The silver feathers on an Anhinga's wings...or...baby's got bling!

When you seen Anhingas at a distance, they appear black, and you might not even know they carry a spectacular pattern of black and white (silver) feathers on their wings. When you're sitting right next to them, however, it's easy to see the "bling" on their backs...

A male Anhinga preening, showing off the striking pattern of black and silvery-white feathers on his wings.

This is the same Anhinga I talked about in two earlier posts that sat very close to me (click here for those close-up photos). Close viewing of the Anhinga's back let me study the beautiful pattern in his wing feathers (coverts and scapulars). I always thought these feathers were white, but up close, I could see they were silver...not white, not dull gray, but shiny silver!

The "white" covert and scapular feathers on an Anhinga are a glossy silver color. From a distance they appear white because of the contrast with the black feathers.

When I got home, I looked up Anhingas to see if they really did have glossy silver wing coverts and scapulars, or had I just imagined it. It turns out they do, and they owe their silver feathers to a special structure in the barbules of the feather. I found a detailed technical article published in the Journal of Morphology that explains why those feathers are indeed silver. Click here to read "Proximate Bases of Silver Color in Anhinga (Anhinga anhinga) Feathers," by Matthew D. Shawkey, Rafael Maia, and Liliana D'Alba.

...whether silver or white, the pattern on the back of an Anhinga is striking.

Bird feathers contain a center shaft called a rachis. Barbs branch off the rachis, and barbules branch off the barbs. The barbules run almost parallel with the rachis and hook together to make the feather strong.  The barbules in silver feathers are different--they are longer than those in other feathers, and they are flattened. Additionally, they twist a little, and one side is black and the other side is translucent. The twist means part of the translucent barbule is exposed, which creates the silver sheen. I found an article on the BBC Earth News site explaining the research of Dr. Ismael Galvan by Matt Walker called "Birds unveil 'silver wings'" (click here). This article is a little easier to understand than the technical research paper and clearly explains how the silver sheen appears on the feathers.

Galvan concluded that dark-colored birds evolved the silver sheen as a way to "become more colorful and conspicuous," while still keeping the benefits of dark-colored feathers (dark feathers contain the pigment melanin, which makes them stronger and protects the feathers from abrasion and UV radiation). 

This is the third part of the Anhinga series:
Part 1: Anhinga close-ups
Part 2: More Anhinga photos; spread-wing posture
Part 3: The silver feathers on an Anhinga's wings

More Anhinga photos; spread-wing posture and feather closeups...

...continued from the previous post, Anhinga closeups: those crazy Anhingas.
If you read the previous post, you know this bird came very close to where I was sitting and started drying out his feathers. Originally he was sunning himself on a branch in the water, then hopped on shore near me. After a while he returned to the branch. If I didn't know better, I'd think he wanted to make sure I could photograph all of him instead of just the closeups of his face. His look back at me seems to say, "Are you getting this?"

A beautiful Anhinga looks over his shoulder at me while I photograph him.
"Yes, Mr. Anhinga. I'm getting it..."

An Anhinga sits in the spread-wing posture as he continues to dry his feathers. 

Anhingas sit in the sun with their wings spread even when they are dry because they also use this posture for thermoregulation. 

Anhingas and cormorants both use this posture to dry their feathers, but Anhingas rely on the posture to help keep them warm too. Anhingas have low metabolic rates and high rates of heat loss from their bodies. This is why you don't find many Anhingas up north. They need the sun's warming rays to survive. According to Stanford University (click here for the article), dry Anhingas use the spread-wing posture when the ambient temperature is cool but the sun is shining brightly. They sit with their backs to the sun for optimum heat absorption. Why don't cormorants do this? Because they don't have to. Their feather structure is different. Although both have "wettable" feathers allowing them to lose buoyancy so they can dive and swim under the water to hunt for fish, only the outer part of a Cormorant's feathers becomes waterlogged. This creates an insulating layer of air next to the skin when the bird is under water.

Anhinga's feathers become wet all the way to the skin. Anihingas use the muscles in their skin to make the feathers stand on end to help them dry.

The sun shines through the wing feathers on an Anhinga (interior view) creating an amber glow.

...small feathers "standing on edge" make the upper part of this Anginga's wings look spiky.

"Water Turkey" is one of an Anhinga's nicknames. It's easy to see its origin...the striped pattern and light tips on a spread Anhinga's tail resemble a turkey's. It's other nickname, "Snakebird," is easy to figure out too. When an Anhinga's body is submerged and only its shiny, wet head and neck are visible above the water, it looks like a black snake swimming along (click here for a photo in a previous post).

...I have another post on this fellow in the works. It focuses on the beautiful pattern of white feathers on the back of an Anhinga's wings. I photographed this bird on June 14, 2012 while we were on our vacation in Hilton Head, SC. I was sitting on the bank of Lake Thomas in the Sea Pines Forest Preserve on Hilton Head Island.

This is the second of three Anhinga posts:
Part 1: Anhinga close-ups
Part 2: More Anhinga photos; spread-wing posture
Part 3: The silver feathers on an Anhinga's wings

Anhinga closeups...

Anhingas are amazing birds—and very exotic to northern girls who don't get to see them up close very often. It's understandable then that I was stunned when this bird plopped down beside me as I sat near Lake Thomas in the Sea Pines Forest Preserve on Hilton Head Island. He had been drying his feathers on a branch sticking out of the water when I first saw him, but I wasn't paying much attention to him then. I had a map in front of me, and I was trying to figure out where a roost of Yellow-crowned Night Herons were. Suddenly, he made a gangly jump-flight and landed about 15-20 feet away from me, like he just wanted to drop in and say "Hello..."

Hello Mr. Anhinga. Charmed, I'm sure...

I really wanted to find the Yellow-crowned Night Heron roost, but adrenalin from the excitement of an unexpected encounter helped me focus my mind on the anhinga and soon washed away all thoughts of the night herons. I was more than happy to drop the map on the grass and just sit beside this incredibly cool bird. With his long, snaky neck and sharp dagger-like bill, it was hard to take my eyes off him...

The sky blue skin on an Anhinga's face is striking. I'm not normally close enough, however, to see it so clearly! This bird landed about 15-20 feet away from me as I was sitting beside the lake.

Anhingas lack oil glands, so they can't waterproof their feathers like ducks and other water birds. His scraggly, wet-dog-fur looking feathers definitely need some attention. A soft fluffy towel to dry off with would have been nice, but the sun and heat did the job just fine. 

He immediately struck up his famous feather-drying pose, and looked around. A few small bugs here buzzing near his face, and he'd shake his head now and then and snap at the tiny insects.

A male Anhinga hanging his feathers out to dry...

Why do Anhingas hold their wings open to dry their feathers?
You might already know about why these birds do not waterproof their feathers. If you don't, click here for a post I wrote last year on Anhingas that explains why waterlogged feathers help Anhingas by reducing their buoyancy so they can swim and fish under water.

...and if you haven't seen it yet, head over to 10,000 Birds to read Nate Swick's I and the Bird post on Cormorants, Anhingas and Darters.

An Anhinga snapping at flying insects from Kelly Riccetti on Vimeo.

I photographed this fellow on June 14, 2012 while we were on our vacation in Hilton Head, SC. It's about time I started posting some of the beautiful South Carolina birds we saw back then! Another post on this guy is in the works...

p.s. I never did find the Yellow-crowned Night Heron roost!

This is the first of three Anhinga posts:
Part 1: Anhinga close-ups
Part 2: More Anhinga photos; spread-wing posture
Part 3: The silver feathers on an Anhinga's wings