Tag Archives: bird

Researchers peer into the brain of birds as they’re singing their best song

Birds, just like artists or athletes, train and finesse their songs. When it’s crunch time, they’d better be ready to bust out their best song — or they may end up not having anyone to mate with. In a new study, researchers have zoomed in on the brains of birds practicing and

Zebra finches. Image via Pixabay.

Zebra finches are common birds in Australia. They’re loud and boisterous singers, and they spend a lot of time working on perfecting their songs. Male zebra finches will often go about their days practicing their courtship melodies, producing variations and trialing different versions of the song. But when they spot an attractive female zebra finch, they stop screwing around.

Researchers have observed that when the game is on, they always sing a singular, perfected version of their song — no more variations or experiments. Essentially, they produce the best song they can.

Researchers wanted to figure out how they do this and what happens inside their brain once they do, and thanks to a novel approach that allows them to monitor up to a hundred bird neurons at a time, they did.

“To figure out how to move, it needs to first try out many different movements, to try out different ways of accomplishing a goal of moving their body,” said Jonna Singh Alvarado, who led this project for his Ph.D. dissertation at Duke. “They need to learn, ‘If I think this, how am I about to move? How will that move my body?’ and it needs to do that in many variations.”

Credits: Alvarado et al. / Nature.

To the human ear, these differences are subtle and hard to detect, explains Richard Mooney, Alvarado’s thesis advisor. But female zebra finches are very receptive to these subtleties. They dislike practice songs, but a precise game-time song makes them intrigued and attentive.

When the males practice the not-serious song, neurons in an area of the brain called the basal ganglia (which is also responsible for controlling major movements) allow variation in the song. Various neuron circuitries are used, corresponding to different songs. But when it’s go-time, these alternative pathways are shut down by a squirt of the neurotransmitter noradrenaline in the basal ganglia.

“You’ve established this kind of brain-to-movement dictionary, where you’ve explored all these different ways that you can give commands and they can move your body,” said Alvarado, who is now a post-doctoral researcher at Harvard University. “And then, you can exploit the mapping you’ve created. ‘I’ve explored, I have this dictionary, let me grab the right words from this dictionary and perform exactly what I know I can perform, given what I know the female wants to hear.’ “

To keep this ‘best’ song in good shape, a lot of practice is required. Much like a human athlete or artist, birds practice a lot — and also just like in humans, practicing variations helps build a “dictionary” of workable notes that can then be used. The birds explore their vocal range and different musical combinations until they zoom in on the one they want to use. To Mooney, a self-described Jimi Hendrix fan, the males’ practice songs are a bit like Hendrix’s music.

“It kind of goes everywhere, there’s the kernel of one song, but then it sort of morphs. It’s like free jazz or something. And, you know, I think he was just really, really good at exploring when he was alone.”

Of course, tracking the neurons responsible for this is not an easy task. It took a lot of work from a lot of people working in different fields, Mooney explains.

“One of the things that’s been really hard in other animals is to figure out what the link is between the variability you’re producing, and the variability you want to produce,” said John Pearson, an assistant professor of biostatistics and bioinformatics at Duke, who led the statistical analysis of the neurons. “This is the first time that people have gotten a real sizable population of these cells, and we can begin to try to link the variability in vocal performance to the variability in neural activity.”

In addition to understanding how birds do things, this type of study could also be useful from a human perspective. The basal ganglia are present in all vertebrates, and in humans, it’s linked to conditions such as Parkinson’s, Huntington’s disease, and Tourette’s syndrome, among others. Understanding

But the work is important because insight into the bird’s basal ganglia has direct relevance to human movement disorders, including Parkinson’s and Huntington’s diseases, Tourette’s syndrome, and others, Mooney said. Understanding how basal ganglia neurons function normally and what happens when they malfunction is paramount to understanding how these conditions take shape — and how they can be fixed.

Journal Reference: Alvarado et al, Neural dynamics underlying birdsong practice and performance, Nature (2021). DOI: 10.1038/s41586-021-04004-1

Humans are worse than jays at spotting magic tricks

Magic tricks, from sleight of hand to mentalism, have fascinated humans for centuries. Researchers are also interested in magic tricks — not as a form of entertainment, but rather because they allow us to zoom in on the limitations of our perception. Turns out, humans are relatively easy to deceive with such tricks. Eurasian jays, on the other hand, are much keener.

Eurasian jay observing a French drop sleight-of-hand illusion. Credit: Elias Garcia-Pelegrin.

The French drop — not just for humans

The French drop (or “Le Tourniquet) is one of the simplest tricks you can do. It’s essentially a sleight of hand trick used to vanish a small object, most commonly a coin or a ball. It works like this: you hold the object between the thumb and your first two fingertips. You show it to the spectators, and then appear to use your other hand to take it away — but you don’t. The object is palmed in your first hand.

Although it’s been done for a very long time, it’s still remarkably effective. I’ve just explained how it works, you should know what to expect, and yet, when you see it in action, it still kind of works:

But jays are better than humans at not getting deceived.

“Results from palming and French drop experiments suggest that Eurasian jays have different expectations from humans when observing some of these effects. Specifically, Eurasian jays were not deceived by effects that required them to expect an object to move between hands when observing human hand manipulations,” the researchers write.

To test the birds’ perceptual blind spots, a team of researchers at the University of Cambridge taught six Eurasian jays to peck on a human fist to receive a treat in the hand. If the bird chose the correct hand, they got a treat. If they missed, they got nothing. They tested the birds with three magic tricks: the above-described French drop, the palm transfer (which works by hiding an object in the palm), and the fast pass (which works by passing the object so fast between hands that the watcher loses track of it).

Jays were chosen because, alongside several corvid species, they seem to be one of the smartest species of birds and they also use trickery to keep other animals from stealing their food stores.

The researchers tested the magic tricks on the birds multiple times, keeping track of their success rate. They then ran the same test with human volunteers online. Similar to humans, jays were misled by magic effects that utilize fast movements. However, the birds were significantly better at keeping track of the treat during palming and the French drop tricks.

Credit: Proceedings of the National Academy of Sciences (2021). doi/10.1073/pnas.2026106118

“We demonstrate that, similar to humans, Eurasian jays are susceptible to magic effects that utilize fast movements. However, unlike humans, Eurasian jays do not appear to be misled by magic effects that rely on the observer’s intrinsic expectations in human object manipulation,” the researchers led by Elias Garcia-Pelegrin write in the study.

It’s not clear just how to interpret this finding in evolutionary terms. However, it seems that magic tricks can indeed provide an insightful methodology to investigate perception and attention shortcomings in human and nonhuman animals. It seems that jays have different expectations than humans, and also different perception abilities.

The end goal for researchers is to develop custom-made magic tricks that can help us better understand how we and other animals see the world. This is an avenue that has been recommended by Garcia-Pelegrin since last year, when he published a paper noting that magic tricks can “prompt the comparison of behavioral reactions among diverse species, in which magic effects might exploit similar perceptive blind spots and cognitive roadblocks.”

Journal Reference:  Exploring the perceptual inabilities of Eurasian jays (Garrulus glandarius) using magic effects, Proceedings of the National Academy of Sciences (2021). www.pnas.org/cgi/doi/10.1073/pnas.2026106118

A new species of bird discovered in Brazil has a green head, yellow belly, and a high risk of going extinct soon

An international team of ornithologists reports discovering a new species of bird in north-eastern Brazil. Sadly, the forests it calls home have been almost completely cut down.

The black-throated trogon (Trogon rufus). Image credits Moisés Silva Lima.

The new species has been christened the Alagoas black-throated trogon (Trogon muriciensis), and is part of the Trogonidae family of tropical birds. Comprising around 43 species and almost 110 subspecies, the trogons are some of the most colorful birds in the world — at least, the males. They sport patterns of various colors including iridescent green, blue, violet, and purple, with bright red, orange, or yellow abdomens. The females have to make do with gray or brown feathers.

