It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Fossils reveal how ancient birds molted their feathers— which could help explain why ancestors of modern birds survived when all the other dinosaurs died
IMAGE: FEATHERS FROM A BABY BIRD THAT LIVED 99 MILLION YEARS AGO, PRESERVED IN AMBER.view more
CREDIT: PHOTO BY SHUNDONG BI.
Every bird you’ve ever seen— every robin, every pigeon, every penguin at the zoo— is a living dinosaur. Birds are the only group of dinosaurs that survived the asteroid-induced mass extinction 66 million years ago. But not all the birds alive at the time made it. Why the ancestors of modern birds lived while so many of their relatives died has been a mystery that paleontologists have been trying to solve for decades. Two new studies point to one possible factor: the differences between how modern birds and their ancient cousins molt their feathers.
Feathers are one of the key traits that all birds share. They're made of a protein called keratin, the same material as our fingernails and hair, and birds rely on them to fly, swim, camouflage, attract mates, stay warm, and protect against the sun’s rays. But feathers are complex structures that can’t be repaired, so as a means of keeping them in good shape, birds shed their feathers and grow replacements in a process called molting. Baby birds molt in order to lose their baby feathers and grow adult ones; mature birds continue to molt about once a year.
“Molt is something that I don't think a lot of people think about, but it is fundamentally such an important process to birds, because feathers are involved in so many different functions,” says Jingmai O’Connor, associate curator of fossil reptiles at Chicago’s Field Museum. “We want to know, how did this process evolve? How did it differ across groups of birds? And how has that shaped bird evolution, shaped the survivability of all these different clades?” Two of O’Connor’s recent papers examine the molting process in prehistoric birds.
A paper in the journal Cretaceous Research published in May 2023 detailed the discovery of a cluster of feathers preserved in amber from a baby bird that lived 99 million years ago.
Today, baby birds are on a spectrum in terms of how developed they are when they're born and how much help they need from their parents. Altricial birds hatch naked and helpless; their lack of feathers means that their parents can more efficiently transmit body heat directly to the babies’ skin. Precocial species, on the other hand, are born with feathers and are fairly self-sufficient.
All baby birds go through successive molts— periods when they lose the feathers they have and grow in a new set of feathers, before eventually reaching their adult plumage. Molting takes a lot of energy, and losing a lot of feathers at once can make it hard for a bird to keep itself warm. As a result, precocial chicks tend to molt slowly, so that they keep a steady supply of feathers, while altricial chicks that can rely on their parents for food and warmth undergo a “simultaneous molt,” losing all their feathers at roughly the same time.
The amber-preserved feathers in this study are the first definitive fossil evidence of juvenile molting, and they reveal a baby bird whose life history doesn’t match any birds alive today. “This specimen shows a totally bizarre combination of precocial and altricial characteristics,” says O’Connor, who was the first author of the paper alongside senior author Shundong Bi of the Indiana University of Pennsylvania. “All the body feathers are basically at the exact same stage in development, so this means that all the feathers started growing simultaneously, or near simultaneously.” However, this bird was almost certainly part of a now-extinct group called the Enantiornithines, which O’Connor’s previous work has shown were highly precocial.
O’Connor hypothesizes that the pressures of being a precocial baby bird that had to keep itself warm, while undergoing a rapid molt, might have been a factor in the ultimate doom of the Enantiornithines. “Enantiornithines were the most diverse group of birds in the Cretaceous, but they went extinct along with all the other non-avian dinosaurs,” says O’Connor. “When the asteroid hit, global temperatures would have plummeted and resources would have become scarce, so not only would these birds have even higher energy demands to stay warm, but they didn’t have the resources to meet them.”
Meanwhile, an additional study published July 3 in Communications Biology by O’Connor and Field Museum postdoctoral researcher Yosef Kiat examines molting patterns in modern birds to better understand how the process first evolved.
In modern adult birds, molting usually happens once a year in a sequential process, in which they replace just a few of their feathers at a time over the course of a few weeks. That way, they're still able to fly throughout the molting process. Simultaneous molts in adult birds, in which all the flight feathers fall out at the same time and regrow within a couple weeks, are rarer and tend to show up in aquatic birds like ducks that don’t absolutely need to fly in order to find food and avoid predators.
It’s very rare to find evidence of molting in fossil birds and other feathered dinosaurs, and O’Connor and Kiat wanted to know why. “We had this hypothesis that birds with simultaneous molts, which occur in a shorter duration of time, will be less represented in the fossil record,” says O’Connor— less time spent molting means fewer opportunities to die during your molt and become a fossil showing signs of molting. To test their hypothesis, the researchers delved into the Field Museum’s collection of modern birds.
“We tested more than 600 skins of modern birds stored in the ornithology collection of the Field Museum to look for evidence of active molting,” says Kiat, the first author of the study. “Among the sequentially molting birds, we found dozens of specimens in an active molt, but among the simultaneous molters, we found hardly any.”
