Category: Birds

Dutch police training Eagles to grab drones out of the sky

On By A.P.In drone, eagleLeave a comment

For hundreds of years in the skies over Asia, people have used eagles to hunt down prey with deadly results.

That tradition has been in decline for decades, but now the bird’s keen eyesight, powerful talons and lethal hunting instincts are being used to take out a new kind of 21st-century vermin: drones.

The animal-vs.-machine moment is brought to you by Guard From Above, which describes itself as “the world’s first company specialized in training birds of prey to intercept hostile drones.”

The Hague-based company’s latest customers are Dutch police, who have been looking for ways to disable illegally operating drones. A police spokesman told Dutch News.nl that the effort remains in a testing phase, but he called the use of birds to combat drones a “very real possibility.”

“It’s a low-tech solution to a high-tech problem,” national police spokesman Dennis Janus told Reuters.

He added: “People sometimes think it’s a hoax, but it’s proving very effective so far.”

The rise of drone technology has been matched in speed by the rise of anti-drone technology, with companies creating radio jammers and “net-wielding interceptor” drones to disable quadcopters, according to the Verge.

“For years, the government has been looking for ways to counter the undesirable use of drones,” Guard From Above’s founder and chief executive, Sjoerd Hoogendoorn, said in a statement. “Sometimes a low-tech solution for a high-tech problem is more obvious than it seems. This is the case with our specially trained birds of prey. By using these birds’ animal instincts, we can offer an effective solution to a new threat.”

A video released on Sunday by Dutch police shows an eagle swooping in at high speed to pluck a DJI Phantom out of the air using its talons. The drone is immediately disabled as the bird carries it off.

“The bird sees the drone as prey and takes it to a safe place, a place where there are no other birds or people,” project spokesman Marc Wiebes told Dutch News.nl. “That is what we are making use of in this project.”

Said Hoogendoorn, according to Reuters: “These birds are used to meeting resistance from animals they hunt in the wild, and they don’t seem to have much trouble with the drones.”

Janus, the police spokesman, told the Associated Press that the birds get a reward if they snag a drone.

Eagles’ talons, as the New York Daily News points out, are known for their powerful grips; it’s unknown whether they could be damaged by a drone’s carbon-fiber propellers.

HawkQuest, a Colorado nonprofit that educates the public about birds of prey, says eagles have enough power to “crush large mammal bones” in animals such as sloths.

“Scientists have tried to measure the gripping strength of eagles,” HawQuest notes. “A Bald Eagle’s grip is believed to be about 10 times stronger than the grip of an adult human hand and can exert upwards of 400 psi or pounds per square inch.”

According to a study cited by Wired in 2009, raptor talons are not merely powerful, but also finely tuned hunting instruments:

“…accipitrids, which include hawks and eagles, have two giant talons on their first and second toes. These give them a secure grip on struggling game that they like to eat alive, ‘so long as it does not protest too vigorously. In this prolonged and bloody scenario, prey eventually succumb to massive blood loss or organ failure, incurred during dismemberment.’”

A handler in the video, the Daily News notes, claims the birds are adequately protected by scales on their feet and legs, but researchers hope to equip the animals with another layer of defense.

The potential impact on the animals’ welfare is the subject of testing by an external scientific research institute.

“The real problem we have is that they destroy a lot of drones,” Hoogendoorn said, according to Reuters. “It’s a major cost of testing.”

The decision about whether to use the eagles is still several months away.

https://www.washingtonpost.com/news/worldviews/wp/2016/02/01/trained-eagle-destroys-drone-in-dutch-police-video/

New research identifies similarity between how pigeons and human children learn equivalent of words

On By A.P.In Nature, Neuroscience, pigeon2 Comments

The more scientists study pigeons, the more they learn how their brains—no bigger than the tip of an index finger—operate in ways not so different from our own.

