Monthly Archives: March 2012

Chicken Vision

You should be able to file this entry into the “stuff I didn’t know” category.  I have had some experience with chicken vision, and was aware of some of the basic ideas of the “weirdness” that bird sight entails.  As I started writing this, I wanted to make sure I got my facts right (ish), so looked up a few things, and they led to a few more, and half my evening got lost in obscure eye facts that will never be clinically useful to me, but will be GREAT fodder at the next cocktail party.

How do chickens see?  What do chickens see?  Why do they bob their heads around like that?  Why do they look at you sideways?  Can they see at night?  How much can blind chickens see? 

Chickens see the same way we do….light comes in through the cornea and iris,

Chicken eye....about 25 times as large as a human a percentage of head size

then stimulates nerve endings in the retina at the back of the eyeball.  A major difference, however is that chickens have tetra-chromatic vision, while we have tri-chromatic.  In english, chickens have 4 wavelengths they are sensitive to, while we see 3 (red, green and blue).  The chicken eye sees red, green and blue as well, but they are also sensitive to ultraviolet light.  This seems kinda interesting at first glance, but the implications are actually staggering.

The fact that chickens see an extra sector of the light spectrum means that EVERYTHING they see looks different from what we see.  Their concept of the

The 4 peaks of sensitivities of the chicken eye.....they see UV light (grey line), as well as all the colours we see

green colour of grass is as different as our comparison of aquamarine and the colour of grass.  We have no concept or description for how much UV is reflected from any substance.  There is evidence that birds can find direction by looking at the sky and seeing the gradation of UV, and knowing which way is north as easily as you or I looking at a grey-scale drawing and knowing which side is closer to white.  It also means that we have a really hard time understanding what they are seeing.  In the following picture, there is a cockatiel.  Males and female cockatiels look the same to us, but if you

Left: bird and egg the way RGB eyes see them….Center: UV reflection of the same bird and egg….Right: What a chicken sees….

 look at the UV contribution, you see something else.  The picture on the left is human sight…..the picture in the middle is UV spectrum only, and the right hand picture is a rendering that approximates how another bird would sense that bird. 


Now….chickens have a disability when compared to us….their night vision is poor. This is a big part of the reason that chickens need protection at night from predators.  The retina in mammals is made up of rods and cones…..rods to see at night, and cones to see color.  Chickens have very few cones, and they are not especially sensitive.  This difference between rod to cone ratio, and the light sensitivities of cones in birds vs mammals is explained because mammals all but disappeared from evolution long ago, and the only types of mammals that survived  were nocturnal and insect eaters.  Mammals that survived this evolutionary bottleneck re-developed colour vision after millions of years, but since we evolved our cones from a different starting point than birds (they evolved from dinosaurs, and never spent millennia as nocturnal creatures), we developed our colour vision a little differently.  It’s another case of convergent evolution….kinda like whales and dolphins evolving to look like fish, because that’s the body type that works best in the water.

Bird’s colour vision is also different from ours because they have coloured filters mixed in with their nerve cells……little coloured drops of oil filter out different wavelengths, and act similarly to wearing yellow goggles when skiing

This is what you look like to a chicken....or at least a good guess

on a bright day….the contrast is enhanced.  Now imagine wearing yellow and blue and red goggles all at the same time… increases contrast and brightness and sensitivity, all at once, and we mammals can’t even imagine what it might look like. 

Chickens also have much better motion sensing ability than we do.  Not as good as hawks, but better than us….again because of a structure called a double cone in the retina.  This is important if you use flourescent lights in your coop.  Flourescent lights flicker on and off at a rate above what we can see….you notice it on old flourescent tubes that are dying….the flicker rate slows down and we can see it.  It is exceptionally annoying.  Birds can see the flicker in many flourescent lights, especially dimmable ones that are at lower intensity.  It would be like being in a dance club with strobe lights on…..all the time….it drives them nuts…literally.  On objects sitting still, chickens may not have as much acuity as we do, however.  This explains why hens are as “spooky” as they are when somebody makes a sudden movement, and why one bird jumping from something can cause the entire flock to take wing, even if they didn’t see the offending stimulus. 

