I’ve had at least one broody chicken hatch a year for the past few years, and those have all gone well (knock on wood). I even take the eggs out from under the hens on the 18th night and vaccinate them in ovo, then slip them back under. The hens have been fine with that too. Watching the chicken hens is how I know what mom is supposed to do when she feels her eggs hatching! She’s supposed to get a glazed look in her eye and just zone out, locked down tight while eggs hatch. Some of my hens seem like their legs hurt afterwards and I wonder if they are crouching over the eggs to give the chicks room to hatch, like the ultimate squat?
Anyway, I didn’t think guinea hens are unique in their difficulties hatching. In general, my guinea hens have been much better “setters” than “hatchers”, which I’ve read can be problematic in chickens too. There are plenty of tales of bad broody chickens! If you Google or search on BYCs for something like “hens killing chicks”, you will find all sorts of horror stories… I can’t find the post now, but someone posted about how “setting” is a different behavior than “hatching” and “brooding”, and that hens have to be good at switching between all of these to successfully incubate, hatch, and raise their chicks. So some hens are good setters but bad at everything else… I would guess that guinea hens also differ in their abilities. Anyway Sydney, that’s great that Rosie is so capable! Maybe you can find eggs of a drivable distance to give her next year, and she will go broody in the coop for you? I expect that she will still be laying and willing to go broody without a cock around, or at least a chicken hen would…