2 December 2021
We take for granted that birds sleep on a perch without falling off, yet we drop whatever we’re holding when we fall asleep. (Many’s the time that my book falls off the bed!)
How do birds continue to hold on after they fall asleep? The answer is in this vintage article.
(photos from Wikimedia Commons; click in the caption to see the originals)
30 November 2021
We humans assume that what we see is what everyone else sees, including other species. But this isn’t so.
Peregrines see much finer details at a greater distance that we do. The details don’t blur for them in a 200 mph dive. (Click the link to learn more.)
Cats cannot see red-green nor distant details, but they see much better in the dark. Who needs distance vision while looking for a nearby mouse at night? Click here to see photos of our vision versus cats’. Notice the normal vs. red-green-color-blind examples below.
White-tailed deer see regular blaze orange as gray but if the orange has fluorescence it stands out for them. Their vision is best in the blue range so that they see well in twilight.
Birds see ultraviolet light though we cannot. Here’s how we know this and a hint at what birds look like in ultraviolet light.
Do other species see what we see?
No. Birds see more.
(peregrine photos by Chad+Chris Saladin, deer photo by Kate St. John, remaining photos from Wikimedia Commons)
28 October 2021
Have you ever noticed that birds gulp their food? Of course they don’t chew — they don’t have teeth — but much of what they eat still has to be “chewed” before they can digest it.
That’s where grit comes in.
Birds chew with their gizzards, a specialized stomach with thick muscular walls that grind up food, often aided by particles of stone or grit.
Birds regularly eat grit to aid their digestion, as Ecco is doing in the photo below.
So when you see birds swallowing things whole rest assured they’re chewing inside … in the gizzard.
p.s. Other animals have gizzards too including crocodiles, alligators, mullet (a fish) and earthworms.
(photos from Steve Gosser, Wikimedia Commons, and the National Aviary snapshot camera at Univ of Pittsburgh)
4 October 2021
Teeth are so important that every toothless animal today is descended from ancestors that had them. This includes anteaters, baleen whales, pangolins, turtles, and birds.
The ancestors of birds were theropod dinosaurs. They definitely had teeth.
Then about 116 million years ago a common ancestor of all birds developed genetic mutations that inactivated the genes for tooth formation. Eventually birds’ teeth disappeared, replaced by horn-like beaks.
There are probably several reasons why teeth disappeared but the main one is this: In order to fly well it’s important to reduce excess body weight. Bones and teeth are heavy so over time birds evolved hollow bones and toothless beaks. They compensate for the lack of teeth by chewing food in their gizzards.
They also compensated by using their beaks as multi-purpose tools to grasp, twist, pry, crack open shells, and sever tendons.
Each species developed a beak for its lifestyle. A few of them evolved beak modifications that resemble teeth.
Among tooth-billed hummingbirds (Androdon aequatorialis) the males have a “straight bill with a prominent hooked tip and backward-pointing tooth-like serrations on the distal half. The modification is absent on the female bill, and thus may be related to sexual selection,” describes Birds of the World. Perhaps the “teeth” are used for fighting.
The critically endangered tooth-billed pigeon (Didunculus strigirostris), the national bird of Samoa, has a stout curved bill with a specially toothed lower mandible.
[The bill] is adapted to feed on Wild Mahogany Dysoxylum spp. fruits, although first-year birds apparently cannot do so. These fruits have a tough capsule that it is able to open using its strong bill, removing the flesh using a sawing action with the lower mandible.
Birds of the World, Tooth-billed pigeon account
If you want to stretch the definition of “teeth” peregrines have two of them. The tomial tooth on each side of the upper beak is used “to kill prey quickly by biting their necks and severing the vertebrae.”
Does that make them birds with teeth? Not really. No dentin, no enamel, and they aren’t using them to chew.
(photos from Wikimedia Commons; click on the captions to see the originals. Peregrine photo by Chad+Chris Saladin)
10 September 2021
When I think of the word “wry” the first thing that comes to mind is sarcastic or dry mocking humor. “He made a wry comment” and everyone smiled like this:
At its root “wry” means twisted, bent or turned abnormally to one side. Two birds have “wry” in their names and their bodies show it.
The wrybill (Anarhynchus frontalis) is a plover endemic to New Zealand whose bill is permanently twisted, always to the right.
The Eurasian wryneck (Jynx torquilla) is named “twisted neck” but his neck is straight …
… until he gets frightened.
Another magic day on Dream Island with FOUR Wryneck seen, including this bird living up to its name. What a remarkable anti-predator response. pic.twitter.com/izcDCXeiRr
— Skokholm Island (@SkokholmIsland) September 5, 2021
All birds can twist their necks to preen, as Ecco demonstrates this week at the Pitt peregrine nestbox.
But the wryneck moves his neck in an mesmerizing way to distract predators.
We stop and stare when his neck is awry.
(images from Wikimedia Commons; click on the captions to see the originals)
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):
More details:
Even more details:
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)
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.
(photo by Joel Kluger on Flickr, recording by Kate St. John)
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.
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.
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)
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.
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.)
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.
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.
Juvenile northern cardinals (dark bird on branch) resemble their mothers but the juveniles have dark beaks. Their mothers (at right) have orange beaks.
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.
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.
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)
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.
Notice that the male’s head becomes mottled green (below) and then dull brown (photo at top).
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.
Eventually the male starts to molt back to his typical plumage. Partway there he looks like this.
And by November he’s back to his normal flashy self in time to court his springtime mate.
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)