Birds and mammals have a structure called a fovea in their retinas too…..its a small pit that, because of its shape, acts as an image enlarger.  You can see yours in action by looking at something out of the corner of your eye, then looking at it directly in front of you…..its way clearer in front of you, and why you look slightly down at anything you are concentrating on (the fovea is a little above the middle of the retina).  Chickens have 2 foveas (fovei?), and they act a little differently.  One is for distant vision, and one is for in close….think of built-in bifocals.  The funny thing is that the up close one is oval, and sideways….thats why, when you approach a bird, once you get to the focal distance of about 2-4 feet, birds will often bob their heads, and tilt their heads somewhat sideways to get the image better lined up on the second fovea.  Birds actually can’t reliably recognize flock mates until they are within about 24 inches.

Finally, blind birds can see light.  Birds reproductive cycles are controlled by their pineal gland, which is located in the middle of the bird’s forehead, just under the skull.  The skull is thin enough that reasonably bright light penetrates it and will still stimulate the hormone cascade that begins lay.  Even blind chickens can “see” spring coming.

This post is way too long already, so I will cut it off here….just remember, even if you and your chickens can see eye-to-eye, you still won’t see what they see…..keep it in mind when you try to figure out why they do what they do.

Mike the Chicken Vet

Spring is Coming….So is Coccidiosis!

Yesterday, spring sprung.  It was the warmest, sunniest, “springiest” St. Patricks day ever!  There were people in green t-shirts and shorts all over the place.  Shorts….in March….in Ontario, Canada.  This has been the year of the absent winter, and so I guess it shouldn’t surprise me that spring has come early.  I’m guessing that the spring has caught some backyard hen keepers a little by surprise.  There are some things that you should keep in mind, if you have hens outdoors this time of year.

All the organisms in your backyard are waking up….the water is sinking into the lawn, melting the frost, and sparking growth in plants, flowers, worms, bugs and all sorts of good things.  Unfortunately, along with all the good things, the nasty things in your yard are also waking up and rearing their ugly heads.  In terms of backyard hens, the big risk is parasites that have been lying dormant or under control all winter, that are bound to become more of a challenge for the flock as the weather gets warmer and wetter.

Coccidiosis is by far the biggest concern for backyard chickens.  Coccidiosis is a disease that encompasses a bunch of different “bugs” that live in the intestines of the bird, and are deposited in the environment every time the bird poops.  According to wikipedia, coccidia ” is a subclass of microscopic, spore-forming, single-celled obligate intracellular parasites belonging to the apicomplexan class Conoidasida.”  Hope you got that.   In english, coccidia are small parasites that MUST live inside the intestine cells of animals (in this case, chickens). The interesting thing is that they produce spores when they reproduce.  A spore makes a cockroach look like a frail butterfly.  Nuclear war, napalm and fire-breathing dragons are the only reliable ways to kill cocci spores.  This means that if you have chickens, you WILL have cocci spores in the area in which they live.  Spores start to develop and become infective after they get moist.

Cocci under a microscope. The shell around the 2 organisms is INCREDIBLY tough, and can live in your soil for months to years before it becomes infective.

Depending on how you manage your coop, now is the time that any build up of manure from over the winter will have the best chance of getting wet.  Also, any fresh droppings this time of year will sporulate almost immediately, since most chicken runs at this time of year are bound to have muddy areas.  Although treating coccidiosis is usually relatively effective, depending on the strain of cocci you have, and what other bacteria are present in your environment, birds can become very ill very quickly if coccidiosis gets going in your flock.  For this reason, it is best to manage the problem before it happens, since responding to it is sometimes too late. 

This is a milder stage of coccidiosis. She just looks "off", with ruffled feathers, a shrunken comb, and droopy wings. She will be contaminating the environment for the other hens.

If at all possible, move your chicken run regularly.  Any area that is consistently fouled with manure will eventually become severely contaminated with bacteria, viruses and parasites, so this is a good management practice regardless.  You should make it a special priority to move the run in the spring, however.  Because of the “load” that has built up over the winter, the disease challenge during spring thaw and muddy period  is especially high.  If you can get the hens to a clean area for several weeks until the yard dries up, you can prevent most of the parasite infections, and the severe illnesses that can follow coccidiosis infection, which can result in sudden death in affected hens.

This is a severely affected pullet. Notice the ruffled feathers, closed can imagine how quiet and depressed she will act

If your birds do get coccidiosis, you will see chickens that look ruffled, rough coated, lethargic and will want to spend a lot of time sitting around.  Sometimes they will lay on their sides to keep pressure off their sore stomachs.  Their droppings will range from diarrhea to green paste, to blood tinged loose manure to black blobs that are made primarily of digested blood.