In a new study from the University of Iowa, researchers found that pigeons can categorize and name both natural and manmade objects—and not just a few objects. These birds categorized 128 photographs into 16 categories, and they did so simultaneously.

Ed Wasserman, UI professor of psychology and corresponding author of the study, says the finding suggests a similarity between how pigeons learn the equivalent of words and the way children do.

“Unlike prior attempts to teach words to primates, dogs, and parrots, we used neither elaborate shaping methods nor social cues,” Wasserman says of the study, published online in the journal Cognition. “And our pigeons were trained on all 16 categories simultaneously, a much closer analog of how children learn words and categories.”

For researchers like Wasserman, who has been studying animal intelligence for decades, this latest experiment is further proof that animals—whether primates, birds, or dogs—are smarter than once presumed and have more to teach scientists.

“It is certainly no simple task to investigate animal cognition; But, as our methods have improved, so too have our understanding and appreciation of animal intelligence,” he says. “Differences between humans and animals must indeed exist: many are already known. But, they may be outnumbered by similarities. Our research on categorization in pigeons suggests that those similarities may even extend to how children learn words.”

Wasserman says the pigeon experiment comes from a project published in 1988 and featured in The New York Times in which UI researchers discovered pigeons could distinguish among four categories of objects.

This time, the UI researchers used a computerized version of the “name game” in which three pigeons were shown 128 black-and-white photos of objects from 16 basic categories: baby, bottle, cake, car, cracker, dog, duck, fish, flower, hat, key, pen, phone, plan, shoe, tree. They then had to peck on one of two different symbols: the correct one for that photo and an incorrect one that was randomly chosen from one of the remaining 15 categories. The pigeons not only succeeded in learning the task, but they reliably transferred the learning to four new photos from each of the 16 categories.

Pigeons have long been known to be smarter than your average bird—or many other animals, for that matter. Among their many talents, pigeons have a “homing instinct” that helps them find their way home from hundreds of miles away, even when blindfolded. They have better eyesight than humans and have been trained by the U. S. Coast Guard to spot orange life jackets of people lost at sea. They carried messages for the U.S. Army during World Wars I and II, saving lives and providing vital strategic information.

UI researchers say their expanded experiment represents the first purely associative animal model that captures an essential ingredient of word learning—the many-to-many mapping between stimuli and responses.

“Ours is a computerized task that can be provided to any animal, it doesn’t have to be pigeons,” says UI psychologist Bob McMurray, another author of the study. “These methods can be used with any type of animal that can interact with a computer screen.”

McMurray says the research shows the mechanisms by which children learn words might not be unique to humans.

“Children are confronted with an immense task of learning thousands of words without a lot of background knowledge to go on,” he says. “For a long time, people thought that such learning is special to humans. What this research shows is that the mechanisms by which children solve this huge problem may be mechanisms that are shared with many species.”

Wasserman acknowledges the recent pigeon study is not a direct analogue of word learning in children and more work needs to be done. Nonetheless, the model used in the study could lead to a better understanding of the associative principles involved in children’s word learning.

“That’s the parallel that we’re pursuing,” he says, “but a single project—however innovative it may be—will not suffice to answer such a provocative question.”

http://now.uiowa.edu/2015/02/pigeon-power

To beat a parasite, birds teach their young a password.

On By A.P.In Birds, bronze-cuckoo, brood parasites, CIAF, Diane Colombelli-Négrel, fairy-wren, Flinders University, Mary Bates, parasite, password, Sonia KleindorferLeave a comment

By Mary Bates

I’ve written before about the evolutionary arms race between brood parasites (who lay their eggs in the nests of other birds, leaving them to raise their chicks) and their hosts. In these systems, host birds benefit from recognizing and removing parasite eggs or chicks from their nests. Meanwhile, the brood parasites keep trying to trick the hosts into accepting and caring for their young.

Hosts must walk a precarious line in defending themselves against brood parasites. Too lax, and they end up spending valuable time and energy raising another bird’s chicks. Too strict, and they run the risk of rejecting one of their own eggs by mistake. For the best results, hosts should modify how defensive they are against parasites in relation to the risk they pose.

