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10 Behind-the-Scenes Secrets of Zoos

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Zoos are a constantly evolving workplace. Over the past 50 years, exhibits have gotten increasingly naturalistic, diets for certain species have become more standardized, and captive breeding programs have turned into nationwide campaigns. Yet if one thing’s remained constant, it’s the fact that keeping the animals in our zoos both happy and healthy requires a great deal of time, coordination, expense, and old-fashioned willpower. It’s not an easy job, but most zookeepers say they wouldn’t trade it for the world.

1. PANDAS ARE VERY, VERY EXPENSIVE.

Giant pandas are one of the biggest draws for zoos that manage to snag a pair. But the big mammals also come with an extremely high price tag. Famously finicky, they dine almost exclusively on bamboo. Since these plants don’t offer much in the way of nutritional value, pandas need to consume about 26 to 84 pounds of them every day. Maintaining a fresh supply is a costly endeavor, especially for zoos located in cooler areas where bamboo doesn’t grow as well. The Toronto Zoo, for example, spends $500,000 CDN per year (about $370,000 US) flying in bamboo from a Memphis-based supplier.

Food-related expenses are just the tip of the iceberg: China’s government effectively maintains a global panda monopoly. To put one of these rare, in-demand critters on display, a foreign zoo must lease it from the Chinese for a full decade. During this period, an annual payment has to be made—and the going rate is sky-high. For example, the Edinburgh Zoo is currently paying £600,000 (about $740,000) per year for its resident pair. Across the pond, the Smithsonian’s National Zoo in Washington, D.C. shells out $550,000 annually in order to keep two adult pandas. By the way, if one of those bamboo-eaters should die because of some human error, China will administer a roughly $400,000 fine.

2. KEEPERS WARN EACH OTHER ABOUT GUESTS WHO DON’T FOLLOW THE RULES.

Using clearly marked signs, zoos warn their guests not to do certain things that might harm the animals. Unfortunately, some people ignore these notices. Glass-tapping is a particularly common offense. While it might not seem like a big deal to human patrons, this can really stress out captive creatures. “Imagine if somebody’s knocking on your living room window all the time,” Bruce Beehler of the Milwaukee County Zoo says. “I think you would be annoyed.” He adds that tossing coins—or, indeed, anything else—into an animal’s enclosure is another big no-no. Not only can these bits of currency get swallowed, they’re also liable to contaminate an animal’s water supply.

When mental_floss interviewed Bob, Terry, and Nancy*—three keepers who work at a zoo in the southern U.S.—and asked them to name their biggest job-related pet peeve, all three cited rule-breaking visitors. “Read signs and listen to keepers,” Bob implores. “If I ask you not to tap the glass, don’t tell me it’s just for fun and you can tap the glass all you like. If a keeper asks you not to stand your child on the railing of an animal’s enclosure, do not put them down and then wait ‘till we walk away. When we see anyone doing something that endangers our animals, we do follow you.”

Security guards are on hand to remove those who ignore repeat warnings. Additionally, zoo staffers will often use their radios to tip each other off about problematic visitors. “Depending on where they are, we might alert the next area down the line,” Nancy explains. “We’ll say ‘Hey, I saw these people disturbing the animals in this area and they’re heading towards your area. Keep your eyes open.’ Each area will then make the call about how serious the situation is and whether they should call security.”

Nancy also told us that she’s personally had to discourage patrons from, among other things, throwing food at gorillas and dropping various objects (money, juice boxes, etc.) into the alligator pool. It should go without saying, but the posted rules are there for a reason. Respect the animals’ homes and you’ll have a more enjoyable visit.

3. LOTS OF ZOO ANIMALS AREN’T ON PUBLIC DISPLAY.

Purchase a standard zoo ticket and you’ll get to see most of the critters in their collection. But you can bet that at least a handful of specimens will be kept from view, stowed away in backroom terrariums or birdcages. “Animals live behind the scenes for a number of reasons,” Terry says. Some of these so-called “off-exhibit” creatures are used for educational purposes, including occasional public shows and private birthday parties. By utilizing animals that most visitors never see, staffers can put together a live creature presentation without emptying any displays in the process.

