This PDF link provided by the Purple Martin Conservation Association (PMCA) a non profit organization. www.purplemartin.org
An active landlord perform regular nest checks and record his/her data on an appropriate form. Landlords do nest checks to observe and monitor for any problems that are usually easily fixed when found early. Keeping the information written down will help you know how old the nestlings are (among other things) so you will know when to stop nest checks. The above form includes a place for the cavity number, age of male/female, date first egg is laid, and the earliest possible fledge date. There is also a total column that includes eggs, number of nestlings, and number of fledglings. Nest checks should be conducted on at least five-day intervals. A nest check is done by lowering the Purple Martin house, opening each compartment and recording anything present. Martins may temporarily be alarmed but will soon return and even watch from a safe perch to watch you do the check. Contrary to popular myths, martins will NOT abandon their nests and are very tolerant of our actions and have even been know to remain on the nests while the check is being performed. After you have preformed the nest checks be sure each cavity is closed and that you raise the house oriented in the same direction that it was originally.
Know the difference between a martin nest and a sparrow nest. A sparrow's nest is usually filled to the ceiling and fills the entire cavity. A martin's nest is a simple flat nest with a bowl area usually toward the back. Most martin nests are made of twigs, straw, pine needles or grass. A martin's nest sometimes has a mud dam formed at the front near the entrance hole. If a sparrow's nest is present be sure to remove it immediately. Sparrows will often continue to try to build a nest so frequent "tear outs" of sparrow nests will be needed. Keep an accurate count of the number of martin eggs or nestlings present. When the nestlings reach an age of about 20 days, you should stop doing nest checks to prevent the youngsters from leaving the nest too early.
We at PurpleMartins-R-Us.com want you to know that whatever type of purple martin bird house you decide on, we want you to be successful. We are NOT a generic pet or bird website selling a product we are not familiar with. We have our own colony of purple martins that return every year. Many of the products we sell we use in our own colony. If you have questions about any of the items we sell, please email or call us and we will be happy to assist you.