A few years ago, Diane Colombelli-Négrel, Sonia Kleindorfer, and colleagues from Flinders University in Australia discovered a remarkable way one bird fights back against brood parasites. Female superb fairy-wrens teach their embryos a “password” while they’re still in their eggs. Each female’s incubation call contains a unique acoustic element. After they hatch, fairy-wren chicks incorporate this unique element into their begging calls to ask for food. Colombelli-Négrel, Kleindorfer, and colleagues showed that chicks whose begging calls most resembled their mothers’ incubation calls received more food. But the brood parasites of the fairy-wren, Horsfield’s bronze-cuckoos, produced begging calls that did not so closely resemble the parental password.

In a new study, Colombelli-Négrel, Kleindorfer, and colleagues again looked at the relationship between superb fairy-wrens and Horsfield’s bronze-cuckoos to see if a greater threat of brood parasitism would cause the fairy-wren to up its teaching efforts.

First, the researchers recorded calls from 17 fairy-wren nests in South Australia. They found the similarity between the mother’s password and the chick’s begging call was predicted by the number of incubation calls produced by the mother: If females made many incubation calls, their chicks ended up producing more similar begging calls.Next, the researchers conducted a playback experiment at 29 nests. They broadcast either the song of Horsfield’s bronze-cuckoo or a neutral bird. After the cuckoo calls, but not after the neutral bird calls, female fairy-wrens made more incubation calls to their embryos. In other words, female fairy-wrens that heard a cuckoo near their nest increased their efforts to teach their password to their embryos.

Colombelli-Négrel and Kleindorfer say their results provide a mechanism for how fairy-wrens could get better at decision-making and lower the probability of committing an acceptance error for a cuckoo chick or a rejection error for one of their own chicks.“When there are cuckoos in the area, you should call more to your eggs so that they have a higher call similarity after hatching and you can decide if the offspring is yours,” Colombelli-Négrel and Kleindorfer wrote in an email. “We show a mechanism that starts in the nest and involves active teaching and sensorimotor learning in embryos.”Colombelli-Négrel, Kleindorfer, and their colleagues are continuing to study how fairy-wrens teach their passwords to their chicks. They’re currently looking at how the fairy-wren embryos learn using heart rate and magnetic resonance imaging (MRI) scans, and whether parents do anything special to help their offspring learn, such as investing in egg nutrients that promote learning.

To beat a tricky brood parasite, superb fairy-wrens have to start teaching their offspring early and often. And when they detect a threat, these dedicated parents double-down on their teaching efforts to make sure their chicks get the message.

References:

Kleindorfer, S., Evans, C. and Colombelli-Négrel, D. (2014). Females that experience threat are better teachers. Biology Letters 10: 20140046. doi: 10.1098/rsbl.2014.0046.

Colombelli-Négrel, D., Hauber, M. E., Robertson, J., Sulloway, F. J., Hoi, H., Griggio, M. and Kleindorfer, S. (2012). Embryonic learning of vocal passwords in superb fairy-wrens reveals intruder cuckoo nestlings. Current Biology 22: 2155-2160. doi: 10.1016/j.cub.2012.09.025.

http://www.wired.com/2014/06/to-beat-a-parasite-birds-teach-their-young-a-secret-password/

Video of kangaroo eating penguin: herbivores are not all strict vegetarians

On By A.P.In Australia, Birds, carnivore, Graeme Coulson, herbivore, kangaroo, Nature, Penguin, University of Melbourne, zoology2 Comments

WHILE KANGAROOS ARE known to munch grass, with the addition of fruit, flowers, sap and bark for tree kangaroos, who knew they favour an occasional bite of meat?

Sam Murray, who captured this curious footage, happened upon this western grey kangaroo (Macropus fuliginosus) tucking into a penguin on the beach at Cape Le Grande national park, located east of Esperance, WA in March 2013.