This is one way coccidiosis can show up in the manure....wet droppings with a fair bit of mucus.

If you see any of these signs, quick response is important.  Besides not wanting you birds to be sick, it’s important to treat the birds because they are full of cocci, and they are vigorously contaminating the run and coop, putting all the hens at greater risk of getting sick.  If you do get coccidiosis, it is most effective to treat the entire flock, since sub-clinical cocci is very common.  If you treat individual birds, you will just get one better, then another will come up sick.  If you treat them all, you break the life cycle of the bug, and the hens can get back to normal.

So remember, keeping the hens’ environment dry and clean will prevent many infections from occurring.  I realise this can be very difficult, depending on the weather, but the effort is worth it.  Also, treating the entire flock at the first sign of infection will help prevent more hens from coming down with the disease.

Mike the Chicken Vet

Be Careful what you Wish For….EU Egg Crisis

I am “up” on the animal welfare issues facing laying hen farmers across the world.  Different jurisdictions are dealing with hen housing in different ways, trying to find a balance between production efficiencies, animal welfare, consumer demands, environmental impact, food safety, and many other concerns.  The European Union has been touted as the leader in this regard, leading the way in banning conventional cages as of January 1/ 2012.  Animal rights organizations have long been using this as the “gold standard” when they criticized other areas for not moving fast enough on this issue.

Unfortunately for the EU, their policy has had some holes in it.  Recent newspaper articles have shown that there is an egg supply crisis in the EU…

“Britain’s supermarket shelves could be empty of key products within a month as an acute shortage of eggs threatens to have serious consequences for the country’s food chain. New EU rules banning the housing of hens in conventional cages are being blamed for what some in the industry are already labelling a “crisis”, as competition among food manufacturers to source eggs sends prices rocketing. The price of eggs on the EU wholesale market has nearly quadrupled over the past week to more than four euros a kilo.” The Guardian, Mar 4/2012


“France is now suffering a shortfall of 21 million eggs a week or 10 per cent of overall production, the National Union of Egg Industries and Professionals said in a statement. As a result, egg prices shot up 75 per cent between October last year and February”  Ottawa Citizen, Mar 2/ 2012

The mistake that the EU made was that they tried to be too much to too many people, and they did not enforce a “phase-in” period.  (As an aside, I would like to point out that I have the benefit of hindsight and the ability to analyze what other jurisdictions have done since the EU directive was enacted in 1999….I am NOT criticizing the program, or the people who developed it.  They were WAY ahead of the curve, and did an excellent job.  They weren’t perfect however, and this situation can serve as a cautionary tale for other jurisdictions, like Canada, that are still deciding how to deal with the issue.)

The EU (under pressure from animal rights groups), decided that conventional cages were unacceptable, and legislated them out of existence.  They gave a 12 year “accommodation period” for the industry to adapt to the legislation, but didn’t demand a gradual uptake of alternative housing.  What happened is that farmers put off the huge investment for as long as they could (remember the unlucky coincidence of the world-wide recession in this period).  The legislation also discouraged farmers from investing in furnished cages (again, because any cage system was discouraged by animal rights groups), by categorizing them as “cage” eggs, and not paying a premium for them.  This resulted in many farms hesitating to moving to free-run or aviary systems, since they are less efficient and much different to manage.

There are two situations that have resulted….some countries have aggressively adopted the new requirements, and have been importing the eggs that they have not been able to produce locally, since the new systems are somewhat less efficient.  Now, however:

“Under the new rules, manufacturers are not now permitted to source their eggs from non-compliant EU countries, 13 of which have yet to introduce the new pens.” The Guardian, Mar 4/2012.  Because of this, even compliant countries are short of eggs, especially for commercial markets, such as for bakeries and food production facilities that use liquid or powdered eggs as ingredients.

“Cake and brioche manufacturers [in France] may soon be forced to shut down production and temporarily lay off workers if shortages continue.” Ottawa Citizen, Mar 2/2012.  I’m not 100% sure what brioche is, but it sounds yummy, and if it not produced anymore, I expect the world will suffer.

Countries in the EU are still unhappy with the directive….Irish sources state:


“Unfortunately, the cost of complying with the directive and the way in which it was implemented forced an estimated 10% to 15% of our producers out of business. This has resulted in a tightening of egg supplies and a rise in the price of eggs. ” Belfast Telegraph, Mar 10/2012.

