Perhaps you have seen them while visiting the Missouri Botanical Garden’s William T. Kemper Center for Home Gardening — large white, multi-compartment birdhouses on poles about 14 feet high. In spring and summer, the housing is fully occupied by purple martins (Progne subis), a swallow species.

St. Louis today is possibly home to the largest number of nesting pairs of purple martins of any urban area in the birds’ nesting range throughout eastern North America: approximately 100 pairs in scattered housing (Chicago city parks also host some, and Cubs fans are welcome to challenge our standing).

A Brief History of Purple Martins in North America

The fact that purple martins call St. Louis home did not happen by accident. Intentional housing is necessary to court a purple martin population because the species has become totally dependent upon it and no longer nests in natural cavities, other than a small population of closely related western martins (Progne subis arboricola).  

The long relationship between purple martins and humans is generally attributed to Native Americans, although historical documentation probably needs more inquiry. In his book American Ornithology (1808), Alexander Wilson implies that, while visiting Choctaw and Chickasaw settlements in the late 1700s, he saw natural gourds for martins on poles made of long canes.

People in colonial America began to host purple martins early on, on purpose or by accident — maybe some martins moved into houses provided for pigeons and doves, which were kept for meat. 

In the early 1700s, English naturalist Mark Catesby, visiting his sister in Virginia, wrote that “people host martins in lockers prepared for them against houses, much like for pigeons.” John James Audubon wrote, circa 1831, that in southern states, a martin house was often incorporated into the signboard above inns, and “the handsomer the martin house, the better the inn.”

And so the tradition spread in rural areas and cities throughout the eastern martin’s breeding range in North America, from southern Florida well into Alberta, Canada. One can assume housing for martins was provided in St. Louis early on, although a search of archival material finds no references to until the early 20th Century. 

Finding a Home at the Garden

According to a June 10, 1914 St. Louis Post Dispatch article, a birding group observed purple martins in “Shaw’s Garden,” and the unnamed birder submitting the report urged George Thomas Moore (1871-1956), then head of the Missouri Botanical Garden, to improve the martin housing, writing that “Jenny Wren” in particular seemed to be “scolding” for improvements in both wren and martin housing, concluding that both species “prefer housing in the garden to the city’s narrow streets, often patrolled by cats.” 

Why a swallow species would choose to live in an urban area might seem odd. Purple martins tend to feed very high, a thousand or sometimes several thousand feet where they capture any flying insect. Are there adequate bugs high in the sky above St. Louis? Apparently so.

At least a small population of martins likely was sustained in housing at the Garden, and perhaps Tower Grove Park, through the decades in the mid-20th century, and likely some housing in private yards, although the latter is rare today in the city and may no longer exist.

An urban purple martin revival of sorts occurred in St. Louis in 1981. W. Ashley Gray III, then vice president of development with Rankin Technical College, took a stroll in the Garden one evening the year before. His wife, Charla, a Garden volunteer, was attending an evening event in the Gladney Rose Garden. Gray, who resides in Creve Coeur today, had had an interest in purple martins from his youth when he watched the birds in housing that his parents provided at a weekend home Missouri’s Pike County. He also hosted the birds in martin houses at his home at the time in Manchester.

Gray noticed two older wooden houses in the Garden, poorly located among trees (martins prefer very open sites for their houses) and likely not occupied. “I told that to Dr. [Peter] Raven (then Garden President) and said that it was a shame, as pretty as the rest of the Garden was.”

Raven promptly appointed Gray “Curator of Purple Martins” and new housing was installed in 1981 in an open area about 200 yards north of the Japanese Garden. The housing attracted at least three nesting pairs the first season. Gray oversaw management of the housing, including cleaning it yearly and keeping the units plugged in winter to prevent house sparrows, an invasive species, from moving in. Occupancy continued to grow to at least several dozen pairs. 

By 1991, the Garden hosted a 10th anniversary purple martin event, with Gray speaking to a capacity audience about how to attract and manage a colony. The event included someone in an elaborate purple martin costume, named “Zapper” in recognition of the martins diet of flying insects, including many harmful garden pests. That year, martin housing also was erected two blocks east of the Garden by the late Jack Parker, owner of O’Connell’s Pub, on the restaurant parking lot. Parker’s housing attracted just a few pairs its first year, but continues to be occupied to this day by about a dozen pairs each season.

A Regional Resurgence

In 2005, John Miller, author of this piece, initiated further St. Louis purple martin urban renewal. Miller, who had learned about the birds while growing up in Kentucky, chirped pretty much incessantly until Forest Park gave him permission to place a house in Steinberg Meadow (with funding support from Jack Parker), and he convinced Forest Park Forever to add one to Wildlife Island. The same year, the park’s Probstein Golf Course was completed and Miller worked with the staff to erect more housing for martins in natural areas.

Miller practices martin monitoring techniques developed by the Purple Martin Conservation Association, including weekly “nest checks” during the breeding season to document numbers of pairs and chicks. Volunteer Jack Hambene of University City helps at Forest Park and Steve King, of the city, assists at the Garden.

In 2007, upon Miller’s request, Dr. Raven authorized the construction of newer housing in locations selected by the Garden’s Chip Tynan, including one large structure in the Kemper Center Demonstration Gardens and two additional houses in an open meadow adjacent to the Garden’s Bayer Center one block west of the Garden.

Why host these birds at all? Sustaining the species is the priority. Enchantment helps. Watching purple martins soar above the city in summer is pretty cool. Or maybe it’s simply, as Dr. Raven says, that “birds make our own lives more interesting.”

More information about purple martins can be found on the Purple Martin Conservation Association website. 

John Miller