Category Archives: Bird Anatomy

A Tip For Identifying Confusing Fall Warblers

Bird Anatomy, Songbirds
A confusing fall warbler, autumn 2011 (photo by Steve Gosser)

2 September 2021

The remnants of Hurricane Ida held back bird migration for two days in Pittsburgh but the logjam has broken. Today and tomorrow hold the promise of many migrating birds in southwestern Pennsylvania including mixed flocks of confusing fall warblers. Here’s a tip on how to identify them. This even works hours later at home with your reference guides.

In the field with a hard-to-identify bird, write down every feature you see as if you were going to draw the bird. Don’t forget habitat and behavior.

Details, details, details! The more details the better. If you get only a fleeting glimpse describe whatever jumps out at you.

The details will be useful when you get home and look at field guides.

Let’s try it on this bird.

At first glance (squint your eyes to see less):

  • perched in a tree
  • smaller than a sparrow; warbler size
  • charcoal gray back
  • yellow chest
  • white wing bars
  • plain face
  • (Under the Tail is important too but we can’t see it here.)

More details:

  • yellow chest has pale gray necklace with stripes

Even more details:

  • broken eye ring
  • throat above necklace is yellow
  • some stripes on flanks
  • greenish patch on back
  • maybe a white patch on topside of the tail

Tools: The Warbler Guide by Tom Stephenson and Scott Whittle has free downloadable tools that show all the warblers side by side. Get them here: QuickFinder PDF (my favorite) or QuickFinder JPGs.

Practice! Use this technique in the field. See how I used it to identify another confusing fall warbler: Orange Crowned or Simply Yellow.

So what bird is pictured above?

Leave a comment with your answer and — most important! — the details that led you to that conclusion.

UPDATE, 3 Sept 2021, the answer is: Magnolia warbler

(photo by Steve Gosser)

Birds’ Inner Ears Can Recover Lost Hearing

Bird Anatomy, Musings & News
American robin, watching and listening (photo by Joel Kluger via Flickr Creative Commons license)

12 August 2021

On Monday when I wrote about the handsome trig (red-headed bush cricket) that sings loudly at 7000 Hertz, I mentioned that upper range hearing loss prevents me from hearing him. Hearing aids help a little but nothing can fix it. My hearing will never return to its youthful ability.

Birds don’t have this problem. If the loss is in their inner ear, their bodies repair the damage. Learn more in this vintage article: Birds Can Recover Lost Hearing.

Perhaps birds can recover their hearing because their lives depend on it. Gene Henderson reminded me of a high-pitched danger call that American robins make. At 7200 to 8400 Hertz it’s now outside my hearing range. Can you hear the four calls in the recording below at 2,5,8 and 11 seconds? They look like checkmarks on the sonogram.

American robin danger call (recording by Kate St. John)

(photo by Joel Kluger on Flickr, recording by Kate St. John)

What Sex Is This Bird?

Bird Anatomy, Songbirds
What sex is this hummingbird? (photo from Wikimedia Commonss)

6 August 2021

In late summer in eastern North America a different looking ruby-throated hummingbird (Archilochus colubris) shows up. If you don’t look closely you may misidentify it.

It doesn’t look exactly like an adult, pictured below, but it resembles the female.

Adult male and female ruby-throated hummingbirds (photos from Wikimedia Commons)

So is it female? No!

See the red dots on the throat? It’s a young male, born this spring, who is already developing his red gorget.

Before he has red dots you can still identify him by the stippling (dotted lines) on his throat. This young male, below, has stippling without red dots.

Juvenile male ruby-throated hummingbird (photo from Wikimedia Commons)

Unfortunately the bird pictured at top was misidentified as female on Wikimedia Commons. I corrected the description but cannot change the filename that contains the word “female” so he will still confuse people.

Proving that you should not believe everything you see on the Internet.

For detailed tips on identifying young ruby-throated hummingbirds, see this article at The Spruce: Ruby-throated Hummingbird Identification.

(photos from Wikimedia Commons; click on the captions to see the originals)

I Don’t Look Like My Parents

Bird Anatomy, Nesting & Courtship, Songbirds
Juvenile chipping sparrow (photo by Marcy Cunkelman)

8 July 2021

Summer is a challenging time to identify birds when fledglings look quite different from adults. Here are seven species whose babies can honestly say, “I don’t look like my parents.”

American robin adults (left) have plain rust-colored breasts. Juveniles (right) have spotted breasts.

American robin: adult and fledgling (photos by Steve Gosser and Charity Kheshgi)

The differences between juvenile and adult downy woodpeckers are subtle. Juveniles (left) have a faint red patch on top of the head while adult males (right) have a vibrant splash of red on the back of the head. (Don’t be fooled by the red flower behind the male in this photo.)

Juvenile downy woodpecker (left) being fed by father (photo by Marcy Cunkelman)

Red-bellied woodpecker juveniles (middle photo) are very plain with no red on their heads. Adult males (left) are red from bill to nape while adult females (right) have red napes, pale foreheads, and a spot of red at the bill.

Red-bellied woodpeckers: adult male, juvenile, adult female (photos by Marcy Cunkelman and Cris Hamilton)

In breeding plumage adult European starlings (left) are iridescent glossy black while fledglings are dull brown (right). Check out the shape of the fledgling’s beak and how he opens it. He has that in common with his parents.

Adult and juvenile European starlings (photos by Chuck Tague and Charity Kheshgi)

Juvenile northern cardinals (dark bird on branch) resemble their mothers but the juveniles have dark beaks. Their mothers (at right) have orange beaks.

Northern cardinal: Adult male feeding juvenile, female has orange beak (photos by Bob Kroeger, Cris Hamilton)

Juvenile brown-headed cowbirds never look like their foster parents. These dull brown, chunky birds have short, fat necks and “fat” beaks. The beak is the clue.

Brown-headed cowbird chick begging from song sparrow host (photo from Wikimedia Commons)

And finally, young chipping sparrows look so different from their parents that you’d think they’re another species. The juveniles are stripey brown (photo at top) while their parents have plain pale breasts and rusty caps. The best way to identify a fledgling chipping sparrow is to watch who it begs from.

Adult chipping sparrow tries to ignore its begging youngster (photo by Marcy Cunkelman)

A Hat Tip for this topic goes to Mary Ann Pike who described it in a comment yesterday.

Did you find any fledglings hard to identify this year? Let me know in a comment.

(photos by Marcy Cunkelman, Steve Gosser, Charity Kheshgi, Cris Hamilton, Bob Kroeger, Wikimedia Commons)

Mallards in Eclipse

Bird Anatomy, Water and Shore
Male mallard in eclipse plumage, Colorado, July 2016 (photo from Wikimedia Commons)

7 July 2021

In the middle of summer the male ducks disappear — or so it seems. The males are still present but they look like females because they’ve molted into eclipse plumage.

Let’s take a look at mallards to see how this works.

Mallards (Anas platyrhynchos) replace all their feathers once a year but males and females do it at different times. Females molt while nesting (February–May); males molt after the breeding season (June–August).

The molt begins with a complete loss of remiges (wing flight feathers) that takes only a few days, rendering the bird flightless for 3-4 weeks. Fortunately males simultaneously replace their brightly colored body feathers with dull ones so they can hide in dense marshes. Eclipse plumage keeps them out of danger.

Here’s the transformation.

Male mallard gradually changing into eclipse plumage (photo from Wikimedia Commons)

Notice that the male’s head becomes mottled green (below) and then dull brown (photo at top).

Male mallard, head color is changing during molt (photo from Wikimedia Commns)

Once the males have made this transition it’s a challenge to tell them apart from females but here’s a clue. Look at their bills. In the summer males have yellow or greenish-yellow bills while females have dull orange-ish bills.

