Myth or Truth?
The consensus among wild pig and boar experts seems to be that boar are among the animals with the worst eyesight. Just go to any website maintained by hunting ranches, guides and outfitters and you can read all about the extremely poor eyesight of wild pigs and boar. If you can believe them it is possible to almost stumble over a wild pig before it can even see you. And if it does, you look like some dark blob to him.
Looks to me like one expert is copying from another while all are chanting in unison 'Pigs can't see. Pig can't see.' But does that make them right?
Swine, domestic pigs (porkus porkus) have long been used by science as research animals. Their anatomy, their circulatory system, their interior organs and their skin are very similar to those of humans. The Greek researcher Erasistratos used domestic pigs approximately 250 to 300 years B.C to investigate mechanics and physiology of human breathing. In Roman times Galen, the most widely known and respected father of medicine from Roman times to the dawn of modern scientific research, used pigs to explore the mysteries of blood circulation. His anatomical studies on pigs were so important to the beginnings of modern medicine that early modern scientist and medical doctors had to fight very hard and for a long time to overcome his deeply entrenched teachings and dogmas – even when they were obviously incorrect.
In modern times pigs, especially miniature pigs, play an ever increasing important role in medical research. “. . . given their anatomical similarities to humans particularly in terms of skin, skeleton, teeth, gastrointestinal tract, pancreas, liver, kidney, lung, and immune status they are often used as models for humans. In cardiac research, they are often the model of choice, particularly for studies on cholesterol. They are widely used in pharmacology research and diabetes research. During recent years, pigs have become utilized for their biological parts, e.g. cardiac valve replacement; the area of xenotransplantation . . .”. (lJ.J. Zonderland et al. / Applied Animal Behaviour Science 111 (2008)
Regarding the eyesight of pigs the author concludes:
“Their eyesight is good but it is their sense of smell that is the most highly developed and rooting behavior is the primary means of food searching."
This comes at the end of long and detailed studies and experiments with with pigs under high intensity and low level lighting conditions. The animals were asked to identify shapes of objects or symbols at greatly varying object sizes and light levels. Zonderland summed up the results of his studies and concluded:
“The detail of the visual cue (symbol size) had a more pronounced effect on the pigs’ ability to
distinguish visual cues, compared to the illuminant level. Increasing the light intensity from 12 to
40 lx (lux, metric unit of illuminance of a surface, defined as an illumination of one lumen per square meter – editor's note) has little effect on the pigs’ ability to distinguish visual cues. Furthermore, the pigs failed to discriminate visual cues below 20 mm (.8661 inches). Visual acuity (ability to distinguish details and shapes) showed large individual differences ranging from <0.001 to 0.03. These values are lower compared to cattle and much lower compared to humans.”
J.J. Zonderland et al. / Applied Animal Behaviour Science 111 (2008) 28–37
Wild pig experts rejoice, boar hunting guides savor the sweetness of victory. Boar cannot see as well as humans! Or Betsy the lead cow of your herd. That should make you feel even better.
As long as you keep in mind that we are talking about symbols or objects less than about one inch in size. Pigs can not tell the difference between a circle and a square when the size of the symbol is less than an inch! Humans, cows and deer can. Woooooohhhhhoooooooooo!
I have googled in vain for any mention of inch sized boar hunters. No luck. Thus I conclude that wild pigs, boar and swine (porkus porkus) can see well enough to recognize standard humans and visual cues transmitted in their body posture and language from far away. Though research pigs failed to identify small objects close up, they had no trouble discerning larger objects from close and far away.
Do you agree that boar hunters fall into the category of large objects that wild pigs can spot and identify easily?
I know they can. At more than one occasion I have had the benefit of observing other hunters (who did not know of my presence) stalking wild pigs. Though the hunters were most likely convinced that the boar had not spotted them, it was obvious from my vantage point that the small group of wild pigs deliberately and, dare I say, intelligently avoided contact with the hunting party that at one point was too close for comfort.
In another case the hunters were close, very close. That is until the moment when the boar sort of froze and stopped moving while the hunters kept on going in the direction in which they thought the wild pigs were fleeing. The hunters filtered right past the boar. With the hunters now well ahead, the hunted started to track the hunters at a relatively safe distance right behind them. When all came close to some rocky outcrop at the top of a hill, the boar suddenly disappeared among the rocky overhang as if the earth has swallowed them up. Three happy boar alive and three tired hunters disappointed.