“We were walking down to the beach in the late evening before sunset, and we noticed a group of five or six kangaroos gathered on the beach. We started towards them and all the others were quick to hop away, but not this smaller one,” Sam says.

“He was really quite focussed on what he was doing. Even when we got to within a metre and a half of him, he wouldn’t stop eating.”

Kangaroos sometime eat meat
Professor Graeme Coulson, a zoologist at the University of Melbourne, explains that “All living macropods appear to be gentle herbivores. They [generally] lack the equipment to capture and kill other animals, or the digestive system to handle a meaty diet.”

While penguins aren’t a typical kangaroo snack, Graeme says that “Australia once had carnivorous macropods. The largest of these was Propleopus oscillans, which stood up to 2 m tall and had teeth that were well adapted to eating meat. This ‘killer kangaroo’ went extinct tens of thousands of years ago.”

While this footage may strike many as peculiar, Professor Tim Flannery, an expert mammalogist, says “This is unusual, I admit, but most herbivores will eat some protein if it’s available. Tree kangaroos will eat birds and even cows will chew on a bone.”

Graeme also recognizes that known herbivores are not all strict vegetarians. “White-tailed deer in the USA have been reported stealing trout from a fishing camp and removing nestlings from nests hidden in prairie grassland. Captive macropods are known to eat a wide range of foods, including chicken and lamb chops. This western grey kangaroo was simply taking advantage of an easy meal,” Graeme says.

http://www.australiangeographic.com.au/topics/wildlife/2014/02/video-kangaroo-eats-a-penguin

Scientists discover why the chicken lost its penis.

On By A.P.In albatross, Alligator, Ana Herrera, anseriforms, apoptosis, Birds, Bmp4, chicken, cloacal kiss, cracid, crane, Crocodile, Current Biology, Diane Kelly, Dr. Lutter, duck, eagle, emu, flamingo, galliforms, Geese, geese, genital tubercle, greylag goose, gull, hummingbird, kiwi, Martin Cohn, Nature, neoaves, ornithologist, ornithology, ostrich, owl, Patricia Brennan, penguin, Penis, pigeon, programmed cell death, ratites, Science, swan, University of Florida, University of Massachusetts, woodpecker, wrenLeave a comment

Duck_chicken_penisRooster

Researchers have now unraveled the genetics behind why most male birds don’t have penises, just published in Current Biology.
[Ana Herrera et al, Developmental Basis of Phallus Reduction During Bird Evolution]

There are almost 10,000 species of birds and only around 3 percent of them have a penis. These include ducks, geese and swans, and large flightless birds like ostriches and emus. In fact, some ducks have helical penises that are longer than their entire bodies. But eagles, flamingos, penguins and albatrosses have completely lost their penises. So have wrens, gulls, cranes, owls, pigeons, hummingbirds and woodpeckers. Chickens still have penises, but barely—they’re tiny nubs that are no good for penetrating anything.

In all of these species, males still fertilise a female’s eggs by sending sperm into her body, but without any penetration. Instead, males and females just mush their genital openings together and he transfers sperm into her in a maneuver called the cloacal kiss.

To get to the root of this puzzle, researchers compared the embryos of chickens and ducks. Both types of birds start to develop a penis. But in chickens, the genital tubercle shrinks before the little guys hatch. And it’s because of a gene called Bmp4.

“There are lots of examples of animal groups that evolved penises, but I can think of only a bare handful that subsequently lost them,” says Diane Kelly from the University of Massachusetts in Amherst. “Ornithologists have tied themselves in knots trying to explain why an organ that gives males an obvious selective advantage in so many different animal species disappeared in most birds. But it’s hard to address a question on why something happens when you don’t know much about how it happens.”

