The top hen is usually more apparent in a flock of mixed ages, and status of the descending ranks is constantly changing. However, it's very often determined by age seniority with individual temperament contributing a secondary influence.
For example, in my flock of twenty, hens and two roosters, the top hen is a Light Brahma hen who is ten years old. She gets priority at the feeders, enforcing her status with a firm peck on the back of the neck of any subordinate who is slow to move out of her way as she approaches.
Second in seniority and bossiness is a nine-year old Wyandotte hen. After them, the younger members of the flock will defer to three seven-year old hens. And the pecking order then breaks up and is more fluid at the bottom according to assertive temperaments being able to command respect of the very youngest. The four-year old rooster is somewhere in the top five or six, but by no means is he boss of the flock, that position being filled by Lady Di, the ten-year old matriarch.
Usually, with a new flock or sub-flock of all same-age individuals, the role of top chicken will be diffused and ambiguous, being asserted mostly by temperament and a tendency to bully.
