Sunday, August 23, 2009

Structural color and pigment in hummingbird feathers

This is the last post on hummingbirds. I promise!
As I’ve been watching our hummers over the past couple of weeks, I’ve wondered what produces that amazing flash of iridescence in their feathers. In school we learned blue birds don’t have blue pigment in their feathers. Instead, they have structural components that reflect and refract light to produce the blue color (structural color), so I assumed it might have something to do with that, but hummingbirds flash iridescent green, blue, yellow and red when the light hits them just right, so what’s up? I found a lot of info explaining the phenomenon from highly scientific studies to overly simple explanations, so opted for the middle road. Iridescence comes from a combination of pigment and structure. In hummingbirds, melanin granules (dark pigment) stack up in the barbules of each feather. The granules are called platelets, and each is filled with microscopic air bubbles that become tiny reflectors. Light reflects and refracts as it passes through these stacks. The color you see is determined by the angle of your eye as you view the feathers. So unlike pigment, structural color can change. That is why the beautiful ruby-red throat or emerald-green back of a hummingbird can look almost black when the sun isn’t striking it or you’re not looking at the feathers at the right angle.

You can tell the sun is not hitting the top of this
hummer's head or maybe the angle isn't right
because here it looks dark, but in other photos of
the same bird, it flashes brilliant yellow. The ends
of the wings however, lack structural color as I've
never seen iridescence shown in them. They
are always dark, indicating a lot of melanin.

I love the flash of green and yellow shown here.
If you look on her back and on the top of her head,
there is no iridescence--either from lack of
light or the wrong angle, so it looks dark.

Flashes of iridescence among the shadows. It
doesn't even look like the same bird in the first photo.

Beak Bit
In addition to color, the pigment melanin has another use in feathers...it makes them stronger. A clip from Cornell's “All about Birds” Website describes the strengthening characteristics of melanin best:
"Feathers that contain melanin are stronger and more resistant to wear than feathers without melanin. Feathers without any pigmentation are the weakest of all. Many otherwise all white birds have black feathers on their wings or black wingtips. These flight feathers are the ones most subject to wear and tear. The melanin causing the tips to appear black also provides extra strength."
It makes sense the wings and tail feathers
of hummers would be black and have a
lot of melanin. They really get a work out!

Although I read a lot of articles about structural color, I used the "National Geographic Reference Atlas to the Birds of North America," edited by Mel Baughman as my main reference, along with Cornell's "All About Birds".


40 comments:

Tom said...

Kelly- I've enjoyed your hummer images. Your first one on this post really does show how interesting their plumage is- thanks for researching its complexity- I've always wondered why sometimes they're emerald green and other times, sort of brownish.

Tom

Betsy from Tennessee said...

Hi Kel, I never tire of your posts, no matter what the subject matter is. Your hummingbird articles and pictures have been tremendous. They have such gorgeous colors, don't they? And you captured the BEST of those colors.

Hope you have had a great weekend.
Love you,
Bets

Janet Creamer said...

Very nice post Kelly! Great info.

Alan said...

Great info Kelly - very interesting! I've enjoyed reading your hummingbird post.

Caroline said...

Fascinating again, Kelly! I am amazed that it is the same bird too!

Kelly said...

Tom...thanks. It's been fun researching these little birds. I've spent the past 2 weeks reading whenever I had a chance. There is so much to learn!

Betsy...thanky, thanky! All I did was click that button. The bird did all the rest. Today they were drinking nectar like crazy. I wonder if they are starting to fatten themselves up for their big trip south?

Janet and Alan, ....thank you!!!

Caroline....thank you! The colors are like a soap bubble or an oil slick...they change with the light...so it does look like a different bird...very cool!

mick said...

No hummingbirds at all where I live (in Australia)so its very special to see your beautiful photos and read the description of the color. I'm quite happy for more, please :-)

Elaine said...

Kelly, I've learned a lot about the hmmingbirds from you. The explanation of the color we see in a bird's feathers was fascinating. I love your first photo tody, and indeed I have enjoyed every one of your hummer photos. I don't mind if you throw in more posts about the hummingbird. They are a delightful little bird. Besides I'm going to bore you to death before I am finished with the crane migration. I'm hoping to get over to Creamer's Field tomorrow and get more photos, hopefully some nice closeups.

Sue said...

Kelly-these have been such wonderful posts-I've learned a lot. Several of your photos remind me of those old-fashioned Christmas ornaments-so beautiful.
Do you take most of these in your yard?

Roy said...

You could never post enough of these images Kelly, they are fabulous.

Chris said...

Hi Kelly,
What, already the last one!! I guess everybody is happy about these numerous post on humming bird! There are so great shots of a bird we do not see here, so you can publish as many post as you want on them, you're not gonna bother me with them. Again a wonderfuls et of pictures there!

