Category Archives: Bird Anatomy

How To Find Dinosaur Teeth

Closeup of Tyrannosaurus rex , a theropod from the Cretaceous of South Dakota, Field Museum, Chicago (photo from Wikimedia Commons)

How do paleontologists find fossils? Better yet, how do they find small bits such as tiny dinosaur teeth?

Saurornitholestes and his teeth (screenshot from video)

In Wyoming they get help from ants.

In the video below Australian paleontologist Mikael Siversson (“Birds are dinosaurs”) describes a trip he and a colleague made to Wyoming dinosaur country in the late 1990s. The video starts with a picture of the Badlands as he begins to tell the story. Watch for four minutes — or longer if you want to learn about dinosaur teeth. It involves bathtubs.

(photo from Wikimedia Commons, screenshot from video; click on the captions to see the originals)

p.s. The toothy mouth pictured at top is the reconstructed skull of a Tyrannosaurus rex, a theropod ancestor of birds. Did birds have teeth? You bet!

Massive Die Off of Birds in New Mexico … why?

Dead orange-crowned warbler (photo from Wikimedia Commons used as an illustration, not taken in New Mexico)

18 September 2020

In late August reports started trickling in that high numbers of migratory birds were being found dead in New Mexico. The first report was at White Sands Missile Range on 20 August but as time passed the reports became more frequent, the locations increased, and so did the death toll. By now experts believe that hundreds of thousands of birds have died — perhaps millions — not only in New Mexico (red on map below) but in Colorado, Arizona and western Texas (orange highlight on map).

General area of U.S. where massive bird die off is occurring (map from Wikimedia Commons). New Mexico is red

Austin Fisher took a video of the carnage last Sunday, 13 September 2020 in Velarde, New Mexico.

Science Alert reports that only migratory birds are affected, not the local residents. Most of the dead birds are warblers, swallows and flycatchers and “the affected travelers seem to act strangely before their deaths, spending more time on the ground than perched in trees, and generally appearing dazed, sleepy, and lethargic.”

Dr. Andrew Farnsworth at Cornell Lab of Ornithology believes the smoke from the western wildfires is a big factor.

While birds migrate south through the Rockies this fall they must fly through the ubiquitous wildfire smoke blowing across the US from California, Oregon and Washington. Here’s what it looked like via satellite on August 20, the first day dead birds were reported in New Mexico. Notice that the smoke had reached New Mexico that day.

Satellite image of wildfire smoke across the U.S. west, 20 August 2020 (image from NASA)

Unfortunately birds’ respiratory systems are so different from ours and so efficient that they succumb quickly to bad air.

We turn oxygen into CO2 in one breath — in/out. Every exhalation releases the CO2/remains of the air we just breathed in.

When birds breathe, the air that enters their bodies stays inside for two breaths — in/out + in/out. During its 4-step journey, the air molecule travels through the lungs, two sets of air sacs and into the birds’ hollow bones where it waits for the next step. Click on the diagram below to watch the airflow inside a bird.

Birds’ respiratory system, screenshot from animation at Oxford Learning Link

Sadly, the western fires are damaging much more than we realize. UPDATE 23 Sept 2020: a recent study found that the birds died of hypothermia and starvation. See: Explaining the recent mass mortality of western birds.

Read more about the bird die off at Science Alert and the New York Times.

(images from Wikimedia Commons, NASA and a screenshot from Oxford Learning Link. Click on the captions to see the originals)

Similar But Not Related

Greater flamingo in flight, Walvis Bay (photo from Wikimedia Commons)

Just because birds resemble each other doesn’t mean they’re related.

Flamingos and cranes are both tall birds with long necks and long legs but they come from different branches of the taxonomic tree.

Sandhill cranes in flight, Bosque del Apache (photo from Wikimedia Commons)

They resemble each other in flight and on the ground.

Greater flamingos at Kutch (photo from Wikimedia Commons)
Sandhill cranes in Lawrence County PA, July 2020 (photo by Steve Gosser)

However flamingos are related to grebes and cranes are related to sandpipers as shown in the phylogenomic supertree below. (Note the purple rectangles that highlight the birds.)

As odd as it seems, here are flamingos and cranes with much closer relatives.

Pied-billed grebe (by Chuck Tague) and flamingo (from Wikimedia Commons)
Least sandpiper and sandhill cranes (photos by Steve Gosser)

It’s possible to be similar but not related.

Keep this in mind when you look at a hawk and a falcon. They are not closely related either.

(Sandhill cranes in Lawrence County PA by Steve Gosser; pied-billed grebe by Chuck Tague; phylgenomic supertree from MDPI; remaining photos from Wikimedia Commons. Click on the captions to see their origin)

You Are What You Eat

Male northern cardinal feeds his lady, May 2018 (photo by Bob Kroeger)

23 August 2020

Many birds look ragged right now because they’re molting. July and August are the perfect time to replace worn feathers because the breeding season is over, food is plentiful and they aren’t traveling on migration. The cardinal below looks moth-eaten because he’s molting his body feathers.

