Probably all living creatures need at least some calcium in their diets, but female birds (hens) particularly need it when they're laying eggs. If they don't get enough, the shell can be so soft it's hard to push out, and their muscles can get so weak they can't push anything anyway. This condition is called "egg binding," and can be fatal. I have lost more hens than I care to count from this: Fluff Nugget died of egg binding, and Chocolate died of a prolapsed oviduct — the hen pushes so hard she pushes out some of her insides. Very bad news.

I have also saved hens from egg-binding with a timely dose of liquid calcium. Doses, actually. You catch them up, get some calcium in them, pop them in a hospital cage where they can be warm and undisturbed, catch them up in an hour for another dose, and keep that up until they lay the egg.

Darjeeling survived a bout of egg binding a few months ago, but despite my regular calcium regimen, and my periodic research on new things to try, she clearly wasn't feeling well this morning; head tucked back to sleep, breathing heavy. Daytime: unless the bird is really sick you can't catch them, and wouldn't want to try for fear of giving them heart attacks, so I had to wait until dark. Extra calcium in the water, heat light on, and about mid-morning she laid an egg. Not too bad: hard shell, but thin. A close look at her vent area showed that the egg may have broken on the way out, since it looked like there was a drop of white hanging down. So, she's in the hospital cage, she's had a nice dose of calcium, her vent looks messy but I don't see signs of yolk in her body cavity (that's the worst in terms of infection), and I have an appointment at the vet first thing in the morning. She's pretty active in the cage right now.

My fingers are crossed.