That’s where Martin Cohn came in. He wanted to know the how. His team at the University of Florida studies how limbs and genitals develop across the animal kingdom, from the loss of legs in pythons to genital deformities in humans. “In a lab that thinks about genital development, one takes notice when a species that reproduces by internal fertilization lacks a penis,” says graduate student Ana Herrera.

By comparing the embryos of a Pekin duck and a domestic chicken, Herrera and other team members showed that their genitals start developing in the same way. A couple of small swellings fuse together into a stub called the genital tubercle, which gradually gets bigger over the first week or so. (The same process produces a mammal’s penis.)

In ducks, the genital tubercle keeps on growing into a long coiled penis, but in the chicken, it stops around day 9, while it’s still small. Why? Cohn expected to find that chickens are missing some critical molecule. Instead, his team found that all the right penis-growing genes are switched on in the chicken’s tubercle, and its cells are certainly capable of growing.

It never develops a full-blown penis because, at a certain point, its cells start committing mass suicide. This type of ‘programmed cell death’ occurs throughout the living world and helps to carve away unwanted body parts—for example, our hands have fingers because the cells between them die when we’re embryos. For the chicken, it means no penis. “It was surprising to learn that outgrowth fails not due to absence of a critical growth factor, but due to presence of a cell death factor,” says Cohn.

His team confirmed this pattern in other species, including an alligator (crocodilians are the closest living relatives of birds). In the greylag goose, emu and alligator, the tubercle continues growing into a penis, with very little cell death. In the quail, a member of the same order as chickens, the tubercle’s cells also experience a wave of death before the organ can get big.

This wave is driven by a protein called Bmp4, which is produced along the entire length of the chicken’s tubercle, but over much less of the duck’s. When Cohn’s team soaked up this protein, the tubercle’s cells stopped dying and carried on growing. So, it’s entirely possible for a chicken to grow a penis; it’s just that Bmp4 stops this from happening. Conversely, adding extra Bmp protein to a duck tubercle could stop it from growing into its full spiralling glory, forever fixing it as a chicken-esque stub.

Bmp proteins help to control the shape and size of many body parts. They’re behind the loss of wings in soldier ants and teeth of birds. Meanwhile, bats blocked these proteins to expand the membranes between their fingers and evolve wings.

They also affect the genitals of many animals. In ducks and geese, they create the urethra, a groove in the penis that sperm travels down (“If you think about it, that’s like having your urethra melt your penis,” says Kelly.) In mice, getting rid of the proteins that keep Bmp in check leads to tiny penises. Conversely, getting rid of the Bmp proteins leads to a grossly enlarged (and almost tumour-like) penis.

Penises have been lost several times in the evolution of birds. Cohn’s team have only compared two groups—the penis-less galliforms (chickens, quails and pheasants) and the penis-equipped anseriforms (swans, ducks and geese). What about the oldest group of birds—the ratites, like ostriches or emus? All of them have penises except for the kiwis, which lost theirs. And what about the largest bird group, the neoaves, which includes the vast majority of bird species? All of them are penis-less.

Maybe, all of these groups lost their penis in different ways. To find out, Herrera is now looking at how genitals develop in the neoaves. Other teams will no doubt follow suit. “The study will now allow us to more deeply explore other instances of penis loss and reduction in birds, to see whether there is more than one way to lose a penis,” says Patricia Brennan from the University of Massachussetts in Amherst.

And in at least one case, what was lost might have been regained. The cracids—an group of obscure South American galliforms—have penises unlike their chicken relatives. It might have been easy for them to re-evolve these body parts, since the galliforms still have all the genetic machinery for making a penis.

We now know how chickens lost their penises, but we don’t know why a male animal that needs to put sperm inside a female would lose the organ that makes this possible. Cohn’s study hints at one possibility—it could just be a side effect of other bodily changes. Bmp4 and other related proteins are involved in the evolution of many bird body parts, including the transition from scales to feathers, the loss of teeth, and variations in beak size. Perhaps one of these transformations changed the way Bmp4 is used in the genitals and led to shrinking penises.

