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In Their Gourds
Long before humans arrived in the new world Purple Martins – Progne subis – would leave their winter homes in South America and fly north each spring. These large, graceful aerobatic swallows would seek out trees riddled with abandoned woodpecker nests near swamps and prairies. Here they formed colonies of related individuals who made their living plucking insects out of the air - lots of insects. When human numbers began increasing in North America some ten thousand years ago it initially made little difference to the Martins. But sometime in that distant past - when the ancestors of modern Indians began settling in villages - the paths of these two species, ours and theirs, crossed.
Life in a village was messy - no regular trash pickups, no plumbing, no sewage treatment plants - and consequently there were lots of flies. Large numbers of flies are not only annoying they're dangerous to your health. This no doubt caused a great many problems for these first villagers until someone noticed the flies around their village and the fact that Martins eat flies. Putting two and two together they punched some swallow-sized holes in a few spare gourds and hung them in a tree.
Perhaps it took a while for the Martins to catch on but I doubt it - animals, like people, can spot a good opportunity when they see one - at any rate they moved in, the flies moved out, and everybody was happy. Needless to say the idea caught on and soon every village within the Martin's range had several sets of gourds hanging strategically round the village tempting Martins to move in. And move in they did. According to early explorers accounts every permanent village usually had several sets of clustered gourds housing several families of Martins. No doubt the Martin population expanded enormously.
The European invaders who displaced the aboriginal Indians also carried on this custom - and for the same reasons: flies. Throughout the 18th, 19th and early 20th centuries farmsteads, villages and towns throughout the eastern US used artificial nesting to attract colonies of Martins to their neighborhood for insect control.
That this symbiotic relationship is of long standing is borne out by the fact that Martin scouts look first for human presence and only secondarily at the availability of nesting sites around those humans. This trait of having humans nearby is so ingrained in the species' psyche that they will refuse to nest in even the most sumptuous of Martin mansions unless it's within fifty feet of a human house. And so successful has this partnership been for the Martins that today only a single colony of Martins is still known to nest in their natural, ancestral setting - in a woodpecker riddled tree on the edge of a swamp.
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Copyright © 2003 Jim Jung
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