Nancy adds that the newborn offspring of breeding animals are also sometimes withheld from the public. “If your zoo is breeding a given species,” she says, “then it’s likely that the species is already well-represented in your displays. So you wouldn’t need to put all of the babies in the public viewing areas. Visitors might like to see one or two burrowing frogs, but there’d be no point in having an entire wall full of them.” A good percentage of these unseen infants will probably end up getting shipped off to other zoos.

For the record, certain departments hide their critters more frequently than others do. “Reptile, aquarium, and maybe bird areas are most likely to have larger numbers of animals behind the scenes,” Terry says. “It’s easier to house and hold many small animals than large ones … not a lot of places [have] off-exhibit elephants!”

4. TRANSFERRING ANIMALS BETWEEN ZOOS INVOLVES A LOT OF PAPERWORK.

Bob says that when an animal goes from one zoo to another, a “ton of paperwork” usually travels with it. These documents are loaded with need-to-know details about the critter’s health issues, behavioral tendencies, and the amount of training it’s received.

Unhelpfully, new beasts that aren’t acquired from other zoos seldom come with comprehensive paperwork. “Sometimes their history is a mystery,” Bob admits. “Many zoos will get animals through confiscation from Fish and Wildlife services. I’ve even met a South American tamandua [a genus of anteater] who was found walking the streets of Houston!” Over the years, Bob’s also worked with a cougar that had previously been a school mascot, as well as two bobcats believed to have been escaped pets.

In any event, zoos subject all new acquisitions to a mandatory quarantine period. Usually, this lasts anywhere from 30 to 60 days and may take place in an isolated enclosure or at the zoo hospital. “This is to make sure they bring no ailments or parasites to the general zoo population,” Bob says. “If they do show signs it is treated. Once that passes, then the animal is taken to its appropriate new home within the zoo.”

5. FEEDING THE ANIMALS ISN’T EASY (OR CHEAP).

Zoos have high standards when it comes to the quality of their residents’ food. “We’re probably pickier than some restaurants. We have to be very careful because we’re dealing with endangered animals and animals we want to reproduce and live long lives,” Kerri Slifka, the Dallas Zoo’s curator of nutrition, told the Dallas Morning News last year. Nowadays, a growing number of zoos are hiring full-time animal nutritionists to make sure that their critters receive the healthiest possible diets.

Furthermore, in recent decades there’s been a big push to standardize the meal plans for certain species. (For example, the Association of Zoos and Aquariums advises member zoos to feed orangutans a balanced diet consisting of 86 percent produce and 14 percent “nutritionally complete primate biscuits.”) The standardization trend can be traced back to the rise of nationwide breeding programs in the latter half of the 20th century. Under these initiatives, specimens were transferred between different zoos with increasing regularity. As zoological nutritionist Barbara Toddes told the Smithsonian, “Animals need consistency in their diet when they move from place to place. It’s much better for them stress-wise and nutritionally.”

Big appetites are another complicating factor. Consider elephants, which devour 200 to 600 pounds of food every day when fully grown. The cost of feeding a single adult is usually around $15,000 per year. And some animals require specialized diets. In her interview with the Dallas Morning News, Slifka mentioned four Marabou stork chicks that had recently been hatched. In the wild, newborns of this species mostly subsist on the corpses of small animals. To supply its little birds with intact dead prey, the Dallas Zoo paid a pretty penny: By the time the young storks were 110 days old, their food-related expenses had totaled a whopping $10,000.

