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.
Did you know that Tyrannosaurus rex was exclusively(*) a North American dinosaur?
He lived during the Campanian–Maastrichtian ages of the late Cretaceousperiod, 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.
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.
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].
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.
Ecco sunbathes in the heat, 28 Aug 2024, 11:07am (photo from the National Aviary snapshot camera at Univ of Pittsburgh)
Song sparrows: warm in October, cold in snowy March (photos by Steve Gosser)
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.
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.
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.
Maybe you’ve noticed that after watching warblers for a while, sparrows look huge. Gloria (@Lucent508) captured them side by side.
This photo I took today is far from technically perfect but I like it bc it shows the size discrepancy between a White-throated Sparrow that can weigh btw 22-32g and Black&White Warbler that weighs btw 8-15g. The Sparrow looks like a hulk compared to this warbler! pic.twitter.com/pEadhzmWhl
On Day 25 at the peregrine nest at Charing Cross Hospital in London (Fulham and Barnes), one of the chicks explored the nestbox ramp. He stumbled on the last step but enjoyed the outing nonetheless (the stumble is last photo though it actually happened first). At one point his mother looked at him as if to say, “Are you OK out there?”
Day 25 First chick goes out of the box for the first time. Not always elegantly. But the ramp did its job 🙂 It was very easy for the chick to get back in. pic.twitter.com/hBW5OfVklF
Even though they are not “persons,” falconcams give us insight into the individual personalities of the peregrines on camera. This year the new unbanded female at the Wakefield Cathedral Peregrines nest (@WfldPeregrines) in Yorkshire, England has a habit never observed in the previous female: “Our previous female would never stay in the nest whilst the male fed the chicks.”
In the video below the female watches the male feed the chick. Sometimes he passes her a morsel of food which she swallows … or she feeds it to the chick. It’s not often that you see two peregrine parents feeding one chick.
Leucistic common grackle, Frick Park, 26 Oct 2023 (photo by Charity Kheshgi)
7 November 2023
Last month at Frick Park Charity Kheshgi and I saw at least three birds with unusual white feathers in their plumage, a condition that labels them “leucistic.”
Leucism refers to an abnormality in the deposition of pigment in feathers. There is some disagreement as to whether the condition is genetic or caused by pigment cells that were damaged during development. Whatever the cause, the condition can result in a reduction in all types of pigment, causing pale or muted colors on the entire bird. Or the condition can cause irregular patches of white, and birds with these white patches are sometimes described as “pied” or “piebald.”
This common grackle had white feather patches on his head that were not uniform from side to side.
Leucistic common grackle, Frick Park, 26 Oct 2023 (photo by Charity Kheshgi)
The circle of white dashes around his eyes indicate his eyelashes are white. (Did you know birds’ eyelashes are modified feathers?)
Leucistic grackle zoomed in, white dashes around his eyes (photo by Charity Kheshgi)
In early October we saw a white-faced chipping sparrow …
Leucistic chipping sparrow — white face, Frick Park, 7 October 2023 (photo by Charity Kheshgi)
… and a leucistic American robin in the middle of the month.
Leucistic American robin, Frick Park, 18 Oct 2023 (photo by Charity Kheshgi)
It seems that leucism is more common in robins than in other species — or at any rate I see more of them. Here’s one that was photographed in Missouri.
Though 70% of the songbirds in our field guides have sexes that look the same to us, this isn’t true from the birds’ point of view. Birds can see ultraviolet light (we cannot) and often have plumage differences in the ultraviolet range. With the invention of inexpensive UV viewing equipment, scientists looked at birds and were amazed at what they found. 90% of the species tested had differences between males and females under UV light. We humans just can’t see it.
Eurasian blue tits (Cyanistes caeruleus), shown at top, were one of the first wild birds examined in the ultraviolet range. Both sexes look alike … or do they?
Using a spectrophotometry probe to scan the feathers of wild-caught birds, Andersson and his colleagues discovered that blue tits themselves have no problem telling males from females: Males have a patch of feathers on the crown of the head that strongly reflects UV light; females do not.
Both sexes of yellow-breasted chats (Icteria virens) look the same from afar, though in the hand the sexes can be distinguished (interior mouth color for instance). A 2004 study, Sexual dichromatism in the yellow-breasted chat, detected that the male’s throat has ultraviolet colors that make it much brighter than the female’s.
Apparently most birds are sexually dimorphic in ultraviolet including cedar waxwings, barn swallows, mockingbirds and western meadowlarks. According to True Colors: How Birds See The World, biologist Muir Eaton scanned the plumage of museum study skins of 139 songbird species in which males and females appear alike — but they aren’t alike under UV. He concluded, “To the birds themselves, males and females look quite different from one another.”
For more information see:
Photos of birds showing ultraviolet features at uvbirds.com. (Check out the flamingo!)
The great-tailed grackle (Quiscalus mexicanus), a close relative of our common grackle, is so numerous and annoying in Austin, Texas in the winter that there are always news stories about them. This interview with a grackle researcher revealed a very cool fact about great-tailed grackles that probably applies to our grackles as well.
Great-tailed grackles can move their eyes independently to keep watch in two different directions at the same time! Check out the video below.