Jayne said...

Really fascinating facts Kelly!

yen said...

I didn't get bored looking at great photos...keep it coming, who is complaining :)

perfect shots.

Busy Bee Suz said...

I am so fascinated by these little guys too. I love that you can get such good shots of them!!!

Måns Sjöberg said...

This is a very interesting post. Thanks for all the information you are sharing with us!

ShySongbird said...

That was beautifully explained Kelly, I actually understood it ;) The photos are of course stunning!

Warren Baker said...

Thank you Dr. Kelly! Quite a scientist at heart really. :-)

I love the Hummers, when are they due back ? May?

Montanagirl said...

Great post as always, Kelly. Your photos are terrific - so bright and clear. I always like reading your posts.

holdingmoments said...

Kelly, that was fascinating. Even I understood it.
I've really enjoyed your Hummingbird posts, and learnt so much.

Ken Browne. said...

Hi Kelly. Nothing I say about the Hummingbirds colouration will do it justice, so I will just sit back and admire the photo's that you took. What beautiful birds they are.

Atanasio Fernández García said...

Hi Kelly, again you show us some high quality images, but also the accompanying text I found very interesting and instructive. I would love to continue seeing your pictures of this winged wonder! A big hug!

Adrienne in Ohio said...

Wow, thanks for the lesson. That was fascinating! Your hummingbird photos have really been enjoyable, Kelly.

Andy Wilson said...

A pleasure to view, I don't mind one bit if you post more hummingbirds!

Cindy said...

Excellent photos. These birds are so beautiful. I wish I'd see more of them around where I live.

Mary said...

You really researched this! Very interesting and the photos are great! I've often seen the males where it looks like the throat is black rather than red. Never seem to get them in the right light for good photos of the red color.

Larry said...

Awesome captures of the Hummers Kelly! Thanks for doing all the research on them so we can come visit and see the great photos AND get the lowdown on why they are so beautiful!

I'm glad to hear of your plans for a pond and waterfall. You will love all the critters coming to visit. Plus you get that soothing sound of moving water that calms the soul.

Tabib said...

Oh..this is the last post of this beautiful bird?
I love all your birds pictures.

JRandSue said...

Hi Kelly.
Love your Hummingbird Images,outstanding work.
John.

Gabrielle said...

But I'm going to miss the hummers!!! They are departing for warmer climes here at home and now they are leaving your blog, too. *Sniff*

Beautiful pictures as always. I can't get over the detail you've gotten. Can't wait to see what you've got in store for us next!

DK Miller said...

Your hummingbird posts have been great! Thanks for sharing so much great info and photos.

E said...

Lovely, superb, brava! Hugs.

Nick S said...

Beauties Kelly :-)

Kelly said...

Yeah!! It' good to hear no one grew bored of all the hummingbird posts. The Lucifer crocosmia has faded in the past couple of days, but the hummers are still coming to the feeders and the Black and Blue Salvia is still hanging on. I hope to get a few more shots before they head south, but who knows if they will cooperate. I need to get a good book on hummers now...
Thanks for all the wonderful comments!!
Warren....the hummers will be leaving soon and can appear as early as April 25 - May 2. I see them in the woods at that time, but not around my house until later.

dAwN said...

Kelly,
thanks for all the wonderful information.
I am not tired of your hummingbirds one bit!
keep them coming

The-Grizzled-But-Still-Incorrigible-Scribe-Himself! said...

Sorry to be so slow in commenting. When I read and viewed this post on Sunday, I was just astonished at the photos—especially the first one. I've shown this post to several friends, too. And no matter how many times I look at these shots, the more I think they are just terrific! I knew about the pigment/iridescent business from other research, but didn't know about the connection between melanin and feather strength. Your explanation of all this is every bit as great as your photos.

Just a wonderful post!

Kelly said...

Thanks, Dawn!

Scribe...Wow! Thank you!!! You are so nice! I was worried people would get tired of them. There is so much more research out there too. I just bought two new (used) books today. I can't wait to read them!

Rambling Woods said...

Love the hummers and this is great info. I had to laugh as a male RT repeatedly chased away a black-capped chickadee who was trying to get a drink of water out of the center of the hummer feeder. It was so funny....

Kelly said...

...Woods.....ours did the same yesterday and today. I chickadee has taken to sitting near the hummingbird feeder, and the hummingbird chases him off over and over!!

Chad said...

I do like these pictures... can you ever really get tired of taking pictures of Hummingbirds... I don't think I could.

Peg said...

Your Hummingbird photos are wonderful!
Here in NW Wisconsin we are still awaiting their Spring arrival.
And looking at your gorgeous photos makes more eager than ever to see them.