There are many other possible explanations. Maybe a penis-less bird finds it easier to fly, runs a smaller risk of passing on sexually-transmitted infections, or is better at avoiding predators because he mates more quickly. Females might even be responsible. Male ducks often force themselves upon their females but birds without an obvious phallus can’t do that. They need the female’s cooperation in order to mate. So perhaps females started preferring males with smaller penises, so that they could exert more choice over whom fathered their chicks. Combinations of these explanations may be right, and different answers may apply to different groups.

Thanks to Dr. Lutter for bringing this to the It’s Interesting community.

http://www.oddly-even.com/2013/06/06/how-chickens-lost-their-penises-and-ducks-kept-theirs_/

http://news.yahoo.com/why-did-chicken-lose-penis-165408163.html

Blackbird hitches a ride atop a red-tailed hawk

On By A.P.In bird lice, California, Eric Dugan, Napa-Sonoma Marshes Wildlife Area, Ray Gaudette, red-tailed hawk, red-winged blackbirdLeave a comment

Landing On A Raptor

Brave Little Balckbird

These images show a red-winged blackbird standing on the back of a red-tailed hawk, looking as if it’s catching a ride to another destination. The series of images were captured recently by photographer Eric Dugan at Napa-Sonoma Marshes Wildlife Area in Northern California. They first appeared in a San Francisco Chronicle story written by outdoors columnist Tom Stienstra.

Dugan described the event:

“I was exploring the wildlife refuge and heard the screech of a red-tailed hawk, loud and repeated. I scanned the sky but didn’t see anything at first. Then, in the distance, I saw a young red-tailed hawk sitting on a telephone pole and the red-winged blackbirds were jumping on and off its back and head, apparently to drive it away from a nesting area.

“I immediately stopped, changed to my long lens, and set up my camera in anticipation for the show. As I walked closer, I anticipated that the hawk would take flight and the blackbirds would pursue it, to drive it out of their territory. I raised the camera and the blackbird actually landed on the hawk multiple times.

“The small bird was so far more maneuverable in flight that all the hawk could do was tolerate it and fly away.”

Dugan stated via email that the photos “are 100 percent legit” and that his only edits were exposure- and shadow-related since lighting was harsh at certain points because of the bright sunshine.

“I went back to the same spot a few days later hoping lightning would strike twice,” Dugan said. “But the red-tailed hawks were hunting way off in the distance.”

His final remark: “Red-winged blackbirds are fearless.”

http://www.grindtv.com/outdoor/nature/post/blackbird-hitches-a-ride-atop-a-red-tailed-hawk/

Thanks to Ray Gaudette for bringing this to the attention of the It’s Interesting community.

Hatching Order Influences Birds’ Behavior

On By A.P.In Animal Behaviour, Birds, birth order, hatching asynchrony, Ian Hartley, Mark Mainwaring, Nature, Science, siblings, The Brain, zebra finchLeave a comment

121207094343-large

The hatching order of birds influences how they behave in adult life according to research from the Lancaster Environment Centre. Dr Ian Hartley and Dr Mark Mainwaring (LEC) are the authors of the study in Animal Behaviour, which looked at how the birds’ behaviour was affected by the way their parents cared for them as hatchlings.

They found that the youngest members of zebra finch broods are more adventurous than their older siblings in adult life.

Dr Hartley said that the study showed for the first time that hatching order influences birds’ “behavioural repertoires” in adulthood.

Hatching eggs over a period of time, rather than all at once, is known as “hatching asynchrony” and occurs when eggs are incubated as soon as they are laid. For a zebra finch, this means that birds born up to four days apart can share the same nest and must compete for food.

The researchers experimentally controlled hatching synchrony within clutches, so that some clutches hatched simultaneously, while others hatched over a period of days. They then tested the behaviour of over one hundred offspring as adults. They found the youngest birds from asynchronously hatched clutches explored their environment more widely.

