10 THINGS YOU PROBABLY DON’T KNOW ABOUT YOUR FLOCK
Why humans don't taste like chicken, and how they see the world quite differently to us. Words
MANY HUMANS think that the animals and birds under their care have the same sort of senses as humans. They also give them the same sort of thought processes as humans, assuming that they worry about their future, relive the past, or mirror our own desires for comfort and a warm meal on a cold winter's day.
Much of this can be attributed to anthropomorphism, the attribution of human form or other characteristics to anything other than a human being. Many town dwellers don't have contact with animals and birds in a more natural environment so they can have an oversensitised perception of just what an animal or bird is capable of being aware of.
It's interesting to look at what senses birds actually have, where their priorities lie and realising that they act more by instinct than any other heightened brain process because their brains are very small. Their senses work differently to those of humans, making it amazing how much we have in common.
WE’RE VERY SIMILAR
Humans and chickens share more than half of their genes. The International Chicken Genome Sequencing Consortium found approximately 60% of chicken and human genes are nearly identical. But chicken genes are far more streamlined than humans; chickens have a total of about 20,000-23,000 genes in 1 billion DNA base pairs, compared with the human count of 20,000-25,000 genes in 2.8 billion DNA base pairs, mostly because humans have far more ‘junk' DNA.
It might be a little creepy to find out that while it isn't activated, chickens do have the genes required for growing teeth. Scientists tweaked those genes in developing chick embyros to stimulate teeth growth and found the embryos did develop teeth. No live chicks with teeth were allowed to hatch, and it's not known if they would have lived or not or if they would retain the teeth after hatching. It is known that parrot embryos briefly develop ‘teeth' but these are absorbed into the beak before hatching.
CHICKENS HAVE FAR BETTER EYESIGHT THAN US (IN THE DAYTIME)
The chicken eye is about 25 times as large as a human eye as a percentage of head size and their eyesight is much more developed.
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We have tri-chromatic eyesight (we see red, green and blue) while chickens have tetra-chromatic vision so they see four wavelengths (red, green, blue, and ultraviolet).
It means chickens see things very differently to us, with many colours appearing to glow, for example the feathers of other birds which identify them as male or female glow if you're another bird but appear the same colour to humans. It means chickens can also judge direction using changes in the
colour of UV light to guide them.
However, due to evolutionary differences chickens don’t have the rods in their eyes which give us relatively good night vision. They can’t see much at all at night, which is why they roost out of the way of predators once night begins to fall.
CHICKENS TILT THEIR HEADS TO GET A BETTER VIEW
The chicken eye has a form of built-in bifocal, so they can see particularly well over a distance, and things that are right up close. The mechanism (called a fovea) that allows them to see far away sits the right way up in the eye, but the one for closeup vision sits sideways, which is why a chicken tilts its head if you get close-up to it, as it adjusts its vision.
BLIND CHICKENS RESPOND TO LIGHT
A hen’s laying cycle is dependent on light. Once daylight goes above 16 hours, the hormones that govern laying are stimulated and egg production begins. The same hormone levels begin to drop as daylight hours shorten in late summer, which is when birds stop laying and go into a moult.
These hormones are controlled by the pineal gland in the forehead and are stimulated by bright light which is why a blind hen can ‘see’ light and will still lay eggs (assuming she is kept safe and has access to food and water).
CHICKENS USE THEIR FEET AND SKIN TO HEAR
Chickens perceive sound from 15 to 10,000Hz, compared to humans who can hear sounds up to 20,000Hz. But they also have sensory organs in their feet, and to a lesser extent in their skin, so they also feel vibrations in the ground, useful if there’s a sneaky prowling predator in the dark.
Hearing is an important sense. In test conditions scientists have found chicks can find their mothers, even if her hiding place is disguised, by listening for her call.
Hens begin ‘talking’ to their chicks before they hatch, and if you listen carefully in the days before hatching, you’ll hear the chicks peeping back at her.
DEAF CHICKENS CAN REPAIR THEIR HEARING
There’s no such thing as a deaf chicken, and that discovery was accidental. Scientists studying how drugs can cause hearing damage were administering a drug known to cause hearing loss to chickens as part of an experiment to help human hearing loss. After a couple of weeks, as they predicted, the chickens had lost most of the tiny inner ear hair cells that allow chickens (and all mammals) to hear. But three weeks later, the scientists found the chickens in the study had replaced their hair cells, restoring their hearing.
More research showed all vertebrate creatures, except humans, have this ability, and the finding is now the basis of research which scientists hope will cure hearing loss and tinnitus in people.
A SMELLY COOP IS OFFENSIVE TO YOUR FLOCK
Chickens have a good sense of smell, although that’s only recently been proven. Interestingly, the kiwi (which has its nostrils at the tip of the beak) have the best sense of smell of all birds and it’s their primary sense as they feed at night, sniffing out worms and insects.
Chickens can’t smell quite as well as we
can, but new research shows they have a similar number of olfactory receptors to humans.
They use their nostrils to search for food and to recognise other birds. They also have the ability to smell high concentrations of carbon dioxide and ammonia, and have special nerves which make these smells painful so a filthy coop is an uncomfortable place for them to be.
Researchers have found chicks are able to smell even while still in the egg. They rubbed a strawberry scent over developing eggs, then found the resulting chicks preferred strawberry-scented shavings and water.
They also respond in an alert manner if they smell the manure of predator animals, even if they've never had contact with that animal.
THE CHICKEN BEAK IS LIKE A HAND
The beak is a sensory organ through which birds can distinguish hard, soft, hot, cold and structural differences such as rough or smooth.
The beak also feels pain which is why the commercial practice of trimming the sharp hook at the tip to prevent feather pecking and cannibalism is done in the very first days of life before the nerve endings have grown to the tip. This is done in the hatchery when a chick is one day old with a laser light which only touches the very tip of a chick's beak causing it to dry and drop off by the time the chick is a week old so there's no pain for the bird.
WE WOULDN’T TASTE LIKE CHICKEN TO A CHICKEN
Chickens do have taste buds, but only 350 compared with a human's 9000 so making their food ‘tasty' does not have the same importance to them as it does to us, although they can distinguish between sweet, salty, bitter and sour. By the time a chicken tastes something it has eaten, the food is already past the point where it could spit it out.
Commercial foods can vary in looks and textures and it is these which appeal or not to a chicken, rather than taste. Some grains will glow (reflecting UV light) and are very appealing to birds which will peck out these bits first because they glow, not because they are more tasty.