The mix of migrating songbirds is changing this month, but migration is still in full swing. When the weather is right, songbirds take off an hour+ after dusk and may fly eight hours to stop just before dawn. Last week was especially intense for migration, as described by BirdCasts’s Kyle Horton for NBC 7 San Diego.
All of these nighttime migrants are flapping. How much energy does this use up?
Back in 2005 a biotelemetry study of Swainson’s thrushes measured heartbeat and wingbeats in flight and concluded that they flapped about 11 beats per second on sustained migration. In eight hours that means about 311,000 wingbeats — a lot of flapping for a small bird — and some of them flap even more, such as the ruby-crowned kinglets who’ve just started to pass through our area.
Examining wing of Tennessee warbler during banding, Bird Lab at Hays Woods, 16 Sep 2025 (photo by Kate St. John)
30 September 2025. Old news but worth a look.
Lots of data is collected when a bird is banded or collected in a museum including species, sex, age, weight, wing and tarsus length. When nearly half a century of this data was analyzed at Powdermill in 2010 and at Chicago’s Field Museum in 2019 it became apparent that very slowly, over a period of nearly half a century, North American birds have been shrinking and in many cases their wings are getting longer.
Measuring the wing of Lincoln sparrow during banding (photo from Wikimedia Commons)
The Powdermill and Field Museum studies both found a correlation between size change and the annual mean summer temperature of the species’ breeding range. They reached the same conclusion: As the climate heats up, migratory birds are getting smaller.
The birds are shrinking and this is normal. Very slowly, as their home territories heat up, bird bodies are following Bergmann’s Rule regarding body size and temperature.
Bergmann’s Rule: Within a species, populations living in colder climates have larger body size than those in warmer climates. Large animals have a lower surface-area-to-volume ratio so they lose heat more slowly in cold climates. Small animals have a higher surface-to-volume ratio and cool off faster when it’s hot.
To see this side-by-side, check out these song sparrows (Melospiza melodia) in the Carnegie Museum of Natural History’s Section of Birds. Song sparrows collected in Pennsylvania (on the left) are small and in Alaska (right) are large. Southern : warm : small. Northern : cold : large.
Song sparrow geographic size difference, Pennsylvania on left, Alaska on right from Carnegie Museum of Natural History Collection (photo by Kate St. John, Dec 2016)
Birds are adapting to climate change generation after generation.
Female American redstart closeup to show rictal bristles, 16 Sept 2025, Bird Lab at Hays Woods (photo by Kate St. John)
18 September 2025
When I visited Bird Lab’s Hays Woods banding site on Tuesday, I was excited to release an American redstart after she was banded, weighed and measured. Before I let her go I took a good look at her face and was surprised to see she had rictal bristles around her beak. On cats we’d call them “whiskers.”
Rictal bristles are stiff, modified bristle feathers that grow at the base of the birds beak — at the gape, or the nares (nostrils), the lores, or beneath the beak. They may or may not have barbs. They are not like other feathers.
Years ago I’d heard that rictal bristles were used to help capture flying-insect food but experiments have shown that is not the case.
Studies [published in SORA] have been done where the bristles of [willow] flycatcher were removed or were taped down. Neither of those actions adversely affected the birds’ ability to capture prey, indicating that the rictal bristles do not aid in prey capture. In those studies the flycatchers that had their rictal bristles taped down or removed had more debris from their insect prey land on their eyes.
Now that the food capture theory has been thrown out, new studies are looking into the evolutionary origin of avian facial bristles — how many birds have them? Other studies are trying to parse out the feathers’ purpose. Some bristles may protect the eyes or nose. Some may be tactile, just like cats’ whiskers. Some are a mystery.
And that’s where redstarts come in; their bristles made me wonder. Here are better looks at their faces.
On 21 July all three of this year’s young peregrines had been gone from the Cathedral of Learning for more than a month when — Surprise! — a very loud juvie chased Ecco to the nest.
Apparently tired of fending for herself, Yellow arrived on the scene to demand food from her father. But like all good peregrine parents, Ecco would not feed her. She complained bitterly. “I don’t wanna grow up!”
Things went back to normal for a while but six days later, on 27 July, Ecco and Carla arrived at the nest for a bonding session. They had to leave abruptly when a noisy youngster showed up off camera. It was probably Yellow.
Eventually Yellow will get the hint, leave the area and finally grow up. I can imagine Carla telling her, “May you have many children just like you.”
p.s. News from Downtown: I’m happy to see the Downtown peregrines are controlling the airspace.
eBird Checklist S258389927 Wed 9 Jul 2025, 12:24 PM One Oxford Centre, 426–518 4th Ave, Pittsburgh US-PA (40.4383,-79.9986) Reported by: MONTGOMERY BROWN 1 Peregrine Falcon (Falco peregrinus)
The falcon was “harassing” a drone that was 350-400 feet off the ground. After about 30 seconds, the drone operator appeared to realize this and flew the drone off toward the Monongahela.
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.)
The winds of spring blow curiouser and curiouser! At first we thought this was a cackling goose, but nope. She's just an astonishingly small Canada goose. Weighing a mere 400g (closer to a pigeon than a 4kg Canada goose), Lilligoosian is a bit thin but otherwise healthy. pic.twitter.com/YOxnDYM43Z
“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.
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.
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.
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
Leucistic red-tailed hawk in Northampton County, PA, 4 Jan 2025 (photo by Brenda Lindsey)
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!
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.
Leucistic red-tailed hawk in Northampton County, PA, 4 Jan 2025 (photo by Brenda Lindsey)Leucistic red-tailed hawk in Northampton County, PA, 4 Jan 2025 (photo by Brenda Lindsey)
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.
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].