Bird is the word

Trogon rufus is easy to distinguish by the unique combination of a green head in males, brown in females, and a yellow belly,” said Jeremy Kenneth Dickens, a researcher at the Museu de Zoologia da Universidade de São Paulo and the Fundación Para La Tierra, and lead author of the study.

“However, with the collection of more material, it soon became recognized as notoriously variable across its distribution.”

The trogon family was first described in 1788 with the black-throated trogon (Trogon rufus), which is quite common in the lower and mid-levels of humid forests spanning from Honduras to northern Argentina.

After its initial description, however, more observations of this bird made it clear that its characteristics varied quite significantly across its range. In other words, it was possible that what we were seeing wasn’t a single species, but rather a family of species.

In order to get to the bottom of it, the team looked at 547 male and 359 female trogon specimens from the collections of 17 different museums. They factored in morphological, vocal, and genetic datasets, as well as spectral and digital data of their plumage, to establish the family tree of the trogons.

All in all, they identified five populations that show signs of reproductive isolation — in other words, five groups of trogons that don’t interbreed and show differences in traits involved in species recognition such as plumage, behavior, or song. Four of these were already known as the Amazonian black-throated trogon (Trogon rufus), the southern black-throated trogon (Trogon chrysochloros), the (somewhat fancily-named) graceful black-throated trogon (Trogon tenellus), and the Kerr’s black-throated trogon (Trogon cupreicauda).

The fifth population, however, wasn’t identified as a distinct group previously. It makes its home in the mountainous stretches of the Atlantic Forest in the Brazilian state of Alagoas (hence its name). This group is distinct enough morphologically, genetically, and through behavior such as song to represent a completely new species, the team explains. It can be distinguished from most other trogon species by the combination of a green head and bright yellow belly.

“It is only known from Estação Ecológica de Murici in the Alagoas state, at just over 500 m elevation, where it occurs in mid-levels of the montane Atlantic Forest,” the team explains.

“It was presumably once more widespread throughout this habitat in the Pernambuco Centre of Endemism before the deforestation of the region.”

According to the team, finding records and individuals of this species in a single, relatively small area, does not bode well. They further explain that during fieldwork in 2019 in the region, they only found 20 individuals and “explicitly avoided” collecting more than one specimen for further study after seeing how low their numbers appeared to be.

The team recommends that the Alagoas black-throated trogon is immediately listed as Critically Endangered, as only around 30 km2 of forest remains in their known range. These forests are also “mostly small fragments and not all suitable for this species,” casting further doubt on their ability to recover.

The paper “Species limits, patterns of secondary contact and a new species in the Trogon rufus complex (Aves: Trogonidae)” has been published in the journal Zoological Journal of the Linnean Society.

Fossil Friday: leg fragment points to huge, toothy bird with a wingspan of up to 21 feet

Fossils recovered from Antarctica four decades ago belonged to an ancient, massive toothed bird.

Photographs of the fossilized leg fragment. Image credits Peter A. Kloess, Ashley W. Poust, Thomas A. Stidham, Scientific Reports.

The bird belonged to a now-extinct group of birds called pelagornithids and boasted a wingspan of up to 21 feet. That easily makes it dwarf today’s largest bird, the wandering albatross, which can grow up to a 11½-foot wingspan.

It also kind of had teeth.

Biggest bird

The pelagornithids filled an ecological niche similar to that of albatrosses today — they would soar high above the Earth’s oceans feeding on fish and other marine wildlife. They seem to have been especially well-tailored to the task as the pelagornithids kept doing it for at least 60 million years.

We know of this family of birds from a (much smaller) pelagornithid fossil dating from around 62 million years ago. The new fossil however (a partial fossil of the bird’s food), is some 50 million years old and shows that much larger pelagornithids evolved following the mass extinction 65 million years ago when the dinosaurs went extinct. A second pelagornithid fossil, part of a jaw bone, dates from about 40 million years ago.

“Our fossil discovery, with its estimate of a 5-to-6-meter wingspan — nearly 20 feet — shows that birds evolved to a truly gigantic size relatively quickly after the extinction of the dinosaurs and ruled over the oceans for millions of years,” said first author Peter Kloess, a graduate student at the University of California (UC), Berkeley.

Pelagornithids are known as ‘bony-toothed’ birds. They don’t actually have teeth, but they do have bony protrusions (‘struts’) on their jaws that resemble teeth. They don’t have the internal structures that our teeth do, but they are covered in a layer of keratin (the same material in our fingernails and in animal horns). We call them pseudoteeth (lit. ‘false teeth’), and their purpose is to help the bird catch and hold onto slippery prey such as fish or squid on their week-long flights.

The fossilized jaw fragment. Pseudoteeth depicted as dashed outlines. Image credits Peter A. Kloess, Ashley W. Poust, Thomas A. Stidham, Scientific Reports.

Of course, what was most striking about this extinct bird is its sheer size. Large flying animals have made several appearances in the Earth’s past, with the largest known being the pterosaurs, dinosaurs with wingspans of up to 33 feet.

The newly-discovered pelagornithid grew even larger than teratorns — an extinct family of very large birds of prey native to North and South America, which included some of the largest flying birds ever found.

“[Teratorns] evolved wingspans close to what we see in these bony-toothed birds (pelagornithids),” said Poust. “However, in terms of time, teratorns come in second place with their giant size, having evolved 40 million years after these pelagornithids lived. The extreme, giant size of these extinct birds is unsurpassed in ocean habitats.”

The fossils were first discovered in the mid-1980s on Seymour Island, close to the Antarctic Peninsula by UC Riverside paleontologists. They were transferred to UC Museum of Paleontology, where Kloess stumbled upon them as a graduate student in 2015.

To the best of our knowledge, the last pelagornithid died off around 2.5 million years ago as the last Ice Age began.

The paper “Earliest fossils of giant-sized bony-toothed birds (Aves: Pelagornithidae) from the Eocene of Seymour Island, Antarctica” has been published in the journal Scientific Reports.

The lockdown changed the way birds sing in San Francisco

Birds have very distinct calls that don’t typically change, making it easy for bird watchers to recognize a species. But the tunes can actually shift over time, according to a new study. During the lockdown, with less traffic and movements, bird songs have sounded different, at least in the United States.

Credit Wikipedia Commons

Worldwide, elective quarantine and stay-at-home orders have reduced the use of public spaces and transportation networks, especially in cities. The restrictions in public movement led to rarely observed behaviors in animals, such as coyotes crossing the normally heavily trafficked Golden Gate Bridge in San Francisco.

Elizabeth Derryberry and her team studied white-crowned sparrows in San Francisco for more than two decades, comparing their songs with old recordings. They found that when traffic levels increase, the lowest frequencies of sparrow’s songs rise so as not to be drowned by the sound of traffic. But their top frequencies remain the same.

For many bird species, such altered songs are less effective at attracting females and deterring rivals. Birds sing louder in noisy environments, with studies showing the resulting stress can accelerate aging and disrupt their metabolisms. Noisy environments can also prevent them from hearing their own chicks.

When the pandemic lockdown started in March, Derryberry asked herself how the sparrows were responding to the quieter conditions. She couldn’t travel to San Francisco but her colleagues were there to record the birds in the city and the surrounding areas. And the findings were very surprising.

“People were right that birds did sound different during the shutdown and they filled the soundscape that we basically abandoned,” Derryberry told BBC News. “As we moved out of the soundscape, the birds moved in and I think this tells us something about just how big an effect we have on birdsong and on communication, especially in cities.”

The recordings showed sparrows were singing 30% softer, on average, than before the lockdown. But they were also singing songs with bandwidths typical of birds recorded in the 1970s. The combination of less background noise and the better signal from wider bandwidth allowed males to hear each other from twice as far away as before.

The white-crowned sparrows, with distinctive white and black stripes on their heads, are found across much of the US and Canada, where their songs have been widely studied. Different sub-species across the country sing slightly different songs, known for the sweet, whistling introduction, a succession of jumbled whistles, and a trill near the end.

