinese UV flashlights (unknown specific wavelength) to use for sanitation inspection purposes and found that a lot of everyday products are well-dosed with fluorescent dies -- the laces on a pair of trainers I have are enough to light up the room under the UV.
I just checked a chicken egg from the fridge and it produces the same color although not super bright. Maybe it is the calcium carbonate's native wavelength? I guess that if the brightness is an indicator of freshness I might have to have an omelet for supper tonight.
neat and unusual observation especially that the fluorescence is red not blue. Organic stuff on shell would be more commonly blue.
Some calcite (the mineral in crystal form) (egg shell is calcite) fluoresces red when it has the the correct impurities (I don't know what they are, U?). You say you worked at Oak Ridge.....bring anything home for the chickens.......?
At the time I discovered this I did an exhaustive search of the internet and asked numerous people and none had every heard of it. The chances of me discovering something new were so slim to be close to zero but who knows. Several years later I finally saw a reference to fluorescence of eggs and I found this from March 2018: "The red glow, or fluorescence, of eggs under a UV light is due to a particular molecule found in egg shells. This molecule is protoporphyrin IX (PPIX). PPIX is a precursor of haemoglobin, the pigment that gives our blood (and that of chickens) its red colour."
However, I found nothing that suggested the degree of fluorescence decreased with time, or oxidation, or exposure to light or something. So until then, I claim original discovery.
Note that UV lights are commonly available in 365nm and 395-400 something wavelengths. The 365 are FAR better for detecting fluorescence in wood for ID purposes. Good 365nm lights are also more expensive, I paid over $100 for one. The others are far too much towards the visible spectrum and have too much white in them to be useful. But they are a lot cheaper and are useful for some things.
As for what birds can see, I have only this anecdotal information: I gave a cheap UV light close to 400nm to a friend with a variety of birds. She reported that the peacocks, guineas, and various chickens exhibited bright colored markings under the light, invisible in white light. From this I inferred the birds could see that wavelength. I rushed out with my expensive 365nm light and saw NONE of this on any of my birds! This implies the spectrum the birds can see may not extend to the shorter wavelengths. I still have a few of the cheap "worthless" lights I have yet taken out at night to test this.
As for how far the lights are effective - just take a walk in the woods with a good 365 nm light. Those big striped millipedes you see under logs and rocks? They are crawling EVERYWHERE at night. Under UV they glow brilliant green and are visible for at least 20-30 feet away. It's a great adventure for a kid to look for these! I also see a lot of fluorescence in certain fungi. No help with hunting for morel mushrooms! Tried that.
As for wood, I've posted this before. Lots of species fluoresce. A couple of the brightest are redheart and black or honey locust. The fluorescence of locust is a perfect way to distinguish it from some look-a-likes.
BTW, if looking for a good UV light, I just bought an inexpensive one as a test. It had good comments. Came yesterday and I think it's a winner for the price. Two brightness settings, uses either a single 18650 rechargable battery but should also work with two CR123 lithium batteries, at least those are interchangeable on some of my other lights.
I bought one for about $7 and it was great, a good 365nm but not real bright. So I ordered some more. They were terrible - the Chinese company had switched LEDs and the newer ones had way too much white light and were worthless for wood ID. Who knows what they are shipping now.
For the past couple of years I've been working on photographing the moths down around my cabin and out on some of my trails that I frequent on my photo safaris.
I was considering some AC powered for under the cabin, but not wanting to invest in that because I'd rather be able to use it around some of the other various habitats. I guess Ill need to do a bit more research to see what wave length moths are attracted to.
Have you used your lights with any of the UV cure adhesives?
The role of protoporphyrin IX in egg color was first described in the 1930's. I suppose it was known that this compound is fluorescent well before that. But I could find no studies on egg age and the amount of this compound in the shell. It may be that this compound is readily air oxidized and hence it goes away over time.
To get fluorescence the molecule must be big and relatively flat like a plate. This molecule fits that description. Fluorescence involves the molecule absorbing light, some molecular mumbo jumbo as the energy of this light gets redistributed in the molecule and then an emission of this energy as light at a longer wavelength. In this case light at 400 nm wavelength is absorbed (ultraviolet) and reemitted as reddish light.
Unfound is why birds put this stuff in eggs to begin with. Could it be an antioxidant?
protoporphyrin IX is closely related to hemoglobin. Is blood fluorescent?
I have bought two "Pee" houses at foreclosure. (You don't get to preview them, so you get what you get.) One was unbelievable, the neighbor later told us the owner had left her dogs shut up in the house for months and would stop by occasionally to feed them. A dog's got to do what a dog does. The second one was less so. I got a cheap UV light to search for the urine. Had to have total darkness and the florescence was weak, not much help. I found a couple of chemical sprays that helped kill the odor. Now I wonder if a better light would have helped significantly? Hope I never need to find out. Dried urine will fluoresce.
Interesting that the first linked light lists resin curing as one of its uses. I'm assuming that this is the same sort of resin used in dentistry. If so, this light is putting out some really serious radiation. I've added it to my personal Amazon wish list in case I ever get bored enough to start playing with such stuff again.
Eggshells are amazingly complex structures. Much more than just the signature rigid calcium shell. Hemoglobin degradation products to heme, porphyrins and who knows what else are excreted into the cloaca which is the common outlet for bile, urine, stool and of course the emerging egg. Bile pigments appear to be important in eggshell colors. Visible indicators of this are naturally colored eggs.
Eggs start out white. Brown pigment seems to be incorporated late in shell formation with color on the outside and not the inside of the shell. Blue shells as seen in canaries, robins and some species of chickens is added early with the blue color found throughout the shell. Why the color differences and timing difference??
