My walk in the park last week led me to Gallant Farm, where I watched in fascination as dozens of purple martins flew in and around gourd-nest houses, their iridescent purple feathers shining in the sun.

As insectivores, they eat beetles, wasps, dragonflies, butterflies and other flying insects that they snatch high in the sky as they perform their aerial acrobatics.

As entrancing as their behavior is, I was even more interested in the fact that more than 100 baby birds were living in those nest gourds. In fact, as of June 30, the nests held 134 babies, with 18 more waiting to hatch. All that flying around by the adults had a purpose: to find food to fill the open mouths of those babies.

We often talk about protecting and helping wildlife species by preserving open space and improving habitat. In many cases, that's all the human intervention that birds, bees and other wildlife need to carry on with their business of eating, sleeping and reproducing.

Purple martins are an exception. Because of centuries of adaptation, purple martins -- specifically those that live east of the Mississippi River -- are dependent on people for their survival. That's because they live solely in man-made structures.

That was not always the case. As cavity nesters that don't carve out their own space, purple martins historically have nested in openings found in natural crevices in rock formations or cliffs, or created by other animals.

But thousands of years ago, people starting providing housing for these birds by hanging up dried, hollow gourds. These nesting locations proved successful, and over time, this led to a shift in nesting habits by the eastern species of the birds.

Western species still will live in natural cavities, including saguaro cacti in the Southwest and woodpecker holes in the Pacific Northwest. However, in Eastern states, including Ohio, purple martins live in colonies of gourd-like structures or compartmentalized "hotels." At Gallant Farm, just northwest of the city of Delaware, Preservation Parks has 33 gourd houses set up on three tall poles. The activity around these houses is what held my attention last week.

Parks volunteer Judy Houston and her husband, Henry Kline, have managed the colony for three years. They hang the houses when the season begins, visit them every three or four days, count the eggs and babies and enter data on the Cornell Lab of Ornithology NestWatch website. The couple changes out gourds as needed, keeps track of fledgling dates (the time between hatching and flight), and monitors the health of the colony.

Houston said the colony grows each year: The birds head to Brazil each winter and when they return, there are more and more young birds. She added birds will be loyal to nesting sites where they had breeding success the year before.

Houston said caring for the colony is a passion for her and Kline. She loves the sociable nature of the birds: They talk to her, she said. I can see that. During my visit, the birds peeked out from their nest entrances and chirped away, as if they were trying to have a conversation with me.

We at the parks also provide housing for other birds, among them boxes for Eastern bluebirds and tree swallows, cared for by staff and volunteers. But these birds instinctively hunt out natural cavities, unlike the purple martins.

I am most grateful for wildlife staff and volunteers across the country who work with purple martin colonies. Their efforts ensure these beautiful birds, with their social chatter and high-flying beauty, will continue to thrive.

For information on how to help with nest boxes in Preservation Parks, call volunteer coordinator Sandra McBrearty at 740-524-8600, ext. 6. To watch purple martin babies through a livestream nest cam, visit purplemartin.org.

Sue Hagan is marketing and communications manager for Preservation Parks of Delaware County.