The finding is “good news from the point of view of the birds,” Sue Anne Zollinger, an ornithologist at Manchester Metropolitan University who was not involved in the work, told Science. The findings show that species with more flexible behaviors can adapt to suit changes in their environment quite quickly.

The study was published in the journal Science.

Insect-hunting dino “the size of a teacup” unearthed in Madagascar

A diminutive fossil is teaching us about how dinosaurs evolved to their impressive sizes.

3D restoration of Kongonaphon kely.
Image credits Frank Ippolito / American Museum of Natural History (AMNH).

Christened Kongonaphon kely, meaning ‘tiny bug slayer’, this dinosaur is unusually proportioned — it was about the size of a coffee cup. The dino belonged to the group which dinosaurs and pterosaurs (flying dinosaurs) eventually branched away from.

Small, but dangerous!

“There’s a general perception of dinosaurs as being giants,” says palaeontologist Christian Kammerer from the North Carolina Museum of Natural Sciences, first author of the paper describing the findings.

“But this new animal is very close to the divergence of dinosaurs and pterosaurs, and it’s shockingly small.”

The tiny dino lived on Madagascar during the Triassic period some 237 million years ago. It stood a measly 10 centimetres (about 4 inches) in height, but its extended family — group Ornithodira — would go on to evolve into the giant dinosaurs we saw in Jurassic Park.

Researchers are, understandably, keen to better chart this transition from very small to colossal, but we haven’t found many specimens from the early Ornithodira lineage.

Artist’s impression of the tiny dino.
Image credits Alex Boersma.

The current fossil was unearthed during fieldwork in 1998 at a fossil site in southwestern Madagascar alongside hundreds of other specimens. The authors say it “took some time before we could focus on these bones”, but they quickly figured out the fossil was quite unique.

This tiny dinosaur belongs to the Lagerpetidae family, an early group of the Ornithodira lineage. While all Lagerpetidae were small, this is the smallest one we’ve found so far. The team believes these diminutive sizes weren’t by accident, but by design.

“Although dinosaurs and gigantism are practically synonymous, an analysis of body size evolution in dinosaurs and other archosaurs in the context of this taxon and related forms demonstrates that the earliest-diverging members of the group may have been smaller than previously thought, and that a profound miniaturisation event occurred near the base of the avian stem lineage,” the team writes in a new paper.

The team bases this hypothesis on the teeth of the dinosaur. Their pits and abrasions suggest the animals mostly ate hard-shelled insects, a source of food larger dinosaurs wouldn’t even bother taking into consideration. It’s possible then that this ‘miniaturization event’ allowed dinosaurs to gain an evolutionary advantage by entering new ecological niches.

Along with a smaller size,  K. kely and its archosaur fellows likely also evolved traits that are hallmarks of today’s birds: new modes of bipedal movement, primitive fluff and down to keep warm, even primitive stages of flight, the researchers suggest.

The paper “A tiny ornithodiran archosaur from the Triassic of Madagascar and the role of miniaturization in dinosaur and pterosaur ancestry” has been published in the journal PNAS.

Wildfires can change the songs birds sing

Wildfires seem to alter the songs of birds living in affected forests, a new paper suggests.

The study focused on Hermit Warblers, a small songbird native to North and Central America. These birds woo their mates with songs following formulas and patterns, unlike the ones they use to defend territory — these are more complex and creative. Oftentimes, there is a song formula that becomes dominant within certain populations or geographic areas.

Hermit Warbler (Dendroica occidentalis).
Image via Wikimedia.

Researchers recorded over a thousand of their songs in California from 2009 to 2014. They report finding over 35 regional dialects in song formulas, and that wildfires and other disturbances have a significant effect on the way these birds sing their songs in the short term by mixing populations together.

Environmental artists

“Our surveys suggest that song dialects arose in sub-populations specialized to different forest types,” said the paper’s lead author, Brett Furnas. “Over the longer term, fire caused some birds to flee and created a vacuum for other birds to fill. The net result is that some areas now have birds singing more than one dialect resulting in a complex diversity of songs throughout California.”

The species is immediately — and negatively — impacted by disturbances such as wildfires or elective timber harvests, according to the authors. However, they do ultimately fare well under the effects of such events, due to changes in forest structure and an increased influx of pollinating insects (food).

The authors proposed that birdsong can help us understand how biodiversity is maintained in certain environments. These birds learn songs through imitation, and with time this creates song variants that are characteristic of individual areas.

The study recorded the formulaic songs from 1,588 males across 101 study sites in the state between 2009 and 2014, providing the first comprehensive mapping of Hermit Warbler songs throughout California. Each song fit one of 35 dialects.

Song dialects tended to be isolated to different forest types. Local song diversity, meanwhile, increased with the amount of local fires. Using data from ten study areas revisited in 2019, the researchers also showed that song structure had begun to change since the initial visits 5-10 years earlier, with locations that saw wildfires between visits showing the greatest increase in diversity.

The paper, “Wildfires and Mass Effects of Dispersal Disrupt the Local Uniformity of Type I Songs of Hermit Warblers in California,” has been published in the journal The Auk: Ornithological Advances.

Hummingbird eyes can detect UV, allowing them to see the world in colors that humans can’t even imagine

The male broad-tailed hummingbird can see combinations of colors like ultraviolet plus green or ultraviolet plus red. In fact, the bird’s throat, which looks like magenta to us, is likely perceived as ultraviolet plus purple by birds.

Compared to many birds, such as the delightful hummingbird (Colibri), humans are color-blind, says Mary Caswell Stoddard. The Princeton University professor, along with colleagues, showed that hummingbirds are able to discriminate various ultraviolet (UV) color combinations, allowing the birds to see the world in additional colors that humans can’t even comprehend.

A hidden world of ultraviolet

Humans essentially see the world in a combination of three colors: red, green, and blue. Each primary color is detected and decoded by corresponding specialized cones in the eye.

The hummingbird, however, has a fourth color cone, which extends its color-vision range into the ultraviolet. But, how exactly does this additional color cone morph the bird’s vision?

In their new study, Stoddard and colleagues left their labs at Stanford and traveled to Gothic, Colorado, for fieldwork in the alpine meadows each summer over the course of three years.

Their work mainly focused on how hummingbirds sense non-spectral colors, which are combinations of hues from widely separated parts of the color spectrum. A clear example of a non-spectral color is purple, which combines blue and red wavelengths of light, but not green. In contrast, teal (blue-green) and yellow (green-red) are blends of neighboring colors in the spectrum.

In fact, purple is the only non-spectral color that humans can sense. But birds should theoretically be able to see up to five, thanks to their extra color cone type. In addition to purple, birds should also be able to see combinations of ultraviolet and red, green, yellow, and purple, respectively.

“Most detailed perceptual experiments on birds are performed in the lab, but we risk missing the bigger picture of how birds really use color vision in their daily lives,” Stoddard said in a statement. “Hummingbirds are perfect for studying color vision in the wild. These sugar fiends have evolved to respond to flower colors that advertise a nectar reward, so they can learn color associations rapidly and with little training.”

The research team performed a series of experiments with wild broad-tailed hummingbirds (Selasphorus platycercus) that had two feeders at their disposal that they could use. One contained sugary water, the other just plain water.

Each feeder had an LED tube that flashed various colors. The tube that corresponded to sugar water emitted one color, while the other emitted a different color — with an important caveat.

To you or I, both colors look the same, i.e. green. However, the LEDs can display a broad range of colors, including non-spectral colors like ultraviolet plus green. If the birds could indeed see additional non-spectral colors, this should be obvious from their choice of feeders.

The researchers swapped the positions of the rewarding and unrewarding tubes at random intervals of time to make sure the birds weren’t going to the same location to pinpoint the treat. They also performed control experiments to rule out the influence of smell or anything other non-vision-related cues.

