By Master Naturalist Doug Jackson
With the arrival of spring, our migratory birds wintering here head north to their breeding grounds. Likewise, our summer birds arrive from the south to breed here. Amongst these new arrivals are one of my most anticipated and favorite friends, Progne subis, the Purple Martin.
Let me tell you why I have such a soft spot in my heart for these special birds.
Over the past hundreds, if not thousands, of years the Purple Martin has adapted to be an almost domesticated bird. Though still quite wild, they have come to depend on human involvement for their health and survival during their breeding season here in the eastern half of North America.
This most likely started when the Native Americans pruned saplings and erected canes to hang hollowed out gourds, or calabashes, to attract the birds to nest near their homes. They found that these swallows (the largest American species of the Hirundinidae family) did a great job of controlling insect pests such as flies and mosquitoes.
This tradition passed on to, and continued with, the early European settlers who soon made a fashion out of Purple Martin housing, erecting larger and more elaborate Martin apartment houses over the years. In those days, many homes and businesses along urban streets and rural farmsteads needed good fly control due to the abundance of horse manure. Their buildings often included holes in their eves and cornices to accommodate swallow nests, the Purple Martins being the favorite guests.
Because of these large Martin apartment houses, the Purple Martins have become colony nesters – building nests in tight proximity to other nesting pairs with social interaction. This type of behavior is not seen in the western U.S., where Martin housing was never a fad, and Martins remain mostly solitary nesters finding homes in natural cavities of trees and cacti.
The Martins have learned over the past 200 years that humans help keep predators away and help reduce parasites in their nests. So they have come to prefer man-made housing of particular specifications. The homes need to be mounted on a pole around 15’ above ground, preferably white to keep it cooler, within 100’ of a human dwelling, but not too close, and have a fairly open flyway to see and avoid predators.
Martin landlords, as we call ourselves, are conscientious and fastidious to the care of our colonies. We do nest checks every week or so, clean and replace nesting material when needed, and carefully inspect the eggs and hatchlings for good health. The adult Martins seem agitated by this, to the novice, as they swoop and squawk at the nosey landlords. But the Martins actually find comfort and assurance from this activity.
So it is that these birds have adapted and habituated to human involvement for their nesting and breeding success.
But come late summer, when the fledglings have successfully left their nests, the adults, with their young, gather in large roosts away from their colonies to prepare for their migration south. Here in Michigan, this process begins around the end of August to early September. As they fly further south, they join up with more groups to form larger roosts – some in the 10s of thousands.
On their journey south to Brazil, their wintering habitat, they’ll roost at many of our favorite winter vacation spots such as South Carolina, Florida, Cancun, and Cozumel.
Here, the story takes a turn toward a message of conservation. The island of Cozumel was so named by the native Mayan because of the sheer number of Martins, they so revered, roosting there after crossing south over the Gulf of Mexico. The Mayan name for the Purple Martin is “Cozumel.”
Now that the island is covered with resorts, the number of Martins is not as impressive as in days past. But that is not the only reason Purple Martin numbers have dropped. Their numbers, like the Bluebirds’, had been doing very well in the first half of the 20th century. However, two factors joined forces by mid century to wreak havoc on these birds’ populations: DDT, and two invasive bird species – the House Sparrow and the European Starling. Both these species had been introduced to New York City in the latter part of the 19th century, and by now have aggressively spread across the continent finding these man-made Bluebird and Martin houses as ideal nesting sites for themselves.
As Martin landlording slowly lost appeal in the ‘80s and ‘90s, most of their apartment houses became neglected and overtaken by the sparrows and Starlings. Martin numbers dropped considerably to where, for a few years in the ‘90s, there were little to no Martins recorded in Michigan.
With a greater effort toward conservation of our migratory birds in the past couple of decades, Martin and Bluebird landlords are being more vigilant in clearing out invasive nests and monitoring the native birds’ health and safety, including predator proofing and invasive species discouragement.
Now that May is approaching, the Martins are back in North America and will eventually make it this far north in Michigan by Mother’s Day to begin a new breeding season again.
The earliest arrivals can show up as soon as late March and are usually the older adults. We call these early arrivals “scouts”. However, the colonies don’t actually have scouts. The colonies are essentially formed from random pairs of birds gathering each year from the same area, and if well maintained, can increase in number each year.
After waiting nearly six years to attract a single Martin to my yard, last summer I had my first successful couple raise and fledge four new Martins. I can’t wait to see who moves into my apartments this year, and to listen to their sweet chortling and clicking during their courtships. They simply bring a smile to my heart.
You can learn more about attracting Purple Martins to your yard by visiting the Purple Martin Conservation Association at www.purplemartin.org.
