Pig Use Mirrors to Find Hidden Food

In just five hours, an average farm pig can learn how to interpret an image in the mirror and use it to find hidden food.

Scientists consider the ability to use a mirror a sign of complex cognitive processing and an indication of a certain level of awareness. In addition to humans and some primates, dolphins, elephants, magpies and a famous African grey parrot named Alex have all been known to retrieve objects or remove marks on their body using a mirror. Now it looks like pigs should be added to the list of clever critters that can master a mirror: After spending five hours with a mirror in their pen, seven out of eight pigs could use the reflection to find a hidden bowl of grub.

“This is the first demonstration of the ability of pigs to use mirrors,” animal behavior expert Donald Broom of the University of Cambridge wrote in an e-mail. “Finding sophisticated learning and awareness in animals can alter the way that people think about the species and may result in better welfare in the long run.” Broom co-authored the paper published this month in Animal Behaviour.

Like most animals, the pigs were immediately curious when researchers placed the shiny, reflective object in their pen. They approached the mirror until they bumped into it with their snout, and then checked to see what was behind the mirror. The pigs spent an average of 20 minutes gazing at their reflection, often turning in different directions to inspect themselves from several angles.

“These kind of movements suggest that the pigs were correlating the movements of their body with the visual stimulus they were receiving from the mirror, and so learning the contingency between the two,” biologist Louise Barrett of the University of Liverpool wrote in a commentary about the paper, also published this month in Animal Behaviour.

After five hours with a mirror, the pigs were placed in a new test area that contained a food bowl hidden behind a barrier. Although the pigs could see the reflection of the bowl in the mirror, they couldn’t see the food directly. A fan above the bowl circulated the scent of food around the room, prohibiting the pigs from smelling their way to the treat.

Seven out of eight of the pigs with previous mirror experience spotted the reflection of the food bowl and correctly interpreted its location: Instead of searching for the food in its apparent position behind the mirror, the pigs headed around the barrier and straight for the true location of the bowl. When the researchers tested pigs with no prior mirror exposure, however, nine out of 11 of them became confused, searching behind the mirror for the food.

“These results suggest not only that pigs learn the contingency between their own movements and their image in the mirror,” Barrett wrote, “but that their knowledge incorporates the layout of the environment as well, so that they can locate objects in space.”

The researchers say their experiment is more than a nifty trick: The fact that pigs can learn to use a mirror means they are capable of a type of awareness called assessment awareness, which means they can understand the significance of a situation in relation to themselves, over a short period of time. In this case, the pigs remembered how their own movements appeared in the mirror, and were able to apply that knowledge to a separate situation involving a hidden food bowl.

“Having a sense of self and using it is a form of assessment awareness,” Broom wrote. Although the mirror experiment doesn’t directly prove that pigs have a sense of self, the researchers suggest that given how quickly the pigs learn to recognize their own movements in a mirror, they may have some degree of self-awareness. “We have no conclusive evidence of a sense of self,” Broom wrote, “but you might well conclude that it is likely from our results.”

Other mirror tests have been used to more directly examine an animal’s sense of self — if researchers apply a yellow mark to the black feathers of a magpie, for instance, the bird will use a mirror to clean itself off. Unfortunately, Broom says the mark experiments just don’t work on pigs: Pigs are so accustomed to being streaked with mud, they don’t much care if researchers apply extra marks on their bodies. “We have put marks on pigs,” Broom wrote. “They take little notice of them.”

Combined with a host of other research studies demonstrating the keen intelligence of pigs, the researchers hope their study will lead to better treatment of the farm animals. “If an animal is clever,” Broom wrote, “it is less likely to be treated as if it is an object or a machine to produce food, and more likely to be considered as an individual of value in itself.”

Image: Flickr/The Pug Father

See Also:

• Pig Video Arcades Critique Life in the Pen
• Tiny Flower Turns Pig Poop into Fuel
• Swine Flu Ancestor Born on U.S. Factory Farms

Cruelty to Animals // Pigs

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Pigs on Factory Farms

Mother pigs are confined to cages so small that they can’t even turn around.

Many people think of Charlotte’s Web and Babe when they imagine how pigs are raised for meat. Unfortunately, these Hollywood tales do not depict reality. Almost all of the 100 million pigs killed for food in the United States every year endure horrific conditions in controlled animal feeding operations (CAFOs), the meat industry’s euphemism for factory farms.⁵ Smarter than dogs, these social, sensitive animals spend their lives in overcrowded, filthy warehouses, often seeing direct sunlight for the first time as they are crammed onto a truck bound for the slaughterhouse.⁶

A mother pig, or sow, spends her adult life confined to a tiny metal crate. She will never feel the warmth of a nest or the affectionate nuzzle of her mate—she will spend her life surrounded by thick, cold metal bars, living on wet, feces-caked concrete floors. When she is old enough to give birth, she will be artificially impregnated and then imprisoned again for the entire length of her pregnancy in a “gestation crate,” a cage only 2 feet wide—too small for her even to turn around or lie down in comfortably.⁷

After giving birth, a mother pig is moved to a “farrowing crate,” a contraption even worse and smaller than a gestation crate, with only a tiny additional concrete area on which the piglets can nurse.⁸ Workers will sometimes tie the mother’s legs apart so she cannot get a break from the suckling piglets. She may develop open “bed sores” on her body from the lack of movement. This practice is so barbaric that gestation crates have been banned in Florida, the U.K., and Sweden and will be banned in the European Union in 2013.^9,10

Pigs develop sores from living in filthy conditions that are too cramped to even stand up in.