6. TO PREVENT THEIR CRITTERS FROM GETTING BORED, KEEPERS OFFER WHAT’S KNOWN AS “ENRICHMENT.”

Adequate food and space will keep captive animals alive, but stimulation—both the physical and psychological sort—is what helps them to thrive. “Enrichment” is a process whereby zookeepers prompt their critters into exercising their minds or displaying certain behaviors they’d normally exhibit in the wild. A quick scenery change can make for a good start. At zoos, caretakers occasionally add or remove certain things from their animals’ enclosures, forcing the residents to utilize their natural instincts as they mentally process the alteration. For example, Japanese macaques at the Minnesota Zoo wake up every so often to discover a brand-new leaf pile to dig through. Enrichment can also be aromatic: At Disney World’s Animal Kingdom in Orlando, the staff place various perfumes and spices around their tiger paddock. When confronted with odd new smells, the big cats might respond by rubbing, scratching, or marking their territories.

According to the Fort Worth Zoo, enrichment increases the “behavioral choices available to animals.” Simply put, by changing the status quo, enrichment provides animals with the opportunity to make decisions about how to react. Give an elephant a bright-pink volleyball (as the Columbus Zoo did recently), and he might bat at it with his trunk, kick it through a pond, or try to squish it with his feet.

7. ZOO VETS USUALLY MAKE LESS MONEY THAN REGULAR VETS.

You might think that the opposite would be true, but according to data provided by the Bureau of Labor Statistics and the American Veterinary Medical Association, vets who work at zoos have a lower median salary than general veterinarians. Why? To begin with, many AZA-accredited zoos are nonprofit establishments. Therefore, vets who work there don’t always make the sort of income that a private practice might yield. Also, since there are only so many zoos in the world, job opportunities are rather limited.

Still, to hear most zoo vets tell it, you’d be hard-pressed to find a more rewarding career. “[There] is an exciting moment every single day,” says Dr. Suzan Murray of the Smithsonian’s National Zoo. As chief veterinarian, she’s expected to tackle a wide array of fascinating challenges. “Each one is a little bit different, whether it’s coming up with a treatment for coral, diagnosing a problem in a Burmese python, or visiting an elephant we’re hoping is pregnant,” Murray explains. “Every day offers a bounty of surprises.”

8. ANIMALS IN NOCTURNAL EXHIBITS DON’T ADJUST RIGHT AWAY.

Certain zoos have designated nocturnal houses, thick-walled buildings that allow guests to check out bats, bearcats, civets, and other creatures of the night during normal business hours. By day, they’re usually lit with dim red, blue, green, and yellow lights. But late at night, bright white fluorescent bulbs are turned on. This has the effect of reversing the resident animals’ normal sleep cycles so that they’re more active when zoo visitors are around and sleep when the humans do.

For the critters involved, the transition can take time. “When we get animals from a non-nocturnal building, there is an adjustment period,” Bob says. “Most seem to adapt in about a week’s time. We had one [kinkajou, also known as a honey bear], though, that took over a month to adjust.”

9. CAPTIVE BREEDING TAKES CROSS-COUNTRY COORDINATION.

What do Przewalski’s horse, the Arabian oryx, and golden lion tamarin have in common? Without captive breeding efforts—mating orchestrated in controlled environments like zoos and wildlife preserves—they might be critically endangered, or worse.

One of the ways zoos contribute to conservation efforts is by participating in Species Survival Plans (SSPs). Organized by the AZA, these are rigorously regulated breeding programs for rare, threatened, or endangered animals. The goal is to form a genetically diverse captive population, with member animals usually dispersed among several zoos and/or aquariums. In total, there are almost 500 individual SSPs, each headed by a coordinator.

Craig Saffoe, a curator at the National Zoo, leads several different breeding programs for big carnivores, all done in accordance with the appropriate SSP committee. “The first step is that we have to find two animals that actually get along together and are compatible breeding partners,” he says. “For that, we don’t just look at the current collection at the National Zoo. We look at the whole zoo population within the United States.”

Choosing the right pair is a process that involves working closely with the relevant SSP. “When the Species Survival Plan group gets together, they decide what the best route is to keep the entire North American population genetically healthy,” Saffoe notes. “Once my team and I have worked successfully with the SSP to match two animals on paper … it’s our job then to find out if the animals are actually physically compatible.” More often than not, at least one animal will have to be transferred between zoos before any first dates can take place.

