This past summer I posted these first two Loggerhead Shrike images as evidence that the ventral colors of the species change from white to almost black as the summer wears on and asked my readers why this occurs. Several responded with a logical explanation.
Three days ago I photographed a Horned Lark that may demonstrate that those readers were right.
I’m re-posting the first two images to bring everyone up to speed.
For most of the year the breast and belly of the Loggerhead Shrike is white but…
but by mid-summer those whites turn much darker, almost black in some places. The reason for this rather dramatic color change really puzzled me but Brian Gatlin and Bryce Robinson provided the explanation. I’ll quote Brian who said:
- “a combination of wear and/or absence of feathers is creating gaps in the plumage, exposing the darker bases of the feathers that we don’t usually see. If you pick up body feathers off the ground, you’ll often notice that the color that you see on the bird is usually limited to the feather tip, with a darker base.”
As Bryce mentioned in his comment, when feathers wear to expose the darker feather bases it is sometimes called “wearing to dark”.
All this seemed logical to me but it’s one thing to read the words and quite another to actually see evidence of it in the field. That evidence was provided three days ago by a completely different species – a Horned Lark.
This time of year I’m not sure if this Horned Lark is a juvenile or an adult female but either way it was posing on a rock in marginal light and I took some shots of it. Notice the typical colors of the belly and breast.
But when a sudden breeze came up, voila! – the dark feather bases were exposed. It now made even more sense to me that (in some species) when the lighter colored feather tips are worn it can expose their darker bases and change the color that we see.
I’m sure there are many variables involved in different species. For example, I haven’t seen any Horned Larks with almost black bellies and breasts but perhaps that’s because the white feather ends are longer than those in shrikes so they never wear far enough to expose the darker colors (pure speculation on my part).
Like many folks I’m a visual learner so actually seeing these dark feather bases on a living bird (rather than on a discarded feather) made an impression on me and I thought it was worth sharing.
Thanks Brian and Bryce!
Ron
I wonder if the Shrike has a lot of wear on that part of his chest from birds he’s killed dangling against it as he’s carrying them off? I got a photo last Xmas bird count of a Shrike with a Chickadee dangling from it’s beak. It was so cool! I had never seen a Shrike kill before.
Ron:
Very good work. Your images are stunning, detail is spectacular.
Bill Fenimore
This is why many waterbirds have black tips on their light wings; white wears out faster than black so the black tips keep the wings strong. If you find moulted gull feathers you’ll often find that the white spots on the tips have worn off.
It is the melanin in the vanes that make the darker plumage areas stronger.
Bill
Lovely images to document this interesting discussion. I’ve noticed it with our Eastern Yellow Robins, in particular, too. I wonder if it happens with some darker breasted species as well, but is less obvious – something else to look out for!
“something else to look out for”
Exactly, Sonja. There’s always something new and interesting out there.
Thank you so much. I love the education I get here. Education and beauty. And a bit of jealousy – I am rapidly wearing to grey here. Wearing to dark would be welcome.
Ha, I’m wearing to bald, Elephant’s Child. Trade you…
I must be heyoka…doing everything backwards, as usual…while some are wearing to black and some to gray, and one even claims to bald, I’m wearing to white! Even worse, some just find me wearing, period!
White is a great deal more elegant that grey (or bald). And I cannot imagine anyone of taste finding you wearing.
I agree, Elephant’s Child!
Again, supplementing exceptional images with an informative and interesting discussion to illustrate a point. Pure professionalism Ron. I’m very impressed.
It’s just pure fun too. Love the post, as always.
Bryce, As far as I’m concerned this post is part yours because of your major contribution. So take a bow…
Very interesting. Now the Greater Roadrunner we were watching last winter makes sense. It had its back exposed to the sun, and must have moved its feathers in such a way that it looked like it had a large black spot on its back. I love it when seemingly crazy things suddenly make sense. Between what you teach us, Ron, and what your readers share, this is a fabulous forum for learning about birds and other animals.
Ahmen! (Awomen, too)
Sometimes you crack me up, Patty- this made me smile!
Believe me, I learn as much as anyone here, Susan. I’m delighted that this post helped you realize what was going on with the roadrunner.
More great photos. I love that I learn so much from you. What a lesson!!! thank you Ron.
Thanks very much, Ellen.
Hi Ron, I can only speak about raptors, but the same effect might be happening with other birds. A Red Tail’s body feathers, for example, are usually brown with large white scallops around the edges. For some reason, feather lice eat only the white part of the feathers, leaving the brown sections alone. Of course, there are color variations between Red Tails, but sometimes we will catch a Red Tail that looks particularly dark, but it turns out to be a bird with a heavier than normal lice infection (they almost always have some) that have eaten away the white portion of the feathers, leaving the brown, making the bird look darker.
I remember our discussion about feather lice in a previous post, Mark. Makes me wonder if lice might cause part of the “wear” we see in birds other than raptors.
Another occasion to view the different coloration along a contour feather is after a bird has bathed, been heavily rained upon, displaying an aggressive pose or for many raptors when they have a large crop. Redtails (and most raptors)are a great example of seeing the difference in coloration along the rachis. We are use to seeing this on a flight feather but because of the way many contour feathers lay upon one another we don’t often see the area closer to the base rather than the tip. Their head feathers are brown at the tips but white further along the feather toward the point of emergence where they are white. The occipital area foreshadows the white feathering and it is found on much of their body.
Many owls display the same color differences on their contour feathers and on their facial disks.
Bill
Interesting stuff, Bill. Thank you.
Amazing shots Ron and a wonderful explanation! Thanks for sharing!
Charlotte
Thanks, Charlotte.
This has got to one of the best cases of serendipity ever. There is no question it’s the same bird on the same rock. This is one for the text books, seriously. This great teaching material. I’ve wondered about this “graying” in Blue Jays. Thanks for the explanation (that Horned Larks one cute bird!)…
I thought these photos worked pretty well to illustrate the point, too. Thank you, Patty.
Excellent lesson with real life pictures to prove the point!! Well done Ron!!
I have a Master Bander’s license that is on hold because I haven’t banded for several years and have observed what you have just shown many times during my banding from the 60’s-2000. It is so nice to concisely see the lesson aptly proven in your excellent images. Many thanks for sharing.
Thanks, Dick. I’m certainly no expert on this subject so your confirmation is appreciated!