When pregnant sows are ready to give birth, they are moved from a gestation crate to a farrowing crate. One worker describes the process: “They beat the shit out of them [the mother pigs] to get them inside the crates because they don’t want to go. This is their only chance to walk around, get a little exercise, and they don’t want to go [back into a crate].”¹¹

The piglets are taken away from their mother after less than a month—in nature, they would stay with their mother for several months.¹² She is impregnated again, and the cycle of forced breeding and imprisonment continues. For such an intelligent animal, this intensive confinement causes debilitating stress and boredom. With nothing to do but stare at the bars in front of her, a mother pig may go insane. This is often exhibited by neurotic chewing on the cage bars or obsessive pressing on her water bottle.¹³ After three or four years, when her body is exhausted and her mind pushed to or even past the brink of insanity, she is shipped off to slaughter.

Piglets are mutilated and castrated without the use of painkillers; some die from shock.

Meanwhile, the sow’s piglets have their testicles cut out of their scrotums, their tails cut off, many of their teeth clipped in half, and their ears mutilated, all without any pain relief.¹⁶ Terrified and in extreme pain, the piglets are often put alone into tiny metal wire cages (called “battery cages” by the farmers). These cages are stacked on top of each other, and urine and excrement constantly fall on the piglets in the lower cages. After the piglets have grown too big for the cages, they are placed into small, cramped pens crowded with many other piglets, where they are kept until they are large enough for slaughter. The animals are given almost no room to move because, as one pork-industry journal put it, “[O]vercrowding pigs pays.”¹⁷ Impeccably clean by nature, pigs on factory farms are forced to live in their own feces, vomit, and even amid the corpses of other pigs.

Pigs in factory farms never get to go outside until they are sent to slaughter.

Overcrowding, poor ventilation, and filth cause rampant disease. Respiratory problems are common because of high levels of humidity and toxic gases from the manure pits—in fact, 70 percent of pigs on factory farms have pneumonia by the time they’re sent to the slaughterhouse.¹⁶ Many pigs die from infections caused by the noxious fumes and filth of their enclosures. Pigs are fed massive doses of antibiotics to keep them alive in these conditions. Conditions are so filthy that at any given time, more than one-quarter of pigs suffer from mange.¹⁸

Because of illness, lack of space to exercise, and genetic manipulation that forces them to grow too big too fast, pigs often develop arthritis and other joint problems.¹⁹ Many pigs on factory farms live on slatted floors above giant manure pits. Smaller pigs often suffer severe leg injuries when their legs get caught between the slats.²⁰

Always concerned with their bottom line, some farmers kill sick animals instead of giving them medicine or veterinary care. A PETA investigation found that a manager at an Oklahoma farm was killing pigs by beating them with metal gate rods, and others were left to die without food or water. Unwanted “runts” were killed, as they are on most farms, by “thumping,” which involves slamming the animals’ heads against the floor.²¹ Watch video from that investigation.

After enduring months in these hellish conditions, pigs are forced onto trucks, bound for a horrific and agonizing death at the slaughterhouse.

Read about transport and slaughter.

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⁵ Food and Agriculture Organization of the United Nations, “Pigmeat, Slaughtered/Production Animals (Head) 2002,” 10 Jun. 2003.
⁶ Cambridge Daily News.
⁷ Marc Kaufman, “In Pig Farming, Growing Concern,” The Washington Post, 18 Jun. 2001.
⁸ Kaufman.
⁹ The Humane Society of the United States, “Maryland: Support Minimum Crate Size for Pregnant Pigs,” HSUS Online, 2005.
¹⁰ The European Union, “Animal Health and Welfare: Pigs,” The European Union Online (Europa), 2005.
¹¹ Eisnitz, p. 219.
¹² Lauren Ornelas and Juliet Gellatley, “A Report on the U.S. Pig Industry,” Viva! USA, 2004.
¹³ A.J. Zanella and O. Duran, “Pig Welfare During Loading and Transport: A North American Prespective,” I Conferencia Vitrual Internacional Sobre Qualidade de Carne Suina, 16 Nov. 2000.
¹⁴ James Cromwell, “Veterinarians Should Act to Stop Crating of Pregnant Pigs,” The Chicago Sun-Times, 6 Nov. 2004.
¹⁵ William Luce et al., “Managing the Sow and Litter,” Oklahoma Cooperative Extension Service, March 1995.
¹⁶ Gene and Lorri Bauston, “Brutality: Main Crop of Factory Farms?” EarthSave International Online, 2004.
¹⁷ “Swine Diseases (Chest): Mycoplasma Pneumonia,” Iowa State University College of Veterinary Medicine, 2005.
¹⁸ IVOMEC Pharmaceutical advertisement, Pork Magazine, 17 Dec. 2002.
¹⁹ Cindy Wood, “Don’t Ignore Feet and Leg Soundness in Pigs,” Virginia Cooperative Extension, June 2001.
²⁰ Jessica Gentry and John McGlone, “Alternative Pork Production Systems: Overview of Facilities, Performance Measures, and Meat Quality,” International Meeting on Swine Production, April 2003.
²¹ “Seaboard Pig Farm Investigation Video,” PETA Online, 2001.
²² Kelly Pedro, “Pigs Found Dead, Dying,” The London Free Press, 15 Oct. 2003.