10. THE WORD “DEDICATION” WAS INVENTED FOR ZOOKEEPERS.

Make no mistake, this isn’t an easy line of work to break into. Just ask the San Diego Zoo’s HR department, whose employees report that it’s “not unusual” for them to receive literally hundreds of applications when a single animal care job opens up. If you beat the odds and get hired, note that the average American zookeeper takes home a salary of just $29,000 per year.

Despite all this, keepers can rank among the most passionate and devoted people you’ll ever meet. “Just recently when Hurricane Matthew hit, tons of keepers [in affected areas] slept in their zoos, hunkered down in case the animals needed emergency help,” Bob says. In his eyes, such dedication is the rule, rather than the exception. “We go in at two A.M. to check on new moms … We are constantly researching ways to improve welfare and our own personal knowledge.”

What’s more, zookeepers enjoy a tight-knit community. According to Bob, “Everyone knows someone who works at another zoo and on Facebook, everyone is so supportive. There are closed groups of keepers where new ideas are constantly exchanged and people help support strangers when they lose an old, beloved animal. What we do is so hard and stressful and you always have to fight caregiver stress syndrome, but we power through and I wouldn’t trade this life for anything!”

*Some names have been changed.

All photos via iStock.

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Scientific Reports, Fernando Ramirez Rozzi
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Stones, Bones, and Wrecks
Humans Might Have Practiced Brain Surgery on Cows 5000 Years Ago
Scientific Reports, Fernando Ramirez Rozzi
Scientific Reports, Fernando Ramirez Rozzi

In the 1970s, archaeologists discovered a site in France containing hundreds of cow skeletons dating back 5000 to 5400 years. The sheer number wasn't surprising—human agriculture in that part of the world was booming by 3000 BCE. What perplexed scientists was something uncovered there a few decades later: a cow skull bearing a thoughtfully drilled hole. Now, a team of researchers has released evidence that suggests the hole is an early example of animal brain surgery.

Fernando Ramírez Rozzi, a paleontologist with the French National Center for Scientific Research, and Alain Froment, an anthropologist at the Museum of Mankind in Paris, published their findings in the journal Nature Scientific Reports. After comparing the opening to the holes chiseled into the skulls of humans from the same era, they found the bones bore some striking similarities. They didn't show any signs of fracturing from blunt force trauma; rather, the hole in the cow skull, like those in the human skulls, seemed to have been carved out carefully using a tool made for exactly that purpose. That suggests that the hole is evidence of the earliest known veterinary surgery performed by humans.

Trepanation, or the practice of boring holes into human skulls, is one of the oldest forms of surgery. Experts are still unsure why ancient humans did this, but the level of care that went into the procedures suggests that the surgery was likely used to treat sick patients while they were still alive. Why a person would perform this same surgery on a cow, however, is harder to explain.

The authors present a few theories, the first being that these ancient brain surgeons were treating a sick cow the same way they might treat a sick human. If a cow was suffering from a neural disease like epilepsy, perhaps they though that cutting a hole in its head would relieve whatever was agitating the brain. The cow would have needed to be pretty special to warrant such an effort when there were hundreds of healthy cows living on the same plot of land, as evidenced by the skeletons it was found with.

Another possible explanation was that whoever operated on the cow did so as practice to prepare them for drilling into the heads of live humans one day. "Cranial surgery requires great manual dexterity and a complete knowledge of the anatomy of the brain and vessel distribution," the authors write in the study. "It is possible that the mastery of techniques in cranial surgery shown in the Mesolithic and Neolithic periods was acquired through experimentation on animals."

Either way, the bovine patient didn't live to see the results of the procedure: The bone around the hole hadn't healed at all, which suggests the cow either died during surgery or wasn't alive to begin with.

