Dana Downie 
ent does not assist the young of com- 
peting adults. As a result, chick rec- 
ognition has evolved in most colonially 
breeding animals. Not being able to 
recognize their nestlings is a trait pur- 
ple martins share with the related and 
solitary-nesting rough-winged swallow 
C Stelgidopteryx ruficollis). 
What could have caused purple 
martins, at least in the eastern United 
States, to abandon their largely soli- 
tary life style and become a colonial 
backyard bird? This was probably 
brought about by the original clearing 
of much of the eastern forest, which 
eliminated many natural nesting sites, 
and the erection of birdhouses, both 
of which began in the early 1800s. 
This massive environmental perturba- 
tion essentially changed the nature of 
the purple martin’s available nesting 
Howard Worthington, a farmer in Pleasantville, Iowa, who built this 
birdhouse for purple martins, left, about fifty years ago, reports 
that in the last few years he hasn’t had many residents. 
A skyscraper for purple martins, below, was constructed in the mid-1960s by 
the Jaycees of Griggsville, Illinois. The elaborateness of the structure, 
and the extravagant claim of mosquito consumption, are in keeping 
with the town's boosterism of these birds. The self-proclaimed 
“Purple Martin Capital of the World,’’ Griggsville plays host 
to about as many martins as it has inhabitants — roughly 2,000. 
Bill Thomas 
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