Being a purple martin landlord

I can tell you that spring has finally arrived because purple martins took up residence at our apartment complexes last Tuesday. It sure is a joy to listen to their chatter and watch them do their thing.

If you want to get into the purple martin landlord business, you still have time to put up a house and perhaps get some tenants yet this season. If you do decide to "get into the business" by purchasing an apartment house, you will find that you have a decision to make about the style of entrance hole into the apartment house.

Most purple martin apartments have entrance holes that are either round or keyhole-shaped. If you have never had an apartment house, start with this kind of entrance hole. Purple martins prefer this style of entrance hole because it is easy for them to get into and out of the apartment.

You will also find apartment houses with entrance holes that are shaped like either half-moons or ovals. These styles of entrance holes were developed to discourage starlings from taking up residence in the apartments. It seems that purple martins are more nimble than starlings. The martins can bend, wiggle and hunker down to get into the apartment through these oval or half-moon holes, while the starlings can't.

Two purple martins perched outside an apartment. (Fred Lynch)

I would only put up a house with half-moon or oval entrance holes in an area where you have an existing population of purple martins returning year after year. Martins are no dummies. Since it is easier for them to go in and out of a round hole than a compressed hole, they will inhabit an apartment complex with round holes first. On the other hand, if they are used to returning to a particular area annually, they will use an apartment with an oval or half-moon hole if that is the only offering by the purple martin landlord.

Most purple martin apartments have a 6-by-6-inch floor area. Several gardeners researching information on purple martin houses have told me that if you use the oval or half moon doors on your house, then you must modify your house so that the apartment floor space is at least 6-by-12 inches. It seems that purple martins, for some unknown reason, will not establish residence in a small apartment if the entrance hole is oval or half-moon shaped.

It is known that deep apartments provide more protection against predators. Purple martins always build their nest to the back of any apartment. One theory suggests that purple martins will trade off the convenience of a round entrance hole for the security provided by a larger apartment floor. I have no idea whether this theory is correct.

It is known that if you have apartments with large floor space, you must constantly monitor your apartment complex for the presence of sparrows. In some cases, it is known that sparrows will build a nest in front of the purple martin nest. The sparrow nest obstructs the entrance hole and martin young are left to die in the martin nest to the rear of the apartment.

I do know one thing: If you have purple martins in your landscape, it is both a joy to behold and a responsibility to be aware of. Make sure that no matter what kind of house you put up for your martins, you monitor the apartment usage on a daily basis. If you find that sparrows or starlings are trying to take up residence, get rid of them. Martins are not aggressive compared to sparrows or starlings. They may need your help in keeping the apartment complex open for just their friends.

Send your gardening and landscape questions to Paul Schnare at P.O. Box 699, Cape Girardeau, Mo. 63702-0699 or by e-mail to news@semissourian.com.