Good to Grow: Human-friendly Purple Martins control garden insects

By By Chris Postalwait
Good to Grow

Being an avid vegetable and fruit gardener, I spend most of my time wishing birds would just fly over my patch of earth and go feed in the nearest neighboring state.

However, I cannot say that about North America’s largest swallow, the Purple Martin.

These feathered friends average 6 to 8 inches in height, with a wingspan from 14 to 16 inches. The females are mainly brown with a grayish-white underbelly.

The adult males are the real showstoppers when it comes to color. They are a solid, glossy blue from head to toe, making them one of the showiest birds in West Virginia.

Besides being the largest and prettiest swallows in North America, the Purple Martin has a unique relationship with folks in the eastern United States.

Purple Martins exclusively nest in bottleneck gourds and birdhouse condominiums provided by people east of the Rocky Mountains.

Native Americans began hanging hollowed dried-out gourds on poles to provide the Martins a place to nest near their villages. The gourds, in return, gave the birds more space than a hollow tree to nest in, which allowed the Purple Martins to expand in population by having better sites that were free of predators.

Over time, these birds stopped nesting in the eastern wild and now will only nest near humans. It is widely speculated that without human-made nesting sites, these birds would die off in the eastern U.S.

Why would the Native Americans go to all that trouble to help the Purple Martin? The same reason we are still helping these birds: Insects.

Purple Martins only eat insects — not seeds, worms or, best of all, crops. Plus, some insects sense the birds’ presence and leave the nesting areas for safety. Insect control in the garden doesn’t get more sustainable than birds eating insects.

Purple Martins eat moths, flying beetles, dragonflies, mosquitoes and squash bugs, just to name a few. They will also keep away blackbirds and crows, which is why these birds are welcomed in my yard anytime.

Purple Martins feed their young a mix of glass, metal, sand and ground-up eggshells to help them digest the hard exoskeletons of the insects. The Martins feed while flying in large flocks and can be observed doing some truly amazing sky acrobatics to catch dinner. It’s a lot of fun to watch feeding take place high in the sky.

They also drink water while flying. The birds fly low over a surface of water and open their bills to scoop it up.

To attract a Purple Martin family to your yard, you will need to do a few things.

First, do you have the right habitat for the birds to nest? You will need a space of 50 feet in diameter or more, free of trees, structures and other bird houses. If you do not have a big enough open space, the Martins will not nest on your property.

Next, they need a fresh water source near the nesting site.

After you have made sure your location meets the Purple Martins’ habitat requirements, buy or make your own bird condominium for new nesting parents.

At minimum, the condo should have at least six nesting boxes. Remember, they like to live in colonies.

The house will need to be mounted at 15 to 20 feet high. Make sure you buy a pole kit that allows you to lower the birdhouse for cleaning and weekly inspection of the new nestlings.

Purple Martins do not mind humans looking into their nests, which makes this a fun hobby to do with children at any age.

For the best chance of attracting a Martin, paint the birdhouse white and face it south or southwest.

Once the birdhouse is installed, you are ready to attract a few mating pairs of Purple Martins. Most of the time they will find the box on their own, but sometimes they need help to find your vacancy.

Purchase Purple Martin dawn-song recordings online to call the birds into your yard. Start looking for the Martins to show up in early April. By mid-May they will start looking for a nesting site.

Keep an eye out for European Starlings and House sparrows. Both are an invasive species to North America and will take over the Purple Martins’ birdhouse. That’s one more reason to do weekly inspections of your birdhouse. If you find these intruders in your box, destroy the nests and eggs.

Keeping some pine shavings and straw around in a bucket will help the Martins with nest construction and giving you one more opportunity to watch these fascinating birds work.

One more tip: Don’t get discouraged if you don’t attract a Purple Martin colony your first, second or third year. It may take them awhile to locate their new home.

Chris Postalwait is the agricultural and environmental research station and greenhouse manager for West Virginia State University Research & Development Corporation. He is also the former owner of Orange Vine LLC, a wholesale commercial pumpkin and vegetable farm in Mason County. Contact Chris at postalcm@wvstateu.edu.

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