The Mysterious Appearance of 30 Purple Martins at an Unused Martin House
Ken Kostka
Purple Martin Preservation Alliance
http://www.purple-martin.org
Pittsburgh, PA
03/05/05

        At dawn on Saturday, June 22nd, 1985, approximately 30 Purple Martins were discovered perched on the unused 24 compartment wooden martin house that stood in the orchard behind my parent's home near Pittsburgh, PA.  Erected late in 1979, the martin house had failed to attract a single breeding pair in five years.  Suddenly, 30 martins, including many adult males, had mysteriously appeared overnight!
    After trying unsuccessfully for 10 years to establish a colony, I had the bad luck to be out of town and out of touch during the weekend of this spectacular purple martin arrival. I was in State College, PA, staying with a friend and looking for an apartment to rent for my return to Penn State University in the fall of 1986.  My parents, however, gave me a thorough account of the event. They did fail to take a photograph, something I've always regretted. This group of Purple Martins, which was present at daybreak, stayed until about noon, then departed.  They were present again the following morning for about the same amount of time.  During their stay, these martins thoroughly examined the house and explored the surrounding area, with a large wooded hillside overlooking the Allegheny River 1/3rd of a mile to the east, and typical suburban housing to the west. They busily inspected the various compartments, sat about on the porches, and perched on a row of 5 ft. tall tomato plant cages at the edge of the garden below the martin house. But these birds, unlike those at established breeding sites, were skittish. If anyone walked too near the house, the martins flew up as if alarmed.

    When I returned Sunday night and was informed that 30 Purple Martins had been using the house that very morning and the morning before, I mounted an all night vigil to await what I hoped would be their return for the third morning in a row. In the meantime, I pondered two basic questions: Where did they come from, and what were they doing here? 
    The first question was answered with reasonable certainty. I later learned that on May 31, 1985 (three weeks earlier) a swarm of killer tornadoes had hit 14 counties in Northwestern and Central Pennsylvania, as well as New York, Ohio, and Canada. Eleven tornado "families" with 41 touchdowns occurred in a period of eight hours, killing 65 people and causing $300 million dollars in property damage.  Pittsburgh is in Allegheny Co., just south of several tornado-stricken counties.  The martins in my parent's backyard were probably refugees from this natural disaster that had most likely destroyed their colony house. They may also have been a colloection of martins from several houses that were taken down by the storm.

    To my great personal disappointment, the martins failed to return for a third consecutive morning. I did not see another martin on the house for five years. But an intriguing question remained - and remains to this day, almost 20 years later - what were they doing here? Were they still searching for a new site to colonize, or had they abandoned any renesting efforts? Three weeks has passed since they presumably lost their home, and they were south of the disaster site. This led me, initially, to believe that they had begun an early migration and were meandering south to some staging area. Years later, it was discovered that most martins in southwestern Pennsylvania actually gather at Presque Isle State Park on Lake Erie, which is actually north of the disaster site and about 100 miles north of Allegheny Co. However, it is possible that Presque Isle was not being used as a premigratory roosting site in the 1980's.

     On May 31st, an average pair of adult Purple Martins in western Pennsylvania would have been at about the egg-laying stage of their reproductive cycle. Some pairs may have had nestlings, but many, if not most, would have still been egg-laying or incubating eggs when the tornadoes hit. Surely they would have attempted to renest? But what had these martins been doing in the three weeks following the tornadoes? Surely there were houses available, although unmanaged.  Such a large number of martins would surely be able to muscle out a few pairs of starlings or House Sparrows. At just what point in the season does it become too late to renest? After incubation has begun? Furthermore, were these martins attempting to collectively colonize a new breeding site?  What, if anything, is known about their behavior following such an event? Were they still functioning as a colony? Would pair bonds remain intact? Why didn't they stay? Did they eventually renest somewhere else?  Did they stay together, and -if so- for how long?

    Unfortunately, it is not known what became of this group of martins. They may have found a site and attempted to renest there. They may have wandered around until joining  a large premigratory roost at the end of the summer. Whatever the case may be, their group behavior was certainly intriguing and leaves a lot of questions unanswered. I don't believe there is much known about the behavior of a colony of martins following the loss of their colony house to a natural disaster at this particular point (egg-laying) in the breeding season. Feel free to weigh in on this. E-mail your comments or theories about what you think was going on, and I'll try to get them posted here at the end of the article. Thanks!

From Dr. Euguene Morton:

Hi Ken, I would guess that their colony housing was destroyed. If it had been replaced, they probably would have renested at the same site. However, I think finding a completely new location, for older birds, is much more traumatic such that they were probably nonbreeders that year. That's a guess. Too bad they didn't stay or return next year. It's possible the testes on the males were pretty small by late June. Nice story!

From Stan Kostka:

Ken, Certainly a noteworthy observation,  and a reminder that much can be learned from events that we do not intend.  Some of these questions may be answered by partially recreating similar circumstances in an experiment,   wherein all martins at a colony are captured and color banded early in the season,  then the housing removed at about the same time in the reproductive cycle as when the tornadoes hit.   Regular monitoring of active and inactive martin housing around the area should locate some if not most of the displaced breeders.   Such an experiment would require a lot  of coordination and cooperation,  and clear conservation implications for knowledge obtained by displacing breeding martins would need to be articulated in advance in order to justify such an action. As in natural settings,  martins in artificial housing sometimes lose their nesting cavities,  either in the off season or during reproduction.   Last year I became aware that a group of nestboxes at a marina were going to be taken down during the off season due to complaints of bird droppings on boats.  No problem for the birds I figured,  they would simply relocate, individually or in groups,  to other regional colonies, or they would colonize new sites.    The only regret I had over the situation was that I had not known about the planned nestbox removal early enough to trap and color band all the adults,  so they could be tracked to their new sites. 

From Doug Falk: