No person, firm or corporation shall keep, maintain or harbor any pigeons within the City in a suitable house or coop which is more than 800 cubic feet in size and not more than 100 pigeons shall be kept by any one person, firm or corporation at any time. Pigeon houses or coops may also have an attached enclosed runway, but all structures for keeping the pigeons shall be constructed so as to keep the pigeons properly confined and prevent their flying abound.