On page 27 of the Tall Timbers book they say “…we suggest a minimum acreage of contiguous habitat for an isolated site to be about 1,500 acres — based on the declining likelihood of quail leaving a property as size increases, and the ability of a population to survive random events.” The book talks a lot about the landscape context that a property sits in. Basically you could have quail on 100 acres if you’re surrounded by large quail plantations. But if your land is isolated you need a minimum of about 1,500 acres.