When we have chicks, juvies and meatbirds going, we can get up in the 90-100 range. Approx 3/4 of an acre I think.
We only keep/maintain usually around 40 year round. City code allows for birds and no limits, just no complaints/don't be a nuisance.
We try to limit who's ranging where/when though so as not to panic people about how many.

We try to limit who's ranging where/when though so as not to panic people about how many.