While these are modern birds, not fossils, they provide a useful proxy. “In paleontology, we have to get creative, since we don’t have complete data sets. Here, we used statistical analysis of a random sample to infer what the absence of something is actually telling us,” says O’Connor. In this case, the absence of molting fossil birds, despite active molting being so prevalent in the sample of modern bird specimens, suggests that fossil birds simply weren’t molting as often as most modern birds. They may have undergone a simultaneous molt, or they may not have molted on a yearly basis the way most birds today do.
Both the amber specimen and the study of molting in modern birds point to a common theme: prehistoric birds and feathered dinosaurs, especially ones from groups that didn’t survive the mass extinction, molted differently from today’s birds.
“All the differences that you can find between crown birds and stem birds, essentially, become hypotheses about why one group survived and the rest didn’t,” said O’Connor. “I don't think there's any one particular reason why the crown birds, the group that includes modern birds, survived. I think it's a combination of characteristics. But I think it's becoming clear that molt may have been a significant factor in which dinosaurs were able to survive.”
Illustration of what a newly hatched Enantiornithine bird may have looked like.
CREDIT
Image by Yu Chen and Shundong Bi.
An illustration of a more mature juvenile Enantiornithine.
Illustration showing a young Enantiornithine bird.
CREDIT
Image by Yu Chen and Shundong Bi.
Mourning Doves in the Field Museum's bird collections, used to examine molting in living birds.
Mallard ducks (IMAGE)
FIELD MUSEUM
Mallard ducks in the Field Museum's bird collections, used to study molting in modern birds.
CREDIT
Field Museum, Kate Golembiewski
JOURNAL
Communications Biology
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Rarity of molt evidence in early pennaraptoran dinosaurs suggests annual molt evolved later among Neornithes
ARTICLE PUBLICATION DATE
3-Jul-2023
Saturday, October 07, 2023
Record amount of bird deaths in Chicago this week astonishes birding community
Camille Fine, USA TODAY Updated Fri, October 6, 2023 Scientists and volunteers at the Field Museum in Chicago collected nearly 1,000 birds Thursday, Oct. 5. The museum said it was the most amount of bird deaths recorded in their 40 years of data collection.
These preventable tragedies occur every year, especially during fall and spring migration, but this incident was noticeably worse. Nearly 1,000 birds died after striking the windows at McCormick Place convention center Thursday, “the most Field collecting efforts have documented in the past 40 years,” a post by the museum said.
The incident has set Chicago’s birding community “abuzz,” reported WTTW, a PBS member television station in Chicago.
According to WWTW, migrating birds were passing over some points of the city at a high-intensity rate of 100,000 that day amid adverse flying conditions. Both factors led to an overwhelming number of birds toward Chicago’s Lake Michigan beachfront along their harrowing journey.
In addition to higher incidences of bird collisions, recent evidence has pin-pointed climate change’s impact on birds. Birds in both North and South America are getting smaller as the planet warms, and the smallest-bodied species are changing the fastest, according to previous USA TODAY reporting.
According to the Field Museum, smaller bodies hold on to less heat and larger bodies hold on to more, which helps animals stay a comfortable temperature in different environments. Meanwhile, the birds’ wingspans may have increased so the birds are still able to make their long migrations, even with smaller bodies to produce the energy needed for flight, the Field Museum said.
Data from the Field Museum — collected by a team of scientists and volunteers who search for birds that collide into the center’s windows every day during the migration seasons — has been used in studies to make the case for more protections to make collisions less frequent to help vulnerable birds.
According to Audubon Great Lakes, collisions with human-made structures are a leading cause of bird deaths in the United States, causing up to 1 billion bird deaths each year in North America. Evidence shows "the total number of birds in the sky on a given night and the direction of the wind both play a role in mortality, but the biggest determining factor was light," Field Museum said.
"It doesn't have to be this way," Audubon Magazine writes. "Though we might not be able to reverse human development, we can be proactive about preventing bird deaths that results from our man-made obstacles."
Groups including Audubon and BirdCast provide the following tips:
Make your windows obvious to avoid confusing birds.
Do not use landscape lighting to light up trees or gardens where birds may be resting.
Close blinds at night to reduce the amount of light being emitted from windows
Hundreds of migrating birds die after crashing into Chicago buildings
Mike Bedigan Fri, October 6, 2023
Ornithology enthusiasts in Chicago were left stunned by a “major bird collision” in the city, which has left hundreds of the animals dead.
The incident which occurred earlier this week comes amid a major migration in the area, with adverse weather, glass and high-intensity migration thought to be among the causes.
The Chicago Bird Collision Monitors reported that its volunteers had collected “close to 300 injured birds”, with many more dead, on Thursday alone.
The group’s volunteers work to protect and recover migratory birds killed and injured in the downtown Chicago area each year during spring and autumn migrations.
PhD candidate Taylor Hains, who works at the Chicago Field Museum and assists with bird collection told WTTV News that birds were “still colliding” with windows at the McCormick Place building as rescue operations continued.
The Independent understands that the total number of birds collected on Thursday eventually totalled nearly 900.
David Willard is a retired bird division collections manager at the Chicago Field Museum, where his duties included administering, preserving and cataloguing the museum’s collection of 500,000 bird specimens as well as searching for bird strikes as part of migration research.
He told the Associated Press that the scenes outside McCormick Place was like “a carpet of dead birds at the windows”.
“A normal night would be zero to 15 (dead) birds. It was just kind of a shocking outlier to what we’ve experienced,” Mr Willard said. Dead birds in Chicago following a ‘major bird collision’ event (Taylor Hains)
“In 40 years of keeping track of what’s happening at McCormick, we’ve never seen anything remotely on that scale.”
A post from BirdCast, an organisation which provides real-time predictions of bird migrations, read: “Our colleagues and friends in the Chicago, Illinois area have sad news about a major bird collision event that occurred last night and this morning, 4-5 October 2023.
“Reports from the area indicate that large numbers of birds died in collisions while major migration was occurring in the area.
“Although details are still emerging, this event appears to be a combination of high-intensity migration, adverse weather conditions for flying, and light and glass – a mix we know too well can be deadly.”
(Taylor Hains)
The organisation also urged “all businesses, building owners and private residences, as well as operators of any illuminated structures, to heed lights-out warnings for non-essential lights to be turned off during the migration season.”
The American Bird Conservancy estimates 1 billion birds a year die from colliding with glass, with window strikes known to be an issue in almost every major US city.
Birds do not see clear or reflective glass and do not understand it is a lethal barrier. When they see plants or bushes through windows or reflected in them, they head for them, killing themselves in the process.
Birds that migrate at night, like sparrows and warblers, rely on the stars to navigate. Bright lights from buildings both attract and confuse them, leading to window strikes or birds flying around the lights until they die from exhaustion — a phenomenon known as fatal light attraction
Nearly 1,000 migrating songbirds perish after crashing into windows at Chicago exhibition hall
In this image provided by the Chicago Field Museum, the bodies of migrating birds are displayed, Thursday, Oct. 5, 2023, at the Chicago Field Museum, in Chicago. The birds were killed when they flew into the windows of the McCormick Place Lakeside Center, a Chicago exhibition hall, the night of Oct. 4-5. According to the Chicago Audubon Society, nearly 1,000 birds migrating south during the night grew confused by the exhibition center's lights and collided with the building.
In this image provided by the Chicago Field Museum, workers at the Chicago Field Museum inspect the bodies of migrating birds, Thursday, Oct. 5, 2023, in Chicago, that were killed when they flew into the windows of the McCormick Place Lakeside Center, a Chicago exhibition hall, the night of Oct. 4-5, 2023. According to the Chicago Audubon Society, nearly 1,000 birds migrating south during the night grew confused by the exhibition center's lights and collided with the building In this image provided by the Chicago Field Museum, the bodies of migrating birds are displayed, Thursday, Oct. 5, 2023, at the Chicago Field Museum, in Chicago. The birds were killed when they flew into the windows of the McCormick Place Lakeside Center, a Chicago exhibition hall, the night of Oct. 4-5. According to the Chicago Audubon Society, nearly 1,000 birds migrating south during the night grew confused by the exhibition center's lights and collided with the building. In this image provided by the Chicago Field Museum, workers at the Chicago Field Museum inspect the bodies of migrating birds, Thursday, Oct. 5, 2023, in Chicago, that were killed when they flew into the windows of the McCormick Place Lakeside Center, a Chicago exhibition hall, the night of Oct. 4-5, 2023. According to the Chicago Audubon Society, nearly 1,000 birds migrating south during the night grew confused by the exhibition center's lights and collided with the building.
In this image provided by the Chicago Field Museum, workers at the Chicago Field Museum inspect the bodies of migrating birds, Thursday, Oct. 5, 2023, in Chicago, that were killed when they flew into the windows of the McCormick Place Lakeside Center, a Chicago exhibition hall, the night of Oct. 4-5, 2023. According to the Chicago Audubon Society, nearly 1,000 birds migrating south during the night grew confused by the exhibition center's lights and collided with the building.
(Lauren Nassef/Chicago Field Museum via AP)
TODD RICHMOND Updated Fri, October 6, 2023
David Willard has been checking the grounds of Chicago's lakefront exhibition center for dead birds for 40 years. On Thursday morning he found something horrible: Hundreds of dead songbirds, so thick they looked like a carpet.
Nearly 1,000 songbirds perished during the night after crashing into the McCormick Place Lakeside Center 's windows, the result, according to avian experts, of a deadly confluence of prime migration conditions, rain and the low-slung exhibition hall's lights and window-lined walls.
“It was just like a carpet of dead birds at the windows there,” said Willard, a retired bird division collections manager at the Chicago Field Museum, where his duties included administering, preserving and cataloging the museum's collection of 500,000 bird specimens as well as searching for bird strikes as part of migration research.
“A normal night would be zero to 15 (dead) birds. It was just kind of a shocking outlier to what we've experienced," Willard said. "In 40 years of keeping track of what's happening at McCormick, we've never seen anything remotely on that scale."
Researchers estimate hundreds of millions of birds die in window strikes in the United States each year. Scientists with the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service released a study in 2014 that put the number between 365 million and 988 million birds annually.
Window strikes are an issue in almost every major U.S. city. Birds don't see clear or reflective glass and don't understand it's a lethal barrier. When they see plants or bushes through windows or reflected in them, they head for them, killing themselves in the process.