Mallards bills: male in eclipse, female in summer (photos from Wikimedia Commons)

Eventually the male starts to molt back to his typical plumage. Partway there he looks like this.

Male mallard in eclipse in Illinois (photo from Wikimedia Commons)

And by November he’s back to his normal flashy self in time to court his springtime mate.

Male mallard in spring plumage including the curly tail (photo from Wikimedia Commons)

This summer when you see a mallard, look at the bill. Maybe he’s a male in eclipse.

(photos from Wikimedia Commons; click on the captions to see the originals)

Not Sick, Just Temporarily Bald

Bird Anatomy, Songbirds
Bald northern cardinal (photo from Wikimedia Commons)

6 July 2021

If you see an odd and ugly bird like this northern cardinal don’t worry that he’s ill. He isn’t sick. He’s just temporarily bald.

Many birds molt in the summer when they’ve finished breeding and food is plentiful. Warm weather is the perfect time to lose worn out feathers, a few at a time, and grow in new ones. Some northern cardinals and blue jays however lose all their head feathers simultaneously and become bald for about a week. This happens so often among blue jays in North Carolina that it’s considered normal there.

Birds also go temporarily bald during the molt if they have feather mites on their heads. Lose all the head feathers and lose the mites, too.

Bald birds are ugly, though. Their ears are just holes near their eyes, their heads look small, and their skin doesn’t match the missing feathers. Nonetheless, it’s temporary.

So don’t worry if you see a bird like this one in the video. He’s not sick. He’s just bald.

(photo of bald northern cardinal photo from Wikimedia Commons; click on the caption to see the original)

Color Is Not The Only Clue

Bird Anatomy, Songbirds
Screenshot from video tweet by pacificnorthwestkate

14 May 2021

Every once in a while we find a very unusual bird that defies identification.

This one was filmed by pacificnorthwestkate (@pnwkate) at the Delta in Vancouver, BC, Canada on Thursday 6 May 2021. Its chest and belly look like an eastern towhee (Pipilo erythrophthalmus) but its shape, beak, voice and behavior are like a red-winged blackbird (Agelaius phoeniceus). The final clue is that he hangs out in marshes with red-winged blackbirds.

As you watch him move and hear him sing you know who he is.

A commenter on the tweet remarked that this bird has been frequenting the Delta for about three years now. Speculation is that he’s leucistic rather than hybrid.

When you identify birds, color is not the only clue!

(tweet and screenshot from pacificnorthwestkate @pnwkate)

Red-Winged Black Bird in South Africa?

Bird Anatomy, Songbirds, Travel
Long-tailed widowbird, South Africa (photo from Wikimedia Commons)

16 April 2021

There’s a black bird with red wings in South Africa that resembles North America’s red-winged blackbird except for his outrageously long tail.

The long-tailed widowbird (Euplectes progne) is not related to red-winged blackbirds (Agelaius phoeniceus). The widowbird is a weaver (Ploceidae), red-wings are New World blackbirds (Icteridae), yet male and female widowbirds have very similar coloring to male and female red-wings. The similarity ends when you see his tail.

Long-tailed widowbird, male and female, South Africa (photo from Wikimedia Commons)

His tail is an important part of his courtship flight display.

Long-tailed widowbird in flight (photo from Wikimedia Commons)

In the video he briefly lands near a female on the ground.

Female long-tailed widowbirds don’t have long tails but they must exert a lot of selective pressure for the longest tailed males.

That tail doesn’t look like a safe accessory. I’m sure some females are widowed during the breeding season. 😉

(photos from Wikimedia Commons)

We Get Pretty By Wearing Out

Bird Anatomy, Songbirds
Lapland longspur, Oct 2018 (photo by Lauri Shaffer)

9 March 2021

If you saw lapland longspurs (Calcarius lapponicus) in the fields this winter you know how hard they are to notice, even when abundant. Unlike horned larks that are visible when they walk, longspurs barely move while foraging for seeds in low brown vegetation. They match the ground.

