Starting a colony with a 12 compartment house is great but if you would like you colony to grow and thrive you should offer multiple housing choices for your martins. Ideally you should offer 24 nesting compartments. For example you could add gourds to your house or add a gourd rack, even add a second house. Don’t forget Purple Martins love to socialize and perch make sure you have areas for them to enjoy each other. Diversity is always a good choice. You could lose you martins with out diversity; a single house could be damaged in a storm. Also male domination provides a detrimental role in allowing your colony to flourish, poach dividers help this matter greatly. Don’t forget to protect you martins from predators, owl guards, pole predator guards, sparrow traps, starling proof doors; also diatomaceous earth will protect your birds from mites.