Birds that migrate at night, like sparrows and warblers, rely on the stars to navigate. Bright lights from buildings both attract and confuse them, leading to window strikes or birds flying around the lights until they die from exhaustion — a phenomenon known as fatal light attraction. In 2017, for example, almost 400 passerines became disoriented in a Galveston, Texas, skyscraper's floodlights and died in collisions with windows.
“Unfortunately, it is really common,” said Matt Igleski, executive director of the Chicago Audubon Society. “We see this in pretty much every major city during spring and fall migration. This (the window strikes at McCormick Place) was a very catastrophic single event, but when you add it all up (across the country), it's always like that.”
Conditions were ripe for a massive wave of songbird southern migration over Chicago on Wednesday evening, said Stan Temple, a retired University of Wisconsin-Madison wildlife ecology professor and avian expert.
Small songbirds feed during the day and migrate at night to avoid air turbulence and predators. They’ve been waiting for northerly winds to give them a boost south, Temple said, but September saw unusually warm southern winds that kept birds in a holding pattern here. On Wednesday evening a front swept south, providing a tailwind, and thousands of birds took to the skies.
“You had all these birds that were just raring to go but they’ve been held up with this weird September and October with temperatures way above normal,” Temple said. “You had this huge pack of birds take off.”
The birds swept south over Chicago, following the Lake Michigan shoreline - and right into a maze of illuminated structures, Temple said.
Pre-dawn rain forced the birds to drop to lower altitudes, where they found McCormick Place’s lights on, Willard said. According to the field museum’s count, 964 birds died at the center. That’s about 700 more than have been found at the center at any point in the last 40 years, Willard said. Members of 33 species died, according to the field museum; most of them were palm and yellow-rumped warblers.
Window strikes and fatal light attraction are easily preventable, said Anna Pidgeon, an avian ecologist at the University of Wisconsin-Madison. Building managers can simply dim their lights, she said, and architects can design windows with markings in the glass that birds can easily recognize. People can add screens, paint their windows or apply decals to the glass as well.
New York City has taken to shutting off the twin beams of light symbolizing the World Trade Center for periods of time during its annual Sept. 11 memorial ceremony to prevent birds from becoming trapped in the light shafts. The National Audubon Society launched a program in 1999 called Lights Out, an effort to encourage urban centers to turn off or dim lights during migration months. Nearly 50 U.S. and Canadian cities have joined the movement, including Toronto, New York, Boston, San Diego, Dallas and Miami.
Chicago also participates in the Lights Out program. The city council in 2020 passed an ordinance requiring bird safety measures in new buildings but has yet to implement the requirements. The first buildings at McCormick Place were constructed in 1959.
Cynthia McCafferty, a spokesperson for McCormick Place, said the exhibition hall participates in Lights Out and interior lighting is turned off unless staff, clients or visitors need it. She added that the center maintains a six-acre (2.4-hectare) bird sanctuary.
McCafferty said an event has been going on all week at the center so the lights have been on when the building was occupied but turned off when it wasn't. She said she wasn't sure what time the window strikes occurred or whether the center was occupied then.
“It's an odd building,” Willard said of the exhibition center. “When it was built, people weren't thinking about bird safety. They still aren't in most architecture. It's right on the lakefront. There are many nights when it's lit up. People are describing the whole night of migration as part of a once in a lifetime thing ... (but) this still is an unacceptable intrusion by humans and their architecture. Just terribly sad and dramatic.”
—-
This story has been updated to correct the name of the exhibition center to McCormick Place, not McCormick Center.
Monday, March 02, 2020
It's OK to feed wild birds: Here are some tips for doing it the right way
Costa’s Hummingbirds are frequent visitors at feeders in Arizona and southern California. Credit: Julian Avery, CC BY-ND
Millions of Americans enjoy feeding and watching backyard birds. Many people make a point of putting food out in winter, when birds needs extra energy, and spring, when many species build nests and raise young.
As awildlife ecologistand a birder, I know it's important to understand how humans influence bird populations, whether feeding poses risks towild birds, and how to engage with birds in sustainable ways.
There is still much to learn about the risks and benefits of feeding birds, particularly through large integrated national citizen science networks like Project FeederWatch. But we now have enough information to promote healthy interactions that can inspire future generations to care about conservation.
A long-term relationship
Birds have been taking advantage of human civilization for thousands of years, congregating where grains and waste are abundant. This means that people have been influencing the abundance and distribution of species for a very long time.
Studies show that providing food has myriad effects on birds' decisions, behaviors and reproduction. One significant finding is that winter bird feeding increases individual survival rates, can encourage birds to lay eggs earlier in the year, and can also improve nestling survival.
All of these factors alter species' future reproductive performance and can increase total bird abundance in later years. It's not always clear how increased abundance of feeder birds impacts other species through competition, but rarer and smaller species can be excluded.
Supplemental food has also led to reduced reproductive success in a few species. This may happen because it improves survival odds for less healthy birds that otherwise would be unlikely to survive and reproduce, or because it leads birds to eat fewer types of natural foods, making their diets less nourishing.
