I. You must offer an open area.
You can no sooner attract a woodpecker to an open field, than you can attract Purple Martins to a wooded area. They have a strong attraction to water, but open fields also give them the airport flyways effect they require.
II. You must control the European Starling and the House Sparrows.
I'm sorry to say but these two cavity-nesting species were introduced to North America by man. Now man must eliminate them by trapping, shooting, converting housing to starling-proof holes, or your colony WILL NOT succeed. These non-natives will peck the Purple Martins’ eggs, and will kill their babies and even adults. They are the only two species that can be legally trapped in the US. All native species are protected by law.
III. You must place your martin houses no closer than forty feet from any building and/or trees.
Yet do not place them further away from your own dwelling than one hundred feet. Purple Martins have adapted to humans and feel safer next to us than out in the middle of a ten-acre field. Fifty to sixty feet from your dwelling works best.
IV. Offer proper housing.
Color: white. Size: America has been informed that Purple Martins need 6” x 6” x 6” compartments. Studies have shown that they prefer a deeper compartment much more. They are then out of reach of owls. Give them an eleven or twelve inch deep compartment, and/or offer ten to fourteen inch gourds. The martin is eight inches long. How would you like to sleep in a six foot bed if you were eight feet tall?
V. Give your Purple Martins the maximum predator protection by adding a predator guard underneath your Purple Martin house.
This will deter raccoons, cats, snakes, etc.
VI. Do regular five day nest checks.
This way you can stay ahead of the game. In doing so, take field notes of what is found inside each compartment at each check. Martins are just like honey-bees, the better you care for them, the better they do.
VII. Control the most threatening parasite, the blowfly larva.
If you don’t, you may end up fledging very few, if any, baby birds. Do so by doing a nest-change when babies are between five and ten days old and then again ten days later. Avoid handling the nestlings when they are twenty days or older. They may fledge prematurely, which could cause their death.
VIII. Offer crushed and dried egg shells in a feeder, or on your driveway,
at your colony site.
All swallow species eat those for grit. IMPORTANT! Heat the egg shells for fifteen minutes at 250° in oven to kill all bacteria. A bacteria called salmonella, found in unheated egg shells, has killed martins.
IX. Keep the grass mowed under your martin houses.
Do not plant flowers or shrubs around the poles. Purple Martins love to be able to see a predator should one come close. They don’t like snakes in the grass.
X. Make all changes to your colony-site three weeks after the first martins arrived, or when you have seen the first piece of nesting material being taken into the compartment.
This speaks for house replacements and/or adding new housing. When martins see that the changes are made by humans, it comforts them and they will accept it. Otherwise, they become skeptical and may never return.