Male northern cardinal molting in July (photo from Wikimedia Commons)

What a red bird eats while he’s molting affects his feathers. Red feathers get their color from carotenoids in food so a diet rich in carotenoids makes a cardinal brighter for the coming year.

Bush honeysuckle, though invasive, is a good source of carotenoids. Unfortunately it’s not as nutritious as our native berries.

Invasive bush honeysuckle (photo by Kate St. John)

This bright red cardinal is eating American beautyberry (Callicarpa americana). The redder he is, the better the ladies like him.

Northern cardinal eating American beautyberry (photo from Wikimedia Commons)

This dull colored cardinal must have missed the red berries last summer.

Dull colored male northern cardinal (photo from Wikimedia Commons)

House finches have a more obvious response to nutrition while molting. Finches without enough carotenoids produce orange feathers instead of red. In Marcy Cunkelman’s photo below there’s an orange house finch on the right, a red one on the left.

Red and orange house finches at the feeder (photo by Marcy Cunkelman)

You are what you eat.

(photos by Bob Kroeger, Marcy Cunkleman, Kate St. John and from Wikimedia Commons)

Show Me Your Hands

Striped cuckoo (photo from Wikimedia Commons)

Riffing on cuckoos …

Like the common cuckoo and brown-headed cowbird, the striped cuckoo (Tapera naevia) of Central and South America is an obligate brood parasite. Called “saci” in Brazil or “sinfín” for its voice, this bird is more often heard than seen and that’s a shame because his behavior is so fascinating. When approaching an unknown saci, here’s what he does:

Whoa! Where did he get those hands?

All birds have them. They’re actually the bird’s thumbs. The complete structure with three to five short feathers is called the alula and is used to prevent a stall during slow flight. Pitt peregrine Dorothy demonstrates them while soaring in this 2008 photo.

Alulas visible as Dorothy soars (photo by Jack Rowley)

The saci has black alulas that contrast with his white breast feathers so they stand out when he dances.

Mighty impressive. Show me your hands!

p.s. The striped cuckoo is called the saci in Brazil because it is related the saci of Brazilian folklore. Read more here.

(photos from Wikimedia Commons and by Jack Rowley)

Who Is This Mystery Bird?

Mystery bird, possible hybrid found by Steve Gosser, 6 June 2020

8 June 2020

On Saturday 6 June 2020, photographer Steve Gosser found a bird in the Pittsburgh area that doesn’t match any field guide. He looks like a cross between a rose-breasted grosbeak and a scarlet tanager. He sings like a scarlet tanager.

So I found this bird today that has all the expert birders scratching their heads. It appears to be a cross between a Rose-breasted Grosbeak and a Scarlet Tanager, possibly a hybrid! No one seems to have any records of a hybrid between these birds! I along with two expert ornithologists will try and relocate this bird in the morning and they are interested enough to possibly try and catch this bird and collect a blood sample so it can be DNA tested. It sang exactly like a Tanager, has black wings like a Tanager, a thinner bill like a Tanager, a red throat like a Tanager but the rest looks very much like a RB Grosbeak. I’ll keep everyone posted as to what we find out!

Steve Gosser Facebook post, 6 June 2020

Here’s who the mystery bird resembles: a male scarlet tanager on the left, a male rose-breasted grosbeak on the right.

Scarlet tanager + rose-breasted grosbeak (photos by Chuck Tague and Marcy Cunkelman)

Yesterday ornithologists Bob Mulvihill and Steve Latta netted the bird and took blood samples for DNA testing. Bob says the bird “bit hard but not as nimbly as a rose-breasted grosbeak.” Rose-breasted grosbeaks have very strong bills.

Mystery bird captured for DNA testing, biting Bob Mulvihill (photo by Steve Gosser)

Unlike a rose-breasted grosbeak, this bird has almost no red color in his axillaries (armpits).

Mystery bird still clamping on Bob’s finger (photo by Steve Gosser)

After the blood sample, Steve had the honor of releasing the bird.

Steve Gosser about to release the mystery bird (photo by Courtney Sikora)

We can hardly wait to find out who this bird is. Visit Steve Gosser’s Facebook page for news.

Congratulations, Steve! What a find!

(mystery bird photos by Steve Gosser and Courtney Sikora via Facebook; scarlet tanager by Chuck Tague, rose-breasted grosbeak by Marcy Cunkelman)

How Do Parrots Speak Like Humans?

Screenshot of Petra about to say “Like, Subscribe” (from the video embedded below)

One of my favorite YouTube stars is Petra the African grey parrot who is so smart that she carries on conversations. Here she asks Google a question.

African greys are the smartest birds but they’re not the only parrots that can mimic humans voices. How do parrots speak like humans when they don’t have the same equipment we have, such as lips and teeth, to form words? The video below shows how.

p.s. I’m sure you noticed that the parrot-speaking video ended abruptly when a woman began to talk. She’s going to promote the WIX website tool but it looks as if she’s going to talk about parrots. She doesn’t. It’s very confusing! So here’s her promo and her link to WIX.