Over the course of 19 experiments, the researchers recorded over 6,000 feeder visits. An analysis of the hummingbirds’ feedings patterns showed that the birds can distinguish ultraviolet plus green from pure ultraviolet or pure green, as well as two different blends of ultraviolet plus red light (one redder, the other less so).

“It was amazing to watch,” said Harold Eyster, a University of British Columbia Ph.D. student and a co-author of the study. “The ultraviolet+green light and green light looked identical to us, but the hummingbirds kept correctly choosing the ultraviolet+green light associated with sugar water. Our experiments enabled us to get a sneak peek into what the world looks like to a hummingbird.”

You might be curious to learn what these additional colors look like. Unfortunately, there is no way to see them — we simply lack the hardware to do so due to the absence of the fourth color cone type.

“The colors that we see in the fields of wildflowers at our study site, the wildflower capital of Colorado, are stunning to us, but just imagine what those flowers look like to birds with that extra sensory dimension,” said co-author David Inouye.

No need to be too jealous, though. The researchers also analyzed a dataset of 3,315 feather and plant colors and found that birds likely perceive many of these colors as non-spectral. However, these non-spectral colors do not stand out relative to other colors that are also visible to humans.

The findings appeared in the journal Proceedings of the National Academy of Sciences.

Oldest modern bird species so far discovered in Belgian limestone quarry

The fossil represents the oldest modern bird species found to date, hailing all the way back to when dinosaurs still roamed the Earth.

The anatomy of the newly-discovered fossil skull.
Image credits Daniel J. Field et al., (2020), Nature.

Nicknamed the “Wonderchicken”, the fossil includes a nearly complete skull and was found in a limestone quarry near the Belgian-Dutch border. The bird likely lived alongside dinosaurs up to the end of the Cretaceous period and will help researchers piece together why birds survived the asteroid impact which wiped dinosaurs off the face of the Earth.

This is the first time a modern bird hailing from the dinosaur era has been found in the northern hemisphere.

Tastes like chicken

“The moment I first saw what was beneath the rock was the most exciting moment of my scientific career,” said Dr. Daniel Field from Cambridge’s Department of Earth Sciences, who led the research.

“This is one of the best-preserved fossil bird skulls of any age, from anywhere in the world. We almost had to pinch ourselves when we saw it, knowing that it was from such an important time in Earth’s history.

The Wonderchicken skull shows a combination of features seen in fowl such as ducks and chickens, suggesting that this species is close to the last common ancestor of the two modern bird families (group Galloanserae). The fossil itself was dated to around one million years before this extinction event.

The team used high-resolution X-ray CT scans to investigate the fossil, which is embedded in a piece of rock about the same size as a deck of cards. Their efforts revealed a stunning discovery: the nearly-complete skull of a 66.7-million-year-old bird.

“Finding the skull blew my mind,” said co-author Juan Benito, also from Cambridge, who was CT scanning the fossils with Field when the skull was discovered.

“Without these cutting-edge scans, we never would have known that we were holding the oldest modern bird skull in the world.”

While the team affectionately refers to the fossil bird as the Wonderchicken, they have also given it a proper scientific name: Asteriornis maastrichtensis, from the Greek Titaness of falling stars Asteria and the Maastrichtian geological age.

“We thought it was an appropriate name for a creature that lived just before the end-Cretaceous asteroid impact,” said co-author Dr. Daniel Ksepka from the Bruce Museum in Greenwich, Connecticut.

“In Greek mythology, Asteria transforms herself into a quail, and we believe Asteriornis was close to the common ancestor that today includes quails, as well as chickens and ducks.”

The paper “Late Cretaceous neornithine from Europe illuminates the origins of crown birds” has been published in the journal Nature.

New tweets: ten species of bustling songbirds discovered on Indonesian islands

An expedition off the coast of Sulawesi has come upon ten new songbird species. It’s a rare discovery that highlights once again the thriving Indonesian biodiversity — but also the threats this biodiversity faces.

The Wakatobi white-eye. Image credits: Seán Kelly.

Deep seas, unique birds

Although they are some of the most-studied groups of animals in the world, new birds are rarely discovered. Maybe it’s because we’ve found most of them, or maybe because birds are easier to spot than other creatures, but identifying new bird species is rare.

In the past two decades, an average of just six new bird species have been described every year. But 2020 is already different.

The expedition was carried out from late 2013 to early 2014. Three small, little-explored islands off the coast of Sulawesi were visited by a team led by Frank Rheindt at the National University of Singapore. The team tried to focus on the areas where they thought it was most likely to find new species. They analyzed geological trends that would have influenced the likelihood of finding birds, zooming in on one particular aspect: how deep the water around the islands is.

Taliabu Myzomela, one of the newly-identified species, carefully watching its surroundings. Image credits: James Eaton / Birdtour Asia.

Sea depth is a surprisingly important factor in determining how distinct an island’s biodiversity is. As the Earth has undergone over 20 glacial periods in the past 2 million years, sea levels have repeatedly risen and dropped, connecting and disconnecting islands with other areas. Islands surrounded by shallow waters would have had periods of communication with the mainland or other islands, producing a gene flow between populations, which slows down the emergence of endemic creatures.

But islands which are surrounded by seas deeper than 120 meters would have remained isolated throughout this period, increasing the likelihood of unique species.

This was exactly the case with Peleng and Taliabu, two of the surveyed islands. In addition, these islands have rarely been explored by biologists, making them an excellent target.

Hill forest in Peleng. Image credits: Philippe Verbelen.

The researchers’ efforts were rewarded as 10 new species were identified — 9 of which on Peleng and Taliabu.

Two of the newly discovered animals are leaf warblers — small, insect-eating songbirds. Others include a type of honeyeater that feeds on nectar and fruit and the Peleng fantail (which, as the name implies, fans its tail feathers when is alarmed), as well as two flycatchers. It’s a fairly diverse group, the majority of which was discovered in the islands’ highlands, over 1,000 meters (3,200 feet) high.

Problems already

As it is so often the case, threats to these new species have already been identified. It already seems like a trope: we’ve found some new species, but they’re at risk. In this case, rampant deforestation on the islands is threatening the survival of the birds. Logging is the main cause of deforestation, although forest fires (exacerbated by climate change) also play a role.

It’s an important reminder that life needs to be protected — even life that we haven’t discovered yet.

Thousands of species have been described in recent years, but most researchers agree that thousands more still remain undescribed. Although Sulawesi has been populated by archaic hominins since before the time of Homo sapiens, its zoology still has surprises to offer.

Holotype of one of the newly-described species. Credits: Rheindt et al (2020) / Science.

This study, just like many others analyzing species of birds, leaves behind another pressing ethical question.

This sort of specimen-collecting expeditions involve, as the name implies, collecting specimens — killing them. In this case, nets were placed at strategic points on the island, and whichever unfortunate birds flew into them are harvested and sent to the lab for later analysis.

Establishing that an animal is a new species cannot be done without this analysis — and yet, it involves killing specimens from a population that may very well be threatened. This has been done for centuries, but the ethics of it are being debated more and more in recent times.

Does the end goal of conservation and study justify this process?

The study was published in Science.

One of the world’s oldest bird species discovered in New Zealand

A fossil discovered in Waipara, North Canterbury, New Zealand sheds light on the evolution of modern birds.

Protodontopteryx fossil showing the bony, tooth-like projections on the bird’s beak.
Image credits Canterbury Museum.

At 62 million-years-old, the newly-discovered species was christened Protodontopteryx ruthae, is one of the oldest known bird species in the world. It lived in New Zealand soon after the dinosaurs died out. This species is among the largest flying birds ever discovered and is the ancestor of many birds today.

Big, ancient, toothy bird

“While this bird was relatively small, the impact of its discovery is hugely significant in our understanding of this family” says Canterbury Museum curator Dr. Paul Scofield, paper co-author.

“Until we found this skeleton, all the really old pelagornithids had been found in the Northern Hemisphere, so everyone thought they’d evolved up there.”

