There's no doubt about it, that silkie x pekin pullet was a great investment. She not only sat perfectly up until half the eggs had hatched (unfortunately ants began to attack the still-hatching chicks), but she's now acting as a mother to all 12 that survived artificial incubation and the ants. It's been so long since I hen-brooded that I'd forgotten how easy it is to raise chicks. Mind you, she won't be sitting many times in one year.
I've also replaced her brooding box (a cat carrier) with a slightly modified nestbox so she and the chicks can all fit comfortably with room to grow. I did this because she's such a small hen that a few chicks might not quite fit under her at night. I wanted to make a really snug nest without any danger of a small chick suffocating. The ideal nest was something with sides that could retain heat, but also breathe.
The result was rather easy using a few bits and pieces I had lying around.
First I made a semicircle of plastic mesh curved into a C shape and fixed to a board (so in cross-section it formed a D lying on its flat edge). This had to be big enough to arch over the hen and her chicks, with extra room to grow.
About 10cm out from this inner D I made another semicircle of mesh, fixed at the edges of the board (imagine two D shapes joined at the straight line, one larger than the other).
I then stuffed the gap between both mesh curves with straw, and made two rear ends out of the same materials fixed slightly apart and stuffed with straw as well.
Over the top of all this (because my brooding area isn't rainproof) I loosely fixed a woven plastic feed bag, with enough slack to ensure that the straw underneath could breathe, and with a small gap around the edges for airflow.
Thus even if the chicks outgrow the hen before they've feathered sufficiently to survive overnight on their own, they'll have a large but very snug nest igloo to grow into.
Unfortunately the hatch was pretty poor, with about half in both the incubator and broodied eggs emerging from the shell. There may have been some B-vitamin shortages in the parent birds, since 4 chicks came out of the incubator with serious leg problems (though all toes were fine). Mild temperature spikes such as I had with this new machine shouldn't result in so many leg issues unless there were genetic or vitamin deficiencies as well. (Remember, these are the light sussex show eggs.)
Oddly, I've ended up with one little ginger-chocolate fellow which looks to be a gold laced wyandotte, only with a straight comb. There were a few ISA brown eggs to round out the two dozen, and they were free, so it hardly matters what he is, but he's certainly pretty.
In any case, since I don't need more than a few birds to pick my meat breeder from, everything so far has turned out fine!