By the way, I observed a flock of Merino sheep at the Big Horn Ranch execute a very similar maneuver. But that is a different story.
Here is another anecdotal observation, since we are in the mode of campfire tales.
I used to hunt on a private ranch in Coalinga earthquake country with a small wild pig and upland game hunting program. The rancher used to go out on his 'implement of husbandry' to bring additional feed to his cattle. Wild pigs would appear to claim their share of the bounty, sometimes following closely behind the vehicle from which the bounty fell. They had learned to recognize the sound pattern of 'implements of husbandry'. Yet they would flee at the sound of an approaching 4x4 vehicle.
Humans could stand on the hay truck in plain view of the boar and wield pitch forks without spooking the boar.
However, a plain straight stick would make the boar disappear in a hurry. No boar in his right mind would risk exposure to the dangers potentially inherent in a stick. All game animals, not only wild pigs, refer to this straight pole as 'fire stick'.
Scientific research on laboratory pigs has clearly established that the eyesight of pigs – domestic or wild – is good although not as good as that of an eagle or Betsy the cow.
However, it is good enough to let them recognize large objects near or far. Wild pigs are more hampered by their relative closeness to the ground and by their inability to lift their head up high to peer over tall grass or other growth than by their eyesight. That is exactly the reason why your chances of surprising a boar in tall grass or undergrowth are actually relatively good – provided he did not hear you are catch a whiff of your human smell.
Considering the outstanding cognitive skills of pigs I would not be astonished if wild pigs also learned to associate the human figure in jeans and a plaid jacket with a harmless rancher on his implement of husbandry while the outline of a human that pretends to blend in with the foliage of trees signifies danger for life and limb to them.
When it comes to eyesight of boar I take solace in a quote from 'Texasboar', a website I have cited before. There I read:
“Their (i.e. the wild pigs) eye sight is severely under estimated, according to Universities who have studied them. Others who have raised them tend to agree with this opinion also, as do I.
I, myself can contribute to this. At over 100 yards my hogs can distinguish not only a human figure, but have eyesight that is capable of distinguishing a "human friend" or "STRANGER" from facial characteristics and build.
They will come running upon my father's or my recognition, to be fed. They will leave running when a stranger approaches. This recognition process has been observed consistently at 100 + yards. They can easily see me coming at 250 + yards. They may not run, they may not pay attention, but don't think they can't see you. Hog are at a disadvantage when it comes to sight mainly because of their low profile. They can't raise their heads high like a deer or other wild animals to see over grass or vegetation.”
As you can see that is a confirmation of my own observation of the cognizant behavior of boar on private active cattle ranches.
For an animal that relies primarily on smell and hearing as weapons of defense and to separate friend from foe that is good eyesight. At least in my book. It is also the reason why I do not deck out in the latest and fanciest military camouflage outfits (except for the pants because of their carrying capacity) but rather prefer well worn (and therefore quiet) casual work wear.
We will explore smell and hearing of boar in an upcoming article on spot and stalk.
Until then good hunting while it is still cool and the wild pigs are busy making more boar.
PJJ
Abridged bibliography for eyesight of pigs :Entsu, S., Dohi, H., Yamada, A., 1992. Visual acuity of cattle determined by the method of discrimination learning. Appl.
Anim. Behav. Sci. 34
Piggins, D., 1992. Visual perception. In: Phillips, C.J.C., Piggins, D. (Eds.), Farm Animals and the Environment. CAB
International, Wallingford,
Grandin, T., 1980. Livestock behaviour as related to handling facilities design. Int. J. Stud. Anim. Prob. 1
Graf, R., 1976. Das visuelle Orientierungsvermo¨gen der Schweine in abha¨ngigkeit von der Beleuchtungssta¨rke. In
Instituut Voor Veeteeltkundig Onderzoek, Zeist
Tanaka, T., Murayama, Y., Eguchi, Y., Yoshimoto, T., 1998. Studies on the visual acuity of pigs using shape discrimination
learning. Anim. Sci. Technol. 69