Pelagornithids, or bony-toothed birds, are an ancient family of seafaring birds. Previously, it was assumed that they evolved in the Northern Hemisphere, but the new species suggests this isn’t at all the case. P. ruthae is the oldest and smallest member of the family, the team explains, hailing from around 62 million years ago. It’s also one of the earliest species of birds ever found.

While later pelagornithids grew very large, being some of the largest flying birds ever to roam the Earth — some boasted wingspans in excess of 5 meters — P. ruthae was only about as large as a seagull. Still, like the rest of its family, it had bony, tooth-like projections on the edge of its beak.

The fossil was discovered by the same team that recently described a 1.6 meter-high penguin found at the same site. A partial skeleton belonging to the new species was found last year at the Waipara Greensand fossil site by amateur paleontologist Leigh Love, who named it after his wife Ruth. Researchers from the Canterbury Museum and the Senckenberg Research Institute and Natural History Museum in Frankfurt helped prepare and describe the fossil.

Based on the age of the fossilized bones, Dr. Scofield says the bird likely evolved in the Southern Hemisphere. The team says that the fossil is “one of the most complete specimens of a pseudotoothed bird” ever found and that it shows a number of features we didn’t know about — all of which will help better our understanding of bird evolution over time.

Protodontopteryxs’ skeleton suggests it was less suited for long-distance soaring than later pelagornithids and probably covered much shorter ranges. Its short, broad pseudoteeth were likely designed for catching fish while later species had needle-like pseudoteeth which were likely used to catch soft-bodied prey like squid. The last pelagornithid species died out around 2.5 million years ago, just before modern humans evolved.

“New Zealand was a very different place when Protodontoperyx were in the skies. It had a tropical climate—the sea temperature was about 25 degrees so we had corals and giant turtles,” Dr. Scofield adds.

The Protodontopteryx fossil will be displayed alongside other discoveries from the Waipara Greensand site in an exhibition about ancient New Zealand at the museum later this year.

The paper “Oldest, smallest and phylogenetically most basal pelagornithid, from the early Paleocene of New Zealand, sheds light on the evolutionary history of the largest flying birds” has been published in the journal Papers in Paleontology.

Tetrax_tetrax

Grassland birds will struggle to have babies because of climate change

Global warming is going to make everything hotter — except birds’ dating lives, new research shows.

Tetrax_tetrax
Image via Pixabay.

A new study published by researchers at the University of East Anglia (UEA) and the University of Porto (CIBIO-InBIO) reports that global warming could reduce the mating activity and success of grassland birds.

Hot singles in your area

“This work has shown how global warming may affect important behavioral mechanisms using the mating system of a lekking grassland bird species as an example,” says Mishal Gudka, who led the research while at UEA’s School of Biological Sciences.

The study examined the little bustard (Tetrax tetrax), a species of grassland bird that’s classified as a vulnerable species in Europe. The aim of the study was to see how rising mean temperatures could affect the future behavior of this (as well as other related) species.

Male little bustards, like male humans, spend most of their time in April and May trying to attract females. They do so in gatherings known as leks. They will bunch up together in a lek and stand upright, letting out a bellowing call to get noticed by prospective mates. Such calls are also employed to scare off competing males from their territory.

The team, with members from the UK, Kenya, Portugal, Spain, and Brazil report that high temperatures reduced this call display behavior among males. Their hypothesis is that if conditions get too hot, the birds have to make a choice between attempting to mate or finding shelter to protect themselves from the heat and save energy.

The team used remote GPS/GSM accelerometer tracking devices that were fitted to 17 wild male little bustards living at five sites in Spain and Portugal. The birds were filmed while the accelerometers recorded their position to record their behavior. Using this data, the team was able to determine the acceleration signature or pattern for snort-calling behavior, which they then tracked for the present study.

Little bustard display behavior is significantly related to temperature and to the particular stage of the mating season reached, the team reports. The average temperature of each day has been inversely linked to how much display behavior the males put out: the higher the temperature, the lower display rates become. The study focused on a region of the Iberian Peninsula (Spain and Portugal) where average daily daytime (5:00—21:00 hours) temperatures varied between 10ºC and 31ºC. Snort-call display probability decreased substantially as temperature increased from 4 to 20ºC, stabilized from 20 to 30ºC, and decreased thereafter.

The team reports that, based on these findings and temperature projections in the area, the average display activity of the birds will drop by 10% by 2100.

“Many people are familiar with the impacts of global warming on wildlife through droughts, storms or wildfires as well as earlier migration with warming springs,” says co-author Paul Dolman, Professor of Conservation Ecology at UEA’s School of Environmental Sciences. “But climate change affects species in many other subtle ways that may cause unexpected changes.”

“Little bustards living in the Iberian Peninsula are already exposed to some of the highest temperatures within their species range. They are one of many bird and mammal species that have an extravagant, energetically demanding display ritual, meaning they are all susceptible to the same issue.”

The paper “Elevated temperature affects male display activity of a lekking grassland bird” has been published in the journal PLOS ONE.

Kea parrot.

Human-driven extinction cost New Zealand 50 million years’ worth of bird evolution

The arrival of humans definitely wasn’t the most fortunate thing to ever happen to New Zealand.

Kea parrot.

Kea parrot, an endangered species that’s native to New Zealand.
Image via Pixabay.

New research shows that half of the island’s bird species have gone extinct since humans arrived. The team estimates it would take approximately 50 million years to recover the same number of bird species.

Gone with the dodo

“The conservation decisions we make today will have repercussions for millions of years to come,” says Luis Valente of Museum für Naturkunde in Berlin and the paper’s lead author.

“Some people believe that if you leave nature alone it will quickly recuperate, but the reality is that, at least in New Zealand, nature would need several million years to recover from human actions — and perhaps will never really recover.”

While the number of lost or threatened bird species often has been quantified, the team explains, the broad-scale evolutionary consequences of human impact on island biodiversity rarely have been measured.

Valente says that the biodiversity levels observed today are the result of millions of years of evolutionary time, and that extinctions caused by humans erase this history. So, for their new study, the team developed a new method to estimate how long it would take for a particular closed ecosystem (i.e. island) to regain the species it lost to human activity.

New Zealand happened to be an ideal case to apply and demonstrate this new method, spawning the present study.

“The anthropogenic wave of extinction in New Zealand is very well documented, due to decades of paleontological and archaeological research,” Valente says.

“Also, previous studies have produced dozens of DNA sequences for extinct New Zealand birds, which were essential to build datasets needed to apply our method.”

The team used computer models to simulate a range of human-induced extinction scenarios and see how the ecosystem fared following these.  All in all, they report that it would take approximately 50 million years to recover the number of species lost since humans first arrived in New Zealand.

If all species currently under threat are allowed to go extinct, they add, it would require about 10 million years of evolutionary time to return to the numbers of species today. However, not all is lost.

“The conservation initiatives currently being undertaken in New Zealand are highly innovative and appear to be efficient and may yet prevent millions of years of evolution from further being lost,” Valente says.

In the future, the team plans to estimate evolutionary return times for several other islands worldwide and see if any risk losing more evolutionary time. They also want to find out which anthropogenic factors play the most significant role in determining those losses.

The paper “Deep Macroevolutionary Impact of Humans on New Zealand’s Unique Avifauna” has been published in the journal Current Biology.

Black-capped chickadee.

Animals can experience post-traumatic stress disorder from exposure to predators

New research at Western University shows that animals can suffer post-traumatic stress disorder-like symptoms following exposure to predators.

Black-capped chickadee.

Black-capped chickadee.
Image via Skitterphoto.

Fear, especially strong fear such as that generated by life-threatening events, can cause significant and long-lasting changes in the circuitry of our brains. These neural changes lead to a host of shifts in behavior that we collectively refer to as post-traumatic stress disorder (PTSD).