Data from Project FeederWatch show Northern Cardinal populations expanding into the upper Midwest, northern New England, the Southwest and southeastern Canada. Credit: Virginia Greene/Cornell Lab of Ornithology, CC BY-ND
Changing bird behavior
Research also shows that birds are extremely promiscuous. One review examined 342 species and found that in approximately 75%, birds had one or more side partners in addition to their nest mate.
It's not always clear why birds cheat, but several studies have found that supplemental feeding can reduce the amount of infidelity in certain species, including house sparrows. This hints that feeding birds might alter their behavior and have an effect on genetic variation in urban populations.
For birds that provide pollinating services, like hummingbirds and lorikeets, there is some evidence that providing them with sugar water—which mimics the nectar they collect from plants—can reduce their visits to native plants. This means they will transfer less pollen. Since much bird feeding happens in densely populated urban areas, it's unclear how much impact this might have.
In one incredible instance, garden feeders seem to have played a role in establishing a new wintering population of migratory blackcaps in the United Kingdom. This group is now genetically distinct from the rest of the population, which migrates further south to Mediterranean wintering grounds.
The band on this black-capped chickadee’s right leg assigns the bird a unique number. Scientists band birds to study their ranges, migration, life spans and other questions. The feeder holds suet, a high-energy food made from animal fat. Credit: Julian Avery, CC BY-ND
Don't feed the predators
Scientists still know little about how bird feeding affects transmission of pathogens and parasites among birds. It is not uncommon for birds at feeders to carry more pathogens than populations away from feeders. Some well-documented outbreaks in the U.S. and U.K. have shown that feeding birds can increase problems associated with disease—evidence that was collected through feeder watch citizen science projects.
Because we still have a poor understanding of pathogen transmission and prevalence in urban areas, it is extremely important to follow hygiene guidelines for feeding and be alert for new recommendations.
Feeding can also attract predators. Domestic cats kill an estimated 1.3 to 4 billion birds in the U.S. every year. Feeders should not be placed in settings where cats are present, and pet cats should be kept indoors.
Feeders can also support both native and introduced birds that outcompete local species. One study found that feeders attracted high numbers of crows, which prey on other birds' chicks, with the result that less than 1% of nearby American robin nests fledged young. In New Zealand, bird feeding largely benefits seed-eating introduced species at the expense of native birds.
Clean feeders and diverse diets
The good news is that studies do not show birds becoming dependent on supplemental food. Once started, though, it is important to maintain a steady food supply during harsh weather.
Treatments on this window at Shaver’s Creek Environmental Center prevent birds from thinking they can fly straight through the building and colliding with the glass. Credit: Julian Avery, CC BY-ND
Birds also need access to native plants, which provide them with habitat, food and insect prey that can both supplement diets and support species that don't eat seeds at feeders. Diverse food resources can counteract some of the negative findings I've mentioned related to competition between species and impacts on bird diets.
Good maintenance, placement and cleaning can help minimize the likelihood of promoting pathogens at feeders. Initiatives like Project FeederWatch have recommendations about feeder design and practices to avoid. For example, platform feeders, where birds wade through the food, are associated with higher mortality, possibly through mixing of waste and food.
It's also important to manage the area around feeders. Be sure to place feeders in ways that minimize the likelihood that birds will fly into windows. For instance, avoid providing a sight line through a house, which birds may perceive as a corridor, and break up window reflections with decals.
There are lots of great reasons to bring birds into your life. Evidence is growing that interacting with nature is good for our mental health and builds public support for conserving plants and wildlife. In my view, these benefits outweigh many of the potential negatives of bird feeding. And if you get involved in a citizen science project, you can help scientists track the health and behavior of your wild guests.
Modern birds can trace their origins to theropods, a branch of mostly meat-eaters on the dinosaur family tree. In some birds, like this cassowary, the resemblance to extinct
What do sparros, geese and owls have in common with a velociraptor or the mighty Tyrannosaurus rex? All can trace their origins to a bipedal, mostly meat-eating group of dinosaurs called theropods ("beast-footed") that first appeared around 231 million years ago, during the late Triassic Period.
The earliest birds shared much in common with their theropod relatives, including feathers and egg-laying. However, certain traits – such as sustained, powered flight – distinguished ancient birds from other theropods, and eventually came to define modern-bird lineage (even though not all modern birds fly).
Today, all non-avian dinosaurs are long extinct. But are birds still considered to be true dinosaurs?
In a word: Yes.
"Birds are living dinosaurs, just as we are mammals," said Julia Clarke, a paleontologist studying the evolution of flight and a professor with the Department of Geological Sciences at the University of Texas at Austin.
In spite of the physical differences that distinguish all mammals from other species, every animal in that group — living and extinct — can trace certain anatomical characteristics to a common ancestor. And the same is true for birds, Clarke told Live Science.
"They're firmly nested in that one part of the dinosaur tree," she said. "All of the species of birds we have today are descendants of one lineage of dinosaur: the theropod dinosaurs." What makes a bird, a bird?
