Chickens: Obsessive-Compulsives of the Bird World

My grandmother used to marvel at how little I grasped of the basic workings of a chicken. But then she was born in 1908 and grew up in a farm town in east-central Illinois. I spent my formative years in a Chicago suburb dropping quarters into video games. It gave me a totally different perspective on live poultry.

It wasn’t until a few years ago that I encountered my first chicken farmer, and of course I had no end of questions for him. The information I picked up was fascinating. For instance, I had no idea that hens need not know the ways of a rooster to start producing eggs. So-called “blood spots” are not, as is popularly thought, tiny chicken embryos. They happen when a blood vessel breaks somewhere near the yolk as the egg is forming.

However the most interesting stuff I learned had to do with the laying behavior of hens. I’d always wondered why hens lay eggs so consistently…almost every day. I mean, it always seemed impossible to me that a bird would behave like that in the wild. Sure, the whole point of chicken breeding has been to bring out the most desirable traits of chickens. I’m sure that over the eons we’ve changed chickens considerably. Still, what base behavior is it that causes chickens to be such prolific egg producers?

Well I found out. Chickens, it seems, are the world’s most obsessive compulsive birds. Left to their own devices they lay their eggs in “clutches”, which is to say collections of about 7-to-10. Each breed has its own magic number. A hen putting down a clutch of eight will lay at the rate of about one egg per day until she gets to eight, stop for a week or more, then do it again.

So far so good. However if, in the course of laying that clutch, a fox comes along and swipes an egg, the hen will lay another to replace it. If a snake then happens along and swallows down another, she’ll lay another one to replace that one. Yet another predator, yet another egg and so on and so on until she can get up to the magic number eight. If it takes a year, so be it. Hens are that uptight.

On the farm, we humans take the place of that random predator, swiping the egg every day and making the hen start from, er…scratch. And so the hen continues the Sisyphean task of finishing the impossible clutch, producing up to 250 eggs every year, over twice as many as a “wild” hen would lay. Fascinating.

Does it bother the hen to made to perform such an impossible, repetitive task? If she’s anything like me, probably not all that much. I mean I pick up my daughters’ shoes from the very same spot in the hallway every darn night, and even though I’m continually frustrated to find them right back there the following evening, I pick them up again anyway. Chickens aren’t the only ones with OCD problems, you know.