Wild animals also experience these same changes in traumatic situations, new research shows. Fear of predators can lead to enduring neural changes that induce fearful behavior, comparable to effects seen in human PTSD patients.

Genetically-dictated fear

“These results have important implications for biomedical researchers, mental health clinicians, and ecologists,” explains Liana Zanette, a biology professor in Western’s Faculty of Science and lead author of the paper.

“Our findings support both the notion that PTSD is not unnatural, and that long-lasting effects of predator-induced fear with likely effects on fecundity and survival, are the norm in nature.”

The team worked with wild-caught black-capped chickadees at Western’s Advanced Facility for Avian Research (AFAR). The birds were individually exposed to audio recordings of either predators or non-predator species for two days. Afterward, all birds were allowed to flock together in outdoor conditions for a week, during which they were not exposed to any further audio recordings.

They gauged ‘enduringly fearful behavior’ after this week-long period by measuring each individual’s reaction to hearing a chickadee alarm call distinct from those they were exposed to seven days previously. The team estimated each bird’s levels of fearfulness by measuring how long they remained ‘vigilant and immobile’ (i.e., ‘freezing’) upon first hearing the alarm calls. They used freezing as a proxy as it is an anti-predator behavior demonstrated in almost every type of animal, they explain.

“To assess effects on behaviour, individuals were again housed solitarily in acoustic isolation chambers, and all were exposed for 15 minutes to playbacks of conspecific alarm calls, a signal which, like hearing predator vocalizations, alerts the hearer to a predator danger,” the paper explains.

The long-term effects of exposure on the brain were assessed by measuring ∆FosB protein levels in the amygdala and hippocampus, two areas of the brain involved in PTSD in humans. The amygdala is responsible for fear processing and the acquisition and expression of fear memories, the team explains, whereas the hippocampus is involved in memory formation. ∆FosB is a transcription factor, meaning it can turn other genes on or off. It is “unusually stable” for a transcription factor (i.e. has long-lasting effects) and, among other things, is known to promote resistance to the consequences of chronic stress.

Zanette’s team is the first to show that the effects of predator exposure on the neural pathways that govern fear in animals can persist far beyond the initial ‘fight or flight’ response. They showed that this response remains measurable over one week later even for animals that have been allowed a peaceful, quality life after exposure.

They explain that retaining a powerful and enduring memory of a life-threatening predator encounter might seem crippling, but it’s actually evolutionarily-rewarding if it helps the individual avoid such events in the future. The team says their findings support the view that PTSD is the cost of inheriting an evolutionarily primitive mechanism that prioritizes survival over the quality of life.

The results suggest predator exposure could impair the behavior of prey species much more, and for longer than previously assumed. They also tie in well with past research in which Zanette and her collaborators show that scared parents are less able to care for their young.

The paper “Predator-induced fear causes PTSD-like changes in the brains and behaviour of wild animals” has been published in the journal Scientific Reports.

Seagull.

Some seagulls will steal your food unless you stare them in the eyes

If you want to keep your snacks safe at the beach, be ready to stare down bold seagulls.

Seagull.

Image via Pixabay.

Researchers at the University of Exeter report that looking straight at a gull that’s stalking your food can help dissuade the bird from approaching. The team placed a clear plastic bag filled with chips in front of herring gulls and tested how long it took the birds to approach when a human was watching them, compared to when they were looking away.

On average, gulls took 21 seconds longer to make a run for the chips when a human was looking at them.

To unboldly steal snacks

“Gulls are often seen as aggressive and willing to take food from humans, so it was interesting to find that most wouldn’t even come near during our tests,” said lead author Madeleine Goumas, of the Centre for Ecology and Conservation at Exeter’s Penryn Campus in Cornwall.

“Of those that did approach, most took longer when they were being watched. Some wouldn’t even touch the food at all, although others didn’t seem to notice that a human was staring at them.

The team attempted to run the test with 74 herring gulls (Larus argentatus) in coastal towns in Cornwall, but most flew away or would not approach. Only 27 finally made a pass at the chips, and out of these, only 19 tried both when watched by a researcher (the experimental condition) and when the researcher looked away (the test condition). Those 19 gulls make the object of this study — so its sample size is quite small.

Staring at the birds did seem to work, they report. Gulls took longer to approach the food when a human was staring at them, and some didn’t even dare attempt to steal the snacks. However, there was significant variation between individual birds’ behaviors. “We found that only 26% of targeted gulls would touch the food, suggesting that food-snatching is likely to be conducted by a minority of individuals,” the paper reads.

The results show that it’s overkill to treat all gulls as being alike, as most are too wary to come near humans. However, it does pay to stare down those few very bold ones, as that might just be the difference between getting your snack stolen or enjoying it yourself.

“We didn’t examine why individual gulls were so different. It might be because of differences in “personality” and some might have had positive experiences of being fed by humans in the past — but it seems that a couple of very bold gulls might ruin the reputation of the rest,” explains senior author Dr. Neeltje Boogert added.

What Dr. Boogert recommends, especially during beach season when gulls are “looking for an easy meal,” is for people to keep an eye on their surroundings for approaching gulls. They often fly down or come from behind people, snatch up food, and run away — but if you can spot them coming and look directly at them, they might just get cold feet.

“Gulls learn really quickly, so if they manage to get food from humans once, they might look for more,” Dr. Boogert explains.

“It seems that just watching the gulls will reduce the chance of them snatching your food.”

The UK’s herring gulls are in decline, the paper further reports, although their numbers are increasing in urban areas. Gulls’ natural diet consists of fish and invertebrates. Both of which are, understandably, hard to get in the city, so the gulls resort to stealing food from humans quite frequently. In the future, the team wants to investigate how eating human foods affects the gulls, and their chicks, in the long term.

The paper “Herring gulls respond to human gaze direction” has been published in the journal Biology Letters.

What’s the difference between birds and mammals

There is a huge variety of organisms on the planet and among them, members of the animal kingdom tend to captivate us humans the most. Birds and mammals are equally remarkable, but very different.

Numerically speaking, only a handful of living organisms have skeletons and an even smaller fraction of vertebrates can regulate their own body temperature. The classes Aves and Mammalia are the only groups that have this special warm-blooded trait and that often leads people to think that birds and mammals are very related—sometimes even that birds are a type of mammal.

The truth is, however, that these two classes are very different in a lot of ways. It’s quite a bit more than the fact that we can’t fly.

“I don’t think this will work out. You’re cute but we’re just too different.” Image credits: Pixabay.

 

Defining the Problem

To start with, mammals and birds are quite different through their very definitions. The definition of a bird requires feathers, a toothless beak, wings (usually allowing for flight), and the ability to lay hard-shelled eggs. Meanwhile, mammals have hair, give birth to live young, and the females produce milk from mammary glands — the structures for which the class is named.

That being said, there are a few species that blur the definitions a little bit.

On the issue of wings, care is taken to not focus too much on the flight itself as several bird species, like penguins, have modified wings specialized for movement through water. Of course, there are also many flightless birds. Meanwhile, there are mammals that have wings and can fly, bats. At the same time, monotremes (a group including the platypus and the echidna) make things even more complicated,

Monotremes defy mammalian definitions in favor of bird-like habits. Although they’re mammals, they lay eggs rather than giving birth to live young — although it has to be said that the platypus and echidna are extremely odd mammals and we shouldn’t generalize based on them (but that is a discussion for a different article).

With those facts noted, however, even the bat’s modified forelimb doesn’t possess feathers and even after laying eggs monotreme mamas are going to feed their growing young on a milk diet.

Judging books by covers

Being humans, it’s fair to assume we get the gist of what mammals are — at least the basics.

But, very few of us have taken the time to consider the specialized form of a bird. To start with, while there is quite a variety in mammalian silhouettes, the basic structure of the bird body is fairly consistent and generally quite different from a mammal’s. Even considering only the most standard mammal form, with four similarly-sized limbs and a tail, there is a notable difference in overall structure from birds.

Image credits: Karen Arnold.