Modern birds have feathered tails and bodies, unfused shoulder bones, toothless beaks and forelimbs that are longer than their hind limbs. They also have a bony plate near their tails called a pygostyle. Other types of extinct theropods had one or more of these features, but only modern birds have all of them, according to Takuya Imai, an assistant professor with the Dinosaur Research Institute at Fukui Prefectural University in Fukui, Japan.
In a primitive bird from Japan called Fukuipteryx — a 120-million-year-old avian that Imai described in November 2019 and the earliest known bird with a pygostyle — the preserved structure closely resembled the pygostyle of a modern chicken, Imai previously told Live Science. In other words, some structures in modern birds can be traced back to some of their earliest ancestors.
However, primitive birds still had much in common with non-avian theropods, said Jingmai O'Connor, a paleontologist specializing in dinosaur-era birds and the transition from non-avian dinosaurs, at the Institute of Vertebrate Paleontology and Paleoanthroplogy in Beijing, China.
In fact, early birds were "very dinosaur-like" compared to modern birds, O'Connor told Live Science in an email. "Some had long, reptilian tails, teeth and claws on their hands," she said. And many theropod dinosaurs that were not birds had true feathers, "which are feathers that have a central part down the middle and branching barbs," according to Clarke.
Paleontologists distinguish between animal groups through precise measurements of subtle variations in bones and other fossilized body tissues, including "little bumps and tubercles [a rounded bulge on a bone] that are related to reorganizing different muscle groups," Clarke said. This morphological data is translated into numbers that are then processed by algorithms to pinpoint how animals are related, O'Connor explained. By using these algorithms in a system known as cladistics, experts can differentiate ancient birds from their theropod relatives.
Early birds
The earliest known bird is Archaeopteryx ("ancient wing"), which lived around 150 million years ago in what is now southern Germany. The creature weighed around 2 pounds(1 kilogram) and measured about 20 inches (50 centimeters) in length; fossil evidence shows that it sported plumage on its tail and body. The shape of its forelimbs and feathers also suggests that Archaeopteryx was capable of powered flight, a trait associated with most modern birds. However, unlike birds today, Archaeopteryx retained individual, clawlike fingers at the tips of its wings.
Fossils of birds from the early Cretaceous Period (145.5 million to 65.5 million years ago) have been found in northeastern China, such as Confuciusornis, which lived around 125 million years ago, and had a beak and long tail-feathers. Some Confuciusornis fossils, described in 2013, even included medullary bone, a spongy tissue found in female birds that are sexually mature, Live Science previously reported.
Another piece of fossil evidence links ancient birds to their modern relatives through their digestion, in the form of the earliest known bird pellet — a mass of indigestible fish bones coughed up by a Cretaceous avian in China around 120 million years ago. Fly, robin, fly
One defining feature of birds is their ability to fly, requiring large forelimbs covered with asymmetrically-shaped feathers and roped in powerful muscles, O'Connor said.
"In the lineage evolving towards birds, most likely a lineage within the Troodontidae [a family of birdlike theropods], flight is what separates birds from their closest non-avian dinosaur (probable troodontid) kin," said O'Connor.
Then, after the evolution of flight, the small bones in birds' hands "become reduced and fused up to create this kind of stiffened structure that supports the feathers of the wing," Clarke said.
After the extinction of the non-avian dinosaurs at the end of the Cretaceous period, birds continued to evolve and diversify, developing more specialized features related to flight, such as an elongated structure in their breastbones (called a keel), and powerful pectoralis muscles to power the downstroke during flight, Clarke said.
"You see bigger and bigger pectoralis that are associated with this deep keel. And that evolved after the origin of flight and is present in living birds," she said.
Today, there are approximately 10,000 bird species worldwide. Birds might be as tiny as a hummingbird or as big as an ostrich; they might soar like an eagle or dive like a penguin. Nevertheless, they still belong to the same group of theropod dinosaurs that hatched Archaeopteryx 150 million years ago.
So, the next time you wonder what dinosaurs may have looked like when they walked the Earth, look no farther than the seagull eyeing your french fries at the beach, the crow scolding you from a fence, or the nearest pigeon pecking at crumbs on the sidewalk.
America's birds are under siege. These are among the most at risk for extinction.
Dinah Voyles Pulver, USA TODAY Sun, May 21, 2023
If you enjoy watching cardinals or bluebirds at a feeder or seeing a great blue heron at the water's edge, it may not be immediately apparent but the nation's birds are under siege.
"Birds are declining," said Ken Rosenberg, a conservation biologist with Road to Recovery, an organization that focuses on recovery of the nation's most rapidly declining birds. "It's death by a million cuts."
They’re imperiled by habitat loss, disease and other threats. Several incidents this spring illustrate a few of the hazards.
In northern Arizona, at least 13 endangered California condors died after being infected by avian flu, and federal officials just approved an emergency vaccine.
In Florida in April, state wildlife officials charged two men with shooting and killing colorful, migratory cedar waxwings, including a blueberry farmer trying to keep them off his bushes.
California condors are among the nation's most imperiled birds, but recovery actions have built their numbers back to more than 500 birds.
Scientists estimate more than 3 billion birds have been lost in the U.S. since 1970 and dozens of species are considered endangered, threatened or at risk. While extensive conservation efforts helped recover the condors, bald eagles and others, dangers remain for many species and climate change poses additional threats to habitats and food resources.
