How long did Tyrannosaurus rex typically live? Until recently, research had pegged their life span at 28-30 years but a new study finds that T-rex did not reach full size until age 40, ten years after it should have died. The previous life span is open to debate.
Dinosaur bones have concentric growth rings (cortical growth marks, CGM) like the rings found in tree trunks. To count the bone rings (CGM), the team obtained slices of leg bones from 17 specimens and ground them so thin that light could shine through them. Illustration below: Pink and blue arrowheads point to growth rings below. Notice that the bone slice is shaped like a ring. Dinosaur bones are hollow, just like bird bones!
Earlier bone studies had ignored or not even seen the tightly packed rings so they estimated the life span at 28-30 years. This study counted everything. That’s how they reached 40.
Starlings (European starlings, Sturnus vulgaris) are the invasive species Americans love to hate. They’ve only been on this continent for 136 years, having been successfully introduced in 1890 & 1891 in Central Park, New York. DNA studies indicate that every starling in the U.S. is descended from the Central Park group.
Have our starlings physically changed since they got here? Have they evolved differently from their native relatives in Eurasia?
In 2023 a team led by Julia M. Zichello(*) set out to answer that question. They measured 1,217 starlings including their beaks, wings and tarsi (plural of tarsus) using historical museum skins and modern birds from the U.S. and Eurasia, especially starlings in the UK.
Their study found that U.S. starlings have indeed changed from their Eurasian relatives:
Beak length in the native range has remained unchanged during the past 206 years, but we find beak length in North American birds is now 8% longer than birds from the native range. … Additionally, body size in North American starlings is smaller than those from the native range.
Graphs from the study show the differences in orange (U.S. starlings) and blue (native-range starlings).
U.S. birds have longer beaks (top graph and histogram).
Both native and U.S. birds have become smaller over time (bottom graphs) but the U.S. birds are overall smaller.
Figure 2 abbreviated description: (a) graph and (b) histogram: Whole beak length (mm) over time, Native range 1816–2022 (blue); introduced: U.S. range 1890–2020 (orange). (c) graph and (d) histogram: Whole tarsus length (mm) over time, Native range 1816–2022 (blue); introduced U.S. range 1890–2020 (orange). From Recent beak evolution in North American starlings after invasion, Julia M. Zichello et al, Nature.com.
Why did U.S. starlings make these changes?
Smaller size: A lot of reasons
The study says, “Smaller birds in North America, versus larger birds in the parent population, occurred rapidly on arrival and this trend has persisted today,” perhaps because (a) U.S. birds experience warmer summer temperatures than the native range (warmth makes organisms trend smaller), (b) starlings experienced “genetic drift” upon arrival, and/or (c) the founder population of birds (the 1890-91 group) may have randomly consisted of smaller bodied birds.
Longer beaks: Livestock grain vs. natural food
Longer beaks were the big revelation in this study and they conclude that it has to do with diet. U.S. starlings eat a lot of grain at cattle feedlots in winter (longer beaks are an advantage). Eurasian starlings don’t.
The most dramatic difference between starling diet in the U.S. and their native range is the intensity of their foraging at dairies and feedlots in the U.S., where they consume substantial amounts of food intended for livestock.
Since 1960, corn production in the U.S. has increased exponentially, which has also enabled a concurrent expansion of the cattle industry. By the 1960’s feedlot operators in several states were reporting major starling disturbance. In our data, 1960 is when we observe a marked increase in proximal starling beak length in the U.S. beyond what is observed in the native range at any time.
Starling flocks on U.S. dairies can exceed 10,000 birds and cause an estimated $800 million dollars of annual lost revenue across the country. … We estimate that starlings may consume [136 million lbs] of livestock feed per year in the United States. An individual bird can eat up to 2.2 lbs (1 kg) of feed per month, and 1,000 birds can consume 630 lbs (286 kg) every hour spent foraging at feedlots.
Traveling the PA Turnpike in fall and winter my husband and I often remarked on the “starling barn,” a dairy farm near Plainfield with a HUGE flock of starlings that always caught our eye as we passed. This winter the starlings were not noticeable, perhaps because USDA “helped” the farmers with their starling problem. Listen to The Controversy Over Controlled Poisoning Of Starlings from WBUR in January 2017. It’s an interview with Bob Mulvihill of the National Aviary.
Understory birds in Costa Rica’s rainforest are often streaked, spotted and striped for camouflage while they move in dim and dappled light near the forest floor. Out of all those streaky birds I have seven favorites from my trip to Costa Rica last month. Six are forest skulkers, the seventh, shown at top, is not an understory bird at all so I don’t know why he’s striped. NOTE: These photos are not to scale; almost all of them are from Wikimedia Commons.
The best way to see a fasciated tiger-heron is to check the edge of a rushing stream. We found two fishing in the Sarapiquí River at Selva Verde Lodge. Obviously the stripes do not camouflage them in this setting. Maybe those stripes are for a different reason.
This species posed nicely for us. He also posed for his Wikimedia Commons photo below.
The Fasciated Antshrike forages, mostly for large insects, in the midstory of tropical lowland forest. He’s found in vine tangles and dense mid-story canopy.
I saw this Life Bird during the Sky Walk at Arenal while there was a pause in the pouring rain. He was on my Wish List.
The streak-crowned antvireo ranges from Honduras through Nicaragua to Costa Rica, living in the understory and mid-story of lowland and foothill evergreen forest. He forages for insects and is often in mixed species flocks (paraphrased from Birds of the World).
Frequent–though not obligate–followers of mixed-species foraging flocks that track insect-flushing swarms of army ants across the forest floor.
The Spotted Antbird’s scientific name means a “spotted watcher of the woodland.” In Panama’s Darien province the species is locally known as ‘corregidor‘ (mayor) for its apparent behavior of directing the activities of other birds found with it, presumably at army ant swarms.
What a skulker! This bird is said to be common but it is very hard to see.
Generally common. Found in a wide variety of wooded habitats, including second growth and plantations, where it forages, apparently for insects in low tangles and other dense vegetation.
The Stripe-breasted Wren has two distinct singing ‘styles’, which are sufficiently at variance to sound as if they were made by completely different types of birds. The first is a series of whistles on the same pitch, somewhat like the calls of a small owl, which song, usually given at dawn, is typically given by a single bird. The second is a series of up to ten bubbling whistles, which is far more typical of the Troglodytidae, and is given in a duet.
When this wren turns his back on you, you can’t see him. If he hadn’t shown his chest I would never have known he has stripes. No photos from the trip; all I have are happy memories. These photos are from Wikimedia Commons.
The male golden pheasant (Chrysolophus pictus), native to forests in western China, is one of the showiest birds on earth. He’s bright red, orange, yellow and blue with a tail twice as long as his body and a black-and-orange ruff that displays to cover his face, except for his eyes.
His beauty is aimed to impress the ladies. Female golden pheasants prefer outrageous males so their mate selection drives male plumage evolution. Fortunately the males don’t incubate eggs. The females are dull colored for camouflage on the nest.
Birds hunted by predators usually have a wide field of view so they can see danger coming from every angle. Pheasants, like pigeons in the diagram below, usually see almost 360° without turning their heads.
But not the male golden pheasant. His fancy head feathers block his field of view above and behind his head. If you can’t see at least one of his eyes, he can’t see you. This guy has a huge blind spot.
Golden pheasants are not the only species with this problem. Male Lady Amherst’s pheasants (Chrysolophus amherstiae) also have a blind spot, especially when they display.
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.