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Animals
15 Incredible Facts About Pigeons
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Though they're often described as "rats with wings" (a phrase popularized by the movie Stardust Memories), pigeons are actually pretty cool. From homing instincts to misleading rump feathers, here are 15 things you might not know about these avian adventurers.

1. THEY MIGHT BE THE FIRST DOMESTICATED BIRD.

The common city pigeon (Columba livia), also known as the rock pigeon, might be the first bird humankind ever domesticated. You can see them in art dating back as far as 4500 BCE in modern Iraq, and they've been a valuable source of food for thousands of years.

2. THEY WON OVER CHARLES DARWIN—AND NIKOLA TESLA.

Pigeon-breeding was a common hobby in Victorian England for everyone from well-off businessmen to average Joes, leading to some fantastically weird birds. Few hobbyists had more enthusiasm for the breeding process than Charles Darwin, who owned a diverse flock, joined London pigeon clubs, and hobnobbed with famous breeders. Darwin's passion for the birds influenced his 1868 book The Variation of Animals and Plants Under Domestication, which has not one but two chapters about pigeons (dogs and cats share a single chapter).

Nikola Tesla was another great mind who enjoyed pigeons. He used to care for injured wild pigeons in his New York City hotel room. Hands down, Tesla's favorite was a white female—about whom he once said, "I loved that pigeon, I loved her as a man loves a woman and she loved me. When she was ill, I knew and understood; she came to my room and I stayed beside her for days. I nursed her back to health. That pigeon was the joy of my life. If she needed me, nothing else mattered. As long as I had her, there was a purpose in my life." Reportedly, he was inconsolable after she died.

3. THEY UNDERSTAND SPACE AND TIME.

In a 2017 Current Biology study, researchers showed captive pigeons a series of digital lines on a computer screen for either two or eight seconds. Some lines were short, measuring about 2.3 inches across; others were four times longer. The pigeons were trained to evaluate either the length of the line or how long it was displayed. They found that the more time a line was displayed, the longer in length the pigeon judged it to be. The reverse was true too: If the pigeons encountered a longer line, they thought it existed in time for a greater duration. Pigeons, the scientists concluded, understand the concepts of both time and space; the researchers noted "similar results have been found with humans and other primates."

It's thought that humans process those concepts with a brain region called the parietal cortex; pigeon brains lack that cortex, so they must have a different way of judging space and time.

4. THEY CAN FIND THEIR WAY BACK TO THE NEST FROM 1300 MILES AWAY.

A pigeon flying in front of trees.
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The birds can do this even if they've been transported in isolation—with no visual, olfactory, or magnetic clues—while scientists rotate their cages so they don't know what direction they're traveling in. How they do this is a mystery, but people have been exploiting the pigeon's navigational skills since at least 3000 BCE, when ancient peoples would set caged pigeons free and follow them to nearby land.

Their navigational skills also make pigeons great long-distance messengers. Sports fans in ancient Greece are said to have used trained pigeons to carry the results of the Ancient Olympics. Further east, Genghis Khan stayed in touch with his allies and enemies alike through a pigeon-based postal network.

5. THEY SAVED THOUSANDS OF HUMAN LIVES DURING WORLD WARS I AND II.

Pigeons' homing talents continued to shape history during the 20th century. In both World Wars, rival nations had huge flocks of pigeon messengers. (America alone had 200,000 at its disposal in WWII.) By delivering critical updates, the avians saved thousands of human lives. One racing bird named Cher Ami completed a mission that led to the rescue of 194 stranded U.S. soldiers on October 4, 1918.

6. TWO PIGEONS ALMOST DISTRACTED FROM THE DISCOVERY OF EVIDENCE OF THE BIG BANG.

In 1964, scientists in Holmdel, New Jersey, heard hissing noises from their antenna that would later prove to be signals from the Big Bang. But when they first heard the sound, they thought it might be, among other things, the poop of two pigeons that were living in the antenna. "We took the pigeons, put them in a box, and mailed them as far away as we could in the company mail to a guy who fancied pigeons," one of the scientists later recalled. "He looked at them and said these are junk pigeons and let them go and before long they were right back." But the scientists were able to clean out the antenna and determine that they had not been the cause of the noise. The trap used to catch the birds (before they had to later be, uh, permanently removed) is on view at the Smithsonian Air & Space Museum.

