About purple martins (see Tuesday’s post, “gourds and cans”): they have become entirely dependent on humans for nests in which to breed along the North American east coast.
Susie at pbmGarden sent me the link to a short (about 8 mins.) NPR documentary about the songbirds and the threats they face in the modern world (the fault is partly in Shakespeare).
Check it out here: “The Mystery of the Missing Martins” by Adam Cole
“Typical birdhouses, gourds and tin cans in Coffee County, Alabama,” April 1939, by Marion Post Wolcott, via Library of Congress Prints and Photographs Division.
Hanging clusters of gourd birdhouses for the purpose of attracting purple martins is an Alabama folk tradition, according to the blog Appalachian History.
Choctaw and Chickasaw gardeners began the practice. The purple* martins would eat damaging insects and mosquitoes and drive away crows and blackbirds from the corn.
Farmers of European and African origins later adopted the custom, particularly as the birds also protect chickens by scaring away hawks.
The gourds should be hung in groups of 10 or more, according to the National Wildlife Federation’s blog. They should also swing from crossbars and wires on poles at least two-stories high.
*They are actually dark blue and black, or pale grey.