Now, let us take a closer look. If you have a pet bird, feel free to smile at it and maybe it will return an excited stare.

Some mammalian smiles sport fangs, and the bird’s mouth can be just as sharp, but it will never quite be able to give you back that excited grin—because, unlike mammals, birds don’t have any teeth. The next thing to note is the most obvious, the nice somewhat rounded feathery bodies and, where a mammal would have forelimbs, birds sport wings. But that’s okay, while they don’t have hands to hold things, if you look a little lower they are sporting a lovely pair of wrinkly clawed feet.

Birds typically possess four toes, three facing forward and one facing backward — this is the part we typically think of as the bird’s feet. However, birds are typically digitigrade meaning that they are actually walking on their toes. What we think of as their knees are actually their ankles. Canines and felines are also digitigrade but, of course, the feet look quite different. And that is just an outside look. Let us get even closer.

 

An Even Closer Look

We really need to appreciate how specially a bird must be built to live its extraordinary life in the air.

The typical internal structure of a pneumatized bird femur.

 

Because they so well adapted for flight, their internal structures can be quite different from our own. Flying requires you to be both strong and lightweight and while we may be able to accomplish the first, no amount of arm flapping will ever get us off the ground.

Since they need to be so lightweight, airborne members of the class Aves have decided to drop the weight in the densest structures in the mammalian body, their bones. Birds possess many bones which are pneumatized (hollow), with crisscrossing struts, like columns on a building, to maintain their shape and structure. Those specialized for swimming like puffins and penguins have none, however. A bit of density helps when you need to go underwater and can’t simply fall from the sky.

But, this is just one of the major ways birds and mammals differ internally to aid in flight. Another fascinating structural difference between birds and mammals is the extraordinary avian respiratory system. Flight takes energy—a lot of it. Try flapping your arms all the way up and down just ten to fifteen times, exhausting isn’t it? Birds need to do this simply to get off the ground and many bird species are not adapted for gliding so they must ­always do this to stay above ground. Hummingbirds flap their wings up to twelve times each second. How can they even keep up with all this exertion?

 

Inhalation: the air sacs expand, pulling oxygenated air from outside into the posterior sacs and deoxygenated air out of the lungs into the anterior air sac. Exhalation: The air sacs contract, the posterior sacs pushing oxygenated air into the lungs and the anterior air sacs pushing oxygen-free air away from the lungs and back up the trachea. In this way, oxygenated air is always in the lungs. Image credits L. Shyamal via Wikimedia Commons.

 

Well, unlike in mammals, birds don’t have a simple system with two neat lungs in the chest. Their respiratory system takes up a large percentage of their bodies. What moves air though bird bodies aren’t their lungs, which don’t expand and contract as ours do. Instead, they have a complex system of air sacs which move air constantly in a cyclical system far more efficient than our own.

As a point of comparison, how the mammalian system works is that we inhale and our lungs fill with air.  Deep in the lungs, there are air sacs called alveoli, covered in capillaries, in which oxygen is exchanged for carbon dioxide in the blood. When this exchange takes place to a sufficient extent we exhale, then inhale again. This system means that air must reverse direction and there is a time when our lungs are devoid of usable oxygen. This, however, is not the case with birds. For them, air goes in one direction at all times, maximizing efficiency so that the lungs always have oxygen to process.

The last thing to mention is the cloaca. While most mammals—again, monotremes are weird—possess distinct regions for defecation, urination, and reproduction (the urethra and vagina actually have distinct exit points), birds work with a one-for-all approach. For these purposes, birds have a single structure called a cloaca. Avian waste is a combination of all solid waste products, leaving their waste two-toned. Instead of liquid urea, they release semi-solid uric acid which is the reason why bird feces left on a car erodes the paint.

So, though there are mammals that can fly and lay eggs, they can never quite be as birds are. Though we haven’t gone to great detail here, birds breathe, give birth, digest and even sing using structures different from those found in mammals. Interesting and complex though mammals are, they are mostly lacking the intricate anatomy needed for flight. Though mammals and birds are all warm-blooded creatures, with four-chambered hearts, that is roundabout where the similarity between mammals and birds ends. Altogether, birds and mammals are entirely different animals.

Fossil Friday: bird encased in amber has an unique, “extreme” toe

The bird’s hyper-elongated third toe is longer than its whole lower leg, the authors report.

Bird in amber.

The fossilized bird, encased in amber. Image credits Linda Xing et al., (2019), Cell Biology.

Researchers in China have discovered a new species of ancient bird preserved in amber– and it’s packing one seriously impressive toe. The fossilized beast, which lived around 99 million years ago, likely used the appendage to draw food out of tree trunks. According to the team, it’s the first time such a food structure has been observed in either living or extinct birds.

Bigtoe

“I was very surprised when I saw the amber,” says first author Lida Xing at China University of Geosciences (Beijing). “It shows that ancient birds were way more diverse than we thought. They had evolved many different features to adapt to their environments.”

The fossils include two isolated wings, an isolated foot with wing fragment, and two partial skeletons, most of them from juvenile individuals. The fossils date back to the Cretaceous period and were found encased in amber in 2014 in the Hukawng Valley of Myanmar. It was christened Elektorornis chenguangi. The new species’ most distinctive feature is its very, very long third toe measuring 9.8 millimeters. It is a full 41% longer than its second toe and 20% longer than its tarsometatarsus, the main bone in the lower legs of birds. Comparison to 20 other extinct bird species from the same time and 62 living birds showed that, showed that Elektorornis chenguangi is the only species so far discovered to evolve this foot structure.

Elektorornis chenguangi is part of a group of extinct birds called Enantiornithes, the most abundant type of bird known from the Mesozoic era. To the best of our knowledge, the Enantiornithines became extinct during the Cretaceous-Paleogene extinction event about 66 million years ago (the one where all the dinosaurs died) and left no living descendants behind. Elektorornis means “amber bird”.

Bird leg.

A 3D reconstruction of the birds’ leg.
Image credits Linda Xing et al., (2019), Cell Biology.

Based on the measurements they’ve taken of the fossils, the team reports that Elektorornis was smaller than a sparrow and that it was arboreal (i.e. it liked trees as opposed to the ground or water surfaces). The bird’s foot measures 3.5 centimeters in length, and weighs 5.5 grams.

“Elongated toes are something you commonly see in arboreal animals because they need to be able to grip these branches and wrap their toes around them,” says co-author Jingmai O’Connor at the Chinese Academy of Sciences. “But this extreme difference in toe lengths, as far as we know, has never been seen before.”

During the Mesozoic area, the Hukawng Valley of Myanmar was heavily forested with trees that produced resin as a defensive mechanism. The area is famed for its amber and fossil-bearing amber bits to this day, all thanks to those trees. The oldest known bee and a feathered dinosaur tail, among many others, have been discovered in amber from this valley. The team obtained the amber from a local trader, who didn’t know what animal this weird foot belonged to.

“Some traders thought it’s a lizard foot, because lizards tend to have long toes,” Xing says. “Although I’ve never seen a bird claw that looks like this before, I know it’s a bird. Like most birds, this foot has four toes, while lizards have five.”

As to why the bird needed such a long leg, the team still can’t say for sure. The only animal today to sport similar digitation is the aye-aye, a lemur that uses its long middle fingers to fish larvae and insects out of tree trunks for food. The team suspects Elektorornis chenguangi used its toe in a similar way.

“This is the best guess we have,” O’Connor says. “There is no bird with a similar morphology that could be considered a modern analog for this fossil bird. A lot of ancient birds were probably doing completely different things than living birds. This fossil exposes a different ecological niche that these early birds were experimenting as they evolved.”

The paper “A New Enantiornithine Bird with Unusual Pedal Proportions Found in Amber” has been published in the journal Current Biology.

Artist impression of the giant bird found in Crimea. Credit: Andrey Atuchin.

Russian scientists find the first ever giant bird fossils in Europe

Artist impression of the giant bird found in Crimea. Credit: Andrey Atuchin.

