15 May 2025
Mr. Blue is back in town!
Why is the indigo bunting so blue in the sun and so dull in shade? It’s because his feathers are not blue. What?!?
Check out this vintage article on Where his Color Comes From:
Why is the Indigo Bunting So Blue?
Category Archives: Bird Anatomy
A Canada Goose the Size of a Pigeon?
7 April 2025
UPDATE: Thank you Amber VanStrien for pointing out that Wild Bird Fund posted this “news” on APRIL FOOL’S DAY … And I fell for it. However, there really are dwarf geese that are less than half the size (44%) of a normal Canada Goose. See revised text below.
Typical Canada geese, like the one shown above, are large birds as tall as our knees when relaxed and foraging and bigger when angry. You can’t hold one in the palm of your hand so I was amazed to see this photo of a Canada goose in New York City that is only the size of a pigeon! (Hah! It’s an April Fool’s joke.)
“Lilligoosian” was supposedly in rehab at the Wild Bird Fund on Columbus Ave, Upper West Side, NYC –> 1/10th the size of a normal Canada goose, half the size of a mallard, and just a few grams heavier than a male pigeon.
Do very small birds like this exist?
David Sibley explains in his article Do “dwarf” birds exist? that “continued poor nutrition [during the gosling stage] results in birds that never reach full size and remain smaller than normal, as several studies on Snow and Canada Geese have shown.” For instance, from a study in 2015:
Canada goose goslings fed low-protein (10%) diets were on average 44% lighter in body mass, had slower growth rates and were delayed >20 days in reaching 90% of asymptotic size compared with Canada goose goslings fed 18% protein.
— from Ecological implications of reduced forage quality on growth and survival of sympatric geese
So “Lilligoosian,” the pigeon-sized Canada goose, was probably Photoshop’d but there are such things as dwarf geese. Goslings can be stunted by unhealthy food and reach only half the size of a normal Canada goose in adulthood.
Why Owls Can Turn Their Heads So Far
13 March 2025
Owls have excellent eyesight but they see the world differently than we do.
When we look straight ahead (fixation point below) our peripheral vision allows us to faintly see our hand waving near our ear — a 200-220° field of view.
Owls have binocular vision similar to ours but their peripheral vision is much narrower. They cannot even see 180°.
To make matters worse they cannot move their eyes!
Since their eyes are always facing forward, they have to move their heads or their bodies to see anything outside their narrow field of view. Moving their bodies would alert their prey, so owls have evolved to move their heads as far back as they need to see — up to 270°.
- Owls have 14 neck bones for greater flexibility. We have only 7 neck bones
- The owls’ atlanto-occipital neck joint has evolved to move the head further back.
When you can’t move your eyes, you have to move your head.
Rare and Wonderful White Hawk
9 January 2025
There were several hours of excitement on New Years Day when a snowy owl showed up at Pymatuning. That same day in Northampton County, PA Steve Magditch thought he too may have found a snowy owl but his camera lens revealed a common bird in uncommon plumage, a leucistic red-tailed hawk (Buteo jamaicensis).
Brenda Lindsey was excited to capture these photos on 4 January.
Leucistic Red-tailed Hawk! I set out this morning to (maybe) see it. (I can’t believe I found it!) Thank you Steve Magditch and Kathleen Itterly Dimmich for your prior postings of this unique Bird of Prey!
— Brenda Lindsey post on Facebook, 4 January 2025
This white hawk is called leucistic, not albino, because it has normal-colored eyes and at least one normally colored feather. See the red feather(s) in its tail.
Though rare, leucistic red-tailed hawks occur throughout their range in North America with a lot of variation in their plumage. Some are spotted, some are blotchy.
See additional photos of white red-tails and learn about leucism in this vintage article.
Birds Have Same Bones But Different Arms
2 October 2024
The diagram above, from Arizona State University’s Ask A Biologist, shows that beneath our skin humans, birds and bats all have the same bones in our arms/wings but the bones have evolved to match our lifestyles.
We humans use our arms to reach and our hands to grab and manipulate. Birds and bats use their “arms” for flying. You can see it in our bones.
Each bone has changed compared to humans.
Big changes start at the wrist with huge changes in the “hands” and fingers.
Birds have only two “fingers” and their “thumbs” (the alula) are used only for slow flight maneuvers.
See more in the original article at Ask A Biologist: Human, Bird, and Bat Bone Comparison
(diagram from asu.edu Ask A Biologist coloring pages for kids, CC BY-SA)
New T-Rex Relative Found in Mexico
1 October 2024
Did you know that Tyrannosaurus rex was exclusively(*) a North American dinosaur?
He lived during the Campanian–Maastrichtian ages of the late Cretaceous period, 72.7 to 66 million years ago, on the former island continent of Laramidia which is now the western part of North America extending from Canada to Mexico.