They say a fool never learns, a smart man learns from his mistakes, and a wise man learns from other men’s mistakes.  If this is true, what can be learned from the EU example? 

First, putting together these types of sweeping rules is VERY complicated, the pitfalls are deep and plentiful, and the repercussions are HUGE.  So, as frustrating as it is to say, it is necessary to approach this issue slowly and carefully.  I have been really frustrated in the pace of change in the industry, but moving forward slowly and correctly is much more effective than moving quickly.  Jurisdictions such as the United States have proposed plans that give a phase in period, but have required benchmarks that require a certain amount of the industry to be compliant an interim times.  Other jurisdictions, such as Manitoba, have started to pay an incentive for hens housed in furnished cages, as well as loose-housed systems. 

I think that improving welfare is important, and it is the right thing to do.  All the farmers I work with agree, and want to do the right thing for their birds.  The unfortunate thing is that the question is so complicated that it is impossible to know for sure what the right answer is.  And the repercussions of moving the wrong way is losing your life’s work.  We can do it, and we can do it right.  I would like to thank the EU for paving the way with a really good first draft of a welfare program.  I can’t wait to be part of the committee that improves on the system of implementation that they developed.

Mike the Chicken Vet


Some Cool things about Chickens

I was asked last week if I could give a tour to some grade school students from the big city to show them where eggs come from (Sobey’s is about as far as most of em get).  I was contacted third-party, and was given the teacher’s address and waited for her to contact me with details.  I had no idea what age group, or what the teacher had in mind as goals for the tour, but since I was working in a chicken barn for a couple of hours, I started thinking about what to tell the kids when they came.  Unfortunately, the tour got postponed, but my ideas are still valid, so I am going to impose them on you…..imagine you are in grade 7… are in a chicken barn for the first time ever, and this super-cool, engaging, professional guy is telling you interesting stuff about chickens….. (if the guy was ACTUALLY super-cool, would he use the term “super-cool”? ….nevermind);

You all know that chickens are different from mammals….but do you know how, or why?

The biggest difference between birds and mammals is that birds fly.  Most of the major differences between birds and mammals are changes that enable birds to fly…….Yes Johnny?  I know bats fly too….don’t worry about it…..that is just an exception.

Chickens have no teeth.  Enamel is very dense and heavy, so not developing them lightens the birds so they can fly more easily.

Chickens lay eggs instead of carrying their young inside them.  Can you imagine a pregnant bird trying to fly?

Chickens have hollow bones, which reduces body weight, which makes them better able to fly.  — Yes Johnny?  I know penguins don’t have hollow bones….they don’t fly either….they have “de-evolved” hollow bones

Chickens have a gut-passage time of 2 hours.  That means that a piece of chicken feed turns into a piece of chicken manure in 2 hours.  This means that the birds digest food and get the nutrients out very quickly….making them carry less weight inside them.

Feathers keep birds warmer than hair does.  This allows birds to have less body fat, and thus less weight.  No Johnny…..skinny cats cannot fly…..

Birds have red blood cells with nuclei in them.  This makes it more efficient for birds to make red blood cells, and so more of the blood is made up of red blood cells, allowing the blood to carry more oxygen than mammals….this is really useful for long flights, since birds don’t get tired easily.

Birds have one way airflow through their lungs…..they don’t inhale, then push the used air out back out, over the lung tissues and back up the windpipe….they have structures called air-sacs…..the air comes in through the windpipe, over the lungs, then into the air-sacs, then out of the windpipe on the NEXT exhalation.  This means that only fresh, oxygen rich air ever touches the lungs.  This makes the lungs more efficient, and gives the bird more energy, which makes them better able to fly long distances.  No, Johnny…..chickens don’t really fly well….but they have all these characteristics because most birds fly a lot.

When chickens relax, their feet close tightly.  This is how they can sleep on perches.  Chickens actually have to actively let go with their feet.  You’re right Johnny…that has nothing to do with flying…..

Chickens can see ultraviolet light, as well as all the visible light we can see.  They see colours that we can’t even imagine.

Chickens have almost no taste buds…..humans have over 10,000 taste buds, while chickens have 20-30 taste buds.  Sigh, Yes Johnny….this also has nothing to do with flying……

Chickens only recognize friends once they get within 24 inches of each other.

Chickens recognize each other by way of facial characteristics.  YES Johnny…..I KNOW you recognize your friends by their faces too…..