Artist impression of the giant bird found in Crimea. Credit: Andrey Atuchin.

Paleontologists have recently discovered the fossils of one of the largest birds that ever roamed Earth inside a cave in Crimea. The newly discovered species lived almost 2 million years ago and could grow almost 10 feet (3 meters) tall and weigh as much as 1,000 pounds (450 kg).

“This formidable weight is nearly three times the largest living bird, the common ostrich, and nearly as much as an adult polar bear,” said study lead author Nikita Zelenkov of the Russian Academy of Sciences.

The cave where the bird’s remains were found was revealed completely by accident during roadworks in the Crimean Peninsula in the summer of 2018. In time, the cave proved to be a treasure trove of megafauna fossils.

At the same site where the giant bird’s fossils were found, Russian scientists also found the bones of giant cheetahs, hyenas, and saber-toothed cats — all highly agile and fast predators that likely kept the ancient bird in check. For this reason, the bird, which scientists named Pachystruthio dmanisensis, was likely fast too.

They also found fossils belonging to mammoths, ancient horses, and even a small wolf that will teach researchers much about Europe’s distant past.

There are bigger birds than Pachystruthio dmanisensis — the distinction for the largest bird belongs to the elephant birds (Aepyornithidae), which roamed Madagascar until they became extinct 1,000 years ago. Instead, what’s truly peculiar about Pachystruthio dmanisensis is its location.

Giant birds like it have only been found in Madagascar, New Zealand, and Australia — all relatively isolated insular regions where there are generally fewer predators. No one ever expected to find a giant bird in Europe, of all places. In fact, Pachystruthio dmanisensis is the first giant bird discovered in the Northern Hemisphere.

The body mass of the bird was reconstructed using calculations from several formulae, based on measurements from the femur bone. Applying these formulae, the body mass of the bird was estimated to be around 450kg. The bird’s gigantism may have occurred in response to the environment, which became increasingly arid as the Pleistocene epoch approached. Animals with a larger body mass have lower metabolic demands, making them better adapted to less nutritious food growing in the open steppe.

Around the time this big bird went extinct between 1.5 and 2 million years ago, our close ancestor Homo erectus occupied a region east of the Black Sea. This means that our ancestor not only lived alongside Pachystruthio dmanisensis, but may have hunted it too. But it’s far too early to say whether humans had any part in the bird’s demise.

The findings were reported in the Journal of Vertebrate Paleontology.

Birds also prefer fancier neighborhoods — as long as there’s enough green space

 

In the developing world, where urbanization is taking place at an accelerated rate, this could be extremely important for native bird populations.

The African Olive Pigeon — a fancy bird which enjoys fancy neighborhoods. Image credits: Dom Henry.

All over the world, mankind is spreading. We’re building bigger cities, wider neighborhoods, more and more roads. Wildlife is trying to cope with this, and it’s doing it in different ways. Some species are thriving in human areas — species like rats and seagulls have grown to unprecedented numbers and follow the development of human settlements. Others (the vast majority) have withdrawn step by step, giving way to relentless urbanization.

Sometimes, this interaction happens in unexpected ways.

A study on birds in South Africa found a “luxury effect”: provided that birds had sufficient green spaces to establish a habitat, more species were present in richer areas than in poorer areas.

This luxury effect was previously described in some developed countries, and it doesn’t only apply to birds — insects, bats, and lizards all seem to prefer fancier neighborhoods. However, it doesn’t happen in all affluent neighborhoods. If there’s too much concrete and not enough green space, populations will dwindle. The effect is particularly visible in areas with greater investment in gardens, parks and other green spaces — think rich, quiet suburbs or large parks.

However, researchers found that tree cover alone can’t explain this effect. The diversity of trees and plants also drives a diversity of birds, and in general, encourages are more varied ecosystem. Lead author Professor Dan Chamberlain from the University of Turin said:

“This study shows that rich, leafy suburbs have more bird species, and probably higher biodiversity in general, than poor areas of the city or areas that have too much asphalt and concrete. Understanding the factors which drive the ‘luxury effect’ will help us to design more biodiversity-friendly cities in the future, thus promoting environmental justice for all urban inhabitants.”

Chamberlain and colleagues analyzed a broad range of environments and neighborhoods, with average incomes varying from $1,000 to $30,000. The findings were generally consistent regardless of the type of environment: the more affluent a neighborhood was, the more bird species it had, as long as it wasn’t too heavily built-up.

The case study is important because it confirms this luxury effect in a developing country and South Africa, in particular, is significant. A country with thriving biodiversity and roaring inequality, South Africa will need to consider its future development carefully if it wants to encourage a stable environment.

According to the study, “maintaining green space in at least an equal proportion to the built environment is likely to provide a development strategy that will enhance urban biodiversity, and with it, the positive benefits that are manifest for urban dwellers.”

The authors hope that the “findings can form a key contribution to a wider strategy to expand urban settlements in a sustainable way to provide for the growing urban population in South Africa, including addressing imbalances in environmental justice across income levels and racial groups.”

Co-author on the study, UCT Associate Professor Arjun Amar said:

“This work is of particular importance because it is one of the few studies conducted in a developing country, and the only study of its kind in Africa, where urbanisation is predicted to occur at a faster rate than any other region on the planet.”

Researchers hope that urban planners will use this information to ensure greater urban biodiversity, something which will help not only wildlife but also the urban dwellers. As for places that already developed without consideration for biodiversity, researchers also hope that they will address “imbalances in environmental justice across all income levels.”

The study “The relationship between wealth and biodiversity: A test of the Luxury Effect on bird species richness in the developing world” by Chamberlain et al was published in the journal Global Change Biology. DOI: 10.1111/gcb.14682

Photograph of the holotype of Avimaia schweitzerae. Credit: Barbara Marrs.

Paleontologists find 110-million-year-old bird fossil with unlaid egg still inside it

Photograph of the holotype of Avimaia schweitzerae. Credit: Barbara Marrs.

Photograph of the holotype of Avimaia schweitzerae. Credit: Barbara Marrs.

A crushed, pancake-like fossil unearthed in northwestern China contains both a bird and its unlaid egg. The fossil also features a medullary bone — a special type of tissue which serves as a readily available store of calcium for the eggshell. This is the first time scientists have found such a bone and an egg together in the same fossil. Ironically, the authors say that the egg is what seems to have killed the mother.

Insight into the reproductive life of ancient birds

The new species, called Avimaia schweitzerae, belongs to a family of ancient birds known as Enantiornithes, which lived alongside their dinosaur cousins for more than 100 million years. Enantiornithine birds were widely distributed across the globe, with remains found in Argentina, North America, Mexico, Mongolia, Australia, Spain, and China. Paleontologists take a special interest in enantiornithines because the species includes both specialized and primitive features, suggesting they represent an evolutionary side branch of early avian evolution.

Paleontologists at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences found bits of eggshell preserved alongside the ancient bird’s fossilized skeleton. These eggshell fragments were detected inside the specimen’s abdomen, showing parts of the egg membrane and cuticle (a protein-covered outer layer that covers the surface of the egg and fills the pores that allow air inside for the growing chick). The researcher also detected small minerals made of calcium phosphate which are typically found among birds who bury their eggs. Previous evidence suggested that Enantiornithes buried their eggs, and these latest findings add more weight to this assumption.

At the same time, this particular eggshell features some unusual characteristics. The shell is too thin and it looks like it had two layers instead of one. This suggests that the mother bird went through egg-binding — when an egg takes longer than usual to pass out of the reproductive tract — and this may have been what ultimately killed her.

The analysis also showed that Avimaia schweitzerae had a reproductive tissue called the medullary bone, making it the only Mesozoic fossil featuring this kind of structure. Previously, scientists had argued that this tissue should to be present in other fossil birds, as well as dinosaurs and pterosaurs, but until now this identification proved ambiguous.

The findings appeared in the journal Nature Communications.