Fifty years ago paleontologists found fossils of a T-Rex relative in Baja California, Mexico: Labocania anomala.
This year they analyzed bones in a drawer at the Museo del Desierto that had been found in the Chihuahuan desert in northern Mexico in 2000. The bones were from a new-to-science relative of T-Rex!
Named Labocania aguillonae, the ancient predator was at least 6.3 m (21 feet) in length — relatively small by tyrannosaur standards [and] closely related to Labocania anomala, Bistahieversor sealeyi, and Teratophoneus curriei.
— Sci News: New Tyrannosaur Species Unearthed in Mexico: Labocania aguillonae
Unlike its heavily built cousin [T-Rex], this animal was long-legged and lightly built, with big eyes that may have helped it hunt in low light and a heavy snout for dispatching helpless prey.
… The species has been named Labocania aguillonae after Martha Carolina Aguillón, the local paleontologist who discovered it [in 2000].
— New York Times: A Leggy Tyrannosaur Emerges From a Mexican Desert
Meet Labocania aguillonae in this short video.
Here’s how the new dino fits in the Tyrannosauridae tree of life.
Read more in the New York Times: A Leggy Tyrannosaur Emerges From a Mexican Desert and in Sci News: New Tyrannosaur Species Unearthed in Mexico: Labocania aguillonae.
(*) Note” Relatives of T-Rex have been found in China but not T-Rex himself.
Adapting To The Heat
29 August 2024
It’s been another hot week with muggy high temperatures and more to come. Birds are adapting by bathing, hanging out in the shade, and avoiding activity during the worst part of the day.
Some birds who live where it’s hot and dry have adapted their bodies to help them cool off. Read about their special air conditioner nasal passages in this 2017 article.
p.s. Yesterday morning when it was 84°F and felt like 86°, Ecco took a sun bath to heat his feathers and force out the parasites. Aaaaaaah. And then he adjourned to the shade to preen them away.
How Birds Deal With Heat: Manipulate the Feathers
15 August 2024
Here’s a little Before and After exercise that spans five to six months. Observe birds who are in your neighborhood all year long. Song sparrows and cardinals are two good choices.
- Before: On a hot day in August notice how plump or thin the birds are. Even better, take a picture of a bird in the heat.
- After: On a cold day in winter, again notice how fat or thin the birds are. Take a picture of the same species out in the cold.
The song sparrows above were photographed by Steve Gosser on a warm October day and on a snowy day in early March.
Spoiler Alert! Here’s what you’ll see.
To See or Not To See Ultraviolet Light
13 August 2024
Just because an animal has UV receptors in its eyes does not mean it can see ultraviolet light. A recent BBC video, below, reveals some surprising things about the use and perception of ultraviolet light in starlings (Sturnus vulgaris) and raptors, especially golden eagles (Aquila chrysaetos). For instance:
- Starlings and golden eagles both have UV receptors in their eyes.
- Female starlings have feathers that reflect UV. The more UV a female reflects the more successful she is at breeding. Male starlings like the glow we humans cannot see.
- UV light scatters more. If you can see UV light, it makes images blurry.
- Raptors have UV receptors in their eyes but they cannot see it because their lenses filter it out. The golden eagle’s vision is sharper because he cannot see UV.
- Scientists used to think kestrels hunted by seeing the UV reflective paths of rodent urine. Nope. Kestrel eyes filter out UV so that theory has been disproved.
Interesting conclusions:
- Because I thought that raptors could see UV, I used to wonder how flashy UV-reflective songbirds managed to evade predators. Answer, the predators cannot see that flashy stuff!
- UV light damages the eye so there is an advantage to not seeing it for most of one’s life.
- Human eyes have UV receptors but we cannot see it because our lens filters out UV. There are exceptions based on age and lack of lenses.
- Exception#1: Young people up to age 30 can see near UV, the wavelengths closest to our visible color range, per a 2018 Univ of Georgia study.
- Exception#2: Those without lenses in their eyes can see near UV. This includes those born without lenses and those who had cataract surgery in the early days. Claude Monet had cataract surgery in 1923 with no lens replacement and could see near UV.
Read more about human perception of UV light in this Live Science article: Can Humans See Ultraviolet Light?
Next on the Agenda: Molting
13 June 2024
As soon as the breeding season is over adult birds molt to change out their old feathers. During this period many birds look ragged. We’ll see a few bald cardinals and blue jays who’ve molted all their head feathers at once. Peregrines will seem lazy while they molt in July and August. Canada geese won’t be able to fly.
This week at Duck Hollow I noticed that Canada geese are already molting. Their white rumps are showing, which indicates they’ve lost all their flight feathers.
At the end of this month Pitt’s peregrines will be molting too. We might see a peregrine feather on the falconcam.
Learn more about molting in this vintage article.