Ultraviolet Aging an Owl
Ultraviolet Aging an Owl
From The Raptor Center
Glimpse into the Glow.
When we recently admitted a young great horned owl, we broke out the black light to take a quick look at its feathers under ultra violet (UV) ight. Why? The pink glow can help us confirm the ow's age. We know this is a bird in its first year of life because all of its wing flight feathers are glowing pink. The glow comes from proteins in new feathers called porphyrins. Under UV light, these porphyrins are fluorescent and visible to the human eye.
As feathers age, these pigments break down and the pink color subsides. The only time all of the feathers are new is when a bird gets its very first set of feathers. As these birds age, they only molt a few flight feathers each year, leading to uneven amounts of pink in older birds.
While we know that owls don't have UV-sensitive cone cells in their eyes like diurnal birds, research shows that they can still detect UV light. There is no definitive answer as to the purpose behind the fluorescence of new feathers; however, it possibly conveys important information between owls in the wild.
It's worth noting that the majority of animals can see in the ultraviolet light spectrum, meaning humans inability to do so is an exception and not the standard. How do you think UV vision would change the way we see our world?
Link has a video if you want to see more feathers glowing, but there's no talking or text beyond what's above here.
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If somehow a bird lost all of its feathers, would they all grow in new?
Not owl-specific, but interestingly penguins go through what’s called a “catastrophic molt” where they replace all their feathers in a short period of time (a few weeks to a month).
This is because they need their feathers to insulate them in the water. Typical bird molting, which lets most birds replace feathers without losing their ability to fly, would be like swimming with a leaky wetsuit for the penguins. This would force the penguins to burn too many calories just to stay warm. Instead they eat extra food leading up to the molt, then mostly stay on land and live off their fat reserves until the molt is finished.
If you made it this far, thanks for reading my bird nerd tangent lol
Very interesting, and it makes a ton of sense in their case!
I was wondering how they eat while having no feathers, but it seems they pig out for a few week before they molt. No wonder they load up, because they wouldn't want to go out in public looking like this!
Yeah they definitely look worse for the wear during the molt. Also, having taken care of penguins before, they have waaay more feathers than you think they would.
Penguins look like a lot of fun, but that projectile poo makes me nervous! 😬
They look like they'd almost feel like a closed cell foam. Do their feathers feel oily or anything like that? I feel they'd have to have a water repellent coating from some thick preening oil.
I didn’t mind the projectile part, probably because they never got me. It is pretty acidic and eventually stains an area no matter how much you clean.
When dry the feathers feel smooth, but not really oily. If you’ve ever pet a duck it’s pretty similar.
I did have an African penguin almost knock me into the pool once. It was nesting season and he tried to take my radio’s antenna. While it was clipped on my belt and I was crouched down scrubbing the edge of the pool. Luckily I regained my balance and he found a real stick to take instead.
Huh, I wouldn't have thought they felt like a duck. They look denser than that.
They seem like fun animals though. The one aquarium staff person showed me to use my hand to make shadows over the water and sometimes they'll chase after it.
Watching them eat is pretty impressive too.
In reality, probably not. If we're talking purely hypothetically, I wouldn't say it's impossible.
Feathers come from follicles in the skin, similar to how we grow new hairs on our bodies. When a feather falls out naturally, hormones trigger the growing of a new feather shaft. As the shaft grows, it gets surrounded by a keratin sheath to protect it while it develops. Inside the sheath, shoots come out forming smaller and smaller barbs. Once the feather is done, the keratin falls off and the feather poofs out. This process usually happens once a year, and with a scattering of feathers so flight and thermal regulation aren't compromised.
If a bird in the wild lost all its feathers, it would either starve or succumb to the environment most likely before feathers would grow in, as it can take up to a year to grow new ones. Feather growth also requires a lot of nutrients and energy, so a weak and starving bird wouldn't physically be able to grow them.
The other factor is the follicles themselves. If something traumatic or disease related damages the delicate follicles, they won't be able to grow new feathers. I don't know much about animal diseases, but I have seen burnt birds, and fire can of course destroy the follicles.
The hypothetical scenario where we could wave our magic wand and cause a full molt at once would theoretically allow the bird to have undamaged follicles. If we kept the bird warm, safe, and fed a ton of nutritious food for a year or so and managed to keep it relatively stress free during that time, I would think it could theoretically grow back the feathers at some point.
Feathers are amazingly complex and diverse structures. If you'd like to learn more, I did a write up on the types of feathers here.
If you want something very technical, I skimmed this article to get you the above answer.
For repair of broken feathers, there is a grafting process known as "imping" that you can read about here, where I talk about the process, and have some comments from someone who has done the process themself as a falconer.
This is an amazing write up. Thank you for linking to it. I'm so glad I found this community, I honestly never subscribe before because I thought this was about football.
I'm going to read your other post right now
I used to have a friend who had parrots, and occasionally, and I don't understand why, they'd lose all their feathers, maybe something to do with being in captivity or stress
I'm glad you finally found us! That is a drawback to the name, especially to non-sports people.
Birds will pull out feathers due to stress. They may be bored or lonely or have a nutritional issue or illness. The repeated pulling of healthy feathers can cause damage to the follicles.
Here's an article discussing some causes and treatments in pet birds.
I hope you enjoy the back catalog of posts. There's hundreds of great photos and lots of facts. If you search "Owl-natomy" you'll get most of my unique anatomy discussions.
If there's anything you want me to post about, just let me know. I try to respond to everyone and answer whatever questions you give me. I'm not an expert, just a fan of owls and researching things that interest me.
Here's the year end review I did for 2023, highlighting some of the best posts from last year. That can be a good starting place for you if you want to catch up on things.
Do all feathers insulate equally? Or do they have different thermal characteristics? I.e for animals that have thermal vision
No, different feathers serve different purposes. Down is the soft fluffy feather type that babies are covered in and is a base layer for the adults. That's what is in clothing/blankets when feathers are used for insulation.
Mamma bird also has a "brood patch" of down she can pluck from herself to add some insulation to a nest.