You know….maybe it’s not a tragedy that the tour got postponed…..maybe Johnny will be sick on the alternate day….

Mike the Chicken Vet

Why Don’t Cities Want Backyard Chickens?

I just got interviewed for a magazine article on backyard flocks (I will read the article, and if I don’t sound like an idiot, I will let you know which magazine it is 😉 ).  A question that the reporter asked me is “why WOULDN’T cities allow backyard flocks of chickens”.  It got me thinking…..I have been involved on both sides of the debate, most recently in Toronto, where the issue was voted down, and the opportunity to legalize henning was not pursued.  I know personally several chicken owners in the city, and they were understandably disappointed, and also confused.  Why? was a question I was asked several times.

HOW could they possibly think this is a bad idea?

The pro’s of keeping backyard hens have been clearly and effectively put forth by the proponents:

  1. Chickens make good pets…they are personable, quiet, small and reasonably cute
  2. Chickens produce eggs….arguements that they will contribute to food security, local food movements, and sustainability
  3. Chickens are not loud or smelly, won’t bite the neighbors (and if they do, they don’t have any teeth anyway), and they teach people (especially kids) about where their food comes from, and makes people appreciate the wonder of food production.

Why, then, would the evil bureaucracy machines not allow chickens to be kept inside city limits?

I am not against keeping chickens in the city.  I feel there is a big benefit to city dwellers learning about and understanding where their food comes from….I think that most urbanites are WAY too ignorant about the food chain, and any knowledge is great.  I also think that chickens can make good pets….not for everyone, but like rats, fish, hedgehogs, lizards and snakes, there are a proportion of people who find them fascinating and wonderful companions.

My concerns, and those of most municipalities that I have advised (I’ve been in the debate in 5 or 6 largish cities in Ontario), is that if chicken keeping is not done well, the risk of animal suffering and human disease is significant.

The biggest risk (ironically, also the biggest benefit) to keeping urban chickens is the general ignorance people have of chickens.  What do chickens need to eat to be healthy?  What temperature should the coop be able to maintain for the birds comfort and health?  How can I dispose of 2 lbs of manure per chicken per week?  What breed is appropriate for my climate?  What should I do with my chickens in the winter?  Should I clean eggs that have manure on them?  How?  What should I do with an egg with a crack in it?  What does a sick chicken look like?  Where could I take a sick chicken to be treated in an emergency?

How do you design a bylaw to prevent this from happening?

These questions are the tip of the iceberg of things that a backyard farmer must know before embarking on the oddessy that is henning.  None of these questions are complicated, or difficult to answer, given a bit of research and motivation.  Ironically, most people who are currently keeping chickens illegally are well educated in these matters, and are capable of keeping chickens in a safe, healthy manner.  The risk of making “henning” legal in a municipality is that anyone can decide, on a whim, to get some hens because it might be fun, and geez….we get FREE eggs!!!

If a municipality condones such an enterprise, they implicitly assume some of the responsibility for what happens when their bylaws are followed.  If complaints come in for chickens freezing to death in a poorly made coop, city council will be asked why they permit that to happen.  If someone gets very ill, or, heaven forbid, dies from food borne illness from backyard eggs, fingers will point towards city hall.  If there is a family of children that get sick from playing in the backyard amongst the manure of hens, well, you get the idea.

So, the challenge that municipalities face is developing a bylaw and a method of policing it that makes it impossible for people to cause themselves or their hens undue stress.  The bylaw also has to deal with keeping vermin to a minimum, finding ways to make appropriate feed available, planning for the disposition of manure (the concern is always, “what if this REALLY catches on?”)

If you saw this in your neighbours yard, would you call city hall to complain?

I have discussed methods of licensing backyard flocks, requirements for the setups that would prevent animal suffering, ways to prove that henners have safe egg handling protocols and ways to trace where eggs go from backyard flocks (let’s face it, not many families will eat 3 eggs per day….eggs will inevitably be given away to neighbors).

These programs are not complicated, and the problems are not insurmountable, but most municipalities find that the cost of setting up and implementing the program insurmountable, especially for the small number of people who are interested in keeping hens.

You may still think that city hall acts as the evil empire, illogically keeping hens out of the city, and you could have good reasons to think that.  At least now you know that their motivation is for the good of the people and animals that they are designing the bylaws for….whether they could do better is another discussion, but (in my experience), councillors hearts are usually in the right place.

Mike the Chicken Vet