7. YOU CAN TRAIN THEM TO BE ART SNOBS …

Japanese psychologist Shigeru Watanabe and two colleagues earned an Ig Nobel Prize in 1995 for training pigeons, in a lab setting, to recognize the paintings of Claude Monet and Pablo Picasso and to distinguish between the painters. The pigeons were even able to use their knowledge of impressionism and cubism to identify paintings of other artists in those movements. Later, Watanabe taught other pigeons to distinguish watercolor images from pastels. And in a 2009 experiment, captive pigeons he'd borrowed were shown almost two dozen paintings made by students at a Tokyo elementary school, and were taught which ones were considered "good" and which ones were considered "bad." He then presented them with 10 new paintings and the avian critics managed to correctly guess which ones had earned bad grades from the school's teacher and a panel of adults. Watanabe's findings indicate that wild pigeons naturally categorize things on the basis of color, texture, and general appearance.

8. … AND TO DISTINGUISH WRITTEN WORDS.

In a 2016 study, scientists showed that pigeons can differentiate between strings of letters and actual words. Four of the birds built up a vocabulary of between 26 and 58 written English words, and though the birds couldn't actually read them, they could identify visual patterns and therefore tell them apart. The birds could even identify words they hadn't seen before.

9. FLUFFY PIGEON FEET MIGHT ACTUALLY BE PARTIAL WINGS.

A white pigeon with curly feathers and fluffy feet.
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A few pigeon breeds have fuzzy legs—which hobbyists call "muffs"—rather than scaly ones. According to a 2016 study, the DNA of these fluffy-footed pigeons leads their hind legs to take on some forelimb characteristics, making muffed pigeon legs look distinctly wing-like; they're also big-boned. Not only do they have feathers, but the hindlimbs are somewhat big-boned, too. According to biologist Mike Shapiro, who led the study, "pigeons' fancy feathered feet are partially wings."

10. SOME PIGEONS DISTRACT FALCONS WITH WHITE RUMP FEATHERS.

In a life-or-death situation, a pigeon's survival could depend upon its color pattern: Research has shown that wild falcons rarely go after pigeons that have a white patch of feathers just above the tail, and when the predators do target these birds, the attacks are rarely successful.

To figure out why this is, Ph.D. student Alberto Palleroni and a team tagged 5235 pigeons in the vicinity of Davis, California. Then, they monitored 1485 falcon-on-pigeon attacks over a seven-year span. The researchers found that although white-rumped pigeons comprised 20 to 25 percent of the area's pigeon population, they represented less than 2 percent of all the observed pigeons that were killed by falcons; the vast majority of the victims had blue rumps. Palleroni and his team rounded up 756 white- and blue-rumped pigeons and swapped their rump feathers by clipping and pasting white feathers on blue rumps, and vice versa. The falcons had a much easier time spotting and catching the newly blue-rumped pigeons, while the pigeons that received the white feathers saw predation rates plummet.

Close observation revealed that the white patches distract birds of prey. In the wild, falcons dive-bomb other winged animals from above at high speeds. Some pigeons respond by rolling away in midair, and on a spiraling bird, white rump feathers can be eye-catching, which means that a patch of them may divert a hungry raptor's focus long enough to make the carnivore miscalculate and zip right past its intended victim.

11. DODOS WERE RELATED TO TODAY'S PIGEONS.

Two blue and green Nicobar pigeons.
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Though most of this list focuses on the rock pigeon, there are 308 living species of pigeons and doves. Together, they make up an order of birds known as the columbiformes. The extinct dodo belonged to this group as well.