Here's what we know about bird species of greatest concern in the continental U.S. Which bird species are most at risk?
It's hard to quantify which birds are most threatened, said Rodney Siegel, executive director of The Institute for Bird Populations. Is it a measure of population, habitat loss, rate of decline or something else? A Florida scrub jay sits atop an oak at Blue Spring State Park in Orange City, Florida. The birds, endemic to Florida, are among the nation's most imperiled birds.
Below is a list of the birds found only in the U.S. that have the lowest populations, based on two sets of estimates kept by Partners in Flight, a network of 150 organizations in the Western Hemisphere, and a list of most imperiled birds from the American Bird Conservancy.
California condor: Largest and rarest, with an estimated 561 in 2022, including 347 birds in the wild, according to the U.S. Fish and Wildlife Service.
Whooping crane: From fewer than two dozen whooping cranes in the 1940s, conservation measures have helped build the population to just under 1,000 cranes.
Island scrub-jay: Found only on Santa Cruz Island off California, these birds have the smallest range. Once numbering more than 12,000, its population is an estimated 2,300 but recovering.
Florida scrub-jay: It has vanished from 10 Florida counties and its habitat is fragmented. Available population estimates vary widely from 7,500 to 11,000. It thrives in the Ocala National Forest where conservation efforts have protected large areas of its habitat.
Gunnison sage-grouse: This bird disappeared from roughly 90% of its range and is found in only 14 counties in Colorado and Utah. An estimated 4,800 remain, according to Partners in Flight data.
Kirtland’s warbler: On the endangered species list for 47 years before being delisted in 2019, it's "a success story," said Nicole Michel, quantitative science director for National Audubon Society. "But we still need to keep working to protect them." Estimated at 4,800, the nation's rarest songbird is found almost exclusively in stands of young Jack pine in Michigan, Wisconsin and Ontario.
Cassia crossbill: These relatives of the red crossbill were named a separate species in 2017. Fewer than 5,800 remain, found only in Idaho's South Hills and Albion mountains, according to the Cornell Lab of Ornithology.
Piping plover: With an estimated population of 8,400, its greatest threat is human activity, Michel said. People walking or playing on the beach where the birds nest on bare sand, or letting dogs run loose, can harm the birds and scare them off their nests. A Florida scrub jay feeds a chick in the nest at Lyonia Preserve in Deltona, Florida. The jay, found only in Florida, is considered one of the most imperiled birds in the U.S.
Which other species are at a tipping point?
An estimated 104 species are at greatest threat, according to Road to Recovery, an independently funded organization to collaborate and focus on recovery of the most rapidly declining birds.
Rosenberg was lead author on the study that identified the loss of at least 3 billion birds, and Road to Recovery grew out of that effort. The group created three "alert" lists – red, orange and yellow – to target the cause of decline and develop recovery strategies. Why are birds declining?
While general threats ‒ such as habitat loss, invasive species and human activities ‒ are broadly understood, many birds continue to decline without scientists being able to identify a specific cause despite decades of research and conservation, according to Road to Recovery.
"A lot of things point to agricultural practices, and the intensifying of agriculture," Rosenberg said.
Many fragments of native prairie and native grasslands important to birds have been cleared, he said. "Not too long ago, there were hedgerows and fallow fields, just sort of enough to sustain birds around the edges. Now it's just all gone."
A juvenile whooping crane takes flight on the Chassahowitzka National Wildlife Refuge in Homosassa, Florida on March 4, 2010. Adult whooping cranes are nearly 5 feet tall.
Birds with very restricted ranges, such as the Kirtland's warbler, are inherently at risk, Siegel said. “Natural disasters and disease outbreaks could take out that population much more easily than a species that is more widely distributed."
Without more successful efforts to identify why birds die and address those losses, scientists said many birds are on a trajectory that could lead to extinction.. Birds now considered extinct
At least seven birds once found in the U.S. are believed to be extinct. The status of an eighth, the ivory-billed woodpecker, is debated. They are:
Bachman’s warbler
Dusky seaside sparrow
Passenger pigeon
Carolina parakeet
Eskimo curlew
Great auk
Labrador duck Search for the ivory-billed woodpecker
The status of the ivory-billed woodpecker – once referred to as the "Lord God bird" for its impressive stature and appearance – remains controversial. While federal officials proposed it be listed as extinct, a group of believers insist the bird is still present deep in Southern swamps.
A study released May 18 presented evidence that researchers said indicates the birds remain in unnamed Louisiana swamps, but The Associated Press reported some experts refuted the new evidence.
Nearly three-fourths of the nation's birds are vulnerable to losing large parts of their range as the climate changes and sea levels rise, on top of the other threats they face, Michel said.
"It's a force magnifier," she said. Why birds matter
"It's not just about the birds," Rosenberg said. It's a broader message. "If we're seeing the common birds around us declining, it's telling us that the health of our environment is also."
Nearly half of the world's birds are on the decline, which experts say is a serious threat to ecosystems
Nicole Mortillaro - 3h ago
It might be one early morning, after a particularly long, dark and snowy winter, that you first hear it: The call of a robin. A signal of spring.