Some of this is known and much remains a question.
My point is that there must be loads of potentially fluorescent compounds and trace elements in addition to the visible colors that bathe the forming shell and get incorporated into it.
I used to think I knew some of this chemistry but it has gone far beyond my ability now. Its a G.O.K. [God only knows].
Asked friend at lunch about the loss of color over time. He thought that molecule would be stable in air. So, no ideas about why fluorescence fads. It was my understanding from reading about this compound in eggs that it caused the color in brown eggs. So if it decomposed over time the egg color would change and I think it doesn't.
the fluorescence is red, not ultraviolet. Ultraviolet is absorbed, red emitted. an interesting experiment would be to see if the egg color is different in sun light which has reasonable 395 nm light vs indoor light which will have none, ie does fluorescence contribute to egg color in sun light?
>>>does fluorescence contribute to egg color in sun light?
I can detect no difference in fresh and aged eggs of the same apparent color in sunlight or artificial light. There may indeed be fluorescence but the white and especially the green our eyes are most sensitive to are overpowering. I cannot detect any red with my most powerful UV lights except in reduced light environments.
An interesting sideline - I make wooden decoy eggs to encourage hens to keep laying eggs in both nest boxes and outdoors in the woods while I steal eggs to incubate. Twice so far, once yesterday, a peahen got broody and started trying to incubate the wooden egg! When this happens I feel guilty and pull an egg or two from the incubator and put it back in the nest and remove the wooden egg. The last time the hen hatched two chicks and was a very happy hen.
A friend suggested that if the birds could see the fluorescence I might consider painting them with a paint that fluoresces.
I use small guinea-egg-sized wooden eggs in nests I find in the woods. The crows here have become adept at locating the nests and eating the eggs, wiping out 30 or more eggs in one day. The guinea egg shells are too hard for them to break so the crows carry them high in the air and drop on my gravel driveway then swoop down to eat the insides. Once a nest with 6 eggs was empty just one hour after I checked it, including the wooden egg. A search found the wooden egg in the driveway, apparently dropped numerous times. I can here it now "hey Charlie, check this out - this is the toughest one yet!"
The peak absorption for that molecule is 395 nm. If that compound is the origin of fluorescence then a long wavelength UV light will be best for exciting it.
People that ask if XXX can detect fluorescence don't understand fluorescence. Nothing can detect the phenomena of fluorescence. Arriving with no prior knowledge one could not tell if the egg was red from red pigment or the egg was red because it was fluorescing red. The observation is simply color. The correct question would be can XXX detect red. One concludes the egg fluoresces red by doing an experiment.
(above is not strictly true because fluorescence would have a spacial signature that would be distinctive if one knew what to look for)
>>>I would be devising some sort of crow killing device. A trap in a decoy nest might work.
I thought of that and dismissed it after thinking some more.
Case in point: I tried a standard raccoon-sized live trap. I first placed guinea eggs in the back. I caught a guinea. I moved some eggs up to the middle. I caught another guinea. I suspect some killing trap would also kill guineas.
I put one egg outside and one just inside the opening with some more eggs in the back. Those easily reached were gone in hours, the other's not touched.
I saw where crows were in the process of taking eggs from a nest. I hid in a blind (behind heavy brush) and waited for an hour with a shot gun. No sign of a crow. Put the shotgun back in the shop and walked back to the nest. The remaining eggs were gone.
Maybe some sort of elevated trap that won't harm other birds would work. Or a drop net or spring-loaded net that will trap the bird, hopefully the crow, and let me release guineas and peacocks unharmed.
The best defense is to find the nest early and remove a few eggs a day for incubating until the crows find it and take the rest. I've hatched 100s of guineas this way. The tricky thing is the extensive surveillance and detective work needed to locate an active nest.
I've protected nests several times and let guineas incubate a nest and hatch the keets but it never worked out well unless I snatched them up immediately and put them in a brooder. Every time something would get all of the little ones within three days or I would find them dead on the ground. A guinea expert said the climate here is too damp in the mornings to for baby guineas.
If serious about raising guineas for sale the alternative is expensive and a lot of work - build cages or buildings and keep the flock inside and safe from predators and where the eggs are easily collected. However this negates the reason to have guineas - to free roam, entertain me and guests, and spend all day eating bugs, ticks, and baby venomous snakes. And I'm not interested in selling them - I give away all I don't want to raise for myself.
>>>Asked friend at lunch about the loss of color over time. He thought that molecule would be stable in air. So, no ideas about why fluorescence fads. ...
His guess is as good as any, I guess.
Another observation: eggs which are partially embedded in the ground fade quickly on the exposed surface and fade slowly on the embedded surface.
I devised a simple experiment today to test for oxidation which I may try when time allows. Acquire fresh eggs that fluoresce nicely. Put one in a sealed jar and displace the air with nitrogen. Put one in a sealed jar and displace the air with oxygen. Put both in a dark place. Compare to a control left in air in a dark place and one left in daylight.
Another set of eggs left exposed to air could provide more info - one exposed to daylight outside, one to a non-uv light source inside, and one to a strong artificial UV source. I have a 25w 110v UV germicidal lamp.
The only significant cost for these experiments would be the loss of breakfast.
If you have children about I would be pleased to judge this experiment at a science fair. Novelty alone would raise it to 1st place.
Not unreasonable the fading could be photooxidation. A good way to do light experiments with a control is to tape with black electrical tape the control area. This control would also make it easier to see any small changes in overall egg color (what I do for wood and wood finish color changes upon exposure to light. )