Flightless and (somewhat) docile, dodos once inhabited Mauritius, an island near Madagascar. The species had no natural predators, but when human sailors arrived with rats, dogs, cats, and pigs, it began to die out, and before the 17th century came to a close, the dodo had vanished altogether. DNA testing has confirmed that pigeons are closely related to the dodo, and the vibrant Nicobar pigeon (above) is its nearest genetic relative. A multi-colored bird with iridescent feathers, this near-threatened creature is found on small islands in the South Pacific and off Asia. Unlike the dodo, it can fly.

12. AT ONE POINT, MORE THAN ONE-QUARTER OF ALL THE BIRDS LIVING IN THE U.S. MAY HAVE BEEN PASSENGER PIGEONS.

Wild/feral rock pigeons reside in all 50 states, which makes it easy to forget that they're invasive birds. Originally native to Eurasia and northern Africa, the species was (most likely) introduced to North America by French settlers in 1606. At the time, a different kind of columbiform—this one indigenous—was already thriving there: the passenger pigeon (Ectopistes migratorius). As many as 5 billion of them were living in America when England, Spain, and France first started colonizing, and they may have once represented anywhere from 25 to 40 percent of the total U.S. bird population. But by the early 20th century, they had become a rare sight, thanks to overhunting, habitat loss, and a possible genetic diversity issue. The last known passenger pigeon—a captive female named Martha—died on September 1, 1914.

13. THEY'RE REALLY GOOD AT MULTITASKING.

According to one study, they're more efficient multitaskers than people are. Scientists at Ruhr-Universitat Bochum put together a test group of 15 humans and 12 pigeons and trained all of them to complete two simple jobs (like pressing a keyboard once a light bulb came on). They were also put in situations wherein they'd need to stop working on one job and switch over to another. In some trials, the participants had to make the change immediately. During these test runs, humans and pigeons switched between jobs at the same speed.

But in other trials, the test subjects were allowed to complete one assignment and then had to wait 300 milliseconds before moving on to the next job. Interestingly, in these runs, the pigeons were quicker to get started on that second task after the period ended. In the avian brain, nerve cells are more densely packed, which might enable our feathered friends to process information faster than we can under the right circumstances.

14. PIGEONS PRODUCE FAKE "MILK."

Only mammals produce genuine milk, but pigeons and doves (along with some other species of birds) feed their young with something similar—a whitish liquid filled with nutrients, fats, antioxidants, and healthy proteins called "crop milk." Both male and female pigeons create the milk in the crop, a section of the esophagus designed to store food temporarily. As is the case with mammal milk, the creation of crop milk is regulated by the hormone prolactin. Newly-hatched pigeons drink crop milk until they're weaned off it after four weeks or so. (And if you've ever asked yourself, "Where are all the baby pigeons?" we have the answer for you right here.)

15. ONE STUDY SUGGESTS THAT, GIVEN THE RIGHT CONDITIONS, THEY'RE AS GOOD AT IDENTIFYING CANCER AS DOCTORS.

We've already established that pigeons are excellent at differentiating between artists and words, but a 2015 study revealed they can also distinguish between malignant and benign growths in the right conditions. Researchers at University of California Davis Medical Center put 16 pigeons in a room with magnified biopsies of potential breast cancers. If the pigeons correctly identified them as either benign or malignant, they got a treat, According to Scientific American.

"Once trained, the pigeons' average diagnostic accuracy reached an impressive 85 percent. But when a "flock sourcing" approach was taken, in which the most common answer among all subjects was used, group accuracy climbed to a staggering 99 percent, or what would be expected from a pathologist. The pigeons were also able to apply their knowledge to novel images, showing the findings weren't simply a result of rote memorization."

Mammograms proved to be more of a challenge, however; the birds could memorize signs of cancer in the images they were trained on but could not identify the signs in new images.

No matter how impressive their results, "I don't anticipate that pigeons, no matter how good they become at pathology or radiology, will be playing a role in actual patient care—certainly for the foreseeable future," study co-author Richard M. Levenson told Scientific American. "There are just too many regulatory barriers—at least in the West."

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