Two lapland longspurs foraging in a field, February 2021 (photo by Lauri Shaffer)

To achieve this camouflage, they molt in July and August while on their breeding grounds, then head south to spend the winter in fields across the northern U.S. and as far south as Texas.

Lapland longspur, October 2018 (photo by Lauri Shaffer)

During the winter, their feathers get older but instead of looking tattered they show more color. Here’s one in mid-January.

Lapland longspur, Illinois, 16 Jan 2016 (photo by Andy Reago & Chrissy McClarren via Wikimedia Commons)

By the time they reach their arctic breeding grounds in late May the males are especially gorgeous.

Male lapland longspur, Alaska Maritime NWR (photo from Wikimedia Commons)

They don’t molt to become this beautiful. Instead the tips of lapland longspurs’ feathers wear off to reveal gorgeous colors just below.

It would be nice if we humans got prettier as we wore out. Instead we just look ragged.

(photos by Lauri Shaffer and from Wikimedia Commons)

p.s. European starlings use the same feather strategy.

Evolve Quickly!

Bird Anatomy, Birds of Prey, Water and Shore
Snail kite with island apple snail, Harns Marsh FL, 2017 (photo from Wikimedia Commons)

Native from Florida to Argentina, the snail kite (Rostrhamus sociabilis) is a gregarious bird of prey that eats only one thing: freshwater snails in the genus Pomacea. Its beak is specially shaped to do so.

Snail kite, Florida 2019 (photo from Wikimedia Commons)

The Snail Kite’s slender, deeply hooked, sharp-tipped upper mandible permits it to cut the columellar muscle of Pomacea snails and remove soft tissues from the shells. The arc of the upper mandible approximates the inner spiral of the snail’s shell.

— paraphrased from Birds of the World, Snail kite account

In the old days before humans took over Florida’s landscape, snail kites ranged over half the state, but we drained and diverted more than 50% of Florida’s wetlands, the snail kite population crashed and was listed as Endangered in 1967. Twenty years ago, from 2000-2007, their population dipped so low that scientists feared they would go extinct in the U.S. Then a curious thing happened. Their food supply changed and the kites changed so they could eat it.

Before this century the snail kite’s main food was the native Florida apple snail (Pomacea paludosa) but an invasive species, the island apple snail (Pomacea maculata), arrived in 2000 and began to spread in Florida’s lakes and water management areas.

Island apple snails eating rushes (photo from Wikimedia Commons)

The island apple snail is two to five times larger than the Florida apple snail as seen below. (The white-and-gray bars are each 5 cm.)

Size comparison of Florida apple snail (P. paludosa) to Island apple snail (P. maculata). Each scale bar is 5 cm (images from Wikimedia Commons)

When the island apple snail first arrived in Florida the snail kite population dropped but less than a decade later the population began increasing. Did the birds initially have a tool problem? Were their beaks too short to get at the snail inside the larger shell? A recent study from the University of Florida indicates this was probably the case. Since 2007…

Researchers found that the birds with bigger bills were surviving, and their offspring were inheriting the bigger bills. …

“We found that beak size had a large amount of genetic variance and that more variance happened post-invasion of the island apple snail. This indicates that genetic variations may spur rapid evolution under environmental change,” Fletcher said.

— paraphrased from UF study: Bird evolves virtually overnight to keep up with invasive prey

We think of evolution as a very slow process but for the snail kite it happened quite fast. Those with longer bills survived. Nowadays they easily eat island apple snails.

Male snail kite with island apple snail, Florida, 2016 (photo from Wikimedia Commons)

When it’s a matter of life and death, evolve quickly!

Read more at the University of Florida study: Bird evolves virtually overnight to keep up with invasive prey.

(photos from Wikimedia Commons; click on the captions to see the originals)