If she just looks normal, just on the nest, just chase her out of there.
If she looks flatter, like she has sunk down and is more laying on the nest rather than perching in the nest, and when you come in, she puffs up to about twice her normal size, and her voice changes, then she is broody.
If she looks flatter, like she has sunk down and is more laying on the nest rather than perching in the nest, and when you come in, she puffs up to about twice her normal size, and her voice changes, then she is broody.