(screenshot from Petra Grey video. To watch the videos on YouTube, click on the word YouTube at bottom right after the video begins)

The Flamingo’s Smile

Closeup of American flamingo head (photo from Wikimedia Commons)

Flamingos’ beaks are quite unusual. Their lower mandibles are larger and stronger than their upper ones and their smiles are upside down.

Their lower jaws are fixed to their heads and their upper jaws move freely. When they open their mouths the top beak moves up like an opening clam shell. This is opposite to us humans. We drop our jaws to open our mouths and take in food.

An American flamingo opens its beak (photo from Wikimedia Commons)

However, flamingos eat with their heads upside down. In this position they drop their (upper) jaws to open their mouths just like we do. When they’re feeding their smiles are right side up.

Illustration of American flamingo head, flipped into feeding position (image from Wikimedia Commons)

Their beaks are designed to catch what they eat. From small crustaceans, mollusks and insects to tiny single-celled plants, their food is suspended in water which they capture by filter feeding, a technique they share with baleen whales and oysters.

Flamingos take water into their mouths and strain it out through the filtering mechanisms in and on the edges their beaks (see illustrations above). When flamingos are feeding rapidly they pump their tongues to suck water in and squish it out. This video from the Galapagos shows how they do it.

That’s why the flamingo’s smile is upside down.

For more information, see this Stanford University article: Flamingo Feeding.

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

Beckoning Beaks

Pair of Gouldian finches at their nestbox (photo from Wikimedia Commons)

Gouldian finches (Erythrura gouldiae) are colorful Australian seed-eating birds that nest in tree holes in the wild or in nest boxes when bred in captivity. Their nests are always dark inside so the nestlings have unusual mouth markings to attract their parents’ attention. Each nestling has:

  • Four opalescent tubercles at the corners of the gape that reflect a bluish light.
  • Patterns inside the mouth that guide toward the gullet.

To further attract attention, the nestlings hold up their mouths and rotate their heads as shown in this video of 3-day-old chicks.

The nestlings’ elaborate show may have evolved because …

Gouldians are among the most difficult finches to breed successfully because they are not wonderful parents and have a tendency to abandon both eggs and babies, or even refuse to nest at all. People who raise Gouldians usually keep society finches as well to serve as foster parents for eggs and babies. Societies are marvelous parents and will be happy to foster other species. 

Gouldian finch description at Lafeber website

The babies that survive are the ones with beckoning beaks.

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

p.s. See more examples of weird baby bird mouths at Audubon Magazine’s What’s Up With the Weird Mouths of These Finch Chicks?

Smaller is Normal

Song sparrow, western Pennsylvania (photo by Steve Gosser)

From their 29% population decline to the continued loss of federal protection the news about birds has not been good in recent months. When a December 2019 study from Chicago’s Field Museum found that North American birds have been shrinking since 1978 you may have wondered, “Is this bad news for birds?” Not exactly.

The study published in Ecology Letters measured 70,000 window-killed birds collected in Chicago since 1978. Analysis showed that the 52 species significantly declined in body size during the 40 year period (1978-2018). This mirrors a 2010 study conducted at Powdermill Nature Reserve in Pennsylvania which used 46 years of banding data (1961-2007) to analyze the body size of nearly 500,000 birds in 102 species. Powdermill also saw a decline in body size.

Both studies correlated the annual mean summer temperature of the species’ breeding range and reached the same conclusion: As the climate heats up, birds are getting smaller.

We should expect this.

There’s a biological rule of thumb called Bergmann’s Rule which states that, within a species, populations living in colder climates have larger body size than those in warmer climates. Bergmann’s explanation is that large animals have a lower surface-area-to-volume ratio so they lose heat more slowly in cold climates while small animals have a higher surface-to-volume ratio and can cool off faster when it’s hot.

Song sparrows (Melospiza melodia) provide a good example of Bergmann’s rule because they range across North America from Alaska to Newfoundland and south to Mexico. I saw their variability up close in the Carnegie Museum of Natural History’s Section of Birds in December 2016. My photo below shows sparrows collected in Alaska in the top row, sparrows from Pennsylvania on the bottom.

Song sparrows in Carnegie Museum of Natural History collection, Alaska on top row, Pennsylvania on bottom row (photo by Kate St. John, Dec 2016)

Here’s a closeup placed side by side (below):

  • On the left, two song sparrows collected in Pennsylvania: Pittsburgh (leftmost) and Geneva Marsh.
  • On the right, song sparrows collected in Alaska’s Aleutian Islands at Unalaska (leftmost) and Sanak.

Alaskan song sparrows are so large that they have to be placed sideways in the tray!

Smaller size is normal where it’s warmer.

It isn’t bad news for birds and it tells us two additional things:

  1. Birds’ bodies have been registering climate change long before we humans noticed or admitted it.
  2. Birds can evolve quickly when they have to.

Read about the Field Museum study at North American birds are shrinking. Read more about the Powdermill study at Birds are getting smaller.

p.s. This article was inspired by Andrew Nikiforuk’s As The Birds Vanish.

(top photo by Steve Gosser, remaining photos by Kate St. John)