It is truly the hen. Some go broody in the spring, summer, fall or winter...some don't go at all. It's no rhyme or reason behind it that anyone knows except the hen. And something tells me she ain't telling.
............But seriously. It seems everyone has a broody hen on this site! We've had these chooks 9 months and no problem. Now sodding, bloody stupid thing thinks it wants babies!! I did what everyone here recommends. Put the poor girl in a wire cage. Now what? She's been sat there for 4 days so far! Poor cow!! How much longer??? Will she ever lay??
Lengthening days often stimulates broodiness which is due to hormonal change in the hen.
If one goes broody, other hens often follow as female animals often co-ordinate their hormonal cycles.
Definitely feels like broody season now!