Cedar waxwing about to swallow whole fruit (photo by Steve Gosser)
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.
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.
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.
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.
Toothbilled hummingbird beak (photo from Wikimedia Commons)
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.
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:
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
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.)
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)
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.
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.
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)
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.
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.
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)
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)
