ARTICLES ABOUT ATTRACTING PURPLE MARTINS:

THE FIVE KEY PRINCIPLES OF SUCCESSFUL MARTIN ATTRACTION
HOW TO BROADCAST DAWNSONG TO ATTRACT PURPLE MARTINS
USING THE SOCIAL ATTRACTION METHOD TO ATTRACT PURPLE MARTINS

     Normally, after a catastrophic weather event  like Agnes,  martins from outside the region would filter into the devastated area over the course of several seasons and fill the vaccuum, slowly rebuilding the martin population.  However, certain other factors have conspired to keep martins scarce in SW PA- even 30+ years after Agnes. 
After the massive die-off of 1972, many landlords lost interest and discontinued management of their colony sites, allowing their martin housing to deteriorate and/or be taken over by European Starlings and House Sparrows.  These two aggressive, abundant, and non-native nest site competitors prevented martins from re-colonizing former breeding sites by becoming entrenched in their housing.  Habitat loss and a general loss of interest in the martin hobby from an increasingly urbanized culture have compounded the problem, and further hampered the recovery of this once abundant and spectacular songbird. Active breeding sites are few and far between throughout the region. 
    Attracting martins to new breeding sites is best accomplished through the use of a technique called "Social Attraction." 
The idea behind Social Attraction is to trick or deceive investigating martins into believing that a potential site is already colonized.  Since Purple Martins are colonial birds, and prefer to nest with other breeding martins, they are much more likely to nest at a site that they believe is already being used by nesting martins.  The use of martin vocalizations, decoys, mirrors, fake nests, fake eggs, and anything else that will create the illusion that a site is already colonized can be employed.