What’s the new high-tech structure atop a pole on the eastern shoreline of Lake Hiawatha? Think of it as an avian condominium unit for purple martins. The structure consists of 12 white gourds designed to give purple martins a home and deter non-native species such as European starlings and house sparrows from nesting. Each gourd is used by one pair of martins and is lined inside with pine needles where martins can construct their nests and lay their eggs.
Lake Hiawatha was chosen as a nesting site because purple martins like water and open spaces. In addition, the lake’s shoreline restoration project is compatible with bringing back native bird species in addition to native plants.
Purple martins, the largest American swallow, are unique because they are the only songbird that is nearly completely dependent on human-supplied housing for reproduction. Native Americans fostered martin colonies in their campsites, hanging clusters of hollowed-out gourds. European settlers continued the tradition, installing gable-roofed martin houses at their farms near a lake or pond. Traditionally, natural gourds were painted white. The white color keeps the inside cooler, reflecting the heat of the sun; otherwise they might turn into “purple martin egg cookers.”
The gourds at Lake Hiawatha will remain up into early fall to attract migrating young adult birds on the look-out for available housing where they can start their own colony next spring. They will be re-hung in the spring when the purple martins return from their winter home along the Amazon River in Brazil.
Martin houses, with their white multi-unit houses mounted on tall poles, were once a common sight on Minnesota farms. But with fewer family farms, and the invasion of non-native house sparrows, purple martin numbers have plummeted-down 78 percent since 1966. The population continues to decline 3.9 percent each year, according to the Audubon Breeding Bird Survey and the East Central Minnesota Purple Martin Recovery Project.
The Lake Hiawatha project is a collaborative effort by the Minneapolis Park and Recreation Board (MPRB), Minnesota River Valley Audubon Club, (MRVAC) and Standish-Ericsson Neighborhood Association (SENA), coordinated by Minneapolis resident Diana Doyle. MRVAC contributed $400 and SENA contributed $200 toward the supplies.
The nearest known active purple martin colony is at the Braemar Golf Course in Edina, eight miles away.