Chickens are not known for their intelligence and cunning. But they’re usually pretty good at being chickens. Except when they are broody (akin to being pregnant).

Pregnant humans often feel like they are losing their minds. And, in some ways, they are. It’s the hormones. To the scientific research on this topic with pregnant humans, I add my own anecdotal evidence from chickens.

My hen Calamity Jane has been ‘pregnant’ twice now. And both times she has lost her little mind. In mammals, a fertilized egg within the body triggers cascades of hormonal changes that allow the female to incubate the fetus. In chickens, the fertilization of the egg is immaterial to the process of being ‘pregnant’. It is a combination of spring and the visual cue of eggs that cause some chickens to become ‘broody’. Broodiness, like pregnancy, is a hormonal change that allows the hen to incubate eggs.

A broody hen sits 23+ hours a day on ‘her’ eggs (or someone else’s, or no one’s if you’ve taken them away). She pulls out her breast feathers to give more heat and humidity to the eggs. She rotates the eggs so they may develop properly. She lowers her head, raises her tail and wings, puffs out all her feathers and growls at a perceived threat. These changes increase her chance of being a successful brooder.

Calamity Jane (and now Little Sister) does a great job sitting on her eggs. But when she steps out for a bit I see other changes that don’t appear as helpful. Calamity Jane gets testy, attacking other hens. She randomly flaps her wings and shrieks. And she becomes, tragically, even less intelligent. Instinct tells her to grab a snack while she is out. But she’s no longer bright enough to accomplish this task (good thing there is feed in the broody box). Most notably, she lamely scratches and pecks at objects that will not yield food. Hardy plants. The tarp. And the whole while she mutters under her breath – “cluck cluck cluck cluck…”

This is obviously the origin of the expression ‘Dumb Cluck’. And it is real. After the eggs hatch Calamity Jane appears ‘intelligent’ again. She’s as bright as she can be and is admirable in teaching her chicks about their world.

What I love about this little story is what it teaches me about myself. We like to think that we are more or less constant. So robust in many ways, but we are fragile in others. It is a delicate delicate balance of chemistry that creates our personalities.