It's not uncommon for a laying hen to go broody, especially in the early spring and summer months. If you need to refresh your flock, you may want to allow your hen to sit on a clutch of eggs (usually 10 to 14) and let them hatch out naturally into fluffy baby chicks. You will either need a rooster so that the eggs are fertilized, or you may purchase or trade for some fertilized eggs.
Finding a Broody Hen
Buff Orpingtons are a breed known for their broodiness. The photo above is a Buff Orpington mama hen with several of her chicks. She hatched eleven chicks for me this spring and is caring for them through cold nights in the 30s - no need for me to fuss with a heat lamp. The chicks are a mix of Speckled Sussex and Buff Orpingtons, the two breeds that make up our flock currently.
One thing to note when mixing breeds: you can do this successfully with two purebred chickens, but allow this next generation to interbreed and you may get some very unsatisfactory results.
Also, some hens just aren't good broodies. You'll need to accept a smaller hatch rate and some failed hatches with this method.
Care of a Broody Hen
We just let our hen sit on the eggs in the nest box, but it's best to move her and the clutch of eggs to a larger nest box of at least one foot square so that she can turn around and move a bit, and set up so that the chicks have enough room to access food and water within reach of the nest box once they're hatched. She will want to be cozy and she will not want to be moved! She will probably peck you if you try to move her so wear gloves. Make sure that the floor of the nest box has soft cushioning like shavings or straw. And you will want to make sure that she can't be messed with by the other hens. If you can put feed and water right in front of the box for her for the duration of her setting (but where she can't knock it over into the eggs), that will also help, as she will only get off the eggs once a day to poop, eat and drink.
Chicks take 21 days to hatch, and a clutch of eggs can take a few days to completely hatch. Mark the date on your calendar!
Any adjustments that need to be made should be done at night when she is sleepiest. She will defend those eggs and baby chicks as best she can and she can peck quite hard. Our dog learned this the hard way when he got curious. Our broody hen puffed herself up and flew right at him, trying to peck his face!
Right around day 21, you will probably begin to hear the little peeps of baby chicks. Exciting! You may not get a good look at them for a while. They tend to stay under mama for one or two days. And remember, some will hatch and then the rest may hatch over the next two to four days. After this time, the rest of the eggs are probably not viable. You can go ahead and try to remove any remaining eggs from under the broody hen - if you dare!
Care of the Baby Chicks
Unlike when you order chicks from a hatchery, baby chicks who are hatched naturally under a broody hen don't need a lot of care. The mother hen provides the heat, so you don't need a heat lamp, but you will need the other basic chick supplies. She will also show the chicks how to eat and drink. They will regulate their temperature naturally by going all the way under her wings or poking their adorable little heads out from underneath her. If she feels there is a threat, she will make a certain clucking noise and they will all gather underneath her. They can walk around under her wings and snuggle up together without much of a problem at all.
Just make sure, like with any chicks, that they have fresh feed and water at all times. You may want to move them to a brooder area with mama once they've all hatched and are a couple of days old, to give them some room. If you can, leave the brooder partially uncovered so that the mother hen can leave the brooder from time to time. You can even put a little ramp so they can follow her - but be careful, observe to make sure that the rest of your flock is not aggressive toward the baby chicks. (Ours have been fine, and I've even seen the roosters "stand guard" by the brooder tub, protecting their babies.)
Once they're big enough, they'll fly right out of the brooder to follow the mother hen. By six weeks, they won't need to be sequestered anymore and you can introduce them to the rest of the flock. Do this at night, just before dark, to minimize aggression, and watch carefully.
Enjoy your experiment, and don't get discouraged if your broody hen doesn't hatch any eggs. Many hens lack the natural instinct to hatch a clutch of eggs. They may leave the nest for too long and let the eggs get too cool, or not set on them long enough (maybe they stop after two weeks). But some hens do have enough mothering instinct to help you out and provide you with healthy, adorable, fluffy baby chicks to add to your flock.