They measured how explorative the zebra finches were by recording how many times they visited bird feeders within an unfamiliar test aviary. They found that the youngest offspring in a brood approached the feeders significantly more often than their peers within a 30 minute period.

Researchers wanted to know how the method of rearing affected the behaviour of offspring beyond the nest, once they were living as independent adult birds. The results have implications for understanding how environmental stability might influence behaviours, and how flexible animals might be at coping with environmental change.

Journal Reference:

1.Mark C. Mainwaring, Ian R. Hartley. Hatching asynchrony and offspring sex influence the subsequent exploratory behaviour of zebra finches. Animal Behaviour, 2012; DOI: 10.1016/j.anbehav.2012.10.009

http://www.sciencedaily.com/releases/2012/12/121207094343.htm

Seagull steals camera and captures sunset over San Francisco Bay

On By A.P.In Birds, California, camera, Nature, San Francisco, SeagullLeave a comment

 

French tourist Nathalie Rollandin was filming the sunset from the beach when the bird snatched her GoPro video camera and flew out over the water.

Luckily for Ms Rollandin, the gull chose to land twenty seconds later on a walkway before dropping the camera. After a few pecks at it, the bird appears to lose interest in its plunder and flies off into the sunset.

After managing to track down her camera – intact and still recording outside a yacht club – Ms Rollardin posted the bird’s footage on YouTube, describing it as “a San Francisco sunset I will hardly forget”.

http://www.telegraph.co.uk/earth/wildlife/9550107/Seagull-steals-camera-and-captures-sunset-over-San-Francisco-Bay.html

Birds hold funerals for the dead

On By A.P.In Animal Behaviour, Bird funeral, Birds, California, dead bird, funeral, Nature, Science, scolds, scrub jay, Teresa Iglesias, UC Davis, University of California, Western scrub jay, zeep-scolds, zeepsLeave a comment

 

When western scrub jays encounter a dead bird, they call out to one another and stop foraging.

The jays then often fly down to the dead body and gather around it, scientists have discovered.

The behaviour may have evolved to warn other birds of nearby danger, report researchers in California, who have published the findings in the journal Animal Behaviour.

The revelation comes from a study by Teresa Iglesias and colleagues at the University of California, Davis, US.

They conducted experiments, placing a series of objects into residential back yards and observing how western scrub jays in the area reacted.

The objects included different coloured pieces of wood, dead jays, as well as mounted, stuffed jays and great horned owls, simulating the presence of live jays and predators.

The jays reacted indifferently to the wooden objects.

But when they spied a dead bird, they started making alarm calls, warning others long distances away.

The jays then gathered around the dead body, forming large cacophonous aggregations. The calls they made, known as “zeeps”, “scolds” and “zeep-scolds”, encouraged new jays to attend to the dead.

The jays also stopped foraging for food, a change in behaviour that lasted for over a day.

When the birds were fooled into thinking a predator had arrived, by being exposed to a mounted owl, they also gathered together and made a series of alarm calls.

They also swooped down at the supposed predator, to scare it off. But the jays never swooped at the body of a dead bird.

The birds also occasionally mobbed the stuffed jays; a behaviour they are known to do in the wild when they attack competitors or sick birds.

The fact that the jays didn’t react to the wooden objects shows that it is not the novelty of a dead bird appearing that triggers the reaction.

The results show that “without witnessing the struggle and manner of death”, the researchers write, the jays see the presence of a dead bird as information to be publicly shared, just as they do the presence of a predator.

Spreading the message that a dead bird is in the area helps safeguard other birds, alerting them to danger, and lowering their risk from whatever killed the original bird in the first place, the researchers say.

Other animals are known to take notice of their dead.

Giraffes and elephants, for example, have been recorded loitering around the body of a recently deceased close relative, raising the idea that animals have a mental concept of death, and may even mourn those that have passed.

http://www.bbc.co.uk/nature/19421217