Or it might be a walk through a park or forest where you hear a particular bird call and look up, hoping to identify it.
Birds are all around us, every day, and they play a crucial role in the health of our planet.
But in the past 50 years nearly three million birds have disappeared across North America and the European Union alone, a recent report noted. And experts are worried that it could be a bigger sign about the health of our ecosystems.
While it's been known for quite some time that the planet's birds are in danger, it was highlighted again by the recent BirdLife's State of the World's Birds 2022 report, something that they call a "biodiversity crisis." It also notes that 49 per cent of the planet's birds are in decline.
"In the 2018 report only 40 per cent of the bird species were found to be in decline. So in four years, we've had this huge jump in the number of birds that are at risk," said Sam Knight, a program manager at the Nature Conservancy of Canada.
"And they've shown that one in eight are actually threatened with extinction. So it's really concerning tat in such a small time period this is what's happened, and the pressures these birds are facing, and biodiversity overall." Birds in North America
"I study birds, I love birds and I'm really concerned that I won't be able to go out for a walk and just hear birdsong in the same way," Knight said. "It's such a great mental health benefit to have these birds and species around; you don't even have to be a bird watcher, I don't think, to really appreciate what birds add to our lives."
Birds serve as pollinators, predators, seed dispersers, scavengers and, as the report noted, "ecosystem engineers." Because they are mobile, they traverse vast distances, linking different ecosystems.
And their losses are considerable.
The International Union for Conservation of Nature's (IUCN) Red List of Threatened Species has found that 1,409 bird species are considered threatened; 755 are vulnerable; 423 are endangered and 231 are critically endangered.
And since the year 1500, at least 187 species of birds have gone extinct, mainly those found on islands. Why is this happening?
Related video: A Wilder View: Why are some birds smarter than others?
The threats to our feathered friends are numerous, ranging from agriculture, logging, invasive species and hunting, to birds flying into homes and buildings, and climate change, only to name a few. And our furry cat companions are a big one, with an estimated 100 million to 350 million birds being killed across Canada each year by outdoor felines, according to a 2013 study.
"Invasive species are another huge threat to birds, and cats are the most invasive species, or the most threatening invasive species that we have in North America," Knight said. "There's no doubt that habitat loss is the biggest threat, but it's really hard to measure what habitat loss looks like when it comes to birds because they move, but cats … that is the biggest number of deaths that we can calculate in North America."
But she noted that there are some solutions available to cat owners who still may want their cat to enjoy some fresh air.
"What we need to do is keep our cats on leashes and keep them tethered when they're outdoors, or in a catio or that kind of thing. So people can still have their cat, enjoy the outdoors, but not be taking out birds," she said.
When it comes to habitat loss, it's grassland birds and insectivores that are most vulnerable, in particular because of the loss of grasslands in place of agriculture, which, Knight said, is understandable since we need to feed people.
"But we also have to kind of think about this balance of how we can also keep grasslands and restore grasslands. And that has knock-on effects on not just birds but other species," she said. "And one great thing that this report highlighted and reminded us is that birds are really good indicators of what's going on with other biodiversity."
And then there's climate change, which is throwing off the timing for some migrating insectivores, as warmer weather is starting earlier in the year, which means insects come out earlier as well.
By the time the birds arrive, most of the insects' numbers have been reduced.
Need for more protections, big and small
Earlier this month, Birds Canada — an international partner of BirdLife — officially launched its Key Biodiversity Areas (KBAs) in an aim to protect not only birds, but other species, such as insects, frogs and turtles, who are facing numerous threats.
These areas require strict criteria to be designated a KBA. At the moment there are roughly 75 in Canada, with 900 in progress or being evaluated, said Andrew Couturier, senior director of landscape science and conservation at Birds Canada, who was not involved in the recent report.
"The [BirdLife] analysis shows that one in eight [birds] are threatened with extinction. That obviously varies geographically. Canada's birds aren't doing nearly as badly as that. But we still have a lot of a lot of work to do here," said Couturier, who was a co-author of the 2019 report on The State of Canada's Birds.
No surprise to Couturier, the 2019 report found that grassland birds in the Prairies were most at risk.
"There's hardly any native grassland left in Prairie Canada, and that's always under threat to be converted to some other use such as row cropping," he said. "But we do have good partnerships with the cattle industry, because those lands are actually providing good habitat for grassland birds and they're actually able to coexist with ranching."
Couturier said there are ways to reverse the trend of the loss of habitats and bird species. These can include individual efforts, such as putting stickers on big windows around our homes and planting bird- and pollinator-friendly gardens. On a larger scale, efforts can include office buildings turning off their lights at night to avoid migrating birds from crashing into them, the development of further KBAs across the country, and better land-use management.
And the report, which also outlines some of these steps, is something Couturier said he sees as positive.
"If you talk to people in the charitable sector, you know, there definitely is a fatigue associated with depressing news all the time, when you're working so hard to try and make a difference," he said. "And then you keep seeing things going down and you wonder what else can we do? What can we do better to reverse this problem?"
