By February, martins are seen well inland, and by mid-April the first martins reach their colony sites in southern Canada. The accompanying map will give you a general idea of when martins should begin reaching your part of the continent. At active colony sites, martin housing should be made available when returning martin scouts are first observed in your area. Before your martins arrive, tree swallows, starlings, house sparrows, and other nest-site competitors may try your martin houses on for size. These species should be excluded from the compartments before the martins return.
Many landlords suggest keeping the cavity openings plugged until the martins arrive.
For those attempting to start new colonies, houses should be kept closed for about four weeks after the scouts arrive in your area. Once you have martins in place, the cycle of courtship and nesting begins. If you provide the proper housing and satisfy all the requirements for the ideal martin lifestyle, you'll get a five-star rating from your martins. With that, and a bit of luck, your colony will grow larger each spring. Easy access for nest cavity inspection and cleaning.