Michigan Compiled Laws, Chapter 324. Natural Resources and Environmental Protection § 324.41703

Sec. 41703. Each game bird hunting preserve shall contain not less than 80 acres or more than 640 acres of land leased or owned by the licensee, except that those preserves whose operations are confined only to ducks may contain a minimum of 50 acres. The exterior boundaries of each preserve shall be clearly defined with signs erected at intervals of 150 feet or less.